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Sample records for povedenie ti zr

  1. Strengthening mechanisms in Ti-Nb-Zr-Ta and Ti-Mo-Zr-Fe orthopaedic alloys.

    PubMed

    Banerjee, Rajarshi; Nag, Soumya; Stechschulte, John; Fraser, Hamish L

    2004-08-01

    The microstructural evolution and attendant strengthening mechanisms in two novel orthopaedic alloy systems, Ti-Nb-Zr-Ta and Ti-Mo-Zr-Fe, have been compared and contrasted in this paper. Specifically, the alloy compositions considered are Ti-34Nb-9Zr-8Ta and Ti-13Mo-7Zr-3Fe. In the homogenized condition, both alloys exhibited a microstructure consisting primarily of a beta matrix with grain boundary alpha precipitates and a low-volume fraction of intra-granular alpha precipitates. On ageing the homogenized alloys at 600 degrees C for 4 hr, both alloys exhibited the precipitation of refined scale secondary alpha precipitates homogeneously in the beta matrix. However, while the hardness of the Ti-Mo-Zr-Fe alloy marginally increased, that of the Ti-Nb-Zr-Ta alloy decreased substantially as a result of the ageing treatment. In order to understand this difference in the mechanical properties after ageing, TEM studies have been carried out on both alloys prior to and post the ageing treatment. The results indicate the existence of a metastable B2 ordering in the Ti-Nb-Zr-Ta alloy in the homogenized condition which is destroyed by the ageing treatment, consequently leading to a decrease in the hardness.

  2. Superelastic properties of biomedical (Ti-Zr)-Mo-Sn alloys.

    PubMed

    Ijaz, Muhammad Farzik; Kim, Hee Young; Hosoda, Hideki; Miyazaki, Shuichi

    2015-03-01

    A new class of Ti-50Zr base biomedical superelastic alloys was developed in this study. The (Ti-Zr)-Mo-Sn alloys exhibited a shape memory effect and superelastic property by adjusting Mo and Sn contents. The (Ti-Zr)-1.5Mo-3Sn alloy revealed the most stable superelasticity among (Ti-Zr)-(1-2)Mo-(2-4)Sn alloys. The superelastic recovery strain showed a strong dependence on heat treatment temperature after cold working in the (Ti-Zr)-1.5Mo-3Sn alloy. The superelastic recovery strain increased as the heat treatment temperature increased although the critical stress for slip decreased. The (Ti-Zr)-1.5Mo-3Sn alloy heat treated at 1073K exhibited excellent superelastic properties with a large recovery strain as large as 7% which is due to the strong {001}β<110>β recrystallization texture.

  3. Al-Ti-Zr master alloys: Structure formation

    NASA Astrophysics Data System (ADS)

    Popova, E. A.; Shubin, A. B.; Kotenkov, P. V.; Pastukhov, E. A.; Bodrova, L. E.; Fedorova, O. M.

    2012-05-01

    The effects of the composition of ternary Al-Ti-Zr master alloys, the overheating of their melts with respect to liquidus, and exposure to low-frequency vibrations on the structure formation in them are studied. It is shown that complex aluminide Al3(Zr x Ti1 - x ) with a metastable L12-type cubic lattice coinciding with the structure type of α Al primarily precipitates during the crystallization of Al-Ti-Zr melts under certain conditions. This fact makes such master alloys promising for modifying aluminum alloys.

  4. Ti-based glassy alloys in Ti-Cu-Zr-Sn system

    NASA Astrophysics Data System (ADS)

    Wang, ZengRui; Dong, DanDan; Qiang, JianBing; Wang, Qing; Wang, YingMin; Dong, Chuang

    2013-07-01

    Bulk amorphous formation in Ti-Cu-based multicomponent alloys, free of Ni, Pd and Be elements, were studied using the cluster-plus-glue-atom model. The basic cluster formula was revealed as [Ti9Cu6]Cu3 to explain the best binary glass forming composition Ti50Cu50=Ti9Cu9, where the CN14 rhombi-dodecahedron Ti9Cu6 was the principal cluster in the devitrification phase CuTi. This basic cluster formula was further alloyed with Zr and Sn and a critical glass forming ability was reached at (Ti7.2Zr1.8)(Cu8.72Sn0.28) and (Ti7.2Zr1.8)(Cu8.45Sn0.55) up to 5 mm in diameter by suction casting, which was the largest in Ti-Cu-based and Ni-, Pd- and Be-free alloys.

  5. Hydriding of TiZrNiFe nanocompounds

    NASA Astrophysics Data System (ADS)

    Żywczak, A.; Shinya, Daigo; Gondek, Ł.; Takasaki, Akito; Figiel, H.

    2010-01-01

    Ti-based quasicrystals belong to the second largest group of the stable quasicrystals, showing attractive properties as hydrogen storage materials. The Ti 45Zr 38Ni 17 intermetallic compound forms an icosahedral ( i-phase) structure, in which Ti and Zr atoms possess very good chemical affinity for hydrogen absorption. We modified the Ti 45Zr 38Ni 17 compounds by substituting 3d metals (iron) for Ni to obtain amorphous phase. The samples were produced by mechanical alloying. The 3d metal atoms are located in the same positions as nickel. The structural characterization was made by means of XRD measurements. Thermodynamic properties were studied by differential scanning calorimetry (DSC) and thermal desorption spectroscopy (TDS). The obtained amorphous phases Ti 45Zr 38Ni (9,13)Fe (8,4) transform to the i-phase at the similar temperature range as Ti 45Zr 38Ni 17. The final concentration of absorbed hydrogen depends on the amount of Fe. When increasing the amount of iron, the hydrogen release temperature becomes lower. After hydriding, the samples decompose into simple metal hydrides.

  6. Amorphous Ti-Zr; Base Metglas brazing filler metals

    SciTech Connect

    Rabinkin, A.; Liebermann, H.; Pounds, S.; Taylor, T. )

    1991-01-01

    This paper is the first report on processing, properties and potential application of amorphous titanium/zirconium-base alloys produced in the form of a good quality continuous and ductile ribbon having up to 12.5 mm width. To date, the majority of titanium brazing is accomplished using cooper and aluminum-base brazing filler metals. The brazements produced with these filler metals have rather low ({approximately}300{degrees} C) service temperature, thus impeding progress in aircraft and other technologies and industries. The attempt to develop a generation of high temperature brazing filler metals was made in the late sixties-early seventies studies in detail were a large number of Ti-, Zr-Ti-Zr, Ti-V and Zr-V-Ti based alloys. The majority of these alloys has copper and nickel as melting temperature depressants. The presence of nickel and copper converts them into eutectic alloys having (Ti(Zr)) (Cu(Ni)), intermetallic phases as major structural constituents. This, in turn, results in high alloy brittleness and poor, if any, processability by means of conventional, i.e. melting-ingot casting-deformation technology. In spite of good wettability and high joint strength achieved in dozens of promising alloys, only Ti-15Cu-15Ni is now widely used as a brazing filler metal for high service temperature. Up until now this material could not be produced as a homogeneous foil and is instead applied as a clad strip consisting of three separate metallic layers.

  7. Thermal stability and hydrogenation behavior of Zr-1Nb alloy with TiNx and Ti/TiNx coatings

    NASA Astrophysics Data System (ADS)

    Kashkarov, E. B.; Vilkhivskaya, O. V.; Zakharchenko, S. A.

    2016-08-01

    Titanium nitride coatings were deposited by reactive dc magnetron sputtering (dcMS) to protect Zr-1Nb alloys from hydrogen embrittlement. Dense titanium (Ti) interlayer was prepared between TiNx protection film and a Zr substrate to improve thermal stability and adhesion between the TiNx and the substrate at high temperatures. Hydrogen absorption of Zr- 1Nb with TiNx and Ti/TiNx at 623 K was reduced in comparison with uncoated Zr-1Nb. No peeling or cracks of Ti/TiNx coatings is observed after thermal cycling up to 1073 K. The high temperature (1073 K) hydrogenation behaviour differs from the hydrogenation at lower temperature by increasing the amount of dissolved hydrogen in the β-phase of zirconium. The higher rate of hydrogen absorption by Zr-1Nb with TiNx was observed due to the coating delamination as a result of differences in thermal expansion coefficients, while Ti/TiNx demonstrates the lower hydrogen absorption at 1073 K and good adhesion strength.

  8. Investigations of the mechanical properties of the Zr8Ti8 random alloy

    NASA Astrophysics Data System (ADS)

    Huang, Sunchao; Zhang, Xiaoli; Zhang, Yongsheng; Hou, Songjun; Yangi, Xiaoyu; Zeng, Zhi

    2016-01-01

    The mechanical property of alloys plays a vital role in applications. In order to probe the mechanical property of the Zr-Ti alloy, we have successfully generated a 16-atom special quasi-random structure (SQS) at concentration 0.5 for the Zr-Ti alloy (Zr8Ti8) with supercell (2×2×2) based on the hcp Bravais cell, which has the same shape with the hcp Bravais cell. Such an SQS can be used as a good template at the 0.5 concentration of all binary hcp random alloys as the initial step for the further description of their alloy properties. Our calculated bulk modulus of Zr8Ti8 is 101.7GPa, falling within the region for the extreme two constituents (B0Zr< B0Zr8Ti8< B0Ti). Obtained B/G of Zr8Ti8 (3.60) is significantly larger than those of Zr (2.75) and Ti (2.64), which means that the ductility of Zr8Ti8 alloy is better than those of its constituents. The maximum Cauchy stress of Zr8Ti8 is 20.53GPa at strain (ɛ)=0.43 in [0001] direction. In addition, this SQS template for Zr8Ti8 has been proved to be mechanically stable.

  9. Evaluation of corrosion resistance of implant-use Ti-Zr binary alloys with a range of compositions.

    PubMed

    Akimoto, Teisuke; Ueno, Takeshi; Tsutsumi, Yusuke; Doi, Hisashi; Hanawa, Takao; Wakabayashi, Noriyuki

    2016-11-18

    Although titanium-zirconium (Ti-Zr) alloy has been adopted for clinical applications, the ideal proportion of Zr in the alloy has not been identified. In this study, we investigated the biocompatibility of Ti-Zr alloy by evaluating its corrosion resistance to better understand whether there is an optimal range or value of Zr proportion in the alloy. We prepared pure Ti, Ti-30Zr, Ti-50Zr, Ti-70Zr, and pure Zr (mol% of Zr) samples and subjected them to anodic polarization and immersion tests in a lactic acid + sodium chloride (NaCl) solution and artificial saliva. We observed pitting corrosion in the Ti-70Zr and Zr after exposure to both solutions. After the immersion test, we found that pure Ti exhibited the greatest degree of dissolution in the lactic acid + NaCl solution, with the addition of Zr dramatically reducing Ti ion dissolution, with the reduction ultimately exceeding 90% in the case of the Ti-30Zr. Hence, although the localized corrosion resistance under severe conditions was compromised when the Zr content was more than 70%, metal ion release reduced owing to Zr addition and the corresponding formation of a stable passive layer. The results suggest that Ti-30Zr or a Zr proportion of less than 50% would offer an ideal level of corrosion resistance for clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  10. Structural and electronic properties of SrZrO3 and Sr(Ti,Zr)O3 alloys

    NASA Astrophysics Data System (ADS)

    Weston, L.; Janotti, A.; Cui, X. Y.; Himmetoglu, B.; Stampfl, C.; Van de Walle, C. G.

    2015-08-01

    Using hybrid density functional calculations, we study the electronic and structural properties of SrZrO3 and ordered Sr (Ti ,Zr )O3 alloys. Calculations were performed for the ground-state orthorhombic (P n m a ) and high-temperature cubic (P m 3 m ) phases of SrZrO3. The variation of the lattice parameters and band gaps with Ti addition was studied using ordered SrTixZr1 -xO3 structures with x =0 , 0.25, 0.5, 0.75, and 1. As Ti is added to SrZrO3, the lattice parameter is reduced and closely follows Vegard's law. On the other hand, the band gap shows a large bowing and is highly sensitive to the Ti distribution. For x =0.5 , we find that arranging the Ti and Zr atoms into a 1 ×1 SrZrO3/SrTiO3 superlattice along the [001] direction leads to interesting properties, including a highly dispersive single band at the conduction-band minimum (CBM), which is absent in both parent compounds, and a band gap close to that of pure SrTiO3. These features are explained by the splitting of the lowest three conduction-band states due to the reduced symmetry of the superlattice, lowering the band originating from the in-plane Ti 3 dx y orbitals. The lifting of the t2 g orbital degeneracy around the CBM suppresses scattering due to electron-phonon interactions. Our results demonstrate how short-period SrZrO3/SrTiO3 superlattices could be exploited to engineer the band structure and improve carrier mobility compared to bulk SrTiO3.

  11. Color tone and interfacial microstructure of white oxide layer on commercially pure Ti and Ti-Nb-Ta-Zr alloys

    NASA Astrophysics Data System (ADS)

    Miura-Fujiwara, Eri; Mizushima, Keisuke; Watanabe, Yoshimi; Kasuga, Toshihiro; Niinomi, Mitsuo

    2014-11-01

    In this study, the relationships among oxidation condition, color tone, and the cross-sectional microstructure of the oxide layer on commercially pure (CP) Ti and Ti-36Nb-2Ta-3Zr-0.3O were investigated. “White metals” are ideal metallic materials having a white color with sufficient strength and ductility like a metal. Such materials have long been sought for in dentistry. We have found that the specific biomedical Ti alloys, such as CP Ti, Ti-36Nb-2Ta-3Zr-0.3O, and Ti-29Nb-13Ta-4.6Zr, form a bright yellowish-white oxide layer after a particular oxidation heat treatment. The brightness L* and yellowness +b* of the oxide layer on CP Ti and Ti-36Nb-2Ta-3Zr-0.3O increased with heating time and temperature. Microstructural observations indicated that the oxide layer on Ti-29Nb-13Ta-4.6Zr and Ti-36Nb-2Ta-3Zr-0.3O was dense and firm, whereas a piecrust-like layer was formed on CP Ti. The results obtained in this study suggest that oxide layer coating on Ti-36Nb-2Ta-3Zr-0.3O is an excellent technique for dental applications.

  12. Some features of the Structure Rearrangement in Mixed and Binary Zr-Ti Sol-xerogels

    NASA Astrophysics Data System (ADS)

    Gaponov, Yury A.; Amemiya, Yoshiyuki; Ito, Kazuki; Kamikubo, Hironari; Karakchiev, Lembit G.; Lyakhov, Nikolay Z.

    Process of thermal decomposition at different temperatures of the Zr/Ti sol-xerogels, chemically identical but prepared by different methods (mixed and binary), was studied by SAXS/WAXD with the use of synchrotron radiation. Primary particles in mixed and binary Zr/Ti sols have different structure and size. Using the qualitative contrast-variation method it was suggested that primary particle in mixed system consists of Ti nuclear surrounded by Zr atoms in the outer layer and the size of primary particle is about 20 nm. Primary particle in binary system consists of Zr nuclear surrounded by Ti atoms in the outer layer and the size of primary particle is about 5 nm. Multistage thermal decomposition of the Zr/Ti xerogels proceeds through an intermediate phase formation. The intermediate phase of mixed Zr/Ti sol has an amorphous anatase (TiO2) structure, which is formed presumably inside the primary particle. The intermediate phase of binary Zr/Ti sol has an amorphous structure consisting probably of the disordered metal atoms surrounded by water molecules. The final product of mixed Zr/Ti system with the crystallite size about of 10÷15 nm is formed during the third stage. The final product of binary Zr/Ti system with the crystallite size about of 20÷25 nm is formed during the second and third stages.

  13. Microstructure and mechanical properties of Ti-Zr-Cr biomedical alloys.

    PubMed

    Wang, Pan; Feng, Yan; Liu, Fengchao; Wu, Lihong; Guan, Shaokang

    2015-06-01

    The Ti-15Zr-xCr (0≤x≤10, wt.%) alloys were investigated to develop new biomedical materials. It was found that the phase constitutions and mechanical properties strongly depended on the Cr content. The Ti-15Zr alloy was comprised of α' phase and a small fraction of β phase was detected with adding 1wt.% Cr. With addition of 5wt.% or more, the β phase was completely retained. In addition, the ω phase was detected in the Ti-15Zr-5Cr alloy and Ti-15Zr-7Cr alloy which exhibited the highest compressive Young's modulus and the lowest ductility. On the other hand, all the Ti-15Zr-xCr alloys without ω phase exhibited high microhardness, high yield strength and superior ductility. Furthermore, the elastic energy of Ti-15Zr-10Cr alloy (5.89MJ/m(3)) with only β phase and that of Ti-15Zr-3Cr alloy (4.04MJ/m(3)) with α' phase and small fraction of β phase was higher than the elastic energy of c.p. Ti (1.25MJ/m(3)). This study demonstrated that Ti-15Zr-3Cr alloy and Ti-15Zr-10Cr alloy with superior mechanical properties are potential materials for biomedical applications.

  14. Various sized nanotubes on TiZr for antibacterial surfaces

    NASA Astrophysics Data System (ADS)

    Grigorescu, Sabina; Ungureanu, Camelia; Kirchgeorg, Robin; Schmuki, Patrik; Demetrescu, Ioana

    2013-04-01

    A two-step anodization of a Ti50Zr alloy results in a various sized nanotube oxide structures, which show an improved antibacterial activity. The nanotubes were formed in glycol with 15 vol.% H2O and 0.2 M NH4F by two-step anodization. The oxide layer grown during 2 h was removed by sonication in deionized water and anodized again for 1 h at the same conditions as in the first step. The removed layer acts as a nano-prepatterned surface, where higher ordered and open nanotubes can be achieved. The surface morphologies were analyzed by SEM and AFM, the surface wettability by contact angle measurements. The diameter and the length of the grown nanotubes are potential dependent between 20 and 100 nm in diameter and 2.3 and 5.7 μm in length, respectively. The antibacterial properties were evaluated in vitro on the formed nanotubes on the TiZr alloy against gram negative Escherichia coli bacteria. The E. coli (ATCC 8738) were cultured in a tube containing Luria Bertani medium at 37 °C. The optical density was determined after 18 h of incubation. In comparison, the smallest nanotubes exhibited the most efficient antibacterial behavior against E. coli bacterium. This suggests the use of small diameter nanotubes on TiZr for antimicrobial surface applications, which are susceptible for biofilms and microbial cultures.

  15. Synthesis of MAX Phases in the Zr-Ti-Al-C System.

    PubMed

    Tunca, Bensu; Lapauw, Thomas; Karakulina, Olesia M; Batuk, Maria; Cabioc'h, Thierry; Hadermann, Joke; Delville, Rémi; Lambrinou, Konstantina; Vleugels, Jozef

    2017-03-20

    This study reports on the synthesis and characterization of MAX phases in the (Zr,Ti)n+1AlCn system. The MAX phases were synthesized by reactive hot pressing and pressureless sintering in the 1350-1700 °C temperature range. The produced ceramics contained large fractions of 211 and 312 (n = 1, 2) MAX phases, while strong evidence of a 413 (n = 3) stacking was found. Moreover, (Zr,Ti)C, ZrAl2, ZrAl3, and Zr2Al3 were present as secondary phases. In general, the lattice parameters of the hexagonal 211 and 312 phases followed Vegard's law over the complete Zr-Ti solid solution range, but the 312 phase showed a non-negligible deviation from Vegard's law around the (Zr0.33,Ti0.67)3Al1.2C1.6 stoichiometry. High-resolution scanning transmission electron microscopy combined with X-ray diffraction demonstrated ordering of the Zr and Ti atoms in the 312 phase, whereby Zr atoms occupied preferentially the central position in the close-packed M6X octahedral layers. The same ordering was also observed in 413 stackings present within the 312 phase. The decomposition of the secondary (Zr,Ti)C phase was attributed to the miscibility gap in the ZrC-TiC system.

  16. In vitro cytotoxicity and hemocompatibility studies of Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf biomedical shape memory alloys.

    PubMed

    Wang, B L; Li, L; Zheng, Y F

    2010-08-01

    The in vitro cytotoxicity and hemocompatibility of the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf biomedical shape memory alloys (SMAs) were investigated by cell culture (L-929 fibroblast cell), hemolytic test and platelet adhesion test, with CP Ti as a reference material. The cytotoxicity test indicates that all the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf SMAs show over 94% cell viability for different incubation times (2, 4 and 7 days) in comparison with a negative control and CP Ti. The cell morphology observation shows good polygon-like adherent growth and proliferation of L-929 in the extracts of all the test samples and CP Ti. These results suggest excellent cytocompatibility for the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf SMAs. The hemolytic test reveals that the hemolysis ratios of the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf alloys are far less than 5%, so they cannot give rise to acute hemolysis. The platelet morphology observation shows almost the same adhered platelet morphology and activation ratio for the test samples in comparison with CP Ti, except the Ti-22Nb-6Hf alloy, which shows a lower activation ratio of platelets, indicating excellent blood compatibility. Therefore, it is proposed that the Ti-Nb, Ti-Nb-Zr and Ti-Nb-Hf SMAs will be candidates to replace Ti-Ni for biomedical applications.

  17. Mono- and multiple TiN(/Ti) coating adhesion mechanism on a Ti-13Nb-13Zr alloy

    NASA Astrophysics Data System (ADS)

    Li, Jianzhong; Zheng, Hua; Sinkovits, Theo; Hee, Ay Ching; Zhao, Yue

    2015-11-01

    Mono- and multiple TiN(/Ti) coatings deposited on Ti-13Nb-13Zr alloy substrates by the filtered arc deposition system were examined using scratch testing and depth-sensing indentation in terms of the relationship between the coating adhesion, deformation mechanism, and microstructure, and mechanical properties at the film/substrate interface. The results show that multilayer TiN/Ti coatings offer a greater resistance to cracking and delamination than monolithic TiN coatings under the same conditions on the Ti-13Nb-13Zr alloys substrates. And increasing the number of layers for TiN multilayer coating improves the coatings adhesion. In contrast, for the coatings on the Ti-13Nb-13Zr alloys substrates that were heat-treated to a higher hardness, the limited deformation in the substrates improved remarkably the coating adhesion indiscriminately. The substrate mechanical properties play the major roles in controlling the coating adhesion, and increasing thickness and layers of the TiN multilayer have a limited improvement to the adhesion of coating.

  18. Partial oxidation of methanol catalyzed with Au/TiO2, Au/ZrO2 and Au/ZrO2-TiO2 catalysts

    NASA Astrophysics Data System (ADS)

    Hernández-Ramírez, E.; Wang, J. A.; Chen, L. F.; Valenzuela, M. A.; Dalai, A. K.

    2017-03-01

    Mesoporous TiO2, ZrO2 and ZrO2-TiO2 mixed oxides were synthesized by the sol-gel method and the Au/TiO2, Au/ZrO2 and Au/ZrO2-TiO2 catalysts were prepared by deposition-precipitation method using urea solution as a precipitating agent. These materials were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), N2 adsorption-desorption isotherms, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and in situ FTIR-pyridine (FTIR-Py) adsorption. XRD patterns of the samples confirmed the formation of ZrTiO4 phase in the ZrO2-TiO2 mixed oxides. TEM micrographs showed that nanosized gold particles on the catalyst had an average diameter smaller than 5 nm. Metallic gold (Au0) and oxidized Au species (Aunδ+) on the surface of the catalysts were evidenced by UV-vis and XPS characterization. In the partial oxidation of methanol (POM) reaction, among the six catalysts, the high metallic Au0/Au+ ratio and low surface acidity in the Au/ZrO2 catalysts are chiefly responsible for the highest hydrogen production rate in the whole temperature range between 210 and 300 °C. Methanol decomposition as secondary reaction was favored on TiO2-based catalysts at higher temperature, producing a large amount of CO. Formation of ZrO2-TiO2 solid solution resulted in generation of both Brønsted and Lewis acid sites; as a result, dehydrogenation and oxidative dehydrogenation of methanol was allowed over Au/ZrO2-TiO2 catalysts.

  19. Investigation on the anomalous structure of the nanocrystal Ti and Zr films

    NASA Astrophysics Data System (ADS)

    Shi, W.; Kong, J.; Shen, H.; Du, Guo-Ping; Yao, W.; Qi, Zhen Z.

    1991-11-01

    The nanocrystal Ti and Zr films were prepared by dc magnetron sputtering method on a liquid N2 cooled copper substrate using Ti and Zr metal targets, respectively. The grain size of the Ti and Zr films is in the range of 5 - 12 nm, determined by both TEM observation and x- ray diffraction patterns using Warren-Averbach analysis. The structure anomaly for Ti and Zr films are found by means of electron diffraction as well as x-ray diffraction. The results of x- ray diffraction show that they are typical bcc structure for Ti films, which appears only at high temperature (more than 885 degree(s)C). The tattice parameter is 0.33178 nm close to that of the diffraction data extended from Ta-Ti alloys (JCPDS-5-628). For Zr nanocrystal films, the x-ray diffraction patterns show that it is (omega) -phase which appears only at high pressure above 39 kbar.

  20. Structure of Bergman-type W-TiZrNi approximants to quasicrystal, analyzed by lattice inversion method

    NASA Astrophysics Data System (ADS)

    Huang, H.; Meng, D. Q.; Lai, X. C.; Liu, T. W.; Long, Y.; Hu, Q. M.

    2014-08-01

    The combined interatomic pair potentials of TiZrNi, including Morse and Inversion Gaussian, are successfully built by the lattice inversion method. Some experimental controversies on atomic occupancies of sites 6-8 in W-TiZrNi are analyzed and settled with these inverted potentials. According to the characteristics of composition and site preference occupancy of W-TiZrNi, two stable structural models of W-TiZrNi are proposed and the possibilities are partly confirmed by experimental data. The stabilities of W-TiZrNi mostly result from the contribution of Zr atoms to the phonon densities of states in lower frequencies.

  1. Microstructural Evolution of Brazed CP-Ti Using the Clad Ti-20Zr-20Cu-20Ni Foil

    NASA Astrophysics Data System (ADS)

    Yeh, Tze-Yang; Shiue, Ren-Kae; Chang, Chenchung Steve

    2013-01-01

    Microstructural evolution of the clad Ti-20Zr-20Cu-20Ni foil brazed CP-Ti alloy has been investigated. For the specimen furnace brazed below 1143 K (870 °C), the joint is dominated by coarse eutectic and fine eutectoid structures. Increasing the brazing temperature above 1163 K (890 °C) results in disappearance of coarse eutectic structure, and the joint is mainly comprised of a fine eutectoid of (Ti,Zr)2Ni, Ti2Cu, Ti2Ni, and α-Ti.

  2. Microstructure and Mechanical Properties of Ti-Mo-Zr-Cr Biomedical Alloys by Powder Metallurgy

    NASA Astrophysics Data System (ADS)

    Elshalakany, Abou Bakr; Ali, Shady; Amigó Mata, A.; Eessaa, Ashraf K.; Mohan, P.; Osman, T. A.; Amigó Borrás, V.

    2017-03-01

    Titanium and its alloys have been widely used as biometals due to their excellent biocompatibility, corrosion resistance and moderate mechanical properties. Ti-15Mo-6Zr-based alloys and a series of Ti-15Mo-6Zr-xCr ( x = 1, 2, 3, 4 wt.%) alloys were designed and fabricated by powder metallurgy for the first time to develop novel biomedical materials. The microstructure, internal porosity and mechanical properties of the sintered Ti-15Mo-6Zr and Ti-15Mo-6Zr-xCr alloys were investigated using scanning electronic microscopy (SEM) and bending and compression tests. The experimental results indicated that the microstructure and mechanical properties of these alloys changed as different Cr levels were added. The addition of small Cr levels further increased the β-phase stability, improving the properties of the Ti-15Mo-6Zr-xCr alloy. However, all of the alloys had good ductility, and the Ti-15Mo-6Zr-2Cr alloy had lower bending and compression moduli (31 and 23 GPa, respectively) than the Ti-15Mo-6Zr-based alloys (40 and 36 GPa, respectively). Moreover, the Ti-15Mo-6Zr-2Cr alloys exhibited higher bending and compression strength/modulus ratios, which were as large as 48.4 and 52.2, respectively; these were higher than those of the Ti-15Mo-6Zr-based alloy (41.3 and 33.6, respectively). In the search for a better implant material, β phase Ti-15Mo-6Zr-2Cr, with its low modulus, ductile properties and reasonably high strength, is a promising candidate.

  3. Microstructure and optical characterizations of mechanosynthesized nanocrystalline semiconducting ZrTiO4 compound

    NASA Astrophysics Data System (ADS)

    Dutta, Hema; Nandy, Anshuman; Pradhan, S. K.

    2016-08-01

    A ZrO2-TiO2 solid solution is obtained by high energy ball milling of equimolar mixture of monoclinic (m) ZrO2 and anatase (a) TiO2. Nanocrystalline orthorhombic ZrTiO4 compound is initiated from the nucleation of TiO2-ZrO2 solid solution with isostructural s-TiO2 (srilankite) base after 30 min of milling. After 12 h of milling, 95 mol% non-stoichiometric ZrTiO4 phase is formed. Post-annealing of 12 h ball-milled powder mixture at 1073 K for 1 h in open air results in complete formation of stoichiometric ZrTiO4 compound. Microstructures of all powder mixtures milled for different durations have been characterized by Rietveld's structure and microstructure refinement method using X-ray powder diffraction data. HRTEM images of 12 h milled and annealed samples provide direct evidence of the results obtained from the Rietveld analysis. Optical bandgaps of ball milled and annealed ZrTiO4 compounds lie within the semiconducting region (~2.0 eV) and increases with increase in milling time.

  4. Microstructure and mechanical properties of Ti-15Zr alloy used as dental implant material.

    PubMed

    Medvedev, Alexander E; Molotnikov, Andrey; Lapovok, Rimma; Zeller, Rolf; Berner, Simon; Habersetzer, Philippe; Dalla Torre, Florian

    2016-09-01

    Ti-Zr alloys have recently started to receive a considerable amount of attention as promising materials for dental applications. This work compares mechanical properties of a new Ti-15Zr alloy to those of commercially pure titanium Grade4 in two surface conditions - machined and modified by sand-blasting and etching (SLA). As a result of significantly smaller grain size in the initial condition (1-2µm), the strength of Ti-15Zr alloy was found to be 10-15% higher than that of Grade4 titanium without reduction in the tensile elongation or compromising the fracture toughness. The fatigue endurance limit of the alloy was increased by around 30% (560MPa vs. 435MPa and 500MPa vs. 380MPa for machined and SLA-treated surfaces, respectively). Additional implant fatigue tests showed enhanced fatigue performance of Ti-15Zr over Ti-Grade4.

  5. Photocatalytic activity of Zr:SrTiO 3 under UV illumination

    NASA Astrophysics Data System (ADS)

    Chen, Liang; Zhang, Shouchen; Wang, Liqiu; Xue, Dongfeng; Yin, Shu

    2009-01-01

    SrTiO 3 is a well-known efficient photocatalyst and has various industrial applications such as water or air purification antibacterial agents and self-cleaning surfaces. In this work, pure SrTiO 3 and Zr:SrTiO 3 photocatalysts were prepared by the sol-gel method and then tested by scanning electron microscopy (SEM) and X-ray diffraction, respectively. The crystal phase of Zr:SrTiO 3 shows a typical perovskite structure, in which Ti sites are substituted by Zr atoms. The as-prepared yellow Zr:SrTiO 3 powders were then used as UV photocatalysts. Photocatalytic degradation activity of methylene blue over zirconium-doped SrTiO 3 catalysts was tested under UV illumination. The high activity of Zr:SrTiO 3 was due to the defects of its crystal lattice, thus the energy needed by the semiconductor photoproduction electron transition to the conduction band was smaller than the intrinsic absorption band. The optimal conditions of our experiments are as follows: under 8% doping density of Zr, 10 mg/l initial concentration of methylene blue, 0.15 g photocatalyst dosage, 6.5 of pH value and 4 h of UV illumination time, the degradation rate of methylene blue can reach 93.6%.

  6. Stability of TiO2 Nanoparticles in Deionized Water with ZrP Nanoplatelets.

    PubMed

    Liu, Zhuowei; Chen, Ying; Mo, Songping; Cheng, Zhengdong; Li, Huawel

    2015-04-01

    The stability of nanofluid is an important property that needs to be researched. In our study, a novel method using Zirconium phosphate (ZrP) discotic colloid to disperse nanoparticles was proposed for improving stability. TiO2 nanofluid was prepared by dispersing TiO2 nanoparticles into exfoliated a-ZrP suspensions at different concentrations. Scanning electron microscopy and X-ray diffraction were used to characterize the shape, average size, and components of primary ZrP nanoplatelets. The absorbance of the suspensions was measured by a UV-VIS spectrophotometer. The results show that the stability first increased, and then decreased with increasing ZrP concentration at 1 wt.% TiO2. The effect was optimal at 2 wt.% ZrP. Thus, the hindrance of nanoplatelets in the aggregation and sedimentation of nanoparticles is the main reason for improving the stability of nanofluids.

  7. Effect of minor addition of Zr on the oxidation behavior of Ti-Cu metallic glasses

    NASA Astrophysics Data System (ADS)

    Park, Sung Hyun; Lim, Ka Ram; Na, Min Young; Kim, Kang Cheol; Kim, Won Tae; Kim, Do Hyang

    2016-03-01

    The oxidation behavior of (TiCu)100-XZrX (x=3, 5, 7 at%) amorphous alloy during continuous heating up to 1073 K has been investigated. The weight-gain due to oxidation occurs in a two-step mode. The first-step oxidation (630 730 K) is associated with supercooled liquid region. The oxidation layer consists of intermixed TiO2 + ZrO2 layer at outer side and amorphous oxide layer at inner side. The oxidation rate at the second-step above 880 K becomes significantly different depending on the Zr content. In x=3 alloy, the oxidation layer consists of TiO2 layer at outer side, intermixed TiO2 + ZrO2 layer, and Ti3Cu3O layer at inner side. As the fraction of ZrO2 increases in x=5 and 7 alloys, the growth of oxide layer is accelerated due to provision of easier diffusion path in the intermixed oxide layer, forming intermixed multi-phase (TiO2 + ZrO2 + Ti3Cu3O + Cu51Zr14) oxide layer.

  8. Extraordinary high strength Ti-Zr-Ta alloys through nanoscaled, dual-cubic spinodal reinforcement.

    PubMed

    Biesiekierski, Arne; Ping, Dehai; Li, Yuncang; Lin, Jixing; Munir, Khurram S; Yamabe-Mitarai, Yoko; Wen, Cuie

    2017-02-02

    While titanium alloys represent the current state-of-the-art for orthopedic biomaterials, concerns still remain over their modulus. Circumventing this via increased porosity requires high elastic admissible strains, yet also limits traditional thermomechanical strengthening techniques. To this end, a novel β-type Ti-Zr-Ta alloy system, comprised of Ti-45Zr-10Ta, Ti-40Zr-14Ta, Ti-35Zr-18Ta and Ti-30Zr-22Ta, was designed and characterized mechanically and microstructurally. As-cast, this system displayed extremely high yield strengths and elastic admissible strains, up to 1.4GPa and potentially 1.48%, respectively. This strength was attributed to a nanoscaled, cuboidal structure of semi-coherent, dual body-centered cubic (BCC) phases, arising from the thermodynamics of interaction between Ta and Zr; this morphology occurring with dual BCC-phases is heretofore unreported in Ti-based alloys. Further, cell proliferation investigated by MTS assay suggests this was achieved without sacrificing biocompatibility, with no significant difference to either empty-well or commercially-pure Ti controls noted.

  9. A Study of Novel Medical Alloys of the Ti - Zr System

    NASA Astrophysics Data System (ADS)

    Lubas, M.; Kulakovska, A.; Gembara, P.

    2016-11-01

    The structure of alloy Ti - 10% Zr is studied after thermal oxidizing. Microstructural, phase and potentiometric analyses of the alloy are performed. The alloy is shown to be suitable for stomatology.

  10. Wear and friction properties of experimental Ti-Si-Zr alloys for biomedical applications.

    PubMed

    Tkachenko, Serhii; Datskevich, Oleg; Kulak, Leonid; Jacobson, Staffan; Engqvist, Håkan; Persson, Cecilia

    2014-11-01

    Titanium alloys are widely used in biomedical applications due to their higher biocompatibility in comparison to other metallic biomaterials. However, they commonly contain aluminum and vanadium, whose ions may be detrimental to the nervous system. Furthermore, they suffer from poor wear resistance, which limits their applications. The aim of this study was to evaluate the tribological performance of experimental Ti-1.25Si-5Zr, Ti-2.5Si-5Zr, Ti-6Si-5Zr and Ti-2.5Si-5Zr-0.2Pd alloys as compared to that of control Ti-6Al-4V, CoCr F75 and CoCr F799 alloys. Friction and wear tests were performed using a standard ball-on-disc rig in serum solution at ambient temperature with Si3N4-balls as counterparts. The alloys microstructure and hardness were investigated using optical microscopy, XRD, scanning electron microscopy (SEM) and Vickers indentation. The coefficients of friction of the experimental Ti-Si-Zr alloys were generally lower than the commercial ones with Ti-6Si-5Zr presenting the lowest value (approx. 0.1). Their wear rates were found to be 2-7 times lower than that of the commercial Ti-6Al-4V alloy, but still higher than those of the CoCr alloys. SEM analysis of worn surfaces showed that abrasion was the predominant wear mechanism for all studied materials. Wear and friction were influenced by the formation and stability of transfer layers, and while commercial Ti-6Al-4V as well as the experimental Ti-Si-Zr alloys demonstrated extensive material transfer to the ceramic counterparts, the CoCr alloys did not show such material transfer.

  11. Reactive magnetron cosputtering of hard and conductive ternary nitride thin films: Ti-Zr-N and Ti-Ta-N

    SciTech Connect

    Abadias, G.; Koutsokeras, L. E.; Dub, S. N.; Tolmachova, G. N.; Debelle, A.; Sauvage, T.; Villechaise, P.

    2010-07-15

    Ternary transition metal nitride thin films, with thickness up to 300 nm, were deposited by dc reactive magnetron cosputtering in Ar-N{sub 2} plasma discharges at 300 deg. C on Si substrates. Two systems were comparatively studied, Ti-Zr-N and Ti-Ta-N, as representative of isostructural and nonisostructural prototypes, with the aim of characterizing their structural, mechanical, and electrical properties. While phase-separated TiN-ZrN and TiN-TaN are the bulk equilibrium states, Ti{sub 1-x}Zr{sub x}N and Ti{sub 1-y}Ta{sub y}N solid solutions with the Na-Cl (B1-type) structure could be stabilized in a large compositional range (up to x=1 and y=0.75, respectively). Substituting Ti atoms by either Zr or Ta atoms led to significant changes in film texture, microstructure, grain size, and surface morphology, as evidenced by x-ray diffraction, x-ray reflectivity, and scanning electron and atomic force microscopies. The ternary Ti{sub 1-y}Ta{sub y}N films exhibited superior mechanical properties to Ti{sub 1-x}Zr{sub x}N films as well as binary compounds, with hardness as high as 42 GPa for y=0.69. All films were metallic, the lowest electrical resistivity {rho}{approx}65 {mu}{Omega} cm being obtained for pure ZrN, while for Ti{sub 1-y}Ta{sub y}N films a minimum was observed at y{approx}0.3. The evolution of the different film properties is discussed based on microstructrural investigations.

  12. Surface modification of stainless steel orthopedic implants by sol-gel ZrTiO4 and ZrTiO4-PMMA coatings.

    PubMed

    Salahinejad, E; Hadianfard, M J; Macdonald, D D; Sharifi Asl, S; Mozafari, M; Walker, K J; Rad, A Tahmasbi; Madihally, S V; Vashaee, D; Tayebi, L

    2013-08-01

    In this paper, the biocompatibility of a medical-grade stainless steel coated with sol-gel derived, nanostructured inorganic ZrTiO4 and hybrid ZrTiO4-PMMA thin films is correlated with surface characteristics. The surfaces of the samples are characterized by atomic force microscopy, the sessile drop technique, and electrochemical corrosion experiments. The viability of adult human mesenchymal stem cells on the surfaces after one day of culture is also assessed quantitatively and morphologically. According to the results, both of the coatings improve the hydrophilicity, corrosion resistance, and thereby cytocompatibility of the substrate. Despite the higher corrosion protection by the hybrid coating, the sample coated with the inorganic thin film exhibits a better cell response, suggesting the domination of wettability. In summary, the ZrTiO4-based sol-gel films can be considered to improve the biocompatibility of metallic implants.

  13. Nanotube nucleation phenomena on Ti-25Ta-xZr alloys for implants using ATO technique.

    PubMed

    Kim, Hyun-Ju; Jeong, Yong-Hoon; Brantley, William A; Choe, Han-Cheol

    2014-10-01

    The purpose of this study was to investigate nanotube nucleation phenomena on the Ti-25Ta-xZr alloys for implant materials, using an anodic titanium oxide (ATO) technique. Ti-25Ta-(0 wt.%-15 wt.%) Zr alloys were prepared using a vacuum arc-melting furnace. The Ti-25Ta-xZr alloys were then homogenized for 12 hr at 1000 degrees C, followed by water quenching. Formation of the nanotubular oxide surface structure was achieved initially on the Ti-25Ta-xZr alloys by anodization in a 1 M H3PO4 electrolyte containing 0.8 wt.% NaF at room temperature, using a potentiostat. After the first formation of the nanotubes was achieved, this initial nanotube layer was eliminated, and further anodization was carried out repeatedly. The microstructure, phase transformation, and morphology of nanotubular Ti-25Ta-xZr alloys and the process of nanotube growth using this ATO method were analyzed by X-ray diffraction, field-emission scanning electron microscopy, and energy dispersive X-ray spectroscopy. Microstructures of the Ti-25Ta-xZr alloys changed from α" phase to β phase. Nanotubes formed with the ATO technique had pit-like top holes, with thinner walls and lower contact angle, compared to the initially formed nanotubes.

  14. Development of Ti-Nb-Zr alloys with high elastic admissible strain for temporary orthopedic devices.

    PubMed

    Ozan, Sertan; Lin, Jixing; Li, Yuncang; Ipek, Rasim; Wen, Cuie

    2015-07-01

    A new series of beta Ti-Nb-Zr (TNZ) alloys with considerable plastic deformation ability during compression test, high elastic admissible strain, and excellent cytocompatibility have been developed for removable bone tissue implant applications. TNZ alloys with nominal compositions of Ti-34Nb-25Zr, Ti-30Nb-32Zr, Ti-28Nb-35.4Zr and Ti-24.8Nb-40.7Zr (wt.% hereafter) were fabricated using the cold-crucible levitation technique, and the effects of alloying element content on their microstructures, mechanical properties (tensile strength, yield strength, compressive yield strength, Young's modulus, elastic energy, toughness, and micro-hardness), and cytocompatibilities were investigated and compared. Microstructural examinations revealed that the TNZ alloys consisted of β phase. The alloy samples displayed excellent ductility with no cracking, or fracturing during compression tests. Their tensile strength, Young's modulus, elongation at rupture, and elastic admissible strain were measured in the ranges of 704-839 MPa, 62-65 GPa, 9.9-14.8% and 1.08-1.31%, respectively. The tensile strength, Young's modulus and elongation at rupture of the Ti-34Nb-25Zr alloy were measured as 839 ± 31.8 MPa, 62 ± 3.6 GPa, and 14.8 ± 1.6%, respectively; this alloy exhibited the elastic admissible strain of approximately 1.31%. Cytocompatibility tests indicated that the cell viability ratios (CVR) of the alloys are greater than those of the control group; thus the TNZ alloys possess excellent cytocompatibility.

  15. Deposition and characterization of TiZrV-Pd thin films by dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Zhang, Bo; Xu, Yan-Hui; Wei, Wei; Fan, Le; Pei, Xiang-Tao; Hong, Yuan-Zhi; Wang, Yong

    2015-12-01

    TiZrV film is mainly applied in the ultra-high vacuum pipes of storage rings. Thin film coatings of palladium, which are added onto the TiZrV film to increase the service life of nonevaporable getters and enhance H2 pumping speed, were deposited on the inner face of stainless steel pipes by dc magnetron sputtering using argon gas as the sputtering gas. The TiZrV-Pd film properties were investigated by atomic force microscope (AFM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and X-Ray Diffraction (XRD). The grain size of TiZrV and Pd films were about 0.42-1.3 nm and 8.5-18.25 nm respectively. It was found that the roughness of TiZrV films is small, about 2-4 nm, but for Pd film it is large, about 17-19 nm. The PP At. % of Pd in TiZrV/Pd films varied from 86.84 to 87.56 according to the XPS test results. Supported by National Natural Science Funds of China (11205155) and Fundamental Research Funds for the Central Universities (WK2310000041)

  16. Mechanism of photochromic effect in Pb(Zr,Ti)O{sub 3} and (Pb,La)(Zr,Ti)O{sub 3} ceramics under violet/infrared light illumination

    SciTech Connect

    Xu, Caixia; Xu, Long; Zhao, Hua; Zhang, Jingwen

    2015-01-14

    Obvious photochromic effects were observed in Pb(Zr,Ti)O{sub 3} and (Pb,La)(Zr,Ti)O{sub 3} (PLZT) ceramics, along with exponential responses to illumination power in both darkening and bleaching processes. An interesting anomalous dispersion in the transparent PLZT was observed and discussed. A tentative physical picture based on photoinduced electron stimulated processes and on structural change was proposed to explain all the interesting observations. Rate equations were established and solved in verifying the validity of the proposed model. This work may serve as guidance in designing tunable achromatic lenses, UV and IR light detectors and sensors.

  17. Thermal Analysis of the Effect of Oxygen Contamination on Undercooling of Zr-Al-Ni-Cu, Cu-Zr-Ti, and Cu-Ni-Zr-Ti Metallic Glasses (Preprint)

    DTIC Science & Technology

    2009-04-01

    been done on systems other than Zr65Al7.5(Cu17.5Ni10). Zr55Al10(Cu30Ni5) was found to be less sensitive to oxygen content than Zr65Al7.5(Cu17.5Ni10...Zr11Ti34 by arc-melting each of the pure elements under a titanium - gettered atmosphere. Starting materials used were: Al pellets, 99.999%; Cu shot...produce 2-6 g alloyed ingots of each composition. Each ingot was flipped typically 4-5 times in a titanium -gettered, high-purity argon atmosphere

  18. Composition dependences of crystal structure and electrical properties of epitaxial Pb(Zr,Ti)O3 films grown on Si and SrTiO3 substrates

    NASA Astrophysics Data System (ADS)

    Okamoto, Shoji; Okamoto, Satoshi; Yokoyama, Shintaro; Akiyama, Kensuke; Funakubo, Hiroshi

    2016-10-01

    {100}-oriented Pb(Zr x ,Ti1- x )O3 (PZT) thin films of approximately 2 µm thickness and Zr/(Zr + Ti) ratios of 0.39-0.65 were epitaxially grown on (100)cSrRuO3//(100)SrTiO3 (STO) and (100)cSrRuO3//(100)cLaNiO3//(100)CeO2//(100)YSZ//(100)Si (Si) substrates having different thermal expansion coefficients by pulsed metal-organic chemical vapor deposition (MOCVD). The effects of Zr/(Zr + Ti) ratio and type of substrate on the crystal structure and dielectric, ferroelectric and piezoelectric properties of the films were systematically investigated. The X-ray diffraction measurement showed that both films changed from having a tetragonal symmetry to rhombohedral symmetry through the coexisting region with increasing Zr/(Zr + Ti) ratio. This region showed the Zr/(Zr + Ti) ratios of 0.45-0.59 for the films on the STO substrates that were wider than the films on the Si substrates. Saturation polarization values were minimum at approximately Zr/(Zr + Ti) = 0.50 for the films on the STO substrates, and no obvious Zr/(Zr + Ti) ratio dependence was detected in the films on the Si substrates. On the other hand, the maximum field-induced strain values measured by scanning force microscopy at approximately Zr/(Zr + Ti) = 0.50 at 100 kV/cm were about 0.5 and 0.1% in the films on the Si and STO, respectively.

  19. Comparative ab initio calculations of SrTiO3/BaTiO3 and SrZrO3/PbZrO3 (0 0 1) heterostructures

    NASA Astrophysics Data System (ADS)

    Piskunov, Sergei; Eglitis, Roberts I.

    2016-05-01

    Using a B3PW hybrid exchange-correlation functional within the density functional theory (DFT) we calculated from the first principles the electronic structure of BaTiO3/SrTiO3 and PbZrO3/SrZrO3 (0 0 1) interfaces. The optical band gap of both BaTiO3/SrTiO3 and PbZrO3/SrZrO3 (0 0 1) interfaces depends mostly from BaO or TiO2 and SrO or ZrO2 termination of the upper layer, respectively. Based on the results of our calculations we predict increase of the Ti-O and Zr-O chemical bond covalency near the SrTiO3/BaTiO3 and SrZrO3/PbZrO3 (0 0 1) interfaces as compared to the BaTiO3 and PbZrO3 bulk.

  20. Comparison of microstructural evolution in Ti-Mo-Zr-Fe and Ti-15Mo biocompatible alloys.

    PubMed

    Nag, S; Banerjee, R; Stechschulte, J; Fraser, H L

    2005-07-01

    The microstructural evolution and attendant strengthening mechanisms in two biocompatible alloy systems, the binary Ti-15Mo and the quaternary Ti-13Mo-7Zr-3Fe (TMZF), have been compared and contrasted in this paper. In the homogenized condition, while the Ti-15Mo alloy exhibited a single phase microstructure consisting of large beta grains, the TMZF alloy exhibited a microstructure consisting primarily of a beta matrix with grain boundary alpha precipitates and a low volume fraction of intra-granular alpha precipitates. On ageing the homogenized alloys at 600 degrees C for 4 h, both alloys exhibited the precipitation of refined scale secondary alpha precipitates homogeneously in the beta matrix. However, while the hardness of the TMZF alloy marginally increased, that of the Ti-15Mo alloy decreased substantially as a result of the ageing treatment. In order to understand this difference in the mechanical properties after ageing, TEM studies have been carried out on both alloys in the homogenized and homogenized plus aged conditions. The results indicate that the omega precipitates dissolve on ageing in case of the Ti-15Mo alloy, consequently leading to a substantial decrease in the hardness. In contrast, the omega precipitates do not dissolve on ageing in the TMZF alloy and the precipitation of the fine scale secondary alpha leads to increased hardness.

  1. Application of the Bons-Azuma method and determination of grain growth mechanism in rolled Ti-Zr alloys

    NASA Astrophysics Data System (ADS)

    Homma, Tomoyuki; Matayoshi, Yusuke; Voskoboinikov, Roman

    2015-12-01

    Zr-containing Ti alloys have widely been developed owing to the infinite solid solubility of Zr in Ti and its avirulence, leading respectively to high strength and good biocompatibility. It is known that the Zr addition gives rise to grain refinement when rolled Ti-Zr alloys are annealed; nevertheless, the governing mechanism by which Zr addition in Ti can reduce grain size is not fully understood. In this study, the grain growth behaviour of rolled Zr-free and Zr-containing (Ti-10Zr, wt.%) alloys is analysed using analytical transmission electron microscopy and the classical and Bons-Azuma methods by evaluating the grain growth exponent. Irrespective of the evaluation technique and Zr content, the grain growth exponent is found to be close to ~0.3, indicating the occurrence of normal grain growth in the Zr-free alloy and solute drag mechanism in the Zr-containing alloy. It is found that the grain size and grain growth rate are significantly reduced by Zr segregation near grain boundaries, resulting from the solute drag mechanism.

  2. Effects of Zr and Si on the Glass Forming Ability and Compressive Properties of Ti-Cu-Co-Sn Alloys

    NASA Astrophysics Data System (ADS)

    Wang, Tan; Wu, Yidong; Si, Jiajia; Hui, Xidong

    2015-06-01

    To succeed in finding novel Ti-based bulk metallic glasses, which are free from Be, Ni, and noble metallic elements, a comprehensive study was performed on the effects of Zr and Si on the microstructural evolution, glass-forming ability (GFA), and mechanical properties of Ti46Cu44- x Zr x Co7Sn3 ( x = 0, 5, 10, 12.5, and 16 at. pct) and Ti46Cu31.5Zr12.5- x Co7Sn3Si x ( x = 0.5, 1, and 1.5 at. pct) alloys. It is shown that with the increase of Zr, the sequence of phase formation is β-Ti + α-Ti + (Ti, Zr)3Cu4 ⇒ β-Ti + α-Ti + TiCu ⇒ β-Ti + Ti2Cu + glass ⇒ glass ⇒ β-Ti + Ti2Cu + TiCuSn. The quinary Ti-Zr-Cu-Co-Sn alloy with 12.5 pct Zr exhibits the best GFA. The addition of 1 pct Si results in the improvement of the critical size of glassy rods up to 3 mm in diameter. The yield stress and Young's modulus of Z-series alloys increases, and the plastic strain decreases with the addition of Zr. The yield stress and ultimate compression stress of Ti46Zr11.5Cu31.5Co7Sn3Si1 glassy alloy reach 2477.9 and 2623.3 MPa, respectively. It was found that the addition of Si promotes the generation and multiplication of shear bands, resulting in certain plasticity in these kinds of glassy alloys.

  3. (Ti/Zr,N) codoped hematite for enhancing the photoelectrochemical activity of water splitting.

    PubMed

    Pan, Haijun; Meng, Xiangying; Liu, Dongyan; Li, Song; Qin, Gaowu

    2015-09-14

    In this theoretical study, first-principles calculations were carried out to explore the photocatalytic activity of cation (Ti or Zr) and anion (N) compensated codoped hematite based on density functional theory (DFT). For (Ti/Zr,N) codoped hematite, the band edges of the conduction band and the valence band move close to each other, leading to an obvious bandgap reduction. Compared with the pure hematite, the optical absorption coefficient of codoped hematite is significantly enhanced in the visible light region. The charge distribution at the conduction band minimum (CBM) and valence band maximum (VBM) is spatially separated after codoping, which is beneficial for extending the carrier lifetime. More interestingly, the CBM becomes electronically delocalized in (Ti,N) doped hematite, which indicates better carrier transport properties in the bulk system. Due to these special features of (Ti/Zr,N) codoped hematite, an improved photocatalytic performance can be expected.

  4. Nanostructured Ti-Zr-Pd-Si-(Nb) bulk metallic composites: Novel biocompatible materials with superior mechanical strength and elastic recovery.

    PubMed

    Hynowska, A; Blanquer, A; Pellicer, E; Fornell, J; Suriñach, S; Baró, M D; Gebert, A; Calin, M; Eckert, J; Nogués, C; Ibáñez, E; Barrios, L; Sort, J

    2015-11-01

    The microstructure, mechanical behaviour, and biocompatibility (cell culture, morphology, and cell adhesion) of nanostructured Ti45 Zr15 Pd35- x Si5 Nbx with x = 0, 5 (at. %) alloys, synthesized by arc melting and subsequent Cu mould suction casting, in the form of rods with 3 mm in diameter, are investigated. Both Ti-Zr-Pd-Si-(Nb) materials show a multi-phase (composite-like) microstructure. The main phase is cubic β-Ti phase (Im3m) but hexagonal α-Ti (P63/mmc), cubic TiPd (Pm3m), cubic PdZr (Fm3m), and hexagonal (Ti, Zr)5 Si3 (P63/mmc) phases are also present. Nanoindentation experiments show that the Ti45 Zr15 Pd30 Si5 Nb5 sample exhibits lower Young's modulus than Ti45 Zr15 Pd35 Si5 . Conversely, Ti45 Zr15 Pd35 Si5 is mechanically harder. Actually, both alloys exhibit larger values of hardness when compared with commercial Ti-40Nb, (HTi-Zr-Pd-Si ≈ 14 GPa, HTi-Zr-Pd-Si-Nb ≈ 10 GPa and HTi-40Nb ≈ 2.7 GPa). Concerning the biological behaviour, preliminary results of cell viability performed on several Ti-Zr-Pd-Si-(Nb) discs indicate that the number of live cells is superior to 94% in both cases. The studied Ti-Zr-Pd-Si-(Nb) bulk metallic system is thus interesting for biomedical applications because of the outstanding mechanical properties (relatively low Young's modulus combined with large hardness), together with the excellent biocompatibility.

  5. Brazing characteristics of a Zr-Ti-Cu-Fe eutectic alloy filler metal for Zircaloy-4

    NASA Astrophysics Data System (ADS)

    Lee, Jung G.; Lim, C. H.; Kim, K. H.; Park, S. S.; Lee, M. K.; Rhee, C. K.

    2013-10-01

    A Zr-Ti-Cu-Fe quaternary eutectic alloy was employed as a new Be-free brazing filler metal for Zircaloy-4 to supersede physically vapor-deposited Be coatings used conventionally with several disadvantages. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) showing a low melting temperature range from 832 °C to 853 °C was designed by a partial substitution of Zr with Ti based on a Zr-Cu-Fe ternary eutectic system. By applying an alloy ribbon with the determined composition, a highly reliable joint was obtained with a homogeneous formation of predominantly grown α-Zr phases owing to a complete isothermal solidification, exhibiting strength higher than that of Zircaloy-4. The homogenization of the joint was rate-controlled by the diffusion of the filler elements (Ti, Cu, and Fe) into the Zircaloy-4 base metal, and the detrimental segregation of the Zr2Fe phase in the central zone was completely eliminated by an isothermal holding at a brazing temperature of 920 °C for 10 min.

  6. Brazing microstructure of Ti-6Al-6V-2Sn with Ti-Zr-Cu-Ni filler metal

    SciTech Connect

    Hsieh, K.C.; Kao, P.W.; Shu, M.F.

    1994-12-31

    Titanium and its alloys have been widely used in the aerospace industry since they have high specific strength and high corrosion resistance. The brazing of titanium is beneficial to join many contact areas simultaneously without severe distortion. The purpose of this study is to investigate the brazing microstructures under different brazing conditions with several Ti-Zr-Cu-Ni filler alloys. In our previous studies, the brazing microstructure of Ti-6Al-4V with Ti-Cu-Ni filler metal have been reported. Since Ti-6Al-6V-2Sn alloy has lower b-transus, the Ti-Cu-Ni filler alloy cannot successfully apply the brazing work. Several Ti-Zr-Cu-Ni alloys were prepared in powder form and pre-alloy form to perform the brazing of Ti-6Al-6V-2Sn at 870{degrees}C. The brazing microstructures are examined under optical metallograph, scanning electron microscopy (SEM), and X-ray analysis. The contents of this report include (1) DTA and phase analysis of Ti-Zr-Cu-Ni filler metals, (2) the brazing microstructure, and (3) the shear test result.

  7. Vacuum Brazing TC4 Titanium Alloy to 304 Stainless Steel with Cu-Ti-Ni-Zr-V Amorphous Alloy Foil

    NASA Astrophysics Data System (ADS)

    Dong, Honggang; Yang, Zhonglin; Wang, Zengrui; Deng, Dewei; Dong, Chuang

    2014-10-01

    Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil was 105 MPa and that with Cu37.5Ti25Ni12.5Zr12.5V12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr4Ti, Cu0.8FeTi, Fe8TiZr3 and Al2NiTi3C compounds were found in the fractured joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil, and Fe2Ti, TiCu, Fe8TiZr3 and NiTi0.8Zr0.3 compounds were detected in the joint brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.

  8. Bone response to a novel Ti-Ta-Nb-Zr alloy.

    PubMed

    Stenlund, Patrik; Omar, Omar; Brohede, Ulrika; Norgren, Susanne; Norlindh, Birgitta; Johansson, Anna; Lausmaa, Jukka; Thomsen, Peter; Palmquist, Anders

    2015-07-01

    Commercially pure titanium (cp-Ti) is regarded as the state-of-the-art material for bone-anchored dental devices, whereas the mechanically stronger alloy (Ti-6Al-4V), made of titanium, aluminum (Al) and vanadium (V), is regarded as the material of choice for high-load applications. There is a call for the development of new alloys, not only to eliminate the potential toxic effect of Al and V but also to meet the challenges imposed on dental and maxillofacial reconstructive devices, for example. The present work evaluates a novel, dual-stage, acid-etched, Ti-Ta-Nb-Zr alloy implant, consisting of elements that create low toxicity, with the potential to promote osseointegration in vivo. The alloy implants (denoted Ti-Ta-Nb-Zr) were evaluated after 7 days and 28 days in a rat tibia model, with reference to commercially pure titanium grade 4 (denoted Ti). Analyses were performed with respect to removal torque, histomorphometry and gene expression. The Ti-Ta-Nb-Zr showed a significant increase in implant stability over time in contrast to the Ti. Further, the histological and gene expression analyses suggested faster healing around the Ti-Ta-Nb-Zr, as judged by the enhanced remodeling, and mineralization, of the early-formed woven bone and the multiple positive correlations between genes denoting inflammation, bone formation and remodeling. Based on the present experiments, it is concluded that the Ti-Ta-Nb-Zr alloy becomes osseointegrated to at least a similar degree to that of pure titanium implants. This alloy is therefore emerging as a novel implant material for clinical evaluation.

  9. New FCC Mg–Zr and Mg–Zr–ti deuterides obtained by reactive milling

    SciTech Connect

    Guzik, Matylda N. Deledda, Stefano; Sørby, Magnus H.; Yartys, Volodymyr A.; Hauback, Bjørn C.

    2015-03-15

    Results for binary Mg–Zr and ternary Mg–Zr–Ti mixtures ball milled at room temperature under reactive deuterium atmosphere (5.6–6.7 MPa) are reported. X-ray and neutron powder diffraction combined with Rietveld refinements show that two new cubic phases were formed during milling. Mg{sub 0.40}Zr{sub 0.60}D{sub 1.78} and Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98} crystallize with disordered face centered cubic metal atom arrangements. Results of differential scanning calorimetry and termogravimetric measurements demonstrate that both deuterides desorb deuterium at lower temperatures than MgD{sub 2}, ZrD{sub 2} or TiD{sub 2}; 528 and 575 K in the Mg–Zr–D and Mg–Zr–Ti–D system, respectively. Interestingly, Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98} stores deuterium reversibly at 673 K and 10 MPa of D{sub 2}. - Graphical abstract: High resolution SR-PXD patterns obtained for Mg{sub 0.40}Zr{sub 0.60}D{sub 1.78} and first time reported Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98}. - Highlights: • Synthesis and characterization of Mg{sub 0.40}Zr{sub 0.60}D{sub 1.78} and Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98}. • New deuterides obtained by milling under H{sub 2} gas pressure in the order of a few MPa. • Phases desorb deuterium at temperature lower than corresponding binary deuterides. • Mg{sub 0.40}Zr{sub 0.26}Ti{sub 0.34}D{sub 1.98} stores hydrogen reversibly at 673 K and 10 MPa of D{sub 2}.

  10. Effects of Fabrication Parameters on Interface of Zirconia and Ti-6Al-4V Joints Using Zr55Cu30Al10Ni5 Amorphous Filler

    NASA Astrophysics Data System (ADS)

    Liu, Yuhua; Hu, Jiandong; Shen, Ping; Guo, Zuoxing; Liu, Huijie

    2013-09-01

    ZrO2 was brazed to Ti-6Al-4V using a Zr55Cu30Al10Ni5 (at.%) amorphous filler in a high vacuum at 1173-1273 K. The influences of brazing temperature, holding time, and cooling rate on the microstructure and shear strength of the joints were investigated. The interfacial microstructures can be characterized as ZrO2/ZrO2- x + TiO/(Zr,Ti)2(Cu,Ni)/(Zr,Ti)2(Cu,Ni,Al)/acicular Widmanstäten structure/Ti-6Al-4V. With the increase in the brazing temperature, both the thickness of the ZrO2- x + TiO layer and the content of the (Zr,Ti)2(Cu,Ni) phase decreased. However, the acicular Widmanstäten structure gradually increased. With the increase in the holding time, the (Zr,Ti)2(Cu,Ni) phase decreased, and the thickness of the (Zr,Ti)2(Cu,Ni) + (Zr,Ti)2(Cu,Ni,Al) layer decreased. In addition, cracks formed adjacent to the ZrO2 side under rapid cooling. The microstructures produced under various fabrication parameters directly influence the shear strength of the joints. When ZrO2 and Ti-6Al-4V couples were brazed at 1173 K for 10 min and then cooled at a rate of 5 K/min, the maximum shear strength of 95 MPa was obtained.

  11. Characterization of multi-principal-element (TiZrNbHfTa)N and (TiZrNbHfTa)C coatings for biomedical applications.

    PubMed

    Braic, V; Balaceanu, M; Braic, M; Vladescu, A; Panseri, S; Russo, A

    2012-06-01

    Multi-principal-element (TiZrNbHfTa)N and (TiZrNbHfTa)C coatings were deposited on Ti6Al4V alloy by co-sputtering of Ti, Zr, Nb, Hf and Ta metallic targets in reactive atmosphere. The coatings were analyzed for elemental and phase compositions, crystalline structure, morphology, residual stress, hardness, friction performance, wear-corrosion resistance and cell viability. For all the films, only simple fcc solid solutions with (111) preferred orientations were found, with crystallite sizes in the range 7.2-13.5 nm. The coatings were subjected to compressive stress, with values ranging from 0.8 to 1.6 GPa. The carbide coating with the highest carbon content (carbon/metal ≈1.3) exhibited the highest hardness of about 31 GPa, the best friction behavior (μ = 0.12) and the highest wear resistance (wear rate K=0.2×10(-6)mm(3)N(-1)m(-1)), when testing in simulated body fluids (SBFs). Cell viability tests proved that the osteoblast cells were adherent to the coated substrates, and a very high percentage of live cells were observed on sample surfaces, after 72 h incubation time.

  12. First-principles appraisal of solute ultra-fast diffusion in hcp Zr and Ti

    NASA Astrophysics Data System (ADS)

    Pasianot, R. C.; Pérez, R. A.

    2013-03-01

    We revisit the ultra-fast diffusion characteristics of Fe, Co, Ni, and Cu solutes, in the hcp hosts Ti and Zr, by using Density Functional Theory. The energetics of several point defect configurations, deemed relevant for solute diffusion, is evaluated. The results support the long standing beliefs that the diffusing species is interstitial in nature, and that some kind of complexing is involved at low temperatures. Though quantitative agreement with experiment is difficult to assess, we show that a rather simple dissociative model is able to rationalize the observed trends, in particular, why the Arrhenius graphs are straight for Ti whereas, generally, they are curved downwards for Zr.

  13. Photoelectric properties of TiO2-ZrO2 thin films prepared by sol-gel method.

    PubMed

    Zhang, Haifeng; Ruan, Shengping; Feng, Caihui; Xu, Baokun; Chen, Weiyou; Dong, Wei

    2011-11-01

    Acidic sols of TiO2, ZrO2 and Ti-Zr mixed oxide precursors were prepared. The sols were then smeared on quartz substrate and annealed at 650 degrees C for 2 hour to form polycrystalline oxide films. XRD, SEM, UV-visible absorption spectra and XPS were carried out to characterize the films. It was found that the crystalline phase of pure titania is an anatase and pure zirconia is a tetragonal. The binary oxides show the anatase phase at the molar ratio of Ti:Zr = 2.73:1, which means that solid solution was formed. The absorption edge of the TiO2-ZrO2 binary oxides showed obvious blue shift as the Zr ratio increased. The results obtained indicate that the band gap of the binary oxides could be adjusted from 3.2 eV (TiO2) to 7.8 eV (ZrO2) by varying the molar ratio of Ti and Zr. Au interdigitated electrodes were produced by planar technology and MSM (metal-semiconductor-metal) structure UV detector based on TiO2-ZrO2 binary oxides was fabricated. Obvious photoelectric response was observed.

  14. Concentration-dependent crystal structure, elastic constants and electronic structure of Zr x Ti1- x alloys under high pressure

    NASA Astrophysics Data System (ADS)

    Yuan, Xiao-Li; Xue, Mi-An; Chen, Wen; An, Tian-Qing

    2014-04-01

    The physical properties of Zr x Ti1- x ( x = 0.0, 0.33, 0.5, 0.67, 0.75 and 1.00) alloys were simulated by virtual crystal approximation (VCA) methods which is generally used for disordered solid solutions modeling. The elastic constant, electronic structure and thermal Equation of state (EOS) of disordered Zr x Ti1- x alloys under pressure are investigated by plane-wave pseudo-potential method. Our simulations reveal increasement of variations of the calculated equilibrium volumes and decreasement of Bulk modulus as a function of the alloy compositions. Lattice parameters a and c of alloys with different Zr concentrations decrease linearly with pressure increasing, but the c/avalues are increasing as pressure increases, indicating no phase transitions under pressure from 0 GPa to 100 GPa. The elastic constants and the Bulk modulus to the Shear modulus ratios ( B/G) indicate good ductility of Zr, Zr0.33Ti0.67, Zr0.5Ti0.5, Zr0.75Ti0.25 and Ti, but the Zr0.67Ti0.33 alloy is brittle under 0 K and 0 GPa. The metallic behavior of these alloys was also proved by analyzing partial and total DOS.

  15. Bio-corrosion and cytotoxicity studies on novel Zr55Co30Ti15 and Cu60Zr20Ti20 metallic glasses

    DOE PAGES

    Vincent, S.; Daiwile, A.; Devi, S. S.; ...

    2014-09-26

    Metallic glasses are a potential and compatible implant candidate for biomedical applications. In the present investigation, a comparative study between novel Zr55Co30Ti15 and Cu60Zr20Ti20 metallic glasses is carried out to evaluate in vitro biocompatibility using simulated body fluids. The bio-corrosion behavior of Zr- and Cu-based metallic glasses in different types of artificial body fluids such as artificial saliva solution, phosphate-buffered saline solution, artificial blood plasma solution, and Hank’s balanced saline solution is evaluated using potentiodynamic polarization studies at a constant body temperature of 310.15 K (37 °C). Surface morphology of samples after bio-corrosion experiments was observed by scanning electron microscopy.more » In vitro cytotoxicity test on glassy alloys were performed using human osteosarcoma cell line as per 10993-5 guidelines from International Organization for Standardization. As a result, the comparative study between Zr- and Cu-based glassy alloys provides vital information about the effect of elemental composition on biocompatibility of metallic glasses.« less

  16. Bio-corrosion and Cytotoxicity Studies on Novel Zr55Co30Ti15 and Cu60Zr20Ti20 Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Vincent, S.; Daiwile, A.; Devi, S. S.; Kramer, M. J.; Besser, M. F.; Murty, B. S.; Bhatt, Jatin

    2014-09-01

    Metallic glasses are a potential and compatible implant candidate for biomedical applications. In the present investigation, a comparative study between novel Zr55Co30Ti15 and Cu60Zr20Ti20 metallic glasses is carried out to evaluate in vitro biocompatibility using simulated body fluids. The bio-corrosion behavior of Zr- and Cu-based metallic glasses in different types of artificial body fluids such as artificial saliva solution, phosphate-buffered saline solution, artificial blood plasma solution, and Hank's balanced saline solution is evaluated using potentiodynamic polarization studies at a constant body temperature of 310.15 K (37 °C). Surface morphology of samples after bio-corrosion experiments was observed by scanning electron microscopy. In vitro cytotoxicity test on glassy alloys were performed using human osteosarcoma cell line as per 10993-5 guidelines from International Organization for Standardization. The comparative study between Zr- and Cu-based glassy alloys provides vital information about the effect of elemental composition on biocompatibility of metallic glasses.

  17. Bio-corrosion and Cytotoxicity Studies on Novel Zr55Co30Ti15 and Cu60Zr20Ti20 Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Vincent, S.; Daiwile, A.; Devi, S. S.; Kramer, M. J.; Besser, M. F.; Murty, B. S.; Bhatt, Jatin

    2015-06-01

    Metallic glasses are a potential and compatible implant candidate for biomedical applications. In the present investigation, a comparative study between novel Zr55Co30Ti15 and Cu60Zr20Ti20 metallic glasses is carried out to evaluate in vitro biocompatibility using simulated body fluids. The bio-corrosion behavior of Zr- and Cu-based metallic glasses in different types of artificial body fluids such as artificial saliva solution, phosphate-buffered saline solution, artificial blood plasma solution, and Hank's balanced saline solution is evaluated using potentiodynamic polarization studies at a constant body temperature of 310.15 K (37 °C). Surface morphology of samples after bio-corrosion experiments was observed by scanning electron microscopy. In vitro cytotoxicity test on glassy alloys were performed using human osteosarcoma cell line as per 10993-5 guidelines from International Organization for Standardization. The comparative study between Zr- and Cu-based glassy alloys provides vital information about the effect of elemental composition on biocompatibility of metallic glasses.

  18. The corrosion behaviour of Ti-6Al-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr in protein solutions.

    PubMed

    Khan, M A; Williams, R L; Williams, D F

    1999-04-01

    Ti alloys are used in orthopaedic applications owing to their appropriate mechanical properties and their excellent corrosion resistance. The release of titanium and the other alloying elements into the surrounding tissue has been reported due either to passive corrosion or accelerating processes such as wear. Since the passive layer can be broken down in certain circumstances by wear it is important to study the ability of these alloys to repassivate in biological environments, in particular in the presence of proteins, and evaluate how the repassivated surface may vary from the original surface. In this study we investigated the ability of Ti-6Al-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr to repassivate in phosphate buffered saline (PBS), bovine albumin solutions in PBS and 10% foetal calf serum in PBS at different pH values and at different albumin concentrations. It was found that an increase in pH had a greater effect on the corrosion behaviour of Ti-6Al-4V and Ti-6Al-7Nb than on Ti-13Nb-13Zr in PBS and that the addition of protein to the PBS reduced the influence of pH on the corrosion behaviour of all the alloys. The effect of the corrosion and repassivation was investigated by measuring changes in the surface hardness of the alloys and it was found that corrosion reduced the hardness of the surface oxides of all the alloys. In PBS the reduction was smallest for Ti-6Al-4V and largest for Ti-13Nb- 3Zr and that corrosion in protein solutions further reduced the hardness of the surface oxides. This effect was greater for Ti-6Al-4V and Ti-6Al-7Nb than for Ti-13Nb-13Zr. In conclusion, proteins in the environment appear to interact with the repassivation process at the surface of these alloys and influence the resulting surface properties.

  19. Photocatalytic enhancement of TiO2 by B and Zr co-doping and modulation of microstructure

    NASA Astrophysics Data System (ADS)

    Fu, Chengxin; Gong, Yinyan; Wu, Yitao; Liu, Jiaqi; Zhang, Zhen; Li, Can; Niu, Lengyuan

    2016-08-01

    Visible-light photodegradation test revealed that B and Zr co-doping can raise the photocatalytic ability of the undoped TiO2 by a fold. XRD crystallography and Raman phonon spectroscopy measurements suggest that the Zr4+ ions replace the Ti4+ ions while the B3+ ions occupy the interstitial sites, expanding the unit-cell volume and reducing crystallite size. The incorporation of interstitial boron dopants creates oxygen vacancies (Ovrad rad) and reduce Ti4+ to Ti3+ to form [Ovrad rad -Ti3+]+, which traps the carriers and prolongs carrier lifetime. Moreover, Zr4+ ions replace Ti4+ ions and form impurity levels, which could improve visible light response. The co-doped samples are benefited from both B interstitials and Zr substitutes.

  20. Preparation and Mechanism of Cu-Decorated TiO2-ZrO2 Films Showing Accelerated Bacterial Inactivation.

    PubMed

    Rtimi, Sami; Pulgarin, Cesar; Sanjines, Rosendo; Nadtochenko, Victor; Lavanchy, Jean-Claude; Kiwi, John

    2015-06-17

    Antibacterial robust, uniform TiO2-ZrO2 films on polyester (PES) under low intensity sunlight irradiation made up by equal amounts of TiO2 and ZrO2 exhibited a much higher bacterial inactivation kinetics compared to pure TiO2 or ZrO2. The TiO2-ZrO2 matrix was found to introduce a drastic increase in the Cu-dopant promoter enhancing bacterial inactivation compared to Cu sputtered in the same amount on PES. Furthermore, the bacterial inactivation was accelerated by a factor close to three, by Cu- on TiO2-ZrO2 at extremely low levels ∼0.01%. Evidence is presented by X-ray photoelectron spectroscopy for redox catalysis taking place during bacterial inactivation. The TiO2-ZrO2-Cu band gap is estimated and the film properties were fully characterized. Evidence is provided for the photogenerated radicals intervening in the bacterial inactivation. The photoinduced TiO2-ZrO2-Cu interfacial charge transfer is discussed in term of the electronic band positions of the binary oxide and the Cu TiO2 intragap state.

  1. Are new TiNbZr alloys potential substitutes of the Ti6Al4V alloy for dental applications? An electrochemical corrosion study.

    PubMed

    Ribeiro, Ana Lúcia Roselino; Hammer, Peter; Vaz, Luís Geraldo; Rocha, Luís Augusto

    2013-12-01

    The main aim of this work was to assess the electrochemical behavior of new Ti35Nb5Zr and Ti35Nb10Zr alloys in artificial saliva at 37 °C to verify if they are indicated to be used as biomaterials in dentistry as alternatives to Ti6Al4V alloys in terms of corrosion protection efficiency of the material. Electrochemical impedance spectroscopy (EIS) experiments were carried out for different periods of time (0.5-216 h) in a three-electrode cell, where the working electrode (Ti alloys) was exposed to artificial saliva at 37 °C. The near-surface region of the alloys was investigated using x-ray photoelectron spectroscopy (XPS). All alloys exhibited an increase in corrosion potential with the immersion time, indicating the growth and stabilization of the passive film. Ti35Nb5Zr and Ti6Al4V alloys had their EIS results interpreted by a double-layer circuit, while the Ti35Nb10Zr alloy was modeled by a one-layer circuit. In general, the new TiNbZr alloys showed similar behavior to that observed for the Ti6Al4V. XPS results suggest, in the case of the TiNbZr alloys, the presence of a thicker passive layer containing a lower fraction of TiO2 phase than that of Ti6Al4V. After long-term immersion, all alloys develop a calcium phosphate phase on the surface. The new TiNbZr alloys appear as potential candidates to be used as a substitute to Ti6Al4V in the manufacturing of dental implant-abutment sets.

  2. Crystal Structure, Transformation Strain, and Superelastic Property of Ti-Nb-Zr and Ti-Nb-Ta Alloys

    NASA Astrophysics Data System (ADS)

    Kim, Hee Young; Fu, Jie; Tobe, Hirobumi; Kim, Jae Il; Miyazaki, Shuichi

    2015-06-01

    The composition dependences of transformation strain and shape memory, and superelastic properties were extensively investigated in Ti-Nb-Zr and Ti-Nb-Ta alloys in order to establish the guidelines for alloy design of biomedical superelastic alloys. The effects of composition on the crystal structure of the parent (β) phase and the martensite (α″) phase were also investigated. Results showed that not only transformation temperature but also transformation strain is tunable by alloy design, i.e., adjusting contents of Nb, Zr, and Ta. The lattice constant of the β phase increased linearly with increasing Zr content, while it was insensitive to Nb and Ta contents. On the other hand, the lattice constants of the α″ phase are mainly affected by Nb and Ta contents. The increase of Zr content exhibited a weaker impact on the transformation strain compared with Nb and Ta. The addition of Zr as a substitute of Nb with keeping superelasticity at room temperature significantly increased the transformation strain. On the other hand, the addition of Ta decreased the transformation strain at the compositions showing superelasticity. This study confirmed that the crystallography of martensitic transformation can be the main principal to guide the alloy design of biomedical superelastic alloys.

  3. Crystallization and nanoindentation behavior of a bulk Zr-Al-Ti-Cu-Ni amorphous alloy

    SciTech Connect

    Wang, J. G.; Choi, B. W.; Nieh, T. G.; Liu, C. T.

    2000-03-01

    The crystallization and nanoindentation behavior of a Zr-10Al-5Ti-17.9Cu-14.6Ni (at.%) bulk amorphous alloy (BAA) were studied. Resulting from the kinetic nature of phase transformation in multicomponent alloys, the crystallization path is complex. Despite the complexity of different crystallization paths, the main final crystallized product in the Zr-based BAA is Zr{sub 2}Cu. Young's modulus and hardness of the BAA were found to increase with an increase in annealing temperature. The observed mechanical properties were correlated with the microstructure of the material. Also, in the present paper, both the observed crystallization and nanoindentation behavior are compared with existing data. Zr-based BAAs exhibit a ratio of hardness to Young's modulus (H/E ratio) of about 1/10, suggesting the interatomic bonding in the alloys is close to being covalent. (c) 2000 Materials Research Society.

  4. The degradation of Isophorone by catalytic wet air oxidation on Ru/TiZrO4.

    PubMed

    Wei, Huangzhao; Yan, Xiaomiao; Li, Xianru; He, Songbo; Sun, Chenglin

    2013-01-15

    The catalyst Ru/TiZrO(4) was applied in the degradation of Isophorone by catalytic wet air oxidation. Mathematical models for the effects of reaction conditions on the Isophorone degradation by catalytic wet air oxidation were developed using a response surface methodology. A model was obtained for each response with multiple regression analysis and then was refined. Analysis of variance revealed that the models developed were adequate. The validity of the models was also verified by experimental data. Analysis of response surface showed that total organic carbon removal and Isophorone conversion were significantly affected (P≤0.01) by reaction time, temperature and their interactions, and affected (P≤0.05) by the square of reaction time. The point of zero charge of Ru/TiZrO(4) catalyst was about 1.72. The total organic carbon removal and Isophorone conversion had a great association with the zeta potential of Ru/TiZrO(4) catalyst. Finally, the degradation pathway of Isophorone in catalytic wet air oxidation was proposed. Within 410 h, the total organic carbon removal remained above 95%, indicating that the Ru/TiZrO(4) catalyst had a good stability.

  5. The effect of C content on the mechanical properties of Ti-Zr coatings.

    PubMed

    Rodríguez-Hernández, M G; Jiménez, O; Alvarado-Hernández, F; Flores, M; Andrade, E; Canto, C E; Ávila, C; Espinoza-Beltrán, F

    2015-09-01

    In this study, Ti-Zr and Ti-Zr-C coatings were deposited at room temperature via pulsed-DC magnetron sputtering. A 70Ti-30Zr at% target and a 99.99% graphite plate were used to deposit samples. In order to modify C content, coatings were deposited at different target powers such as 50, 75 and 100 W. Changes on the structure, microstructure and mechanical properties due to C addition were studied. Results indicate that the as-deposited coatings were partly crystalline and that an increment on C content stabilized α' phase and inhibited the appearance of ω precipitates. Therefore, Ti-Zr-C alloys with C>1.9 at% showed only α' phase whereas the others alloys exhibited α'+ω structures. Hardness values from 12.94 to 34.31 GPa were obtained, whereas the elastic modulus was found between 181.84 and 298 GPa. Finally, a high elastic recovery ratio (0.69-0.87) was observed as a function of composition. The overall properties of these coatings were improved due to C content increment, martensitic α' phase and nanocrystalline grain size (10-16 nm).

  6. First principles theoretical investigations of low Young's modulus beta Ti-Nb and Ti-Nb-Zr alloys compositions for biomedical applications.

    PubMed

    Karre, Rajamallu; Niranjan, Manish K; Dey, Suhash R

    2015-05-01

    High alloyed β-phase stabilized titanium alloys are known to provide comparable Young's modulus as that to the human bones (~30 GPa) but is marred by its high density. In the present study the low titanium alloyed compositions of binary Ti-Nb and ternary Ti-Nb-Zr alloy systems, having stable β-phase with low Young's modulus are identified using first principles density functional framework. The theoretical results suggest that the addition of Nb in Ti and Zr in Ti-Nb increases the stability of the β-phase. The β-phase in binary Ti-Nb alloys is found to be fully stabilized from 22 at.% of Nb onwards. The calculated Young's moduli of binary β-Ti-Nb alloy system are found to be lower than that of pure titanium (116 GPa). For Ti-25(at.%)Nb composition the calculated Young's modulus comes out to be ~80 GPa. In ternary Ti-Nb-Zr alloy system, the Young's modulus of Ti-25(at.%)Nb-6.25(at.%)Zr composition is calculated to be ~50 GPa. Furthermore, the directional Young's moduli of these two selected binary (Ti-25(at.%)Nb) and ternary alloy (Ti-25(at.%)Nb-6.25(at.%)Zr) compositions are found to be nearly isotropic in all crystallographic directions.

  7. Effect of photocatalytic reduction of carbon dioxide by N-Zr co-doped nano TiO2.

    PubMed

    Zhang, Ru; Wang, Li; Kang, Zhuo; Li, Qiang; Pan, Huixian

    2017-01-04

    Modified sol-gel method was adopted to prepare TiO2, Zr-TiO2 and N/Zr-TiO2 composite catalyst. The as-synthesized photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunner- Emmet- Teller measurement and UV-Vis diffuse reflectance spectroscopy. And the photocatalytic performance toward CO2 reduction was evaluated under ultraviolet light. The catalyst particles were demonstrated in the nanometer level size. When N and Zr are co-doped, on the one hand, Ti(4+) can be replaced by Zr4 +, which leads to lattice distortion and inhibits electron-hole recombination. On the other hand, N enters into TiO2 lattice gap to form O-Ti-N bond structure, and partial Ti(4+) are reduced to Ti(3+). Compared with pristine TiO2, the specific surface area and the band gap of N/Zr-TiO2 were improved and reduced, respectively. The N and Zr synergistically contribute to the obviously strengthened absorption intensity in visible region, as well as significantly improved photocatalytic activity. In the gas phase reactor, when the calcination temperature was 550°C, 0.125N/0.25Zr-TiO2 composite performed the highest photocatalytic activity UV irradiation for 8 h, and the corresponding CH4 yield was 11.837 µmol/g, which was 87.8% higher than that of pristine TiO2. For the visible light, the CH4 yield was 9.003 µmol/g after 8 h irradiation, which was 83.9% higher than that of pristine TiO2.

  8. Superelasticity, corrosion resistance and biocompatibility of the Ti-19Zr-10Nb-1Fe alloy.

    PubMed

    Xue, Pengfei; Li, Yan; Li, Kangming; Zhang, Deyuan; Zhou, Chungen

    2015-05-01

    Microstructure, mechanical properties, superelasticity and biocompatibility of a Ti-19Zr-10Nb-1Fe alloy are investigated. X-ray diffraction spectroscopy and transmission electron microscopy observations show that the as-cast Ti-19Zr-10Nb-1Fe alloy is composed of α' and β phases, but only the β phase exists in the as-rolled and as-quenched alloys. The tensile stress-strain tests indicate that the as-quenched alloy exhibits a good combination of mechanical properties with a large elongation of 25%, a low Young's modulus of 59 GPa and a high ultimate tensile stress of 723 MPa. Superelastic recovery behavior is found in the as-quenched alloy during tensile tests, and the corresponding maximum of superelastic strain is 4.7% at the pre-strain of 6%. A superelastic recovery of 4% with high stability is achieved after 10 cyclic loading-unloading training processes. Potentiodynamic polarization and ion release measurements indicate that the as-quenched alloy shows a lower corrosion rate in Hank's solution and a much less ion release rate in 0.9% NaCl solution than those of the NiTi alloys. Cell culture results indicate that the osteoblasts' adhesion and proliferation are similar on both the Ti-19Zr-10Nb-1Fe and NiTi alloys. A better hemocompatibility is confirmed for the as-quenched Ti-19Zr-10Nb-1Fe alloy, attributed to more stable platelet adhesion and small activation degree, and a much lower hemolysis rate compared with the NiTi alloy.

  9. Effects of TiN coating on the corrosion of nanostructured Ti-30Ta-xZr alloys for dental implants

    NASA Astrophysics Data System (ADS)

    Kim, Won-Gi; Choe, Han-Cheol

    2012-01-01

    Electrochemical characteristics of a titanium nitride (TiN)-coated/nanotube-formed Ti-Ta-Zr alloy for biomaterials have been researched by using the magnetic sputter and electrochemical methods. Ti-30Ta-xZr (x = 3, 7 and 15 wt%) alloys were prepared by arc melting and heat treated for 24 h at 1000 °C in an argon atmosphere and then water quenching. The formation of oxide nanotubes was achieved by anodizing a Ti-30Ta-xZr alloy in H3PO4 electrolytes containing small amounts of fluoride ions at room temperature. Anodization was carried out using a scanning potentiostat, and all experiments were conducted at room temperature. The microstructure and morphology of nanotube arrays were characterized by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The TiN coatings were obtained by the radio-frequency (RF) magnetron sputtering technique. The depositions were performed from pure Ti targets on Ti-30Ta-xZr alloys substrates. The corrosion properties of the specimens were examined using potentiodynamic test in a 0.9% NaCl solution by using potentiostat. The microstructures of Ti-30Ta-xZr alloys were changed from an equiaxed to a needle-like structure with increasing Zr content. The interspace between the nanotubes was approximately 20, 80 and 200 nm for Zr contents of 3, 7 and 15 wt%, respectively. The corrosion resistance of the TiN-coated on the anodized Ti-30Ta-xZr alloys was higher than that of the untreated Ti alloys, indicating a better protective effect.

  10. Improved conversion efficiency of dye sensitized solar cell using Zn doped TiO2-ZrO2 nanocomposite

    NASA Astrophysics Data System (ADS)

    Tomar, Laxmi J.; Bhatt, Piyush J.; Desai, Rahul K.; Chakrabarty, B. S.; Panchal, C. J.

    2016-05-01

    TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were prepared by hydrothermal method for dye sensitized solar cell (DSSC) application. The structural and optical properties were investigated by X -ray diffraction (XRD) and UV-Visible spectroscopy respectively. XRD results revealed the formation of material in nano size. The average crystallite size is 22.32 nm, 17.41 nm and 6.31 nm for TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites respectively. The optical bandgap varies from 2.04 eV to 3.75 eV. Dye sensitized solar cells were fabricated using the prepared material. Pomegranate juice was used as a sensitizer and graphite coated conducting glass plate was used as counter electrode. The I - V characteristics were recorded to measure photo response of DSSC. Photovoltaic parameter like open circuit voltage, power conversion efficiency, and fill factor were evaluated for fabricated solar cell. The power conversion efficiency of DSSC fabricated with TiO2, TiO2-ZrO2 and Zn doped TiO2-ZrO2 nanocomposites were found 0.71%, 1.97% and 4.58% respectively.

  11. Physical properties modulation of Fe3O4/Pb(ZrTi)O3 heterostructure via Fe diffusion

    NASA Astrophysics Data System (ADS)

    Chichvarina, O.; Herng, T. S.; Ding, J.

    2016-03-01

    The manipulation of material properties in perovskite oxide heterojunctions has been increasingly studied, owing to their interacting lattice, charge, spin and orbital degrees of freedom. In this work, the switching, ferroelectricity and magneto-transport properties of epitaxially grown perovskite Pb(Zr0.52Ti0.48)O3 layers sandwiched between Fe3O4 (top electrode) and SrRuO3 (bottom electrode) are investigated. These films show a typical ferroelectric polarization of ˜50 μC/cm2. Once the Pb(Zr0.52Ti0.48)O3 films become thinner (˜30 nm), one can set (reset) the Fe3O4/Pb(Zr0.52Ti0.48)O3/SrRuO3 structures into a low (high) resistance state via formation (rupture) of an Fe-related filament in Pb(Zr0.52Ti0.48)O3 through manipulation of an electric field. Interestingly, at the low-resistance state, a prominent magnetoresistance signal of ˜3% was observed. There is no magnetoresistance signal detected in the virgin Pb(Zr0.52Ti0.48)O3 film (before switching), high-resistive state Pb(Zr0.52Ti0.48)O3 film and Au/Pb(Zr0.52Ti0.48)O3/SrRuO3. These phenomena are attributed to the diffusion of Fe-related ions into the Pb(Zr0.52Ti0.48)O3 film, turning a non-magnetic and insulating layer of perovskite Pb(Zr0.52Ti0.48)O3 into a magnetic and semiconducting-like Pb(Zr0.52Ti0.48)O3. The magneto-transport properties of Fe3O4/Pb(Zr0.52Ti0.48)O3/SrRuO3 have been studied extensively. Such resistance-ferroelectric-ferromagnetic coupling in a single compound paves the way to the realization of a non-volatile multiple-state Pb(ZrTi)O3 hybrid memory, as well as new computing approaches.

  12. Thermal Evaporation Loss Measurements on Quasicrystal (Ti-Zr-Ni) and Glass Forming (Vit 106 and Vit 106a) Liquids

    NASA Astrophysics Data System (ADS)

    Blodgett, M. E.; Gangopadhyay, A. K.; Kelton, K. F.

    2015-04-01

    Thermal evaporation loss measurements made using the electrostatic levitation (ESL) technique for one binary Ti-Zr, two ternary Ti-Zr-Ni, and two glass-forming (Vit 106 and Vit 106a) alloy liquids are reported. The containerless environment enables measurements not only for the equilibrium liquids but also for the metastable supercooled liquids. The data follow the Langmuir equation when the activity coefficient of the solute atoms, a measure for the deviation from the ideal solution behavior, is taken into account. An estimate for the activity coefficient of Ni in the Ti-Zr liquid is made from these data, demonstrating the effectiveness of ESL for such measurements.

  13. Ferroelectric Pb(Zr,Ti)O{sub 3} epitaxial layers on GaAs

    SciTech Connect

    Louahadj, L.; Le Bourdais, D.; Agnus, G.; Pillard, V.; Lecoeur, P.; Largeau, L.; Mazet, L.; Bachelet, R.; Regreny, P.; Dubourdieu, C.; Gautier, B.; Saint-Girons, G.; Albertini, D.

    2013-11-18

    Ferroelectric epitaxial Pb(Zr,Ti)O{sub 3} (PZT) layers were grown by pulsed laser deposition on SrTiO{sub 3}/GaAs templates fabricated by molecular beam epitaxy. The templates present an excellent structural quality and the SrTiO{sub 3}/GaAs is abrupt at the atomic scale. The PZT layers contain a- and c-domains, as shown by X-Ray diffraction analyses. Piezoforce microscopy experiments and macroscopic electrical characterizations indicate that PZT is ferroelectric. A relative dielectric permittivity of 164 is extracted from these measurements.

  14. Surface phenomena of HA/TiN coatings on the nanotubular-structured beta Ti-29Nb-5Zr alloy for biomaterials

    NASA Astrophysics Data System (ADS)

    Kim, Eun-Ju; Jeong, Yong-Hoon; Choe, Han-Cheol; Brantley, William A.

    2012-01-01

    Surface phenomena of HA/TiN coatings on the nanotubular-structured beta Ti-29Nb-5Zr alloy for biomaterials have been investigated by several experimental methods. The nanotubular structure was formed by anodizing the Ti-29Nb-5Zr alloy in 1 M H3PO4 electrolytes with 1.0 wt.% NaF at room temperature. Hydroxyapatite (HA)/titanium nitride (TiN) films were deposited on Ti-29Nb-5Zr alloy specimens using a magnetron sputtering system. The HA target was made of human tooth-ash by sintering at 1300 °C for 1 h, and the HA target had an average Ca/P ratio of 1.9. The HA/TiN depositions were performed, using the pure HA target, on Ti-29Nb-5Zr alloy following the initial deposition of a TiN buffer layer coating. Microstructures and nanotubular morphology of the coated alloy specimens were examined by FE-SEM, EDX, XRD, and XPS. The Ti-29Nb-5Zr alloy substrate had small grain size and preferred orientation along the drawing direction. The HA/TiN coating was stable with a uniform morphology at the tips of the nanotubes.

  15. Synthesis and characterization of sulfated TiO2 nanorods and ZrO2/TiO2 nanocomposites for the esterification of biobased organic acid.

    PubMed

    Li, Zhonglai; Wnetrzak, Renata; Kwapinski, Witold; Leahy, James J

    2012-09-26

    TiO(2) nanorods and ZrO(2)-modified TiO(2) nanocomposites have been prepared by hydrothermal synthesis and the deposition-precipitation method. Their sulfated products were tested as solid superacid catalysts for the esterification of levulinic acid which was used as a model bio-oil molecule. SEM and TEM characterization showed that TiO(2) nanorods with diameters ranging from 20 to 200 nm and with lengths of up to 5 μm were synthesized by a hydrothermal method at 180 °C. ZrO(2) nanoparticles with the diameters ranging from 10 to 20 nm were evenly deposited on TiO(2) nanorods. IR and XPS results suggested that sulfated ZrO(2)/TiO(2) nanocomposite has higher content of sulfate groups on the surface with a S/(Zr+Ti) ratio of 13.6% than sulfated TiO(2) nanorods with a S/Ti ratio of 4.9%. The HPLC results showed that sulfated ZrO(2)/TiO(2) nanocomposite have enhanced catalytic activity for esterification reaction between levulinic acid and ethanol compared to sulfated TiO(2) nanorods. The conversion of levulinic acid to ethyl levulinate can reach to 90.4% at the reaction temperature of 105 °C after 180 min.

  16. Biomimetic Hydroxyapatite Growth on Functionalized Surfaces of Ti-6Al-4V and Ti-Zr-Nb Alloys

    NASA Astrophysics Data System (ADS)

    Pylypchuk, Ie V.; Petranovskaya, A. L.; Gorbyk, P. P.; Korduban, A. M.; Markovsky, P. E.; Ivasishin, O. M.

    2015-08-01

    A biomimetic approach for coating titanium-containing alloys with hydroxyapatite (HA) is reported in the article. Two types of Ti-containing alloys were chosen as an object for coating: Ti-6Al-4V (recommended for orthopedic application) and a novel highly biocompatible Ti-Zr-Nb alloy, with good mechanical compatibility due to a modulus that is more close to that of human bones (E ≈ 50 GPa instead of 110 GPa in Ti-6Al-4V). Coating process was carried out in a 10×-concentrated simulated body fluid (SBF)—synthetic analog of human body plasma. The effect of oxidized and carboxylated alloy surface on formation of biomimetic hydroxyapatite has been studied. By XRD, we found influence of thermal conditions on HA crystal formation and size. SEM images and Fourier transform infrared confirmed that hydroxyapatite with different morphology, crystallinity, and Ca/P ratio formed on metallic surfaces. X-ray photoelectron spectroscopy showed that in the Ti-6AL-4V sample the observed Ca/P ratio reach 0.97, whereas in the Ti-Zr-Nb sample the observed Ca/P ratio reach 1.15.

  17. In vitro evaluation of biocompatibility of Ti-Mo-Sn-Zr superelastic alloy.

    PubMed

    Nunome, Shoko; Kanetaka, Hiroyasu; Kudo, Tada-aki; Endoh, Kazuki; Hosoda, Hideki; Igarashi, Kaoru

    2015-07-01

    Shape memory alloys (SMAs) including superelastic alloys have unique properties such as shape memory and superelasticity, thus they are recognized as very useful biomaterials. These properties are very advantageous for medical use, and actually the SMA wires have been widely used in medical field. However, biocompatibility of nickel-titanium (Ni-Ti) alloy, which is the only practical SMA at present, has been questioned because of its high nickel content. The aim of this study was to evaluate the biocompatibility of a newly developed Ni-free Ti-based SMA for medical use. The newly developed SMA made of Ti-Mo-Sn-Zr system was processed into a disk of 15.1 mm in diameter. Pure titanium of the same shape was prepared as control. All the disk surfaces were polished using emery papers, #120, #400, and #600. Scanning electron microscopy and a 3D optics profiler were used to evaluate the surface of the materials. In vitro evaluations included colony examination for evaluation of the cell cytotoxicity, DNA quantification for the cell proliferation, Alamar blue assay for metabolic activity, FDA staining for the live cell imaging, and cell cycle analysis, using Chinese hamster fibroblastic V-79 cells and mouse osteoblastic MC3T3-E1 cells. In colony examination and DNA quantification, there was no significant difference between the Ti-Mo-Sn-Zr and the pure titanium. In FDA staining, cultured cells on the Ti-Mo-Sn-Zr alloy showed the same biocompatibility as those on the pure titanium. The present results suggest that the newly developed Ti-Mo-Sn-Zr alloy showed the high biocompatibility comparable to pure titanium and can be used as efficient biomaterial for medical use.

  18. Surface phenomena of hydroxyapatite film on the nanopore formed Ti-29Nb-xZr alloy by anodization for bioimplants.

    PubMed

    Kim, Eun-Ju; Jeong, Yong-Hoon; Choe, Han-Cheol

    2013-03-01

    In this study, surface phenomena of hydroxyapatite (HA) film on the nanopore formed Ti-29Nb-xZr alloy by anodization for bioimplants have been investigated by electron beam physical vapor deposition (EB-PVD), field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), potentiostat and contact angle. The microstructure of Ti-29Nb-xZr alloys exhibited equiaxed structure and alpha" phase decreased, whereas beta phase increased as Zr content increased. The increment of Zr contents in HA coated nanotubular Ti-29Nb-xZr alloys showed good corrosion potential in 0.9% NaCI solution. The wettability of HA coated nanotubular surface was higher than that of non-coated samples.

  19. An innovative technique to simply fabricate ZrO₂-HA-TiO₂ nanostructured layers.

    PubMed

    Samanipour, F; Bayati, M R; Golestani-Fard, F; Zargar, H R; Troczynski, T; Mirhabibi, A R

    2011-08-01

    For the first time, ZrO₂-HA-TiO₂ layers were synthesized through EPD-Enhanced MAO (EEMAO) technique in only one step where no supplementary treatment was required. SEM, XRD, EDX, and XPS techniques were employed to propose a correlation between the growth parameters and the physical and chemical properties of the layers. The layers revealed a porous structure where applying higher voltages and/or utilizing higher concentrated electrolytes resulted in formation of wider pores and increasing the zirconium concentration in the layers; meanwhile, prolonging the growth time had the same effects. The layers mainly consisted of anatase, hydroxyapatite, monoclinic ZrO₂, and tetragonal ZrO₂ phases. Increasing the voltage, electrolyte concentration, and time, hydroxyapatite as well as tetragonal ZrO₂ was decomposed to α-TCP, monoclinic ZrO₂, and ZrO. The nanosized zirconia particles (d = 20-60 nm) were further accumulated on the vicinity of the layers when thicker electrolytes were utilized or higher voltages were applied. Emphasizing on the chemical and electrochemical foundations, a probable formation mechanism was finally put forward.

  20. The bone tissue compatibility of a new Ti35Nb2Ta3Zr alloy with a low Young's modulus.

    PubMed

    Guo, Yongyuan; Chen, Desheng; Cheng, Mengqi; Lu, Weijie; Wang, Liqiang; Zhang, Xianlong

    2013-03-01

    Titanium (Ti) alloys of the β-type are highly attractive metallic materials for biomedical applications due to their low elastic modulus, high corrosion resistance and notable biocompatibility. A new β-type Ti35Nb2Ta3Zr alloy with a low Young's modulus of approximately 48 GPa was previously fabricated. In the present study, the biocompatibility of this alloy was evaluated. In an in vitro assay, the Ti35Nb2Ta3Zr alloy did not markedly affect the adhesion of MG63 osteoblast cells, but it increased their proliferation, alkaline phosphatase (ALP) activity, calcium deposition and mRNA expression of osteogenic genes (i.e., ALP, osteocalcin, osteopontin). In an in vivo study, no marked histological differences were observed between the new bone formed on the surface of Ti35Nb2Ta3Zr and that formed on the surface of control Ti6Al4V rods placed in the medullary canal of rabbit femurs. Additionally, no significant differences were observed in the failure load of Ti35Nb2Ta3Zr and Ti6Al4V in pull-out tests. In conclusion, the Ti35Nb2Ta3Zr alloy with a lower elastic modulus closer to that of human bone has significant bone tissue compatibility equal to that of Ti6Al4V, which has been widely used in orthopedic applications.

  1. Hypervalent Bismuthides La3MBi5 (M = Ti, Zr, Hf) and Related Antimonides: Absence of Superconductivity.

    PubMed

    Murakami, Taito; Yamamoto, Takafumi; Takeiri, Fumitaka; Nakano, Kousuke; Kageyama, Hiroshi

    2017-04-10

    We successfully synthesized the ternary bismuthides La3MBi5 (M = Ti, Zr, Hf). These compounds crystallize in the hexagonal Hf5Sn3Cu-anti type structure (space group: P63/mcm) consisting of face-sharing MBi6 octahedral chains and hypervalent Bi linear chains, both separated by La atoms. Magnetic susceptibility and electrical resistivity measurements revealed that all of the compounds, including the solid solution La3Ti(Bi1-xSbx)5, exhibit a Pauli paramagnetic behavior without any trace of superconductivity down to 1.85 K, as opposed to a recently reported 4 K superconductivity in La3TiSb5. The absence of superconductivity is supported by first-principles band calculations of La3TiBi5 and La3TiSb5 that demonstrate similar electronic structures with three-dimensional Fermi surfaces.

  2. High temperature phase decomposition in Ti{sub x}Zr{sub y}Al{sub z}N

    SciTech Connect

    Lind, Hans; Pilemalm, Robert; Rogström, Lina; Tasnadi, Ferenc; Ghafoor, Naureen; Forsén, Rikard; Odén, Magnus; Johnson, Lars J. S.; Johansson-Jöesaar, Mats P.; Abrikosov, Igor A.

    2014-12-15

    Through a combination of theoretical and experimental observations we study the high temperature decomposition behavior of c-(Ti{sub x}Zr{sub y}Al{sub z}N) alloys. We show that for most concentrations the high formation energy of (ZrAl)N causes a strong tendency for spinodal decomposition between ZrN and AlN while other decompositions tendencies are suppressed. In addition we observe that entropic effects due to configurational disorder favor a formation of a stable Zr-rich (TiZr)N phase with increasing temperature. Our calculations also predict that at high temperatures a Zr rich (TiZrAl)N disordered phase should become more resistant against the spinodal decomposition despite its high and positive formation energy due to the specific topology of the free energy surface at the relevant concentrations. Our experimental observations confirm this prediction by showing strong tendency towards decomposition in a Zr-poor sample while a Zr-rich alloy shows a greatly reduced decomposition rate, which is mostly attributable to binodal decomposition processes. This result highlights the importance of considering the second derivative of the free energy, in addition to its absolute value in predicting decomposition trends of thermodynamically unstable alloys.

  3. Piezoelectric properties and stabilities of CuO-modified Ba(Ti,Zr)O3 ceramics

    NASA Astrophysics Data System (ADS)

    Zheng, P.; Zhang, J. L.; Shao, S. F.; Tan, Y. Q.; Wang, C. L.

    2009-01-01

    Due to the orthorhombic-tetragonal polymorphic phase transition near room temperature, undesirable large temperature dependence of piezoelectric properties is observed over common usage temperature range in BaTiO3 ceramics with high d33 values. Whereas shifting the phase transition temperature upward by partially substituting Ti with Zr is effective in reducing the piezoelectric temperature dependence, serious long-term degradation occurs. However, it is found that this could be overcome by incorporating a small amount of CuO additive. CuO-modified Ba(Ti0.9625Zr0.0375)O3 ceramics possess excellent piezoelectric properties of d33=300 pC/N, kp=0.493, and k33=0.651 with tan δ=0.011, and its kp remains larger than 0.40 in the broad temperature range from -43 to 73 °C and is almost constant between -25 and 55 °C. The results indicate that CuO-modified Ba(Ti,Zr)O3 ceramics are a promising low-cost lead-free material for practical applications.

  4. Surface analysis, microstructural, mechanical and electrochemical properties of new Ti-15Ta-5Zr alloy

    NASA Astrophysics Data System (ADS)

    Vasilescu, Cora; Drob, Silviu Iulian; Osiceanu, Petre; Drob, Paula; Moreno, Jose Maria Calderon; Preda, Silviu; Ivanescu, Steliana; Vasilescu, Ecaterina

    2015-03-01

    This paper describes the synthesis of a novel Ti-15Ta-5Zr alloy with an α + ß stable, homogeneous, biphasic microstructure (by optical microscopy, X-ray diffraction and scanning electron microscopy) and the determination of its mechanical properties, hardness and a Young's modulus of 42.2 GPa. The alloy passive film composition and thickness were analyzed by X-ray photoelectron spectroscopy; a thick, compact native passive film containing the protective oxides of all constituent elements (TiO2, Ta2O5, ZrO2) was identified. The electrochemical parameters confirmed a nobler behaviour and a more capacitive, resistant passive film on the alloy surface compared to Ti and other existing implant alloys; these facts are due to the alloying elements that, by their oxides stabilize and reinforce the alloy passive film. This passive film thickened in time, which increased its protective capacity. The new alloy had no susceptibility to galvanic or local corrosion. Ti-15Ta-5Zr alloy is recommended as an advanced orthopaedic implant material.

  5. Microstructure, Surface Characterization, and Electrochemical Behavior of New Ti-Zr-Ta-Ag Alloy in Simulated Human Electrolyte

    NASA Astrophysics Data System (ADS)

    Vasilescu, Cora; Drob, Silviu Iulian; Osiceanu, Petre; Moreno, Jose Maria Calderon; Prodana, Mariana; Ionita, Daniela; Demetrescu, Ioana; Marcu, Maria; Popovici, Ion Alexandru; Vasilescu, Ecaterina

    2017-01-01

    A new Ti-20Zr-5Ta-2Ag alloy was elaborated and characterized regarding its microstructure, its native passive film composition and thickness, its surface wettability, its electrochemical behavior in Ringer solution of different pH values, and its ion release. The new alloy has a bi-phase, α + β, acicular, homogeneous microstructure (scanning electron microscopy (SEM)). Its native passive film (12-nm thicknesses) consists of the protective TiO2, ZrO2, and Ta2O5 oxides, Ti and Ta suboxides, and metallic Ag (X-ray photoelectron spectroscopy (XPS) data). The alloy possesses high hydrophilic properties. The main electrochemical parameters of the new alloy are superior to those of Ti as a result of the beneficial influence of Zr, Ta, and Ag alloying elements, which reinforce its native passive film. Electrochemical impedance spectroscopy (EIS) spectra in Ringer solutions for the new alloy displayed better values of impedances and phase angles, proving a more insulate passive film than that on the Ti surface. The main corrosion parameters for the new Ti-20Zr-5Ta-2Ag alloy are more favorable by about 25 to 38 times than those of Ti, confirming extremely resistant passive film. The new Ti-20Zr-5Ta-2Ag alloy releases into Ringer solution low quantities of Ti4+, Zr4+ metallic ions (inductively coupled plasma-mass spectroscopy (ICP-MS)). The Ag+ ions are released in low quantity, conferring to this alloy's low antibacterial activity. All experimental results show that the new Ti-20Zr-5Ta-2Ag alloy fulfills the requirements for biocompatibility, corrosion resistance, and antibacterial protection.

  6. Novel Ti-Ta-Hf-Zr alloys with promising mechanical properties for prospective stent applications

    NASA Astrophysics Data System (ADS)

    Lin, Jixing; Ozan, Sertan; Li, Yuncang; Ping, Dehai; Tong, Xian; Li, Guangyu; Wen, Cuie

    2016-11-01

    Titanium alloys are receiving increasing research interest for the development of metallic stent materials due to their excellent biocompatibility, corrosion resistance, non-magnetism and radiopacity. In this study, a new series of Ti-Ta-Hf-Zr (TTHZ) alloys including Ti-37Ta-26Hf-13Zr, Ti-40Ta-22Hf-11.7Zr and Ti-45Ta-18.4Hf-10Zr (wt.%) were designed using the d-electron theory combined with electron to atom ratio (e/a) and molybdenum equivalence (Moeq) approaches. The microstructure of the TTHZ alloys were investigated using optical microscopy, XRD, SEM and TEM and the mechanical properties were tested using a Vickers micro-indenter, compression and tensile testing machines. The cytocompatibility of the alloys was assessed using osteoblast-like cells in vitro. The as-cast TTHZ alloys consisted of primarily β and ω nanoparticles and their tensile strength, yield strength, Young’s modulus and elastic admissible strain were measured as being between 1000.7–1172.8 MPa, 1000.7–1132.2 MPa, 71.7–79.1 GPa and 1.32–1.58%, respectively. The compressive yield strength of the as-cast alloys ranged from 1137.0 to 1158.0 MPa. The TTHZ alloys exhibited excellent cytocompatibility as indicated by their high cell viability ratios, which were close to that of CP-Ti. The TTHZ alloys can be anticipated to be promising metallic stent materials by virtue of the unique combination of extraordinarily high elastic admissible strain, high mechanical strength and excellent biocompatibility.

  7. Novel Ti-Ta-Hf-Zr alloys with promising mechanical properties for prospective stent applications

    PubMed Central

    Lin, Jixing; Ozan, Sertan; Li, Yuncang; Ping, Dehai; Tong, Xian; Li, Guangyu; Wen, Cuie

    2016-01-01

    Titanium alloys are receiving increasing research interest for the development of metallic stent materials due to their excellent biocompatibility, corrosion resistance, non-magnetism and radiopacity. In this study, a new series of Ti-Ta-Hf-Zr (TTHZ) alloys including Ti-37Ta-26Hf-13Zr, Ti-40Ta-22Hf-11.7Zr and Ti-45Ta-18.4Hf-10Zr (wt.%) were designed using the d-electron theory combined with electron to atom ratio (e/a) and molybdenum equivalence (Moeq) approaches. The microstructure of the TTHZ alloys were investigated using optical microscopy, XRD, SEM and TEM and the mechanical properties were tested using a Vickers micro-indenter, compression and tensile testing machines. The cytocompatibility of the alloys was assessed using osteoblast-like cells in vitro. The as-cast TTHZ alloys consisted of primarily β and ω nanoparticles and their tensile strength, yield strength, Young’s modulus and elastic admissible strain were measured as being between 1000.7–1172.8 MPa, 1000.7–1132.2 MPa, 71.7–79.1 GPa and 1.32–1.58%, respectively. The compressive yield strength of the as-cast alloys ranged from 1137.0 to 1158.0 MPa. The TTHZ alloys exhibited excellent cytocompatibility as indicated by their high cell viability ratios, which were close to that of CP-Ti. The TTHZ alloys can be anticipated to be promising metallic stent materials by virtue of the unique combination of extraordinarily high elastic admissible strain, high mechanical strength and excellent biocompatibility. PMID:27897215

  8. An experimental study of Ti and Zr partitioning among zircon, rutile, and granitic melt

    NASA Astrophysics Data System (ADS)

    Hofmann, Amy E.; Baker, Michael B.; Eiler, John M.

    2013-07-01

    In order to evaluate the effect of trace and minor elements (e.g., P, Y, and the REEs) on the high-temperature solubility of Ti in zircon (zrc), we conducted 31 experiments on a series of synthetic and natural granitic compositions [enriched in TiO2 and ZrO2; Al/(Na + K) molar 1.2] at a pressure of 10 kbar and temperatures of 1,400 to 1,200 °C. Thirty of the experiments produced zircon-saturated glasses, of which 22 are also saturated in rutile (rt). In seven experiments, quenched glasses coexist with quartz (qtz). SiO2 contents of the quenched liquids range from 68.5 to 82.3 wt% (volatile free), and water concentrations are 0.4-7.0 wt%. TiO2 contents of the rutile-saturated quenched melts are positively correlated with run temperature. Glass ZrO2 concentrations (0.2-1.2 wt%; volatile free) also show a broad positive correlation with run temperature and, at a given T, are strongly correlated with the parameter (Na + K + 2Ca)/(Si·Al) (all in cation fractions). Mole fraction of ZrO2 in rutile ( {Xnolimits_{{{{ZrO}}_{ 2} }}^{{rt}} } ) in the quartz-saturated runs coupled with other 10-kbar qtz-saturated experimental data from the literature (total temperature range of 1,400 to 675 °C) yields the following temperature-dependent expression: {{ln}}( {mathop X{{{{ZrO}}_{ 2} }}^{{rt}} } ) + {{ln}}( {a_{{{{SiO}}2 }} } ) = 2.638(149) - 9969(190)/T({{K}}) , where silica activity a_{{{{SiO}}2 }} in either the coexisting silica polymorph or a silica-undersaturated melt is referenced to α-quartz at the P and T of each experiment and the best-fit coefficients and their uncertainties (values in parentheses) reflect uncertainties in T and Xnolimits_{{{{ZrO}}2 }}^{{rt}} . NanoSIMS measurements of Ti in zircon overgrowths in the experiments yield values of 100 to 800 ppm; Ti concentrations in zircon are positively correlated with temperature. Coupled with values for a_{{{{SiO}}2 }} and a_{{{{TiO}}2 }} for each experiment, zircon Ti concentrations (ppm) can be related to

  9. Effect of Zr addition on the mechanical characteristics and wear resistance of Al grain refined by Ti after extrusion

    NASA Astrophysics Data System (ADS)

    Zaid, Adnan I. O.; Al-Qawabah, S. M. A.

    2016-08-01

    Aluminum and its alloys are normally grain refined by Ti or Ti+B to transfer their columnar structure during solidification into equiaxed one which improves their mechanical behavior and surface quality. In this paper, the effect of addition of Zr on the metallurgical, and mechanical aspects, hardness, ductility and wear resistance of commercially pure aluminum grain refined by Ti after extrusion is investigated. Zr was added at a level of 0.1% which corresponds to the peretectic limit at the Al-Zr phase diagram. The experimental work was carried out on the specimens after direct extrusion. It was found that addition of Ti resulted in decrease of Al grain size, whereas addition of Zr alone or in the presence of Ti, resulted in reduction of Al grain size. This led to increase of Al hardness. The effect of the addition of Ti or Zr alone resulted almost in the same enhancement of Al mechanical characteristics. As for the strain hardening index,n, increase was obtained when Zr was added alone or in the presence of Ti. Hence pronounced improvement of its formability. Regarding the effect of Zr addition on the wear resistance of aluminum; it was found that at small loads and speeds addition of Ti or Zr or both together resulted in deterioration of its wear resistance whereas at higher loads and speeds resulted in pronounced improvement of its wear resistance. Finally, the available Archard model and the other available models which consider only the mass loss failed to describe the wear mechanism of Al and its micro-alloys because they do not consider the mushrooming effect at the worn end.

  10. Phase stability and elastic modulus of Ti alloys containing Nb, Zr, and/or Sn from first-principles calculations

    SciTech Connect

    Hu Qingmiao; Li Shujun; Hao Yulin; Yang Rui; Johansson, Boerje; Vitos, Levente

    2008-09-22

    The alloying effects of Nb, Zr, and/or Sn on the phase stability and elastic properties of Ti are investigated by using a first-principles method. Our calculation results indicate that a carefully designed Ti-Nb-Zr-Sn system can be a good candidate for low modulus biomedical materials. We find that the well-known correlation between the e/a ratio and both elastic and phase stabilities for Ti alloyed with transition metal elements breaks down for the Ti-Sn alloy.

  11. Photo-induced and electrooptic properties of (Pb,La)(Zr,Ti)O{sub 3} films

    SciTech Connect

    Dimos, D.; Warren, W.L.; Tuttle, B.A.

    1993-07-01

    Photo-induced changes in the hysteresis behavior of sol-gel derived Pb(Zr,Ti)O{sub 3} (PZT) and (Pb,La)(Zr,Ti)O{sub 3} (PLZT) films have been characterized. Film photosensitivity has been evaluated with respect to magnitude of effects, time response and spectral dependence. Photo-induced hysteresis changes exhibit a stretched-exponential time dependence, which implies a dispersive mechanism. The spectral dependence is strongly peaked at the band edge ({approximately} 3.4 eV), which indicates that generation of electron-hole pairs in the material is critical. The photo-induced hysteresis changes are reproducible and stable, which indicates that the controlling charge traps are stable. However, improvements in film photosensitivity will be required to develop these materials for optical memory applications.

  12. Impedance Spectroscopic Studies of BiFeO3-Pb(ZrTi)O3 Nanocomposites

    NASA Astrophysics Data System (ADS)

    Choudhary, R. N. P.; Barik, Subrat K.; Katiyar, R. S.

    BiFeO3-Pb(ZrTi)O3 [i.e., (Bi1-xPbx)(Fe1-xZr0.6xTi0.4x)O3 (x = 0.15, 0.25, 0.40, 0.50)] nanocomposites were synthesized using mechanical activation followed by a solid-state reaction technique. The dielectric parameters (capacitance, dissipation factor D, impedance Z and phase angle Φ) of all the samples were measured in a wide range of frequencies (1 kHz-1 MHz) and temperatures (300-630 K) in air atmosphere using an impedance analyzer with low signal amplitude of 500 mV. Electrical properties of the compounds were studied using a complex impedance spectroscopy (CIS) technique. The frequency dependence of electrical data was analyzed in the framework of conductivity and modulus formalisms. AC conductivity spectrum obeys Jonscher's universal power law.

  13. Molecular dynamics study of the ternary Cu50Ti25Zr25 bulk glass forming alloy

    NASA Astrophysics Data System (ADS)

    Senturk Dalgic, S.; Celtek, M.

    2011-05-01

    The structure and thermodynamic properties of a ternary Cu50Ti25Zr25 metallic glass forming alloy in solid-liquid to glass phases were studied using molecular dynamics (MD) method based on tight-binding (TB) potentials. An atomic description of the melting, glass formation and crystallization process has been analyzed using different heating and cooling rates. The computed Glass Forming Ability (GFA) parameters are in good agreement with experimental data. The structure analysis of the Cu50Ti25Zr25 based on molecular dynamics simulation will be also presented and compared with available MD results. We have also discussed the crystallization transition with two different interatomic potentials used in this work

  14. Partial amorphization of a Cu-Zr-Ti alloy by high pressure torsion

    SciTech Connect

    Revesz, Adam; Hobor, Sandor; Labar, Janos L.; Zhilyaev, Alex P.; Kovacs, Zsolt

    2006-11-15

    High pressure torsion was applied to produce disk-shape specimen of Cu{sub 60}Zr{sub 20}Ti{sub 20} composition. Radial dependence of the microstructure was monitored by x-ray diffraction, scanning, and transmission electron microscopies. The disk consists of a top surface layer, homogeneous on a micrometer scale with an average thickness of 10-20 {mu}m, and an inhomogeneous bulk region of 200 {mu}m thickness. Calorimetric studies revealed that the disk contains detectable amount of amorphous phase. Characteristics of this amorphous content were compared to a fully amorphous melt-quenched Cu{sub 60}Zr{sub 20}Ti{sub 20} ribbon.

  15. Low temperature electrical conductance in (FeCoZr)x(PbZrTiO3)(100-x) nanocomposite films

    NASA Astrophysics Data System (ADS)

    Boiko, Oleksandr

    2016-09-01

    In this paper, the temperature and frequency dependences of conductivity, capacity and phase angle of two nanocomposite samples containing Fe0.45Co0.45Zr0.10 - based nanoparticles embedded in a doped PbZrTiO3 ferroelectric matrix were studied. AC measurements have been performed for the low temperatures (15 K <= TP) and within frequency range 50 Hz - 1 MHz. The nanocomposites studied were deposited by ion beam sputtering with use of different synthesis atmosphere in a vacuum chamber. The samples were subdued by a 15-min annealing in air in the temperatures of TA1 = 698 K and TA2 = 623 K. It was found that for the nanocomposite sample produced using low oxygen content in the synthesis atmosphere (x1 = 57.6 at.%) negative values of phase angle θ occur, which indicates capacitive type of conduction in the material. We can also notice the strong rapid frequency and temperature dependences of conductivity for this sample. It can be related with hopping carrier transport in the nanocomposite. For the nanocomposite sample with x2 = 57.6 at.%, which was produced using high oxygen content in the synthesis atmosphere we can observe occurrence of positive values of θ for frequencies f > 5×104 Hz. It can be related with the additional oxidation of Fe0.45Co0.45Zr0.10 nanoparticles during the annealing process (potential barriers surround nanoparticles). The type of carrier transport in the nanocomposite samples is defined as hopping.

  16. Speculation of equilibrium pressure of Ti36Zr40Ni20Pd4 icosahedral quasicrystal

    NASA Astrophysics Data System (ADS)

    Huang, Huogen; Chen, Liang

    2015-08-01

    Ti-Zr-Ni quasicrystals have been demonstrated to store a large number of hydrogen atoms, which implies strong potential application in hydrogen energy field for them. However, the desorption of hydrogen atoms in the quasicrystals is quite difficult, with the indication of high desorption temperature and slow desorption rate. The shortage limits their use in the field to a large extent. But this kind of quasicrystals might be used in nuclear fusion energy field, because tritium as a coral fuel for nuclear fusion needs tight storage. However, equilibrium pressure at room temperature of Ti-Zr-Ni quasicrystals, important for their application in fusion energy field, has not been clear yet. In this work, we designed a gas-solid reaction system with the pressure resolution of 10-8Pa and carried out hydrogen desorption investigation at different temperatures on Ti36Zr40Ni20Pd4 icosahedral quasicrystal. Based on three Pressure-Composition-Temperature desorption curves, we speculate according to Van't Hoff theory about hydrogen storage that its equilibrium pressure at room temperature could be at the magnitude of 10-6Pa, displaying good stability of hydrogen in the quasicrystal and also implying application prospects in fusion energy field for quasicrystals of this type.

  17. Microstructural and Mechanical Characterization of Ti-12Mo-6Zr Biomaterials Fabricated by Spark Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Daoush, Walid Mohamed Rashad Mohamed; Park, Hee Sup; Inam, Fawad; Lim, Byung Kyu; Hong, Soon Hyung

    2015-03-01

    Ti-12Mo-6Zr/Al2O3 (titanium biomaterial) was prepared by a powder metallurgy route using Spark Plasma Sintering (SPS). Ti, Mo, and Zr powders were mixed by wet milling with different content of alumina nanoparticles (up to 5 wt pct) as an oxide dispersion strengthening phase. Composite powder mixtures were SPSed at 1273 K (1000 °C) followed by heat treatment and quenching. Composite powders, sintered materials, and heat-treated materials were examined using optical and high-resolution electronic microscopy (scanning and transmission) and X-ray diffraction to characterize particle size, surface morphology, and phase identifications for each composition. All sintered materials were evaluated by measuring density, Vickers hardness, and tensile properties. Fully dense sintered materials were produced by SPS and mechanical properties were found to be improved by subsequent heat treatment. The tensile properties as well as the hardness were increased by increasing the content of Al2O3 nanoparticles in the Ti-12Mo-6Zr matrix.

  18. A theoretical study of the low-lying states of Ti2 and Zr2

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.; Rosi, Marzio

    1991-01-01

    The low-lying states of Ti2 and the valence isoelectronic Zr2 are examined theoretically by means of a multireference configuration-interaction (MRCI) method. MRCI calculations demonstrate that two of the Zr2 states are very low-lying and that the resulting vertical excitation is consistent with the optical spectrum of Zr2. The ground state is predicted for Ti2 on the basis of valence correlation with the MRCI method and the average coupled-pair functional technique. Calculations of the inner-shell correlation effects are estimated and found to lower the 3Delta g state to a ground state, and another to a very low-lying state. The ground state of Ti2 is assigned to 3Delta g since it is lower than the other state at all levels of correlation and is derived from the same atomic asymptote. This conclusion is supported by the lack of an electron-spin resonance signal but contradicts the absence of subcomponents on the Raman spectral lines.

  19. Dynamic Embrittlement in Cu-Cr-Zr-Ti Alloy: Evidence of Intergranular Segregation of Sulphur

    NASA Astrophysics Data System (ADS)

    Chenna Krishna, S.; Radhika, K. V.; Tharian, K. Thomas; Swathi Kiranmayee, M.; Sudarshan Rao, G.; Jha, Abhay K.; Pant, Bhanu

    2013-08-01

    In the present investigation, Cu-0.6Cr-0.005Zr-0.0045Ti alloy was subjected to different heat treatment and thermomechanical treatment (TMT) to simulate the conditions experienced during brazing and forming, respectively. Grain coarsening was observed in the samples subjected to heat treatment, and grain refinement was observed in the samples subjected to TMT. Tensile tests conducted with these samples at room temperature and 600 °C have shown that Cu-Cr-Zr-Ti alloy was susceptible to dynamic embrittlement (DE). However, the observation was limited to coarse-grained samples (280-350 μm) at 600 °C. On the other hand, the fine-grained samples (20-40 μm) showed good ductility. Electron microscopy studies conducted on the tensile-tested specimens prone to DE indicated the presence of sulfur on the fractured surface and intergranular segregation of sulfur. Therefore, it can be inferred from the results that DE due to sulfur can occur in Cu-Cr-Zr-Ti alloy at elevated temperature for coarse-grained samples.

  20. The structural, electronic and magnetic properties of quaternary Heusler alloy TiZrCoIn

    NASA Astrophysics Data System (ADS)

    Yan, Peng-Li; Zhang, Jian-Min; Xu, Ke-Wei

    2016-04-01

    Employing the first-principles calculations, we have investigated the structural, electronic and magnetic properties of quaternary Heusler alloy TiZrCoIn. The TiZrCoIn alloy with type (I) configuration is predicted to be half-metallic ferromagnet at its equilibrium lattice constant 6.525 Å with an indirect band gap of 0.930 eV in minority spin channel. The total magnetic moment is 2 μB/f.u., following the Slater-Pauling rule μt=Zt-18. Moreover, the negative formation energy indicates the thermodynamical stability of this alloy. The band gap of minority spin channel is determined by the bonding (t2g) and antibonding (t1u) states created from the hybridizations of the d states of transition metal atoms Ti, Zr and Co. In addition, the HM, character is kept as hydrostatic strain ranged from -10% to 7.6% and tetragonal strain ranged from -19% to 27%.

  1. Bioactivity of coatings formed on Ti-13Nb-13Zr alloy using plasma electrolytic oxidation.

    PubMed

    Sowa, Maciej; Piotrowska, Magdalena; Widziołek, Magdalena; Dercz, Grzegorz; Tylko, Grzegorz; Gorewoda, Tadeusz; Osyczka, Anna M; Simka, Wojciech

    2015-04-01

    In this work, we investigated the bioactivity of anodic oxide coatings on Ti-13Nb-13Zr alloy by plasma electrolytic oxidation (PEO) in solutions containing Ca and P. The bioactive properties of the films were determined by immersion in simulated body fluid (SBF), and their biocompatibility was examined using adult human bone marrow derived mesenchymal stem cells (hBMSCs). The oxide layers were characterised based on their surface morphology (SEM, AFM, profilometry) as well as on their chemical and phase compositions (EDX, XRF, XRD, XPS). We report that anodic oxidation of Ti-13Nb-13Zr led to the development of relatively thick anodic oxide films that were enriched in Ca and P in the form of phosphate compounds. Furthermore, the treatment generated rough surfaces with a significant amount of open pores. The surfaces were essentially amorphous, with small amounts of crystalline phases (anatase and rutile) being observed, depending on the PEO process parameters. SBF soaking led to the precipitation of small crystals after one week of experiment. During culturing of hBMSCs on the bioactive Ti-13Nb-13Zr surfaces the differentiation of human mesenchymal stem cells toward osteoblasts was promoted, which indicated a potential of the modified materials to improve implant osseointegration.

  2. Structural and electronic properties of Sr(Zr,Ti)O3 alloys for use in oxide heterostructures

    NASA Astrophysics Data System (ADS)

    Weston, Leigh; Janotti, Anderson; Cui, Xiangyuan; Himmetoglu, Burak; Stampfl, Catherine; van de Walle, Chris G.

    Sr(Ti,Zr)O3 alloys are promising materials for use in oxide heterostructures, however the fundamental properties of this system have not yet been characterized. Using hybrid density functional calculations, we study the electronic and structural properties of ordered SrTixZr1-xO3 alloys at x=0, 0.25, 0.5, 0.75, and 1. As Ti is added to SrZrO3, the lattice parameter is reduced according to Vegard's law, while the band gap shows a large bowing and is sensitive to the Ti distribution. For x=0.5, arranging the Ti and Zr atoms into a 1 ×1 SrZrO3/SrTiO3 superlattice along the [001] direction leads to a highly dispersive single band at the conduction-band minimum (CBM) that is absent in the parent compounds, and a direct gap close to that of pure SrTiO3. This is explained by the splitting of the Ti 3 d t2 g states in the reduced symmetry of the superlattice, lowering the band originating from the Ti 3dxy orbitals. The lifting of the orbital degeneracy around the CBM suppresses scattering due to electron-phonon interactions. We propose that short-period SrZrO3/SrTiO3 superlattices could be exploited to engineer the band structure and improve carrier mobility compared to bulk SrTiO3. This work was supported by NSF, ONR and ARC.

  3. Interfacial Behavior and Its Effect on Mechanical Properties of Cf/SiC Composite/TiAl6V4 Joint Brazed with TiZrCuNi

    NASA Astrophysics Data System (ADS)

    Fan, Dongyu; Huang, Jihua; Cui, Bing; Yang, Jian; Chen, Shuhai; Zhao, Xingke

    2017-02-01

    In order to characterize the interfacial behavior of brazed joints and offer theoretical basis for the applications of TiZrCuNi-based composite fillers, Cf/SiC composite and TC4 were brazed by TiZrCuNi filler, and the microstructures of joints versus temperature and versus holding time were systematically studied in this paper. The mechanical properties of brazed joints were measured and analyzed. The results showed that Ti(Zr)C, Ti5Si3, Ti2Cu, TiNi, TiZrCu2, Ti2(Cu,Ni) and Ti(s,s) were the predominant compounds in the joints. Brazing temperature had a distinct effect on the microstructures of joints: with the increase of brazing temperature, the structure of brazed joints was reduced from four parts to three parts, and the wavy reaction layer became continuous and much thicker. While holding time had a similar but weaker effect on microstructures: with the extension of holding time, the reaction layer became thicker, but it was difficult to induce the decrease in the structural parts of joint. The thickness of reaction layer determined the mechanical properties of joints. The results were beneficial for the selection of reinforced phases and the design of composite fillers to obtain better mechanical performances. When the brazing temperature was 940 °C and the holding time was 25 min, the maximum shear strength of brazed joints attained a value of 143.2 MPa.

  4. 17O NMR studies of local structure and phase evolution for materials in the Y 2Ti 2O 7-ZrTiO 4 binary system

    NASA Astrophysics Data System (ADS)

    Palumbo, John L.; Schaedler, Tobias A.; Peng, Luming; Levi, Carlos G.; Grey, Clare P.

    2007-07-01

    17O MAS NMR and XRD studies of precursor-derived Y 1.6Zr 0.4Ti 2O 7.2 and Y 1.2Zr 0.8Ti 2O 7.4 have been performed to investigate the development of local and long-range order in these materials as they evolve from a metastable amorphous state upon heating. Zirconium titanate (ZrTiO 4) was also investigated to help interpret the 17O NMR spectra of the ternary compositions. Consistent with earlier studies, crystallization was observed at 800 °C to form a fluorite structure and a small amount of rutile; weak broad reflections were also observed which were ascribed to the presence of small pyrochlore-like ordered domains or particles within the fluorite phase. As the temperature was increased further, the sizes of these domains grew along with the concentration of rutile. At the highest temperature studied (1300 °C), the reflections of the thermodynamic phases, pyrochlore and zirconium titanate (ZrTiO 4), dominated the XRD pattern. The 17O NMR spectra revealed a series of different peaks that were assigned to different 3- and 4-coordinate O local environments. The data were consistent with the formation of a metastable phase Y 2-xZr xTi 2-yZr yO 7+x with pyrochlore-like ordering but with Zr substitution on both cation sites of the pyrochlore structure. At low temperatures, doping on the A (Y 3+) sites predominates (i.e., x> y), consistent with the fact that the pyrochlore develops out of a more disordered fluorite-like, phase. As the temperature is raised, the Zr doping on the A site decreases and the metastable phase at this temperature can now be written as Y 2-x'Zr x'Ti 2-y'Zr y'O 7+x' (i.e., x'< y'); TiO 2 is also observed, consistent with this suggestion. At high temperatures, doping on the B site decreases and the resonances due to the stoichiometric pyrochlore yttrium titanate (Y 2Ti 2O 7) dominate the NMR spectra. Weaker 17O NMR resonances due zirconium titanate (ZrTiO 4) are also observed.

  5. Increasing Ti-6Al-4V brazed joint strength equal to the base metal by Ti and Zr amorphous filler alloys

    SciTech Connect

    Ganjeh, E.; Sarkhosh, H.; Bajgholi, M.E.; Khorsand, H.; Ghaffari, M.

    2012-09-15

    Microstructural features developed along with mechanical properties in furnace brazing of Ti-6Al-4V alloy using STEMET 1228 (Ti-26.8Zr-13Ni-13.9Cu, wt.%) and STEMET 1406 (Zr-9.7Ti-12.4Ni-11.2Cu, wt.%) amorphous filler alloys. Brazing temperatures employed were 900-950 Degree-Sign C for the titanium-based filler and 900-990 Degree-Sign C for the zirconium-based filler alloys, respectively. The brazing time durations were 600, 1200 and 1800 s. The brazed joints were evaluated by ultrasonic test, and their microstructures and phase constitutions analyzed by metallography, scanning electron microscopy and X-ray diffraction analysis. Since microstructural evolution across the furnace brazed joints primarily depends on their alloying elements such as Cu, Ni and Zr along the joint. Accordingly, existence of Zr{sub 2}Cu, Ti{sub 2}Cu and (Ti,Zr){sub 2}Ni intermetallic compounds was identified in the brazed joints. The chemical composition of segregation region in the center of brazed joints was identical to virgin filler alloy content which greatly deteriorated the shear strength of the joints. Adequate brazing time (1800 s) and/or temperature (950 Degree-Sign C for Ti-based and 990 Degree-Sign C for Zr-based) resulted in an acicular Widmanstaetten microstructure throughout the entire joint section due to eutectoid reaction. This microstructure increased the shear strength of the brazed joints up to the Ti-6Al-4V tensile strength level. Consequently, Ti-6Al-4V can be furnace brazed by Ti and Zr base foils produced excellent joint strengths. - Highlights: Black-Right-Pointing-Pointer Temperature or time was the main factors of controlling braze joint strength. Black-Right-Pointing-Pointer Developing a Widmanstaetten microstructure generates equal strength to base metal. Black-Right-Pointing-Pointer Brittle intermetallic compounds like (Ti,Zr){sub 2}Ni/Cu deteriorate shear strength. Black-Right-Pointing-Pointer Ti and Zr base filler alloys were the best choice for brazing Ti

  6. Experimental partitioning of Zr, Ti, and Nb between silicate liquid and a complex noble metal alloy and the partitioning of Ti between perovskite and platinum metal

    NASA Technical Reports Server (NTRS)

    Jurewicz, Stephen R.; Jones, John H.

    1993-01-01

    El Goresy et al.'s observation of Nb, Zr, and Ta in refractory platinum metal nuggets (RPMN's) from Ca-Al-rich inclusions (CAI's) in the Allende meteorite led them to propose that these lithophile elements alloyed in the metallic state with noble metals in the early solar nebula. However, Grossman pointed out that the thermodynamic stability of Zr in the oxide phase is vastly greater than metallic Zr at estimated solar nebula conditions. Jones and Burnett suggested this discrepancy may be explained by the very non-ideal behavior of some lithophile transition elements in noble metal solutions and/or intermetallic compounds. Subsequently, Fegley and Kornacki used thermodynamic data taken from the literature to predict the stability of several of these intermetallic compounds at estimated solar nebula conditions. Palme and Schmitt and Treiman et al. conducted experiments to quantify the partitioning behavior of certain lithophile elements between silicate liquid and Pt-metal. Although their results were somewhat variable, they did suggest that Zr partition coefficients were too small to explain the observed 'percent' levels in some RPMN's. Palme and Schmitt also observed large partition coefficients for Nb and Ta. No intermetallic phases were identified. Following the work of Treiman et al., Jurewicz and Jones performed experiments to examine Zr, Nb, and Ti partitioning near solar nebula conditions. Their results showed that Zr, Nb, and Ti all have an affinity for the platinum metal, with Nb and Ti having a very strong preference for the metal. The intermetallic phases (Zr,Fe)Pt3, (Nb,Fe)Pt3, and (Ti,Fe)Pt3 were identified. Curiously, although both experiments and calculations indicate that Ti should partition strongly into Pt-metal (possibly as TiPt3), no Ti has ever been observed in any RPMN's. Fegley and Kornacki also noticed this discrepancy and hypothesized that the Ti was stabilized in perovskite which is a common phase in Allende CAI's.

  7. Microstructural Evolution of the Interface Between Pure Titanium and Low Melting Point Zr-Ti-Ni(Cu) Filler Metals

    NASA Astrophysics Data System (ADS)

    Lee, Dongmyoung; Sun, Juhyun; Kang, Donghan; Shin, Seungyoung; Hong, Juhwa

    2014-12-01

    Low melting point Zr-based filler metals with melting point depressants (MPDs) such as Cu and Ni elements are used for titanium brazing. However, the phase transition of the filler metals in the titanium joint needs to be explained, since the main element of Zr in the filler metals differs from that of the parent titanium alloys. In addition, since the MPDs easily form brittle intermetallics, that deteriorate joint properties, the phase evolution they cause needs to be studied. Zr-based filler metals having Cu content from 0 to 12 at. pct and Ni content from 12 to 24 at. pct with a melting temperature range of 1062 K to 1082 K (789 °C to 809 °C) were wetting-tested on a titanium plate to investigate the phase transformation and evolution at the interface between the titanium plate and the filler metals. In the interface, the alloys system with Zr, Zr2Ni, and (Ti,Zr)2Ni phases was easily changed to a Ti-based alloy system with Ti, Ti2Ni, and (Ti,Zr)2Ni phases, by the local melting of parent titanium. The dissolution depths of the parent metal were increased with increasing Ni content in the filler metals because Ni has a faster diffusion rate than Cu. Instead, slow diffusion of Cu into titanium substrate leads to the accumulation of Cu at the molten zone of the interface, which could form undesirable Ti x Cu y intermetallics. This study confirmed that Zr-based filler metals are compatible with the parent titanium metal with the minimum content of MPDs.

  8. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    PubMed Central

    2013-01-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail. PMID:24369051

  9. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors.

    PubMed

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-12-26

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

  10. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-12-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

  11. Influence of alloying elements Nb, Zr, Sn, and oxygen on structural stability and elastic properties of the Ti2448 alloy

    NASA Astrophysics Data System (ADS)

    Dai, J. H.; Song, Y.; Li, W.; Yang, R.; Vitos, L.

    2014-01-01

    The mechanisms of how alloying elements and oxygen influence the stability and elastic properties of binary Ti-X (X = Nb, Zr, or Sn) and Ti2448 (Ti-24Nb-4Zr-8Sn in wt.%) alloys are studied via first principles calculations. In addition to the fully disordered solid solution phase, we consider 44 quasirandom configurations to search for the possible distributions of the alloying elements in Ti2448. Our results show that all alloying elements considered here are good β-stabilizers for Ti, and the formation energies are greatly affected by their distributions. The site preference of oxygen and its concentration dependence in binary Ti alloys and in Ti2448 are also investigated. Oxygen prefers to occupy the octahedral site regardless of the concentrations of the alloys and strongly interacts with Ti and Nb in Ti-Nb. The elastic properties of Ti2448 alloy and the influence of oxygen on the elastic parameters are evaluated. The calculated polycrystalline Young's modulus of the Ti2448 alloy is very close to that of the human bone (10-40 GPa). We find that oxygen has a weak effect on the elastic moduli of Ti2448. The electronic structures are analyzed to reveal how the alloying elements and oxygen influence the stability of binary Ti-X and Ti2448 alloys.

  12. Preparation and wear resistance of Ti-Zr-Ni quasicrystal and polyamide composite materials

    NASA Astrophysics Data System (ADS)

    Wang, Xinlu; Li, Xuesong; Zhang, Zhenjiang; Zhang, Shanshan; Liu, Wanqiang; Wang, Limin

    2011-07-01

    Ti-Zr-Ni icosahedral quasicrystal powders (Ti-QC), prepared by mechanical alloying and then annealing in a vacuum furnace, were used as a novel filler material in polyamide 12 (PA12). The melt processability of the composite was studied using a Haake torque rheometer. This indicates that PA12/Ti-QC composites can be melt-processed into a wear-resistant material. Further, these composites, fabricated by compression molding, were tested in sliding wear against a polished bearing steel counterface. The results from wear testing show that the addition of Ti-QC filler to PA12 enhances wear resistance and reduces volume loss by half compared with neat PA12. Furthermore, it is found that the hardness of the composite increases with increasing content of Ti-QC filler. In addition, PA12/Ti-QC composites exhibit a slightly higher crystallization temperature and better thermal stability than PA12. These combined results demonstrate that Ti-QC filler may be a desirable alternative when attempting to increase the wear resistance of PA12.

  13. Phase evolution, microstructure and mechanical properties of equi-atomic substituted TiZrHfNiCu and TiZrHfNiCuM (M = Co, Nb) high-entropy alloys

    NASA Astrophysics Data System (ADS)

    Park, Hae Jin; Na, Young Sang; Hong, Sung Hwan; Kim, Jeong Tae; Kim, Young Seok; Lim, Ka Ram; Park, Jin Man; Kim, Ki Buem

    2016-07-01

    In this study, alloys with composition of equi-atomic substituted TiZrHfNiCu, TiZrHfNiCuCo, and TiZrHfNiCuNb high-entropy alloys (HEAs) were produced by suction casting method. The effects of addition elements on phase composition, microstructure and mechanical behaviors of the HEA were studied. The suction casted Ti20Zr20Hf20Ni20Cu20 HEA exhibits single C14 Laves phase (MgZn2-type) with fine homogeneous microstructure. When Co or Nb elements are added, morphologies are slightly modulated toward well-developed dendritic microstructure, phase constitutions are significantly changed from single Laves phase to mixed multi-phases as well as mechanical properties are also altered with increased plasticity and high strength. It is believed that modulated mechanical properties are mainly ascribed to the change of phase constitution and crystalline structure, together with the microstructural characteristics. This clearly reveals that the selection and addition of supplementary elements based on the formation rule for HEAs play an important role on the evolution of phase, microstructural morphology and mechanical properties of Ti20Zr20Hf20Ni20Cu20 HEA.

  14. Histomorphometric and histologic evaluation of titanium-zirconium (aTiZr) implants with anodized surfaces.

    PubMed

    Sharma, Ajay; McQuillan, A James; Shibata, Yo; Sharma, Lavanya A; Waddell, John Neil; Duncan, Warwick John

    2016-05-01

    The choice of implant surface has a significant influence on osseointegration. Modification of TiZr surface by anodization is reported to have the potential to modulate the osteoblast cell behaviour favouring more rapid bone formation. The aim of this study is to investigate the effect of anodizing the surface of TiZr discs with respect to osseointegration after four weeks implantation in sheep femurs. Titanium (Ti) and TiZr discs were anodized in an electrolyte containing DL-α-glycerophosphate and calcium acetate at 300 V. The surface characteristics were analyzed by scanning electron microscopy, electron dispersive spectroscopy, atomic force microscopy and goniometry. Forty implant discs with thickness of 1.5 and 10 mm diameter (10 of each-titanium, titanium-zirconium, anodized titanium and anodized titanium-zirconium) were placed in the femoral condyles of 10 sheep. Histomorphometric and histologic analysis were performed 4 weeks after implantation. The anodized implants displayed hydrophilic, porous, nano-to-micrometer scale roughened surfaces. Energy dispersive spectroscopy analysis revealed calcium and phosphorous incorporation into the surface of both titanium and titanium-zirconium after anodization. Histologically there was new bone apposition on all implanted discs, slightly more pronounced on anodised discs. The percentage bone-to-implant contact measurements of anodized implants were higher than machined/unmodified implants but there was no significant difference between the two groups with anodized surfaces (P > 0.05, n = 10). The present histomorphometric and histological findings confirm that surface modification of titanium-zirconium by anodization is similar to anodised titanium enhances early osseointegration compared to machined implant surfaces.

  15. Mechanical and electrochemical characterisation of new Ti-Mo-Nb-Zr alloys for biomedical applications.

    PubMed

    Nnamchi, Paul S; Obayi, C S; Todd, Iain; Rainforth, M W

    2016-07-01

    The development and characterisation of new metallic biomaterials that contain non-toxic and non-allergic elements but possess low elastic modulus and low biodegradation rates, has become a topic of serious investigation in orthopaedic implant application. The lowering of elastic modulus and improving of corrosion resistance can be achieved by specific chemical alloying and super-elasticity effects, associated with a stress-induced phase transformation from the BCC metastable beta phase to the orthorhombic α″ martensite. Using this framework, this paper focuses on the effect of Nb and/or Zr micro-additions on the elastic modulus/yield strength balance and discusses microstructure, and the mechanical and electrochemical behaviour of four new β-Ti-8Mo-xNb-xZr (x=2-5) alloys, using tensile tests, X-ray diffraction, SEM characterisation, ultrasound technique and potentiodynamic polarisation methods. The results reveal that the alloys exhibit a pronounced microstructural sensitivity response, with alloying elements and excellent agreement between β-stability and high mechanical strength, with increasing Nb additions. Although all the alloys possess excellent corrosion resistance and low Young׳s modulus, Ti-8Mo-4Nb-2Zr alloy, which consists of β+α'' phases, exhibits a low Young modulus of 35GPa, which is lower than those of the commercial alloys already used in biomedical implantation. The significant corrosion resistance, nontoxicity and better mechanical compatibility are properties pertinent to preventing stress shielding and bone resorption in orthopaedic implant applications.

  16. Properties of Porous TiNbZr Shape Memory Alloy Fabricated by Mechanical Alloying and Hot Isostatic Pressing

    NASA Astrophysics Data System (ADS)

    Ma, L. W.; Chung, C. Y.; Tong, Y. X.; Zheng, Y. F.

    2011-07-01

    In the past decades, systematic researches have been focused on studying Ti-Nb-based SMAs by adding ternary elements, such as Mo, Sn, Zr, etc. However, only arc melting or induction melting methods, with subsequent hot or cold rolling, were used to fabricate these Ni-free SMAs. There is no work related to powder metallurgy and porous structures. This study focuses on the fabrication and characterization of porous Ti-22Nb-6Zr (at.%) shape memory alloys produced using elemental powders by means of mechanical alloying and hot isostatic pressing. It is found that the porous Ti-22Nb-6Zr alloys prepared by the HIP process exhibit a homogenous pore distribution with spherical pores, while the pores have irregular shape in the specimen prepared by conventional sintering. X-ray diffraction analysis showed that the solid solution-treated Ti-22Nb-6Zr alloy consists of both β phase and α″ martensite phase. Morphologies of martensite were observed. Finally, the porous Ti-22Nb-6Zr SMAs produced by both MA and HIP exhibit good mechanical properties, such as superior superelasticity, with maximum recoverable strain of ~3% and high compressive strength.

  17. Zr-doped TiO2 supported on delaminated clay materials for solar photocatalytic treatment of emerging pollutants.

    PubMed

    Belver, C; Bedia, J; Rodriguez, J J

    2017-01-15

    Solar light-active Zr-doped TiO2 nanoparticles were successfully immobilized on delaminated clay materials by a one-step sol-gel route. Fixing the amount of TiO2 at 65wt.%, this work studies the influence of Zr loading (up to 2%) on the photocatalytic activity of the resulting Zr-doped TiO2/clay materials. The structural characterization demonstrates that all samples were formed by a delaminated clay with nanostructured anatase assembled on its surface. The Zr dopant was successfully incorporated into the anatase lattice, resulting in a slight deformation of the anatase crystal and the reduction of the band gap. These materials exhibit high surface area with a disordered mesoporous structure formed by TiO2 particles (15-20nm) supported on a delaminated clay. They were tested in the solar photodegradation of antipyrine, usually used as an analgesic drug and selected as an example of emerging pollutant. High degradation rates have been obtained at low antipyrine concentrations and high solar irradiation intensities with the Zr-doped TiO2/clay catalyst, more effective than the undoped one. This work demonstrates the potential application of the synthesis method for preparing novel and efficient solar-light photocatalysts based on metal-doped anatase and a delaminated clay.

  18. First-principles phase diagram calculations for the rocksalt-structure quasibinary systems TiN-ZrN, TiN-HfN and ZrN-HfN

    NASA Astrophysics Data System (ADS)

    Liu, Z. T. Y.; Burton, B. P.; Khare, S. V.; Gall, D.

    2017-01-01

    We have studied the phase equilibria of three ceramic quasibinary systems Ti1-x Zr x N, Ti1-x Hf x N and Zr1-x Hf x N (0  ⩽  x  ⩽  1) with density functional theory, cluster expansion and Monte Carlo simulations. We predict consolute temperatures (T C), at which miscibility gaps close, for Ti1-x Zr x N to be 1400 K, for Ti1-x Hf x N to be 700 K, and below 200 K for Zr1-x Hf x N. The asymmetry of the formation energy ΔE f(x) is greater for Ti1-x Hf x N than Ti1-x Zr x N, with less solubility on the smaller cation TiN-side, and similar asymmetries were predicted for the corresponding phase diagrams. We also analyzed different energetic contributions: ΔE f of the random solid solutions were decomposed into a volume change term, Δ {{E}\\text{vc}} , and a chemical exchange and relaxation term, Δ {{E}\\text{xc\\text{-rlx}}} . These two energies partially cancel one another. We conclude that Δ {{E}\\text{vc}} influences the magnitude of T C and Δ {{E}\\text{xc\\text{-rlx}}} influences the asymmetry of ΔE f(x) and phase boundaries. We also conclude that the absence of experimentally observed phase separation in Ti1-x Zr x N and Ti1-x Hf x N is due to slow kinetics at low temperatures. In addition, elastic constants and mechanical properties of the random solid solutions were studied with the special quasirandom solution approach. Monotonic trends, in the composition dependence, of shear-related mechanical properties, such as Vickers hardness between 18 to 23 GPa, were predicted. Trends for Ti1-x Zr x N and Ti1-x Hf x N exhibit down-bowing (convexity). It shows that mixing nitrides of same group transition metals does not lead to hardness increase from an electronic origin, but through solution hardening mechanism. The mixed thin films show consistency and stability with little phase separation, making them desirable coating choices.

  19. First-principles phase diagram calculations for the rocksalt-structure quasibinary systems TiN-ZrN, TiN-HfN and ZrN-HfN.

    PubMed

    Liu, Z T Y; Burton, B P; Khare, S V; Gall, D

    2017-01-25

    We have studied the phase equilibria of three ceramic quasibinary systems Ti1-x Zr x N, Ti1-x Hf x N and Zr1-x Hf x N (0  ⩽  x  ⩽  1) with density functional theory, cluster expansion and Monte Carlo simulations. We predict consolute temperatures (T C), at which miscibility gaps close, for Ti1-x Zr x N to be 1400 K, for Ti1-x Hf x N to be 700 K, and below 200 K for Zr1-x Hf x N. The asymmetry of the formation energy ΔE f(x) is greater for Ti1-x Hf x N than Ti1-x Zr x N, with less solubility on the smaller cation TiN-side, and similar asymmetries were predicted for the corresponding phase diagrams. We also analyzed different energetic contributions: ΔE f of the random solid solutions were decomposed into a volume change term, [Formula: see text], and a chemical exchange and relaxation term, [Formula: see text]. These two energies partially cancel one another. We conclude that [Formula: see text] influences the magnitude of T C and [Formula: see text] influences the asymmetry of ΔE f(x) and phase boundaries. We also conclude that the absence of experimentally observed phase separation in Ti1-x Zr x N and Ti1-x Hf x N is due to slow kinetics at low temperatures. In addition, elastic constants and mechanical properties of the random solid solutions were studied with the special quasirandom solution approach. Monotonic trends, in the composition dependence, of shear-related mechanical properties, such as Vickers hardness between 18 to 23 GPa, were predicted. Trends for Ti1-x Zr x N and Ti1-x Hf x N exhibit down-bowing (convexity). It shows that mixing nitrides of same group transition metals does not lead to hardness increase from an electronic origin, but through solution hardening mechanism. The mixed thin films show consistency and stability with little phase separation, making them desirable coating choices.

  20. Effect of atomic size on undercoolability of binary solid solution alloy liquids with Zr, Ti, and Hf using electrostatic levitation.

    PubMed

    Jeon, S; Kang, D-H; Lee, Y H; Lee, S; Lee, G W

    2016-11-07

    We investigate the relationship between the excess volume and undercoolability of Zr-Ti and Zr-Hf alloy liquids by using electrostatic levitation. Unlike in the case of Zr-Hf alloy liquids in which sizes of the constituent atoms are matched, a remarkable increase of undercoolability and negative excess volumes are observed in Zr-Ti alloy liquids as a function of their compositional ratios. In this work, size mismatch entropies for the liquids were obtained by calculating their hard sphere diameters, number densities, and packing fractions. We also show that the size mismatch entropy, which arises from the differences in atomic sizes of the constituent elements, plays an important role in determining the stabilities of metallic liquids.

  1. Effect of atomic size on undercoolability of binary solid solution alloy liquids with Zr, Ti, and Hf using electrostatic levitation

    NASA Astrophysics Data System (ADS)

    Jeon, S.; Kang, D.-H.; Lee, Y. H.; Lee, S.; Lee, G. W.

    2016-11-01

    We investigate the relationship between the excess volume and undercoolability of Zr-Ti and Zr-Hf alloy liquids by using electrostatic levitation. Unlike in the case of Zr-Hf alloy liquids in which sizes of the constituent atoms are matched, a remarkable increase of undercoolability and negative excess volumes are observed in Zr-Ti alloy liquids as a function of their compositional ratios. In this work, size mismatch entropies for the liquids were obtained by calculating their hard sphere diameters, number densities, and packing fractions. We also show that the size mismatch entropy, which arises from the differences in atomic sizes of the constituent elements, plays an important role in determining the stabilities of metallic liquids.

  2. Cytocompatibility and early osseointegration of nanoTiO2-modified Ti-24 Nb-4 Zr-7.9 Sn surfaces.

    PubMed

    Liu, X H; Wu, L; Ai, H J; Han, Y; Hu, Y

    2015-03-01

    This study aimed to evaluate the cytocompatibility and early osseointegration of Ti-24 Nb-4 Zr-7.9 Sn (Ti-2448) surfaces that were modified with a nanoscale TiO2 coating. The coating was fabricated using a hydrothermal synthesis method to generate nanoTiO2/Ti-2448. The surface characteristics of the samples were evaluated using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The cytotoxicity of the fabricated nanoTiO2/Ti-2448 was determined using MTT assays. The proliferation and alkaline phosphatase (ALP) activity of MC3T3-E1 osteoblasts cultured on nanoTiO2/Ti-2448 were compared with those cultured on Ti-2448. Disk-shaped implants were placed in Wistar rats. The histological sections were stained with haematoxylin and eosin (HE), and the histocompatibility was analysed at 4 and 12weeks post-implantation. Cylindrical implants were embedded in Japanese white rabbits, and the histological sections were stained with HE and anti-TGF-β1 to evaluate the histocompatibility and early osseointegration at 4, 12 and 26weeks post-implantation. NanoTiO2/Ti-2448 exhibited a rougher surface than did Ti-2448. NanoTiO2/Ti-2448 was determined to be non-cytotoxic. More osteoblasts and higher ALP activity were observed for nanoTiO2/Ti-2448 than Ti-2448 (p<0.05). Few inflammatory cells were detected around nanoTiO2/Ti-2448, and the expression of TGF-β1 on nanoTiO2/Ti-2448 peaked at earlier time than that on Ti-2448. The results indicate that the cytocompatibility and early osseointegration were enhanced by the nanoTiO2 coating.

  3. Preparation and Characterization of BaTiO3-PbZrTiO3 Coating for Pyroelectric Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Raghavendra, R. M.; Praneeth, K. P. S. S.; Dutta, Soma

    2017-01-01

    Harvesting energy from waste heat is a promising field of research as there are significant energy recovery opportunities from various waste thermal energy sources. The present study reports pyroelectric energy harvesting using thick film prepared from a (x)BaTiO3-(1 - x)PbZr0.52Ti0.48O3 (BT-PZT) solid solution. The developed BT-PZT system is engineered to tune the ferro to paraelectric phase transition temperature of it in-between the phase transition temperature of BaTiO3 (393 K) and PbZrTiO3 (573 K) with higher pyroelectric figure-of-merit (FOM). The temperature-dependent dielectric behavior of the material has revealed the ferro- to paraelectric phase transition at 427 K with a maximum dielectric constant of 755. The room-temperature (298 K) pyroelectric coefficient (Pi) of the material was obtained as 738.63 μC/m2K which has yielded a significantly high FOM of 1745.8 J m-3 K-2. The enhancement in pyroelectric property is attributed to the morphotopic phase transition between tetragonal and rhombohedral PZT phases in the BT-PZT system. The developed BT-PZT system is capable of generating a power output of 1.3 mW/m2 near the Curie temperature with a constant rate (0.11 K/s) of heating. A signal conditioning circuit has been developed to rectify the time-varying current and voltage signals obtained from the harvester during heating cycles. The output voltage generated by the pyroelectric harvester has been stored in a capacitor for powering wearable electronics.

  4. Characterization of the Ti-10Nb-10Zr-5Ta Alloy for Biomedical Applications. Part 2: Wettability, Tribological Performance and Biocompatibility

    NASA Astrophysics Data System (ADS)

    Braic, V.; Balaceanu, M.; Braic, M.; Vitelaru, C.; Titorencu, I.; Pruna, V.; Parau, A. C.; Fanara, C.; Vladescu, A.

    2014-01-01

    The Ti-10Nb-10Zr-5Ta alloy, prepared in a levitation melting furnace, was investigated as a possible candidate for replacing Ti6Al4V alloy in medical applications. The sessile drop method, pin-on-disc and in vitro tests were used to analyze wettability, wear resistance, and biocompatibility of the new alloy. The characteristics of the Ti-10Nb-10Zr-5Ta alloy were assessed in comparison to those of the Ti6Al4V alloy. The Ti-10Nb-10Zr-5Ta system was found to have hydrophilic characteristics with similar contact angle as the Ti6Al4V alloy. In all environments (deionized water, simulated body fluid and Fusayama Meyer artificial saliva), the friction coefficient showed a stable evolution versus sliding distance, being similar for both alloys. On overall, the wear resistance of Ti-10Nb-10Zr-5Ta alloy was lower than that of Ti6Al4V for all testing environments. The Ti-10Nb-10Zr-5Ta alloy exhibited good biocompatibility characteristics at in vitro test compared to Ti6Al4V alloy. The cell viability on Ti-10Nb-10Zr-5Ta surfaces was higher than the one observed on Ti6Al4V samples, regardless the number of days spent in osteoblast-like cells culture. A high degree of cell attachment and spreading was observed on both alloys.

  5. Metallic glass alloys of Zr, Ti, Cu and Ni

    DOEpatents

    Lin, Xianghong; Peker, Atakan; Johnson, William L.

    1997-01-01

    At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM.sub.1-x Ti.sub.x).sub.a Cu.sub.b (Ni.sub.1-y Co.sub.y).sub.c wherein x is from 0.1 to 0.3, y.cndot.c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b.

  6. Shift of morphotropic phase boundary in high-performance [111]-oriented epitaxial Pb (Zr, Ti) O3 thin films

    NASA Astrophysics Data System (ADS)

    Yu, Qi; Li, Jing-Feng; Zhu, Zhi-Xiang; Xu, Ying; Wang, Qing-Ming

    2012-07-01

    High-performance epitaxial niobium-doped lead zirconate titanate thin films [Pb(ZrxTi1-x)0.98Nb0.02O3] with a fixed thickness were deposited on [111]-cut single-crystalline SrTiO3 substrates by a sol-gel process as a function of Zr/Ti ratio ranging from 20/80 to 80/20. An obvious shift of morphotropic phase boundary (MPB) was observed in the [111]-oriented epitaxial films. Deviating from the Zr/Ti ratio of 52/48 in bulk materials, the MPB composition in the as-deposited films was found to move to a lower Zr/Ti ratio between 30/70 and 40/60, which agrees with the theoretical analysis on the basis of lattice mismatch between films and substrates and is further confirmed by the XRD patterns and Raman spectrum as well as ferroelectric test. Furthermore, a superior remnant polarization (Pr) value among all the compositions was obtained at a Zr/Ti ratio of 30/70, indicating that the extrinsic ferroelectric polarization near the new morphotropic phase boundary will lead to outstanding dielectric and piezoelectric performance in the epitaxial PZT thin film system.

  7. Bone bonding bioactivity of Ti metal and Ti-Zr-Nb-Ta alloys with Ca ions incorporated on their surfaces by simple chemical and heat treatments.

    PubMed

    Fukuda, A; Takemoto, M; Saito, T; Fujibayashi, S; Neo, M; Yamaguchi, S; Kizuki, T; Matsushita, T; Niinomi, M; Kokubo, T; Nakamura, T

    2011-03-01

    Ti15Zr4Nb4Ta and Ti29Nb13Ta4.6Zr, which do not contain the potentially cytotoxic elements V and Al, represent a new generation of alloys with improved corrosion resistance, mechanical properties, and cytocompatibility. Recently it has become possible for the apatite forming ability of these alloys to be ascertained by treatment with alkali, CaCl2, heat, and water (ACaHW). In order to confirm the actual in vivo bioactivity of commercially pure titanium (cp-Ti) and these alloys after subjecting them to ACaHW treatment at different temperatures, the bone bonding strength of implants made from these materials was evaluated. The failure load between implant and bone was measured for treated and untreated plates at 4, 8, 16, and 26 weeks after implantation in rabbit tibia. The untreated implants showed almost no bonding, whereas all treated implants showed successful bonding by 4 weeks, and the failure load subsequently increased with time. This suggests that a simple and economical ACaHW treatment could successfully be used to impart bone bonding bioactivity to Ti metal and Ti-Zr-Nb-Ta alloys in vivo. In particular, implants heat treated at 700 °C exhibited significantly greater bone bonding strength, as well as augmented in vitro apatite formation, in comparison with those treated at 600 °C. Thus, with this improved bioactive treatment process these advantageous Ti-Zr-Nb-Ta alloys can serve as useful candidates for orthopedic devices.

  8. Atomic study of fracture progress of Fe[110]/TMC[100] (TM = Ti, Zr and Hf) semi-coherent interfaces

    NASA Astrophysics Data System (ADS)

    Li, Jinchun; Song, Hongquan; Qian, Ping; Shen, Jiang

    2014-09-01

    Using first-principle calculation in combination with the Chen-Möbius inversion method, we get the interfacial potentials of the Fe[110]/TMC[100] (TM = Ti, Zr and Hf) interface system. Based on the interfacial potentials, we investigate the interfacial stability, misfit dislocations and tensile fracture of the semi-coherent interfaces of Fe[110]/TMC[100] (TM = Ti, Zr and Hf). The different sizes of the misfit dislocation models are employed to compare the interfacial energy. Results indicate that Fe[110]/HfC[100] interface is more stable than Fe[110]/TMC[100] (TM = Ti and Zr). The analysis of different tensile fracture processes shows that the misfit dislocations play an important role in the fractures of interfaces between iron and transitional metal carbides.

  9. Development of finely dispersed Ti- and Zr-doped isotropic graphites for the divertor of next step fusion devices

    NASA Astrophysics Data System (ADS)

    López-Galilea, I.; García-Rosales, C.; Pintsuk, G.; Linke, J.

    2007-03-01

    Finely dispersed Ti- and Zr-doped isotropic graphites have been manufactured using three different starting raw materials. The aim is to obtain doped fine grain isotropic graphites with reduced chemical erosion, high thermal shock resistance and low cost, which aim to be competitive with present carbon-based candidate materials for next step fusion devices. First ITER relevant thermal shock loads were applied on test specimens of these materials. The brittle destruction behaviour of graphite is greatly improved by doping with Ti or Zr, most probably due to a significant increase of thermal conductivity related to the catalytic effect of TiC and ZrC on the graphitization. Doped graphites manufactured with the synthetic mesophase pitch 'AR' as raw material showed the best performance from the three investigated raw materials due to its higher graphitability. The eroded surfaces of doped graphites exhibit a thin solidified carbide layer, probably caused by the segregation of liquid carbide during the thermal shot.

  10. Study of nanostructured (Ti-Zr-Nb)N coatings’ physical- mechanical properties obtained by vacuum arc evaporation

    NASA Astrophysics Data System (ADS)

    Plotnikov, S. V.; Pogrebnjak, A. D.; Yerokhina, L. N.; Yeskermessov, D. K.; erdybaeva, N. K. Y.

    2016-02-01

    The coatings were formed by vacuum arc deposition. Unit cast target (cathodes) was used on the basis of 30 atm. % Ti, 35 at. % Zr and 35 atm. % Nb as the vaporized materials. Molecular nitrogen was used as the working gas. The thickness of the coatings in the experiments was 4.0 microns. The surface morphology fractograph fracture, track friction were investigated in a scanning electron microscope JSM-6390 LV. The use of multicoatings based on carbides is very promising to ensure the high performance properties of the complex, nitrides and silicides of transition metals. Findings - nanostructured coating of (Ti-Zr-Nb) N was obtained by vacuum arc evaporation cathode-cast in a nitrogen gas reaction medium. Multicomponent films have a pronounced columnar structure. Elemental composition was obtained by the vacuum arc deposition of coatings (Ti-Zr-Nb) N, depending on the physical parameters of the deposition process, in particular the pressure of the reaction gas nitrogen.

  11. Preparation of ZrO II/nano-TiO II composite powder by sol-gel method

    NASA Astrophysics Data System (ADS)

    Baharvandi, H. R.; Mohammadi, E.; Abdizadeh, H.; Hadian, A. M.; Ehsani, N.

    2007-07-01

    The effects of concentration of TTIP, amount of distilled water, and calcination temperature on morphology and particle size distribution of ZrO II/nano-TiO II catalysts were investigated. Mixed ZrO II/nano-TiO II powders were prepared by a modified sol-gel method by varying the mole fraction of TTIP from 0.002 to 0.01, H IIO/TTIP fraction from 2 to 8, and various stirring time (2, 4, and 10 h). The prepared ZrO II/nano-TiO II powders have been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and TG/DTA. Each oxide was calcined at the temperature between 110 and 1000°C. The results showed that the calcinations temperature has a pronounced effect on the phase formation and particle size of the calcined zirconium titanate (ZT) powders.

  12. Modifying the TiAlZr biomaterial surface with coating, for a better anticorrosive and antibacterial performance

    NASA Astrophysics Data System (ADS)

    Ionita, Daniela; Grecu, Mihaela; Ungureanu, Camelia; Demetrescu, Ioana

    2011-08-01

    The paper investigates the increase of anticorrosive and antimicrobial properties of a composite elaborated by coating TiAlZr with Ag nanoparticles. Silver nanoparticles (AgNPs) were synthesized by reducing silver salts using NaBH 4, and were characterized using dynamic light scattering instrument to determine the size distribution. The morphological and elemental analysis of Ag nanoparticles on the TiAlZr surface were performed with scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS). Antibacterial activity was evaluated on the basis of the inhibition of the growth of Escherichia coli bacteria, and of the electrochemical parameters from dynamic polarization tests performed in Ringers bioliquid. An empirical model of antibacterial effect of silver nanoparticles at biointerface in the presence of TiAlZr implant was discussed.

  13. Microstructure and Mechanical Properties of Microwave Sintered ZrO2 Bioceramics with TiO2 Addition

    PubMed Central

    Chou, Jyh-Horng

    2016-01-01

    The microwave sintered zirconia ceramics with 0, 1, 3, and 5 wt% TiO2 addition at a low sintering temperature of 1300°C and a short holding time of 1 hour were investigated. Effect of contents of TiO2 addition on microstructure and mechanical properties of microwave sintered zirconia bioceramics was reported. In the sintered samples, the main phase is monoclinic zirconia (m-ZrO2) phase and minor phase is tetragonal zirconia (t-ZrO2) phase. The grain sizes increased with increasing the TiO2 contents under the sintering temperature of 1300°C. Although the TiO2 phase was not detected in the XRD pattern, Ti and O elements were detected in the EDS analysis. The presence of TiO2 effectively improved grain growth of the ZrO2 ceramics. The Vickers hardness was in the range of 125 to 300 Hv and increased with the increase of TiO2 contents. Sintering temperature dependence on the Vickers hardness was also investigated from 1150°C to 1300°C, showing the increase of Vickers hardness with the increase of the sintering temperature as well as TiO2 addition. PMID:27504072

  14. Microstructure and Mechanical Properties of Microwave Sintered ZrO2 Bioceramics with TiO2 Addition.

    PubMed

    Kuo, Hsien-Nan; Chou, Jyh-Horng; Liu, Tung-Kuan

    2016-01-01

    The microwave sintered zirconia ceramics with 0, 1, 3, and 5 wt% TiO2 addition at a low sintering temperature of 1300°C and a short holding time of 1 hour were investigated. Effect of contents of TiO2 addition on microstructure and mechanical properties of microwave sintered zirconia bioceramics was reported. In the sintered samples, the main phase is monoclinic zirconia (m-ZrO2) phase and minor phase is tetragonal zirconia (t-ZrO2) phase. The grain sizes increased with increasing the TiO2 contents under the sintering temperature of 1300°C. Although the TiO2 phase was not detected in the XRD pattern, Ti and O elements were detected in the EDS analysis. The presence of TiO2 effectively improved grain growth of the ZrO2 ceramics. The Vickers hardness was in the range of 125 to 300 Hv and increased with the increase of TiO2 contents. Sintering temperature dependence on the Vickers hardness was also investigated from 1150°C to 1300°C, showing the increase of Vickers hardness with the increase of the sintering temperature as well as TiO2 addition.

  15. Compressive Strength Evaluation in Brazed ZrO2/Ti6Al4V Joints Using Finite Element Analysis

    NASA Astrophysics Data System (ADS)

    Sharma, Ashutosh; Kee, Se Ho; Jung, Flora; Heo, Yongku; Jung, Jae Pil

    2016-05-01

    This study aims to synthesize and evaluate the compressive strength of the ZrO2/Ti-6Al-4V joint brazed using an active metal filler Ag-Cu-Sn-Ti, and its application to dental implants assuring its reliability to resist the compressive failure in the actual oral environment. The brazing was performed at a temperature of 750 °C for 30 min in a vacuum furnace under 5 × 10-6 Torr atmosphere. The microstructure of the brazed joint showed the presence of an Ag-rich matrix and a Cu-rich phase, and Cu-Ti intermetallic compounds were observed along the Ti-6Al-4V bonded interface. The compressive strength of the brazed ZrO2/Ti-6Al-4V joint was measured by EN ISO 14801 standard test method. The measured compressive strength of the joint was ~1477 MPa—a value almost five times that of existing dental cements. Finite element analysis also confirmed the high von Mises stress values. The compressive strains in the samples were found concentrated near the Ti-6Al-4V position, matching with the position of the real fractured sample. These results suggest extremely significant compressive strength in ZrO2/Ti-6Al-4V joints using the Ag-Cu-Sn-Ti filler. It is believed that a highly reliable dental implant can be processed and designed using the results of this study.

  16. Corrosion resistance of Ti-Ta-Zr coatings in the Boiling Acid Solutions

    NASA Astrophysics Data System (ADS)

    Polyakov, I. A.; Lenivtseva, O. G.; Samoylenko, V. V.; Colkovski, M. G.; Ivanchik, I. S.

    2016-11-01

    In this study corrosion resistance of Ti-Ta-Zr coatings fabricated on VT14 titanium alloy workpieces using a high-energy electron beam injected in the atmosphere was investigated. Estimation of corrosion resistance of surface alloyed layers was carried out by the weight-change method. Boiling solution of 65 % nitric acid in water and 5 % of sulfuric acid in water were used as the corrosive environments. Investigation of samples after corrosion tests was carried out using a Carl Zeiss EVO 50 XVP scanning electron microscope.

  17. X-Ray and Electrostatic Levitation Undercooling Studies in Ti-Zr-Ni Quasicrystals Forming Alloys

    NASA Technical Reports Server (NTRS)

    Rogers, J. R.; Hyers, R. W.; Rathz, T. J.; Kelton, K. F.; Gangopadhyay, A. K.; Woo, G. L.; Hannet, L.; Krishnan, S.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The first undercooling nucleation measurements of electrostatic-levitated droplets of TiZrNi alloys that form the icosahedral quasicrystal phase (i-phase) are presented. The reduced undercooling for crystallization decreases with an increasing polytetrahedral order of the primary solidifying phase, supporting the existence of a developing icosahedral short-range order in the undercooled liquid. X-ray diffraction measurements made at the Advance Photon Source on levitated liquid droplets of these alloys at their liquidus temperatures, however, show no evidence for increased icosahedral order. This suggests that significant ordering only occurs below the melting temperature.

  18. Electron dominated thermoelectric response in MNiSn (M: Ti, Zr, Hf) half-Heusler alloys.

    PubMed

    Gandi, Appala Naidu; Schwingenschlögl, Udo

    2016-05-18

    We solve the transport equations of the electrons and phonons to understand the thermoelectric behaviour of the technologically important half-Heusler alloys MNiSn (M: Ti, Zr, Hf). Doping is simulated within the rigid band approximation. We clarify the origin of the electron dominated thermoelectric response and determine the carrier concentrations with maximal figures of merit. The phonon mean free path is studied to calculate the grain size below which grain refinement methods can enforce ballistic heat conduction to enhance the figure of merit.

  19. Electrocaloric Effect of Lead-Free (Ba,Ca)(Zr,Ti)O3 Ferroelectric Ceramic

    NASA Astrophysics Data System (ADS)

    Kim, You Seok; Yoo, Juhyun

    2015-08-01

    In this study, (Ba,Ca)(Zr,Ti)O3 ferroelectric ceramic was fabricated by a conventional solid-state reaction process. The electrocaloric effect was investigated using P- E hysteresis loop characteristics in a wide temperature range from room temperature to 135°C. The results showed that the temperature change Δ T could be calculated as a function of temperature using Maxwell's relation, reaching a maximum value of ~0.096°C at 110°C under an applied electric field of 15.3 kV/cm.

  20. On the Phenomenon of Stress Drop During Hot Deformation of ZrTiAlV Alloy

    NASA Astrophysics Data System (ADS)

    Tan, Yuanbiao; Liu, Wenchang; Yuan, Hui; Liu, Riping; Zhang, Xiangyi

    2013-12-01

    Hot deformation behaviors of 47Zr-45Ti-5Al-3V alloys with different grain sizes were investigated by compression tests. The flow curves exhibited a pronounced stress drop at the very beginning of deformation. The magnitude of the stress drop increased with the decreasing deformation temperature and the increasing strain rate. The sudden stress drop may be associated with the disappearance of mobile dislocations in the grain boundaries. Larger initial grain size increased the flow stress, promoted the stress drop, and enhanced the activation energy of deformation.

  1. Surface Tension and Viscosity of Quasicrystal-Forming Ti-Zr-Ni Alloys

    NASA Technical Reports Server (NTRS)

    Hyers, R. W.; Bradshaw, R. C.; Rogers, J. R.; Rathz, T. J.; Lee, G. W.; Kelton, K. F.; Gangopadhyay, A. K.

    2003-01-01

    The surface tension and viscosity of quasicrystal-forming Ti-Zr-Ni alloys were measured over a range of temperature, including both stable and undercooled liquids by an Electrostatic Levitation (ESL) technique. ESL is a containerless technique which allows processing of samples without contact, greatly reducing contamination and increasing access to the metastable undercooled liquid. The measured viscosity is typical of glass-forming alloys of similar composition to the quasicrystal-forming alloys studied here, while the surface tension shows an anomaly at deep undercoolings.

  2. Metallic glass alloys of Zr, Ti, Cu and Ni

    DOEpatents

    Lin, X.; Peker, A.; Johnson, W.L.

    1997-04-08

    At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3} K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM{sub 1{minus}x}Ti{sub x}){sub a} Cu{sub b} (Ni{sub 1{minus}y}Co{sub y}){sub c} wherein x is from 0.1 to 0.3, y{center_dot}c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b. 2 figs.

  3. The adhesion performance of epoxy coating on AA6063 treated in Ti/Zr/V based solution

    NASA Astrophysics Data System (ADS)

    Zhu, Wen; Li, Wenfang; Mu, Songlin; Yang, Yunyu; Zuo, Xi

    2016-10-01

    An environment-friendly titanium/zirconium/vanadium-based (Ti/Zr/V) conversion coating was prepared on aluminum alloy 6063 (AA6063). The epoxy powder coatings were applied on the AA6063 samples with/without Ti/Zr/V conversion coatings via electrostatic spraying. The morphology and composition of the conversion coating were studied by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The surface free energy components of AA6063 samples were measured by a static contact angle measuring device with Owens method. The adhesion properties of the epoxy coating on AA6063 treated with different conversion times were evaluated using a pull-off tester. The Ti/Zr/V conversion coating was mainly composed of metal oxide (TiO2, ZrO2, V2O5, Al2O3, etc.), metal fluoride (ZrF4, AlF3, etc.) and metal organic complex. The formation time of this conversion coating was reduced to 50 s. After such surface treatment, the samples' surface roughness was increased and the contact angle with water was decreased. Both the surface free energy and the work of adhesion were increased. The adhesion strength between the epoxy coating and AA6063 was enhanced significantly.

  4. The Mechanical Properties of the Mo-0.5Ti and Mo-0.1Zr Alloys at Room Temperature and High Temperature Annealing

    NASA Astrophysics Data System (ADS)

    Cui, Chaopeng; Gao, Yimin; Wei, Shizhong; Zhang, Guoshang; Zhou, Yucheng; Pan, Kunming; Zhu, Xiangwei; Guo, Songliang

    2017-02-01

    Mo-0.5Ti and Mo-0.1Zr alloys were prepared by powder metallurgy. In Mo-0.5Ti and Mo-0.1Zr alloys, there appears the second-phase particles of Ti2O3 and ZrO2 respectively, each of which can effectively prevent the dislocation activity in the process of plastic deformation. The addition of Zr can increase the strength of molybdenum alloys. Meanwhile, the ZrO2 formed from the alloy element Zr can refine the grains of molybdenum alloys to improve the recrystallization plasticity. After annealing, the tensile strength decreases while the plasticity greatly increases compared to the annealed Mo-0.5Ti and Mo-0.1Zr alloys. With the increase of annealing temperature, both the tensile strength and plasticity of Mo-0.5Ti and Mo-0.1Zr alloys decrease. Compared with pure Mo, after annealing the properties of the Mo-0.5Ti alloy and the plasticity of the Mo-0.1Zr alloy significantly increases.

  5. Microstructure and Room Temperature Properties of a High-Entropy TaNbHfZrTi Alloy (Postprint)

    DTIC Science & Technology

    2014-04-01

    AND ROOM TEMPERATURE PROPERTIES OF A HIGH - ENTROPY TaNbHfZrTi ALLOY (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM...is worth noting that, among all other high entropy alloys with the BCC structure produced so far, the Ta20Nb20Hf20Zr20Ti20 alloy has the highest RT...concentration of the matrix element (solvent) exceeds 60–70%, and these mechanisms may not be applicable to high - entropy alloys , where all elements are at

  6. A Model for the Oxidation of ZrB2, HfB2 and TiB2 (Postprint)

    DTIC Science & Technology

    2007-03-01

    appropriate thermodynamic data and the appropriate physical properties such as molecular weight,0.00055 0.00060 iction tal (Fenter) , 1hr 00 °C 1 100 0.0004...diborides of Zr, Hf and Ti in the temperature range of ~1000– 1800 °C was formulated. Available thermodynamic data and literature data for vapor...behavior of the diborides of Zr, Hf and Ti in the temperature range of 1000– 1800 C was formulated. Available thermodynamic data and literature data for

  7. Improving fatigue resistance of Pb(Zr,Ti)O3 thin films by using PbZrO3 buffer layers

    NASA Astrophysics Data System (ADS)

    Mensur Alkoy, Ebru; Uchiyama, Kiyoshi; Shiosaki, Tadashi; Alkoy, Sedat

    2006-05-01

    Ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin films with PbZrO3 (PZ) buffer layers were prepared on Pt(111)/Ti/SiO2/Si(100) substrates using a hybrid rf magnetron sputtering and sol-gel process. Texture of PZT films was found to depend on Pb content of PZ buffer layers. Buffered PZT films displayed comparable ferroelectric properties (2Pr=38-53 μC/cm2,2Ec=136-170 kV/cm) with unbuffered PZT. Asymmetric leakage current and fatigue behavior with superior fatigue resistance was observed in PZ buffered PZT compared to unbuffered films. PZ buffer layers were found to affect crystallization and texture of PZT, and act as a capacitive interface layer possibly blocking charge injection from electrodes.

  8. (29)Si, (47)Ti, (49)Ti and (195)Pt solid state MAS NMR spectroscopic investigations of ternary silicides TPtSi, germanides TPtGe (T = Ti, Zr, Hf) and stannide TiPtSn.

    PubMed

    Benndorf, Christopher; Eckert, Hellmut; Pöttgen, Rainer

    2016-05-10

    Eight ternary tetrelides TPtX (T = Ti, Zr, Hf; X = Si, Ge, Sn) were synthesized from the elements by arc-melting and subsequent annealing. TiPtSi, ZrPtSi, ZrPtGe, HfPtSi and HfPtGe crystallize with the orthorhombic TiNiSi type structure, in the space group Pnma. The structures of HfPtSi (a = 654.44(9), b = 387.97(6), c = 750.0(1) pm, wR2 = 0.0592, 411 F(2) values, 20 variables) and HfPtGe (a = 660.36(7), b = 395.18(4), c = 763.05(8) pm, wR2 = 0.0495, 430 F(2) values, 20 variables) were refined from single crystal X-ray diffractometer data. TiPtSn adopts the cubic MgAgAs type. TiPtGe is dimorphic with a TiNiSi type high-temperature modification which transforms to cubic LT-TiPtGe (MgAgAs type). All phases were investigated by high resolution (29)Si, (47)Ti, (49)Ti and (195)Pt solid state MAS NMR spectroscopy. In the cubic compounds, the (47/49)Ti NMR signals are easily detected owing to the absence of quadrupolar broadening effects. The (195)Pt resonances of the orthorhombic compounds are characterized by strongly negative isotropic Knight shifts and large Knight shift anisotropies, whereas positive isotropic Knight shifts and no anisotropies are observed for the cubic compounds. These results indicate that the phase transition in TiPtGe is associated with dramatic changes in the electronic properties. Within each group of isotypic compounds the isotropic (29)Si, (47/49)Ti and (195)Pt Knight shifts show systematic dependences on the transition metal or tetrel atomic number, suggesting that the numerical values are influenced by the electronegativities of the metallic (or metalloid) neighbours.

  9. Structural and spectroscopic properties of high temperature prepared ZrO2-TiO2 mixed oxides

    NASA Astrophysics Data System (ADS)

    Gionco, Chiara; Battiato, Alfio; Vittone, Ettore; Paganini, Maria Cristina; Giamello, Elio

    2013-05-01

    ZrO2-TiO2 mixed oxides of various composition, with the molar fraction of TiO2 ranging from 0.1% to 15%, have been prepared via sol-gel synthesis and then calcined at 1273 K to check both their thermal stability and physicochemical properties. These solids are usually employed in photocatalytic processes and as active phase supports in heterogeneous catalysis. As indicated by X-ray diffraction and Raman spectroscopy, solid solutions based on Ti ions diluted in the ZrO2 matrix are formed in the whole range of Ti molar fraction examined. Materials with low Ti loading (0.1%-1%) are basically constituted by the monoclinic phase of ZrO2 while the tetragonal phase becomes prevalent at 15% of TiO2 molar fraction. The presence of Ti ions modify the electronic structure of the solid as revealed by investigation of the optical properties. The typical band gap transition of ZrO2 undergoes, in fact, a red shift roughly proportional to the Ti loading which reach the remarkable value of 1.6 eV for the sample with 10% of molar Ti concentration. Comparing chemical analysis of the solids with XPS data it has been put into evidence that the titanium ions distribution into the solid is not uniform and the concentration of Ti4+ tend to be higher in subsurface layers than in the crystal bulk. The introduction of titanium ions in the structure increases the reducibility of the solid. Annealing under vacuum at various temperatures causes oxygen depletion with consequent reduction of the solid which shows up mainly in terms of formation of Ti3+ reduced centres which are characterized by a typical EPR signal. Ti3+ defects forms, as also forecast by theoretical modelling of the solid, as their energy is lower than that of other possible reduced defective centers. The reduced solids are able to transfer electrons to adsorbed oxygen molecules in mild condition resulting in the formation of surface superoxide anions (O2•-) which are stabilized on surface Zr4+ or, alternatively, on Ti4+ ions

  10. Improving the tribocorrosion resistance of Ti6Al4V surface by laser surface cladding with TiNiZrO2 composite coating

    NASA Astrophysics Data System (ADS)

    Obadele, Babatunde Abiodun; Andrews, Anthony; Mathew, Mathew T.; Olubambi, Peter Apata; Pityana, Sisa

    2015-08-01

    Ti6Al4V alloy was laser cladded with titanium, nickel and zirconia powders in different ratio using a 2 kW CW ytterbium laser system (YLS). The microstructures of the cladded layers were examined using field emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). Corrosion and tribocorrosion tests were performed on the cladded surface in 1 M H2SO4 solution. The microstructure revealed the transformation from a dense dendritic structure in TiNi coating to a flower-like structure observed in TiNiZrO2 cladded layers. There was a significant increase in surface microindentation hardness values of the cladded layers due to the present of hard phase ZrO2 particles. The results obtained show that addition of ZrO2 improves the corrosion resistance property of TiNi coating but decrease the tribocorrosion resistance property. The surface hardening effect induced by ZrO2 addition, combination of high hardness of Ti2Ni phase could be responsible for the mechanical degradation and chemical wear under sliding conditions.

  11. Dynamic recrystallization behavior of a biomedical Ti-13Nb-13Zr alloy.

    PubMed

    Bobbili, Ravindranadh; Madhu, V

    2016-06-01

    The dynamic recrystallization (DRX) behavior of a biomedical titanium Ti-13Nb-13Zr alloy has been investigated using the high temperature compression tests under wide range of strain rates (0.001-1/s) and temperatures 900-1050°C. A constitutive equation represented as a function of temperature, strain rate and true strain is developed and the hot deformation apparent activation energy is calculated about 534kJ/mol. By considering the exponential relationship between work-hardening rate (θ) and stress, a new mathematical model was proposed for predicting flow stress up to the critical strain during hot deformation. The mathematical model for predicting flow stress up to the critical strain exhibits better consistency and accuracy. The DRX kinetic equation of Ti-13Nb-13Zr alloy is described as XDRX=1-exp[-0.32(Ɛ-ƐcƐ(*))(2.3)] . The DRX kinetic model was validated by microstructure observation. It was also found that the process of DRX was promoted by decreasing strain rate and increasing deformation temperature. Eventually, the continuous dynamic recrystallization (CDRX) was identified to be the DRX mechanism using transmission electron microscope (TEM).

  12. Multibit ferroelectric field-effect transistor with epitaxial-like Pb(Zr,Ti)O3

    NASA Astrophysics Data System (ADS)

    Park, Jae Hyo; Kim, Hyung Yoon; Seok, Ki Hwan; Kiaee, Zohreh; Lee, Sol Kyu; Joo, Seung Ki

    2016-03-01

    Being able to control grain boundaries during the phase transformation when processing a ferroelectric thin-film is crucial for the successful development of practical multibit ferroelectric memory. A novel development of ferroelectric thin-film crystallization processing for realizing epitaxial-like single crystals via artificial nucleation by Pt-seeding is reported here. Dividing the nucleation and growth mechanism by Pt-seeding, it is possible to obtain large and uniform rectangular-shaped ferroelectric grains, large enough to fabricate a field-effect transistor (FET) in the inside of the crystal grain. The fabricated ferroelectric FET, Pt/Pb(Zr,Ti)O3/ZrTiO4/Si, showed a large memory window (˜2.2 V), a low operation voltage (˜6 V), and an ultra-fast program/erase speed (˜10-6 s). Moreover, there was no degradation after 1015 cycles of bipolar fatigue testing and the sample even showed a long retention time after 1 yr. All of these characteristics correspond to the best performance among all types of ferroelectric field-effect transistors reported thus far.

  13. Research Update: Magnetic phase diagram of EuTi1-xBxO3 (B = Zr, Nb)

    DOE PAGES

    Li, Ling; Zhou, Haidong; Yan, Jiaqiang; ...

    2014-11-21

    Herein, we report the magnetic phase diagram of EuTi1-xBxO3 (B = Zr, Nb), determined from magnetization and heat capacity measurements. Upon Zr-doping, the antiferromagnetic ordering temperature TN of EuTi1-xZrxO3 gradually decreases from 5.6 K (x = 0) to 4.1 K (x = 1). Whereas a similar decrease in TN is observed for small amounts of Nb doping (x ≤ 0.05), ferromagnetism is induced in EuTi1-xNbxO3 with x > 0.05. Lastly, the ferromagnetic interaction between localized Eu 4f spins mediated by itinerant electrons introduced by Nb doping results in the ferromagnetism in EuTi1-xNbxO3.

  14. Effect of TiO2, ZrO2, and TiO2-ZrO2 on the performance of CuO-ZnO catalyst for CO2 hydrogenation to methanol

    NASA Astrophysics Data System (ADS)

    Xiao, Jie; Mao, Dongsen; Guo, Xiaoming; Yu, Jun

    2015-05-01

    The influence of TiO2, ZrO2, and TiO2-ZrO2 mixed oxide on the catalytic performance of CuO-ZnO catalyst in the methanol synthesis from CO2 hydrogenation was studied. The catalysts were prepared by oxalate co-precipitation method and characterized by TGA, N2 adsorption, XRD, reactive N2O adsorption, XPS, H2-TPR, H2-TPD, and CO2-TPD techniques. Characterization results reveal that all the additives improve the CuO dispersion in the catalyst body and increase the Cu surface area and adsorption capacities of CO2 and H2. The results of catalytic test reveal that the additives increase both the CO2 conversion and methanol selectivity, and TiO2-ZrO2 mixed oxide is more effective than single components of TiO2 or ZrO2. Moreover, the activity of methanol synthesis is correlated directly with CO2 adsorption capacity over the catalysts.

  15. Effects of Zr, Ti, and Al Additions on Nonmetallic Inclusions and Impact Toughness of Cast Low-Alloy Steel

    NASA Astrophysics Data System (ADS)

    Bizyukov, Pavel V.; Giese, Scott R.

    2017-03-01

    A microalloying of the low-carbon and low-alloy cast steel was conducted with Zr, Ti, and Al that were added to the steel in four combinations. After heat treatment, the samples were tested for impact toughness at room temperature using the Charpy method. The highest values of impact toughness were obtained in the group treated with Zr, while Zr-Ti and Zr-Ti-Al groups showed moderate toughness values; the lowest values were observed in the Zr-Al group. Difference among the treatment groups was observed in the fracture mechanisms, morphology, and area distribution of the inclusions. High toughness values achieved in the trials treated with zirconium corresponded with smooth ductile fracture. The metal treated with a combination of zirconium and titanium had a relatively small area occupied by inclusions, but its toughness was also moderate. Lowest impact toughness values corresponded with the larger area occupied by the inclusions in the trials treated with aluminum. Also, a connection between the solubility product [Al][N] and impact toughness was established. The study also provides a qualitative description and quantitative analysis of the nonmetallic inclusions formation as a result of microalloying treatment. The precipitation sequence of the inclusions was described based on the thermochemical calculations for the nonmetallic compounds discovered in the experimental steel. A description of the size distribution, morphology, and composition was conducted for the oxides, nitrides, sulfides, and multiphase particles.

  16. Surface characteristics of TiN/ZrN coated nanotubular structure on the Ti-35Ta-xHf alloy for bio-implant applications

    NASA Astrophysics Data System (ADS)

    Moon, Byung-Hak; Choe, Han-Cheol; Brantley, William A.

    2012-01-01

    In this study, we investigated the surface characteristics of the TiN/ZrN-coated nanotubular structure on Ti-35Ta-xHf ternary alloys for bio-implant applications. These ternary alloys contained from 3 wt.% to 15 wt.% Hf contents and were manufactured in an arc-melting furnace. The Ti-35Ta-xHf alloys were heat treated in Ar atmosphere at 1000 °C for 24 h, followed by water quenching. Formation of the nanotubular structure was achieved by an electrochemical method in 1 M H3PO4 electrolytes containing 0.8 wt.% NaF. The TiN coating and ZrN coating were subsequently prepared by DC-sputtering on the nanotubular surface. Microstructures and nanotubular morphology of the alloys were examined by FE-SEM, EDX and XRD. The microstructure showed a duplex (α‧‧ + β) phase structure. Traces of martensite disappeared with increasing Hf content, and the Ti-35Nb-15Hf alloy had an entirely equiaxed structure of β phase. This research has shown that highly ordered, high aspect ratio, and nanotubular morphology surface oxide layers can be formed on the ternary titanium alloys by anodization. The TiN and ZrN coatings formed on the nanotubular surfaces were uniform and stable. The top of the nanotube layers was uniformly covered with the ZrN film compared to the TiN film when the Ti-35Ta-xHf alloys had high Hf content.

  17. Treatment of olive mill wastewater by photooxidation with ZrO2-doped TiO2 nanocomposite and its reuse capability.

    PubMed

    Sponza, Delia Teresa; Oztekin, Rukiye

    2016-01-01

    Zirconium dioxide (zirconia, ZrO2)-doped TiO2 (TiO2/ZrO2) nanocomposite was used for the photocatalytic oxidation of pollutant parameters [COD components (CODtotal, CODdissolved and CODinert)], polyphenols (catechol, 3-hydroxybenzoic acid, tyrosol and 4-hydroxybenzoic acid) and total polyaromatic amines [aniline, 4-nitroaniline, o-toluidine and o-anisidine] from the olive mill effluent wastewaters at different operational conditions such as at different mass ratios of ZrO2 (50, 25, 14, 10 and 5 wt%) in the TiO2/ZrO2 nanocomposite, at different TiO2/ZrO2 photocatalyst concentrations (1, 4, 15 and 50 mg/L) and pH values (4.0-7.0-10.0) under 300 W UV irradiations, respectively. Under the optimized conditions (pH = 4.6, 15 mg/L ZrO2/TiO2 nanocomposite with a ZrO2 mass ratio of 14 wt%, 300 W UV light, after 60 min photooxidation time, at 21°C), the maximum CODdissolved, total phenol and total aromatic amines photooxidation yields were 99%, 89% and 95%, respectively. High pollutant removal (89%) yields after sequential five times utilization of ZrO2/TiO2 nanocomposite show that this catalyst can be effectively used commercially in the treatment of olive mill effluent.

  18. Microstructures and Stability Origins of β-(Ti,Zr)-(Mo,Sn)-Nb Alloys with Low Young's Modulus

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Li, Qun; Li, Xiaona; Zhang, Ruiqian; Gao, Xiaoxia; Dong, Chuang; Liaw, Peter K.

    2015-09-01

    The present work investigates the microstructural evolution and β-phase stability of a multi-component [(Mo,Sn)-(Ti,Zr)14]-Nb alloy series developed using the cluster-plus-glue-atom model. Low Young's modulus ( E) can be reached, when both low- E elements, Sn and Zr, and β-Ti stabilizers, Mo and Nb, are properly incorporated in the so-called cluster formulas. After the X-ray diffraction and transmission electron microscopy analysis, and in combination with the β-Ti stability measured by the Mo equivalent, the Young's modulus of β-Ti alloys is found to increase with increasing β stabilities and is closely related to both the microstructures of the β matrix and the precipitated phases. More importantly, the morphologies of the β matrix change with β stabilities apparently so that high- E ( E >70 GPa) and low- E ( E ≤70 GPa) β-Ti alloys can be distinguished with the microstructures of the β matrix. The quinary alloy, formulated as [(Mo0.5Sn0.5)-(Ti13Zr1)]Nb1, owns its lowest E of 48 GPa among the present alloy series to the mixed thin-lamellar and rod-shaped morphology of the β structure with the lowest stability for the β formation.

  19. Correlation between corrosion performance and surface wettability in ZrTiCuNiBe bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Wang, Y. B.; Li, H. F.; Zheng, Y. F.; Wei, S. C.; Li, M.

    2010-06-01

    The corrosion properties of two Zr-based bulk metallic glass, Zr41Ti14Cu12Ni10Be23 (LM1) and Zr44Ti11Cu10Ni10Be25 (LM1b) were investigated by electrochemical measurements in simulated body fluid with pH value 7.4. With much lower current density and higher impedance values, as well as higher pitting potential, LM1b showed superior corrosion resistance to LM1. Under identical sample preparation and testing conditions, the difference in corrosion performance is found to relate closely to their surface wettability difference, as contact angle tests showed that LM1b is more hydrophobic than LM1. The excess free volume was measured and found having a close correlation with the wettability or the surface energy.

  20. Continuous production of granular or powder Ti, Zr and Hf or their alloy products

    DOEpatents

    White, Jack C.; Oden, Laurance L.

    1993-01-01

    A continuous process for producing a granular metal selected from the group consisting of Ti, Zr or Hf under conditions that provide orderly growth of the metal free of halide inclusions comprising: a) dissolving a reducing metal selected from the group consisting of Na, Mg, Li or K in their respective halide salts to produce a reducing molten salt stream; b) preparing a second molten salt stream containing the halide salt of Ti, Zr or Hf; c) mixing and reacting the two molten streams of steps a) and b) in a continuous stirred tank reactor; d) wherein steps a) through c) are conducted at a temperature range of from about 800.degree. C. to about 1100.degree. C. so that a weight percent of equilibrium solubility of the reducing metal in its respective halide salt varies from about 1.6 weight percent at about 900.degree. C. to about 14.4 weight percent at about 1062.degree. C.; and wherein a range of concentration of the halide salt of Ti, Zn or Hf in molten halides of Na, Mg, Li or K is from about 1 to about 5 times the concentration of Na, Mg, Li or K; e) placing the reacted molten stream from step c) in a solid-liquid separator to recover an impure granular metal product by decantation, centrifugation, or filtration; and f) removing residual halide salt impurity by vacuum evaporator or inert gas sweep at temperatures from about 850.degree. C. to 1000.degree. C. or cooling the impure granular metal product to ambient temperature and water leaching off the residual metal halide salt.

  1. Surface structures and osteoblast response of hydrothermally produced CaTiO 3 thin film on Ti-13Nb-13Zr alloy

    NASA Astrophysics Data System (ADS)

    Park, Jin-Woo; Tustusmi, Yusuke; Lee, Chong Soo; Park, Chan Hee; Kim, Youn-Jeong; Jang, Je-Hee; Khang, Dongwoo; Im, Yeon-Min; Doi, Hisashi; Nomura, Naoyuki; Hanawa, Takao

    2011-06-01

    This study investigated the surface characteristics and in vitro biocompatibility of a titanium (Ti) oxide layer incorporating calcium ions (Ca) obtained by hydrothermal treatment with or without post heat-treatment in the Ti-13Nb-13Zr alloy. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, X-ray photoelectron spectroscopy, atomic force microscopy and contact angle measurements. In vitro biocompatibility of the Ca-containing surfaces was assessed in comparison with untreated surfaces using a pre-osteoblast cell line. Hydrothermal treatment produced a crystalline CaTiO 3 layer. Post heat-treatment at 400 °C for 2 h in air significantly decreased water contact angles in the CaTiO 3 layer ( p < 0.001). The Ca-incorporated alloy surfaces displayed markedly increased cell viability and ALP activity compared with untreated surfaces ( p < 0.001), and also an upregulated expression of various integrin genes (α1, α2, α5, αv, β1 and β3) at an early incubation time-point. Post heat-treatment further increased attachment and ALP activity in cells grown on Ca-incorporated Ti-13Nb-13Zr alloy surfaces. The results indicate that the Ca-incorporated oxide layer produced by hydrothermal treatment and a simple post heat-treatment may be effective in improving bone healing in Ti-13Nb-13Zr alloy implants by enhancing the viability and differentiation of osteoblastic cells.

  2. Isotropic plasticity of β-type Ti-29Nb-13Ta-4.6Zr alloy single crystals for the development of single crystalline β-Ti implants

    PubMed Central

    Hagihara, Koji; Nakano, Takayoshi; Maki, Hideaki; Umakoshi, Yukichi; Niinomi, Mitsuo

    2016-01-01

    β-type Ti-29Nb-13Ta-4.6Zr alloy is a promising novel material for biomedical applications. We have proposed a ‘single crystalline β-Ti implant’ as new hard tissue replacements for suppressing the stress shielding by achieving a drastic reduction in the Young’s modulus. To develop this, the orientation dependence of the plastic deformation behavior of the Ti-29Nb-13Ta-4.6Zr single crystal was first clarified. Dislocation slip with a Burgers vector parallel to <111> was the predominant deformation mode in the wide loading orientation. The orientation dependence of the yield stress due to <111> dislocations was small, in contrast to other β-Ti alloys. In addition, {332} twin was found to be operative at the loading orientation around [001]. The asymmetric features of the {332} twin formation depending on the loading orientation could be roughly anticipated by their Schmid factors. However, the critical resolved shear stress for the {332} twins appeared to show orientation dependence. The simultaneous operation of <111> slip and {332} twin were found to be the origin of the good mechanical properties with excellent strength and ductility. It was clarified that the Ti-29Nb-13Ta-4.6Zr alloy single crystal shows the “plastically almost-isotropic and elastically highly-anisotropic” nature, that is desirable for the development of ‘single crystalline β-Ti implant’. PMID:27417073

  3. Isotropic plasticity of β-type Ti-29Nb-13Ta-4.6Zr alloy single crystals for the development of single crystalline β-Ti implants.

    PubMed

    Hagihara, Koji; Nakano, Takayoshi; Maki, Hideaki; Umakoshi, Yukichi; Niinomi, Mitsuo

    2016-07-15

    β-type Ti-29Nb-13Ta-4.6Zr alloy is a promising novel material for biomedical applications. We have proposed a 'single crystalline β-Ti implant' as new hard tissue replacements for suppressing the stress shielding by achieving a drastic reduction in the Young's modulus. To develop this, the orientation dependence of the plastic deformation behavior of the Ti-29Nb-13Ta-4.6Zr single crystal was first clarified. Dislocation slip with a Burgers vector parallel to <111> was the predominant deformation mode in the wide loading orientation. The orientation dependence of the yield stress due to <111> dislocations was small, in contrast to other β-Ti alloys. In addition, {332} twin was found to be operative at the loading orientation around [001]. The asymmetric features of the {332} twin formation depending on the loading orientation could be roughly anticipated by their Schmid factors. However, the critical resolved shear stress for the {332} twins appeared to show orientation dependence. The simultaneous operation of <111> slip and {332} twin were found to be the origin of the good mechanical properties with excellent strength and ductility. It was clarified that the Ti-29Nb-13Ta-4.6Zr alloy single crystal shows the "plastically almost-isotropic and elastically highly-anisotropic" nature, that is desirable for the development of 'single crystalline β-Ti implant'.

  4. Isotropic plasticity of β-type Ti-29Nb-13Ta-4.6Zr alloy single crystals for the development of single crystalline β-Ti implants

    NASA Astrophysics Data System (ADS)

    Hagihara, Koji; Nakano, Takayoshi; Maki, Hideaki; Umakoshi, Yukichi; Niinomi, Mitsuo

    2016-07-01

    β-type Ti-29Nb-13Ta-4.6Zr alloy is a promising novel material for biomedical applications. We have proposed a ‘single crystalline β-Ti implant’ as new hard tissue replacements for suppressing the stress shielding by achieving a drastic reduction in the Young’s modulus. To develop this, the orientation dependence of the plastic deformation behavior of the Ti-29Nb-13Ta-4.6Zr single crystal was first clarified. Dislocation slip with a Burgers vector parallel to <111> was the predominant deformation mode in the wide loading orientation. The orientation dependence of the yield stress due to <111> dislocations was small, in contrast to other β-Ti alloys. In addition, {332} twin was found to be operative at the loading orientation around [001]. The asymmetric features of the {332} twin formation depending on the loading orientation could be roughly anticipated by their Schmid factors. However, the critical resolved shear stress for the {332} twins appeared to show orientation dependence. The simultaneous operation of <111> slip and {332} twin were found to be the origin of the good mechanical properties with excellent strength and ductility. It was clarified that the Ti-29Nb-13Ta-4.6Zr alloy single crystal shows the “plastically almost-isotropic and elastically highly-anisotropic” nature, that is desirable for the development of ‘single crystalline β-Ti implant’.

  5. Theoretical and experimental studies of formation and migration of oxygen vacancies in BaM x Ti1- x O3 (M = Zr, Ge)

    NASA Astrophysics Data System (ADS)

    Umeda, Yuji; Aman, Sanshiro; Kuwabara, Akihide; Moriwake, Hiroki

    2016-10-01

    The formation and migration energies of oxygen vacancies in pure BaTiO3, and BaM x Ti1- x O3 (M = Zr, Ge) are calculated by first-principles calculations to understand the effect of doping on the reliability of multilayer ceramic capacitors (MLCCs). The formation and migration energies of oxygen vacancies are found to be larger in BaZr x Ti1- x O3 than in BaTiO3. This finding could be one of the possible reasons behind the improved reliability of Zr-doped MLCCs materials. On the other hand, by substituting Ge, the migration energy of BaGe x Ti1- x O3 becomes larger than that of BaTiO3. This is despite the smaller oxygen vacancy formation energy in BaGe x Ti1- x O3 than in BaTiO3. Even though Zr and Ge are tetravalent in BaM x Ti1- x O3, their valence states are different after the formation of oxygen vacancies, providing an explanation for the differences in vacancy formation and migration energies between BaZr x Ti1- x O3 and BaGe x Ti1- x O3. Our theoretical results are further confirmed by experiments on these model systems.

  6. Enhanced photoassisted water electrolysis using vertically oriented anodically fabricated Ti-Nb-Zr-O mixed oxide nanotube arrays.

    PubMed

    Allam, Nageh K; Alamgir, Faisal; El-Sayed, Mostafa A

    2010-10-26

    Self-ordered, highly oriented arrays of titanium-niobium-zirconium mixed oxide nanotube films were fabricated by the anodization of Ti(35)Nb(5)Zr alloy in aqueous and formamide electrolytes containing NH(4)F at room temperature. The nanostructure topology was found to depend on the nature of the electrolyte and the applied voltage. Our results demonstrate the possibility to grow mixed oxide nanotube array films possessing several-micrometer-thick layers by a simple and straightforward electrochemical route. The fabricated Ti-Nb-Zr-O nanotubes showed a ∼17.5% increase in the photoelectrochemical water oxidation efficiency as compared to that measured for pure TiO(2) nanotubes under UV illumination (100 mW/cm(2), 320-400 nm, 1 M KOH). This enhancement could be related to a combination of the effect of the thin wall of the fabricated Ti-Nb-Zr-O nanotubes (10 ± 2 nm) and the formation of Zr oxide and Nb oxide layers on the nanotube surface, which seems to slow down the electron-hole recombination in a way similar to that reported for Grätzel solar cells.

  7. The comparison of photocatalytic activity of synthesized TiO 2 and ZrO 2 nanosize onto wool fibers

    NASA Astrophysics Data System (ADS)

    Moafi, Hadi Fallah; Shojaie, Abdollah Fallah; Zanjanchi, Mohammad Ali

    2010-04-01

    TiO 2 and ZrO 2 nanocrystals were successfully synthesized and deposited onto wool fibers using the sol-gel technique at low temperature. The photocatalytic activities of TiO 2-coated and ZrO 2-coated wool fibers were measured by studying photodegradation of methylene blue and eosin yellowish dyes. The initial and the treated samples were characterized by several techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and X-ray diffraction. The TEM study shows dispersed particles with 10-30 nm in size for TiO 2-coated and 20-40 nm in size for ZrO 2-coated samples on the fiber surface. Comparison of the photocatalytic activity of the coated samples reveals superiority of TiO 2 modified sample with respect to that of ZrO 2 for degradation of both dyes. Our observations indicate that by applying this technique to the fabrics, self-cleaning materials could be designed for practical application.

  8. Phase Stability in the Mo-Ti-Zr-C System via Thermodynamic Modeling and Diffusion Multiple Validation

    NASA Astrophysics Data System (ADS)

    Kar, Sujoy Kumar; Dheeradhada, Voramon S.; Lipkin, Don M.

    2013-08-01

    Alloys in the Mo-rich corner of the Mo-Ti-Zr-C system have found broad applications in non-oxidizing environments requiring structural integrity well beyond 1273 K (1000 °C). Alloys such as TZM (Mo-0.5Ti-0.08Zr-0.03C by weight %) and TZC (Mo-1.2Ti-0.3Zr-0.1C by weight) owe much of their high temperature strength and microstructural stability to MC and M2C carbide phases. In turn, the stability of the respective carbides and the subsequent mechanical behavior of the alloys are strongly dependent on the alloying additions and thermal history. A CALPHAD-based thermodynamic modeling approach is employed to develop a quaternary thermodynamic database for the Mo-Ti-Zr-C system. The thermodynamic database thus developed is validated with diffusion multiple experiments and the validated database is exercised to elucidate the effects of alloying and thermal history on the phase equilibrium in Mo-rich alloys.

  9. Thermo-Elastic and Lattice Dynamical Properties of Pd3X (X = Ti, Zr, Hf) Alloys: An Ab Initio Study

    NASA Astrophysics Data System (ADS)

    Surucu, G.; Colakoglu, K.; Ciftci, Y. O.; Ozisik, H. B.; Deligoz, E.

    2015-12-01

    Using the generalized-gradient approximation (GGA) based on density functional theory, we have reported the structural, mechanical, electronic, and lattice dynamical properties of the intermetallic compounds Pd3X (X = Ti, Zr, Hf) with D024 and the L12 structures. The elastic constants were predicted using the stress-finite strain technique. We performed numerical estimations of the bulk modulus, shear modulus, Young's modulus, Poisson's ratio anisotropy factor, G/ B ratio, and hardness. Our studies have showed that all Pd3X (X = Ti, Zr, Hf) with D024 and the L12 structures are mechanically stable and relatively hard materials with low compressibility, and they could be considered as ductile systems. Also, the phonon dispersion curves and total and partial density of states were calculated and discussed for Pd3X (X = Ti, Zr, Hf). We finally estimated some thermodynamic properties such as entropy, free energy, and heat capacity at the temperature range 0-1000 K. The calculated phonon frequencies of Pd3X (X = Ti, Zr, Hf) are positive, indicating the dynamical stability of the studied compounds. For the first time, we have performed the numerical estimation of lattice dynamical properties for the compounds and still awaits experimental confirmation. The obtained ground state properties are in good agreement with those of experimental and theoretical studies.

  10. β-type Ti-10Mo-1.25Si-xZr biomaterials for applications in hard tissue replacements.

    PubMed

    Zhan, Yongzhong; Li, Chunliu; Jiang, Wenping

    2012-08-01

    In order to develop new β-type Ti-based biochemical materials, a series of Ti-10Mo-1.25Si-xZr (x=4-13) alloys were designed and prepared using vacuum arc melting method. Phase analysis and microstructural observation showed that all the as cast samples consisted of equiaxed β-Ti phase. With the increase of Zr content, the structure of grain boundary changed from semi-continuous network to denser granular, and the microstructure was refined. The solid solution effect of the β-phase stabilization elements (i.e. Mo, Zr and Si) predominantly determined the mechanical properties. These β-type Ti-10Mo-1.25Si-xZr biomaterials exhibited a good combination of high compressive strength, high yield stress, good plasticity, as well as rather low Young's modulus (in the range of 23.086 GPa-32.623 GPa), which may offer potential advantages in the applications in hard tissue replacements (HTRs).

  11. A first-principle study on the phase transition, electronic structure, and mechanical properties of three-phase ZrTi2 alloy under high pressure*

    NASA Astrophysics Data System (ADS)

    Yuan, Xiao-Li; Xue, Mi-An; Chen, Wen; An, Tian-Qing

    2016-11-01

    We employed density-functional theory (DFT) within the generalized gradient approximation (GGA) to investigate the ZrTi2 alloy, and obtained its structural phase transition, mechanical behavior, Gibbs free energy as a function of pressure, P-V equation of state, electronic and Mulliken population analysis results. The lattice parameters and P-V EOS for α, β and ω phases revealed by our calculations are consistent with other experimental and computational values. The elastic constants obtained suggest that ω-ZrTi2 and α-ZrTi2 are mechanically stable, and that β-ZrTi2 is mechanically unstable at 0 GPa, but becomes more stable with increasing pressure. Our calculated results indicate a phase transition sequence of α → ω → β for ZrTi2. Both the bulk modulus B and shear modulus G increase linearly with increasing pressure for three phases. The G/B values illustrated good ductility of ZrTi2 alloy for three phases, with ω<α<β at 0 GPa. The Mulliken population analysis showed that the increment of d electron occupancy stabilized the β phase. A low value for B '0 is the feature of EOS for ZrTi2 and this softness in the EOS is representative of pressure induced s-d electron transfer. Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjb/e2016-70218-0

  12. Corrosion-Resistant Ti- xNb- xZr Alloys for Nitric Acid Applications in Spent Nuclear Fuel Reprocessing Plants

    NASA Astrophysics Data System (ADS)

    Manivasagam, Geetha; Anbarasan, V.; Kamachi Mudali, U.; Raj, Baldev

    2011-09-01

    This article reports the development, microstructure, and corrosion behavior of two new alloys such as Ti-4Nb-4Zr and Ti-2Nb-2Zr in boiling nitric acid environment. The corrosion test was carried out in the liquid, vapor, and condensate phases of 11.5 M nitric acid, and the potentiodynamic anodic polarization studies were performed at room temperature for both alloys. The samples subjected to three-phase corrosion testing were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX). As Ti-2Nb-2Zr alloy exhibited inferior corrosion behavior in comparison to Ti-4Nb-4Zr in all three phases, weldability and heat treatment studies were carried out only on Ti-4Nb-4Zr alloy. The weldability of the new alloy was evaluated using tungsten inert gas (TIG) welding processes, and the welded specimen was thereafter tested for its corrosion behavior in all three phases. The results of the present investigation revealed that the newly developed near alpha Ti-4Nb-4Zr alloy possessed superior corrosion resistance in all three phases and excellent weldability compared to conventional alloys used for nitric acid application in spent nuclear reprocessing plants. Further, the corrosion resistance of the beta heat-treated Ti-4Nb-4Zr alloy was superior when compared to the sample heat treated in the alpha + beta phase.

  13. Photocatalytic degradation of gaseous toluene with multiphase Ti(x)Zr(1-x)O2 synthesized via co-precipitation route.

    PubMed

    Liu, Baojun; Li, Xinyong; Zhao, Qidong; Ke, Jun; Liu, Jie; Liu, Shaomin; Tadé, Moses

    2015-01-15

    In the present work, the multiphase Ti(x)Zr(1-x)O2 particles containing cubic-phase ZrO2 were fabricated via co-precipitation route. The mole ratios of Ti and Zr elements were controlled by three levels: Ti/Zr=7/3 (maximum), Ti/Zr=5/5 (medium), and Ti/Zr=3/7 (minimum). The materials prepared were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS) and photoluminescence (PL) spectra. For the maximum usage of solar power with fabricated catalysts, elimination of gaseous toluene was chosen as a model to evaluate the performances under visible light. The results indicated that the degradation efficiency of toluene was about 80% after 6 h reaction using Ti(0.3)Zr(0.7)O2 as the photocatalyst. On the other hand, the multiphase Ti(x)Zr(1-x)O2 (x=0.7 or 0.5) photocatalysts showed significant enhancement in the activity, compared with the commercial TiO2 (Degussa P25). The enhanced performances of Ti(x)Zr(1-x)O2 might be attributed to the lower charge recombination rate of photoinduced electron-hole pairs. In addition, some intermediates (the benzaldehyde and benzoic acid) and final product (CO2) adsorbed on the surface of the particles were also detected by using in situ Fourier transform infrared (FTIR) spectroscopy.

  14. Glass forming in La2O3-TiO2-ZrO2 ternary system by containerless processing

    NASA Astrophysics Data System (ADS)

    Kaneko, Masashi; Kentei Yu, Yu; Kumar, Vijaya; Masuno, Atsunobu; Inoue, Hiroyuki; Odawara, Osamu; Yoda, Shinichi

    The containerless processing is an appropriate method to create new glasses, because it sup-presses nucleation at the boundary between liquid and crucible during solidification and it enables molten samples to be solidified without crystallization. Recently, we have succeeded in forming BaTi2 O5 glass in the bulk state by using an aerodynamic levitation furnace. BaTi2 O5 glass includes no traditional glass network former and it possesses high electric permittivity [1, 2]. From the point of view of optical application, BaTi2 O5 glass has high refractive indices over 2.1. BaTi2 O5 glass, however, vitrify only in a small sphere, and it crystallize when its diameter exceed 1.5 mm. In order to synthesize new titanate oxide glasses which possess higher refractive indices and larger diameter than BaTi2 O5 , La and Zr can be used as substitutive components. When Ba is replaced with La, refractive indices are expected to increase because of the heavier element. The addition of a third element is thought to be effective for enhance-ment of glass formation ability and Zr can be a candidate because Ti and Zr are homologous. In this research, we have succeeded in forming new bulk glass in La2 O3 -TiO2 -ZrO2 ternary system by means of the aerodynamic levitation furnace. We investigated the glass forming region, thermal properties and optical properties of La2 O3 -TiO2 -ZrO2 glass. Glass transition temperature, crystallization temperature, density, refractive indices and transmittance spectra were varied depending on the chemical composition. Reference [1] J. Yu et al, "Fabrication of BaTi2O5 Glass-Ceramics with Unusual Dielectric Properties during Crystallization", Chem-istry of Materials, 18 (2006) 2169-2173. [2] J. Yu et al., "Comprehensive Structural Study of Glassy and Metastable Crystalline BaTi2O5", Chemistry of Materials, 21 (2009) 259-263.

  15. A new (Ba, Ca) (Ti, Zr)O3 based multiferroic composite with large magnetoelectric effect

    PubMed Central

    Naveed-Ul-Haq, M.; Shvartsman, Vladimir V.; Salamon, Soma; Wende, Heiko; Trivedi, Harsh; Mumtaz, Arif; Lupascu, Doru C.

    2016-01-01

    The lead-free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 − 0.5(Ba0.7Ca0.3)TiO3 (BCZT) is a promising component for multifunctional multiferroics due to its excellent room temperature piezoelectric properties. Having a composition close to the polymorphic phase boundary between the orthorhombic and tetragonal phases, it deserves a case study for analysis of its potential for modern electronics applications. To obtain magnetoelectric coupling, the piezoelectric phase needs to be combined with a suitable magnetostrictive phase. In the current article, we report on the synthesis, dielectric, magnetic, and magnetoelectric characterization of a new magnetoelectric multiferroic composite consisting of BCZT as a piezoelectric phase and CoFe2O4 (CFO) as the magnetostrictive phase. We found that this material is multiferroic at room temperature and manifests a magnetoelectric effect larger than that of BaTiO3 −CoFe2O4 bulk composites with similar content of the ferrite phase. PMID:27555563

  16. A new (Ba, Ca) (Ti, Zr)O3 based multiferroic composite with large magnetoelectric effect

    NASA Astrophysics Data System (ADS)

    Naveed-Ul-Haq, M.; Shvartsman, Vladimir V.; Salamon, Soma; Wende, Heiko; Trivedi, Harsh; Mumtaz, Arif; Lupascu, Doru C.

    2016-08-01

    The lead-free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 ‑ 0.5(Ba0.7Ca0.3)TiO3 (BCZT) is a promising component for multifunctional multiferroics due to its excellent room temperature piezoelectric properties. Having a composition close to the polymorphic phase boundary between the orthorhombic and tetragonal phases, it deserves a case study for analysis of its potential for modern electronics applications. To obtain magnetoelectric coupling, the piezoelectric phase needs to be combined with a suitable magnetostrictive phase. In the current article, we report on the synthesis, dielectric, magnetic, and magnetoelectric characterization of a new magnetoelectric multiferroic composite consisting of BCZT as a piezoelectric phase and CoFe2O4 (CFO) as the magnetostrictive phase. We found that this material is multiferroic at room temperature and manifests a magnetoelectric effect larger than that of BaTiO3 ‑CoFe2O4 bulk composites with similar content of the ferrite phase.

  17. Material characterization of superplastically formed titanium (Ti-6Al-2Sn-4Zr-2Mo) sheet

    NASA Technical Reports Server (NTRS)

    Ossa, William A.; Royster, Dick M.

    1987-01-01

    The aerospace industry has focused considerable interest on the near-alpha titanium alloy Ti-6Al-2Sn-4Zr-2Mo (Ti-6242) because of both its high-temperature properties and its superplastic forming (SPF) capabilities. This paper describes current research to characterize selected mechanical properties of Ti-6242 sheet in the SPF-strained condition, both with and without heat treatment, and compares the results with those obtained on as-received material. Tensile and creep tests were conducted, and metallographic analysis was performed to show the effect of 100 to 700 percent SPF strain on titanium properties. Analysis shows that as a result of SPF processing, both tensile and yield strengths, as well as elongation, are moderately reduced. Creep tests at 800 F and 1000 F show that the SPF processed material displays superior creep resistance compared with the as-received material. A post-SPF duplex-anneal heat treatment had no beneficial effect on tensile and creep properties.

  18. Incorporating Small Fatigue Crack Growth in Probabilistic Life Prediction: Effect of Stress Ratio in Ti-6Al-2Sn-4Zr-6-Mo (Preprint)

    DTIC Science & Technology

    2012-08-01

    growth rates as well as the variability in the same, in the + titanium alloy, Ti-6Al-2Sn-4Zr-6Mo (Ti- 6 -2- 4 - 6 ) was studied at 260°C. A probabilistic...were obtained in a separate study on the effect of R on the small-crack growth regime in another + titanium alloy, Ti- 6 - 4 [32]. Given that crack...microstructure of Ti-6Al-2Sn-4Zr-6Mo (Ti- 6 -2- 4 - 6 ) at 260°C with particular emphasis on incorporating small-crack data into probabilistic life prediction

  19. Impedance of (CoFeZr)0,559(PbZrTiO3)0,441 nanocomposite annealed in a tubular furnace

    NASA Astrophysics Data System (ADS)

    Boiko, Oleksandr

    2016-12-01

    The objective of the present research has been to determine the influence of annealing in tubular furnace on capacity of (CoFeZr)0,559(PbZrTiO3)0,441 nanocomposite produced by ion beam sputtering using combined argon and oxygen beam. The phase angle of the nanocomposite directly after preparing demonstrates negative values, which indicates the capacitive type of electrical conductivity of the material. The rapid increase of conductivity when frequency increases indicates hopping conductance in the material. The additional polarization of the nanocomposite occurs with its extinction in the area of high frequencies. The electrons relaxation time has been defined as of ca τ = 1,25×10-4 s. Annealing of nanocomposite sample x = 55.9 at.% at temperature Ta = 548 K causes phase angle obtains positive values in high frequency area, which indicates the change of conduction type from capacitive to inductive. The voltage resonance phenomenon occurs in the material. Annealing in temperature of Ta = 648 K causes changes of the nanomaterials capacity. The additional oxidization of CoFeZr metallic phase nanograins which provides to the potential barrier formation around potential wells (CoFeZr nanoparticles).

  20. Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) Alloys for the Hydrogen Separation Membrane.

    PubMed

    Nayebossadri, Shahrouz; Speight, John D; Book, David

    2017-01-25

    Self-supported fcc Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) alloys were studied as potential hydrogen purification membranes. The effects of small additions (1-2.6 at. %) of these elements on the structure, hydrogen solubility, diffusivity, and permeability were examined. Structural analyses by X-ray diffraction (XRD) showed the fcc phase for all alloys with induced textures from cold rolling. Heat treatment at 650 °C for 96 h led to the reorientation in all alloys except the Pd-Cu-Zr alloy, exhibiting the possibility to enhance the structural stability by Zr addition. Hydrogen solubility was almost doubled in the ternary alloys containing Y and Zr compared to Pd65.1Cu34.9 alloy at 300 °C. It was noted that hydrogen diffusivity is decreased upon additions of these elements compared to the Pd65.1Cu34.9 alloy, with the Pd-Cu-Zr alloy showing the lowest hydrogen diffusivity. However, the comparable hydrogen permeability of the Pd-Cu-Zr alloy with the corresponding binary alloy, as well as its highest hydrogen permeability among the studied ternary alloys at temperatures higher than 300 °C, suggested that hydrogen permeation of these alloys within the fcc phase is mainly dominated by hydrogen solubility. Hydrogen flux variations of all ternary alloys were studied and compared with the Pd65.1Cu34.9 alloy under 1000 ppm of H2S + H2 feed gas. Pd-Cu-Zr alloy showed superior resistance to the sulfur poisoning probably due to the less favorable H2S-surface interaction and more importantly slower rate of bulk sulfidation as a result of improved structural stability upon Zr addition. Therefore, Pd-Cu-Zr alloys may offer new potential hydrogen purification membranes with improved chemical stability and hydrogen permeation compared to the binary fcc Pd-Cu alloys.

  1. A Study on Alpha-Case Depth in Ti-6Al-2Sn-4Zr-2Mo

    NASA Astrophysics Data System (ADS)

    McReynolds, Kevin S.; Tamirisakandala, Seshacharyulu

    2011-07-01

    Isothermal oxidation experiments in air were performed on Ti-6Al-2Sn-4Zr-2Mo (Ti-6242) with a bimodal microstructure in the temperature range 811 K to 922 K (538 °C to 649 °C) for up to 500 hours, and α-case depths were quantified using metallography. Alpha-case depth followed a parabolic variation with time. Alpha-case depths in excess of 10 μm formed above 811 K (538 °C) and 100-hour exposures. An activation energy of 244 kJ/mol was estimated for diffusion of oxygen in the α phase of Ti-6242.

  2. The ab initio calculations of the doping Zr's influence on the electronic structure of AlCo2Ti

    NASA Astrophysics Data System (ADS)

    Fu, Hongzhi; Peng, Feng; Cheng, Dong; Gao, Tao; Cheng, Xinlu; Yang, Xiangdong

    2007-08-01

    The electronic structures of the ternary (Hume Rothery) L21-phase compound AlCo2Ti are calculated by first-principles using full potential linearized augmented plane wave (FLAPW) method with the generalized gradient approximation (GGA). The ab initio results are analyzed with a simplified model for Al-based compounds containing transition metal (TM) atoms. The results show that the total DOS depends strongly on the positions of TM atoms, and the TM d DOS plays a crucial role in hybridization with other element valence electrons. However, the Al 3s states are repelled far away from the Fermi energy in studied sample, and the Al 3d states are far more extended-like in the character than the d states. Furthermore, the total DOSs are modulated by Al 3p states and the Al 3p states are more sensitive than d states to change in the electronic interactions. Then, the Al 3p is also important for the ternary stability of the intermetallic compound. The Co Ti interaction becomes stronger by the doping element Zr in the Al4Co8Ti3Zr structure. Especially, the doping Al4Co8Ti3Zr alloy has a larger value DOS at the Fermi level and makes the total DOS gap smaller than the AlCo2Ti.

  3. Nanocrystalline (Pr,Dy)-(Fe,Co)-Zr-Ti-B magnets produced directly by rapid solidification

    NASA Astrophysics Data System (ADS)

    Pawlik, P.; Pawlik, K.; Davies, H. A.; Wysłocki, J. J.; Kaszuwara, W.

    2009-01-01

    Hard magnetic thick ribbon samples of a series of Pr9-xDyxFe60Co13Zr1+yTi3-yB14 alloys (where x=0;1 and y=0;1) (having average thicknesses tr of~ 140 µm) were produced directly by the melt-spinning technique under an Ar atmosphere. The phase constitution of the samples in the as-cast state was determined by X-ray diffractomety and Mössbauer spectroscopy. Hysteresis loops measurements at room temperature indicated very good hard magnetic properties for the alloys, which the coercivity attaining a maximum values of 1.58 MA/m. This is comparable with the coercivities of commercial NdFeB magnets based on melt spun ribbon and with those for nanocrystalline Nd-Fe-B magnets produces by other processes such as mechanical alloying or HDDR.

  4. Crystallographic, Ferroelectric and Electronic Properties of the Sr2ZrTiO6 Double Perovskite

    NASA Astrophysics Data System (ADS)

    Landínez Téllez, D. A.; Carrero Bermúdez, L. A.; Deluque Toro, C. E.; Cardona, R.; Roa-Rojas, J.

    2013-08-01

    In this paper, we report structural analysis, ferroelectric behavior and electronic structure of Sr2ZrTiO6 double perovskite. Samples were produced by the solid state reaction recipe. Crystallographic analysis was performed by Rietveld refinement of experimental X-ray diffraction patterns. Results show that this material crystallizes in a tetragonal perovskite structure which corresponds to the space group I4/m. The curve of polarization as a function of applied voltage evidences a ferroelectric character with saturation polarization on the application of voltages up to 1800 V. Calculations of density of states and band structure for this manganite-like material were carried out by means of the density functional theory implemented into the Wien2k code. Results of total and partial density of states reveal the insulator character of this material with an energy gap of 2.66 eV.

  5. Heat treatment of piezoelectric Pb(ZrTi)O3 ceramic fibers prepared with continuous spinning

    NASA Astrophysics Data System (ADS)

    Xiong, Z. X.; Pan, J.; Xue, H.; Mai, M. F.; Qiu, H.; Chen, L. F.

    2009-07-01

    Ceramic of Pb(ZrTi)O3 is one kind of typical smart materials, with excellent ferroelectric and piezoelectric properties. In this paper, a novel heat treatment was applied for the ceramic fibers prepared via sol-gel route with continuous spinning. Aided with microwave energy, dense ceramic fibers are obtained after treated at around 900°C for 1h, in which the diameters of the fibers are between 5μm and 30μm. The samples were also characterized with thermal analysis, FTIR spectroscopy and X-ray diffraction. By using of a scanning electron microscope, SEM, it was observed that a dense microstructure of the fiber was reached.

  6. Influence of hydroxyapatite on the corrosion resistance of the Ti-13Nb-13Zr alloy.

    PubMed

    Duarte, Laís T; Biaggio, Sonia R; Rocha-Filho, Romeu C; Bocchi, Nerilso

    2009-05-01

    Electrochemical analyses on the biocompatible alloy Ti-13Nb-13Zr wt% in an electrolyte simulating physiological medium (PBS solution) are reported. Hydroxyapatite (HA) films were obtained on the alloy by electrodeposition at constant cathodic current. Samples of the alloy covered with an anodic-oxide film or an anodic-oxide/HA film were analyzed by open circuit potential and electrochemical impedance spectroscopy measurements during 180 days in the PBS electrolyte. Analyses of the open-circuit potential (E (oc)) values indicated that the oxide/HA film presents better protection characteristics than the oxide only. This behavior was corroborated by the higher film resistances obtained from impedance data, indicating that, besides improving the alloy osteointegration, the hydroxyapatite film may also increase the corrosion protection of the biomaterial.

  7. Compliant ferroelastic domains in epitaxial Pb(Zr,Ti)O{sub 3} thin films

    SciTech Connect

    Feigl, L.; McGilly, L. J.; Sandu, C. S.; Setter, N.

    2014-04-28

    Ordered patterns of highly compliant ferroelastic domains have been created by use of tensile strained epitaxial Pb(Zr,Ti)O{sub 3} thin films, of very low defect density, grown on DyScO{sub 3} substrates. The effect of 180° switching on well-ordered a/c 90° domain patterns is investigated by a combination of transmission electron microscopy, piezoelectric force microscopy, and X-ray diffraction. It is shown that ferroelastic a-domains, having an in-plane polarization, can be created and completely removed on a local level by an out-of-plane electric field. The modifications of the ferroelastic domain pattern can be controlled by varying the parameters used during switching with a piezoresponse force microscope to produce the desired arrangement.

  8. Tracking magmatic processes through Zr/Hf ratios in rocks and Hf and Ti zoning in zircons: An example from the Spirit Mountain batholith, Nevada

    USGS Publications Warehouse

    Lowery, Claiborne L.E.; Miller, C.F.; Walker, B.A.; Wooden, J.L.; Mazdab, F.K.; Bea, F.

    2006-01-01

    Zirconium and Hf are nearly identical geochemically, and therefore most of the crust maintains near-chondritic Zr/Hf ratios of ???35-40. By contrast, many high-silica rhyolites and granites have anomalously low Zr/Hf (15-30). As zircon is the primary reservoir for both Zr and Hf and preferentially incorporates Zr, crystallization of zircon controls Zr/ Hf, imprinting low Zr/Hf on coexisting melt. Thus, low Zr/Hf is a unique fingerprint of effective magmatic fractionation in the crust. Age and compositional zonation in zircons themselves provide a record of the thermal and compositional histories of magmatic systems. High Hf (low Zr/ Hf) in zircon zones demonstrates growth from fractionated melt, and Ti provides an estimate of temperature of crystallization (TTiZ) (Watson and Harrison, 2005). Whole-rock Zr/Hf and zircon zonation in the Spirit Mountain batholith, Nevada, document repeated fractionation and thermal fluctuations. Ratios of Zr/Hf are ???30-40 for cumulates and 18-30 for high-SiO2 granites. In zircons, Hf (and U) are inversely correlated with Ti, and concentrations indicate large fluctuations in melt composition and TTiZ (>100??C) for individual zircons. Such variations are consistent with field relations and ion-probe zircon geochronology that indicate a >1 million year history of repeated replenishment, fractionation, and extraction of melt from crystal mush to form the low Zr/Hf high-SiO2 zone. ?? 2006 The Mineralogical Society.

  9. Effect of oxygen pressure on phase composition and magnetic structure of FeCoZr-Pb(ZrTi)O3 nanocomposites

    NASA Astrophysics Data System (ADS)

    Kasiuk, J. V.; Fedotova, J. A.; Marszalek, M.; Karczmarska, A.; Mitura-Nowak, M.; Kalinin, Yu. E.; Sitnikov, A. V.

    2012-01-01

    The elemental and phase compositions and the magnetic state of metal particles in FeCoZr-Pb(ZrTi)O3 granular nanocomposites (GNCs) synthesized by ion-beam sputtering of composite targets in oxygen-containing media at different oxygen partial pressures have been studied. The phase transformations in GNCs have been monitored by the Raman and Mössbauer spectroscopy techniques. Correlation between the oxygen pressure during GNC synthesis and the valence state of iron ions in metal granules has been established. It has been confirmed that (i) the degree of metal oxidation increases with increasing oxygen pressure and (ii) the degree of crystallinity of oxides increases as a result of annealing. It has been established that the percolation threshold in GNCs can also be varied by changing the oxygen pressure during GNC synthesis.

  10. TiZrNbTaMo high-entropy alloy designed for orthopedic implants: As-cast microstructure and mechanical properties.

    PubMed

    Wang, Shao-Ping; Xu, Jian

    2017-04-01

    Combining the high-entropy alloy (HEA) concept with property requirement for orthopedic implants, we designed a Ti20Zr20Nb20Ta20Mo20 equiatomic HEA. The arc-melted microstructures, compressive properties and potentiodynamic polarization behavior in phosphate buffer solution (PBS) were studied in detail. It was revealed that the as-cast TiZrNbTaMo HEA consisted of dual phases with bcc structure, major bcc1 and minor bcc2 phases with the lattice parameters of 0.3310nm and 0.3379nm, respectively. As confirmed by nanoindentation tests, the bcc1 phase is somewhat harder and stiffer than the bcc2 phase. The TiZrNbTaMo HEA exhibited Young's modulus of 153GPa, Vickers microhardness of 4.9GPa, compressive yield strength of σy=1390MPa and apparent plastic strain of εp≈6% prior to failure. Moreover, the TiZrNbTaMo HEA manifested excellent corrosion resistance in PBS, comparable to the Ti6Al4V alloy, and pitting resistance remarkably superior to the 316L SS and CoCrMo alloys. These preliminary advantages of the TiZrNbTaMo HEA over the current orthopedic implant metals in mechanical properties and corrosion resistance offer an opportunity to explore new orthopedic-implant alloys based on the TiZrNbTaMo concentrated composition.

  11. Characterization of the Ti-10Nb-10Zr-5Ta Alloy for Biomedical Applications. Part 1: Microstructure, Mechanical Properties, and Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Vladescu, A.; Braic, V.; Balaceanu, M.; Braic, M.; Parau, A. C.; Ivanescu, S.; Fanara, C.

    2013-08-01

    Ti-10Nb-10Zr-5Ta alloy was investigated as possible material candidate for replacing Ti6Al4V in medical applications. The alloy was prepared in a levitation melting furnace and characterized in terms of elemental and phase composition, microstructure, mechanical properties, and corrosion resistance in simulated body fluid and Fusayama Meyer artificial saliva solutions. The characteristics of the new alloy were compared to those of the Ti6Al4V alloy. The Ti-10Nb-10Zr-5Ta system was found to posses of a polyhedral structure consisting in α' and β phases. X-ray structural analysis revealed a mixture of hexagonal α' martensite (main phase, with grain size of about 21 nm) and β bcc phase. The Ti-10Nb-10Zr-5Ta alloy exhibited some better mechanical properties (Young modulus, tensile properties) and corrosion resistance (polarization resistance, corrosion current density, and corrosion rate), as compared to Ti6Al4V alloy.

  12. Comparisons of immersion and electrochemical properties of highly biocompatible Ti-15Zr-4Nb-4Ta alloy and other implantable metals for orthopedic implants

    NASA Astrophysics Data System (ADS)

    Okazaki, Yoshimitsu; Nagata, Hiroyuki

    2012-12-01

    Metal release from implantable metals and the properties of oxide films formed on alloy surfaces were analyzed, focusing on the highly biocompatible Ti-15Zr-4Nb-4Ta alloy. The thickness and electrical resistance (Rp) of the oxide film on such an alloy were compared with those of other implantable metals. The quantity of metal released during a 1-week immersion test was considerably smaller for the Ti-15Zr-4Nb-4Ta than the Ti-6Al-4V alloy. The potential (E10) indicating a current density of 10 μA cm-2 estimated from the anodic polarization curve was significantly higher for the Ti-15Zr-4Nb-4Ta than the Ti-6Al-4V alloy and other metals. Moreover, the oxide film (4-7 nm thickness) formed on the Ti-15Zr-4Nb-4Ta surface is electrochemically robust. The oxide film mainly consisted of TiO2 with small amounts of ZrO2, Nb2O5 and Ta2O5 that made the film electrochemically stable. The Rp of Ti-15Zr-4Nb-4Ta was higher than that of Ti-6Al-4V, i.e. 0.9 Ω cm2 in 0.9% NaCl and 1.3 Ω cm2 in Eagle's medium. This Rp was approximately five-fold higher than that of stainless steel, which has a history of more than 40 years of clinical use in the human body. Ti-15Zr-4Nb-4Ta is a potential implant material for long-term clinical use. Moreover, E10 and Rp were found to be useful parameters for assessing biological safety.

  13. Phase formation and mechanical properties of Cu-Zr-Ti bulk metallic glass composites

    NASA Astrophysics Data System (ADS)

    Kim, Byoung Jin; Yun, Young Su; Kim, Won Tae; Kim, Do Hyang

    2016-11-01

    The effect of the type of the crystalline phase and its volume fraction on the mechanical property of Cu50Zr50-xTix alloys (x = 0-10) bulk metallic glass composites has been investigated in this study. Up to 6 at% of Ti, B19' phase particles distributed in the glassy matrix, while at 8 and 10% of Ti, B2 phase particles are retained in the glass matrix due to suppression of the eutectoid transformation of B2 phase and by avoidance of martensitic transformation of B2 into B19'. The volume fraction of crystalline phase is strongly dependent on the cooling rate. The larger volume fraction of the crystalline phases results in the lower yield stress, the higher plastic strain, and the more pronounced work hardening behavior. At the crystalline volume fraction below 30%, the variation of the yield strength can be described by the rule of mixture model (ROM), while at the crystalline volume fraction higher than 50% by the load-bearing model (LBM). At the crystal fractions between 30 and 50%, there is a yield strength drop and a transition from the ROM to the LBM. This transition is due to the formation of the crystalline structural framework at higher crystal fraction.

  14. Domain structure of tetragonal Pb(Zr,Ti)O3 nanorods and its size dependence

    NASA Astrophysics Data System (ADS)

    Yamada, Tomoaki; Ito, Daisuke; Sakata, Osami; Kuroishi, Junki; Namazu, Takahiro; Imai, Yasuhiko; Shiraishi, Takahisa; Shimizu, Takao; Funakubo, Hiroshi; Yoshino, Masahito; Nagasaki, Takanori

    2015-10-01

    We fabricated {100} Pb(Zr0.35Ti0.65)O3 (PZT) nanorods by partly etching a film grown on a Nb-doped SrTiO3 substrate using a focused ion beam, followed by annealing to recover the etching damage and promote the formation of a stable domain structure in the form of nanorods. The application of synchrotron micro-X-ray diffraction enabled the detection of the diffraction intensity from a single nanorod, which allowed us to clarify the size dependence of the domain structure of the fabricated nanorods. We found that the a-domain fraction in the tetragonal PZT nanorods decreased with decreasing rod width and that an exclusively c-domain structure was formed in nanorods of ≤1 µm width. The preferred formation of the c-domain in these nanorods can be rationalized in terms of the large depolarizing field in the a-domain and/or the in-plane compressive strain near the PZT/substrate interface.

  15. K-shell ionization cross section for Ti, Fe, Cu, Zr, and Ag

    SciTech Connect

    Benka, O.; Geretschlager, M.

    1981-04-01

    Absolute K-shell ionisation cross sections have been measured for thin targets of Ti, Fe, Cu, Zr and Ag for protons in the energy range 85-790 keV and for thin targets of Ti, Fe and Cu for He ions in the energy range 190-750 keV. In addition the relative variation of the cross sections with energy has been determined with high accuracy. The experimental values are compared to the perturbed stationary state approximation (CPSSR) and the semiclassical approximation (SCA). The CPSSR theory provides the best overall agreement with experimental cross sections. For higher scaled energies the CPSSR theory predicts the energy dependence of the cross sections very well but in the lower energy range it overpredicts the cross sections by as much as a factor of two and this overprediction seems to increase with Z/sub 2/ at a fixed scaled energy y. The SCA theory predicts slightly too large ionisation cross sections except for the lowest pounds values. The relative variation of the cross sections with energy is not well described in either energy range.

  16. First principles investigations of structural, elastic, dielectric and piezoelectric properties of { Ba,Sr,Pb } TiO3, { Ba,Sr,Pb } ZrO3 and { Ba,Sr,Pb } { Zr,Ti } O3 ceramics

    NASA Astrophysics Data System (ADS)

    Akgenc, Berna; Tasseven, Cetin; Cagin, Tahir

    2015-03-01

    We use first-principle density-functional study of structural, anisotropic mechanical, dielectric and piezoelectric properties of {Ba,Sr,Pb}TiO3, {Ba,Sr,Pb}ZrO3 and {Ba,Sr,Pb}{Zr,Ti}O3 alloys in cubic perovskite structures at zero temperature. Because there is significant interest in finding new piezoelectrics that do not contain toxic elements such as lead. In this study, we compare piezoelectric response of those alloys to synthesize outstanding piezoelectric materials. In perovskite structures, the spontaneous polarization is due to enormous values of Born effective charges computed by linear response within density functional perturbation theory, which are much larger than predicted nominal charge. We deeply investigated the effects of composition, order and site defects structure on piezoelectric constants.

  17. Phenomenological thermodynamic potentials for bulk and thin-film Ba (Zr0.08 Ti 0.92 ) O 3 single crystals

    NASA Astrophysics Data System (ADS)

    Peng, J. L.; Li, Q.; Shan, D. L.; Pan, K.; Yu, G. S.; Liu, Y. Y.

    2016-05-01

    Phenomenological thermodynamic analysis is an important theoretical investigation method for ferroelectric materials, however, it cannot be implemented for Ba ( Zr x Ti 1 - x ) O 3 due to the lack of thermodynamic potential coefficients. In this paper, we have constructed a phenomenological thermodynamic potential for bulk Ba ( Zr 0.08 Ti 0.92 ) O 3 single crystals, which reproduces the three phase transition temperatures, dielectric and piezoelectric constants of bulk Ba ( Zr 0.08 Ti 0.92 ) O 3 single crystals well, suggesting that the constructed thermodynamic potential is reliable. Then the thermodynamic potential with appropriate modification is applied to predict misfit strain-temperature phase diagram and electromechanical properties of Ba ( Zr 0.08 Ti 0.92 ) O 3 thin films. It is found that compressive strain favors the tetragonal c phase with an out-of-plane polarization component, while tensile misfit strain favors orthorhombic aa phase with an in-plane polarization component. It also reveals that Ba ( Zr 0.08 Ti 0.92 ) O 3 thin films under appropriate compressive strain show higher piezoelectric coefficient d15 than that of their bulk counterpart. The constructed thermodynamic potential opens a new avenue to theoretical analysis on Ba ( Zr 0.08 Ti 0.92 ) O 3 .

  18. Oriented and ordered mesoporous ZrO{sub 2}/TiO{sub 2} fibers with well-organized linear and spring structure

    SciTech Connect

    Zhu, Luyi; Liu, Benxue; Qin, Weiwei; Liu, Hongjing; Lin, Xuejun; Cai, Ningning; Wang, Xinqiang; Xu, Dong

    2015-08-15

    Graphical abstract: The ultra-stable order mesoporous ZrO{sub 2}/TiO{sub 2} fibers with well-organized linear and spring structure and large surface area under higher temperatures were prepared by a simple EISA process. - Highlights: • The ZrO{sub 2}/TiO{sub 2} fibers were prepared by EISA process combined with steam heat-treatment. • The mesoporous ZrO{sub 2}/TiO{sub 2} fibers have well-organized linear and spring structure. • The fibers were composed of oval rod nanocrystals of ZrTiO{sub 4}. - Abstract: The ultra-stable order mesoporous ZrO{sub 2}/TiO{sub 2} fibers with well-organized linear and spring structure and large surface areas under higher temperatures were prepared by a (simple evaporation-induced assembly) EISA process. The preparation, microstructures and formation processes were characterized by Fourier transformation infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N{sub 2} adsorption–absorption measurements. The fibers take on pinstripe configuration which is very orderly along or perpendicular to the axial direction of the fibers. The diameters of the pinstripe are in the region of 200–400 nm and arranges regularly, which are composed of oval rod nanocrystals of ZrTiO{sub 4}.

  19. Preparation, characterization and photocatalytic performance of TiO 2/Ce xZr 1- xO 2 toward the oxidation of gaseous benzene

    NASA Astrophysics Data System (ADS)

    Zhong, Jun bo; Ma, Di; He, Xi yang; Li, Jian zhang; Chen, Yao qiang

    2010-02-01

    Increasing environmental pollution caused by the volatile organic compounds due to their toxicity makes their removal imperative. So it is crucial to develop processes which can degrade these compounds effectively. The paper demonstrates that the photocatalytic activity of TiO 2 toward the decomposition of gaseous benzene in a batch reactor can be greatly enhanced by loading TiO 2 onto the surface of Ce xZr 1- xO 2 ( x ≥ 0.25) using sol-gel technology. This research investigated the relationship between x amount and the photocatalytic activity of TiO 2. The prepared photocatalysts were characterized by BET, XRD, UV-vis diffuse reflectance and XPS analyses. The specific surface area of photocatalyst decreases as x decreases. XRD results reveal the no peaks of titania were detected. Among the five catalysts prepared, only the binding energy values of Ti2p 3/2 of TiO 2/Ce 0.5Zr 0.5O 2 shift toward lower value. The order of photocatalytic activity is TiO 2/Ce 0.5Zr 0.5O 2 > TiO 2/Ce 0.75Zr 0.25O 2 > TiO 2/CeO 2 ≈ TiO 2/Ce 0.25Zr 0.75O 2 > TiO 2/ZrO 2 ≈ TiO 2. The mechanism role of Ceria-Zirconia mixed oxides in photocatalytic reaction was speculated.

  20. Effect of thermal annealing in vacuum and in air on nanograin sizes in hard and superhard coatings Zr-Ti-Si-N.

    PubMed

    Pogrebnjak, A D; Shpak, A P; Beresnev, V M; Kolesnikov, D A; Kunitskii, Yu A; Sobol, O V; Uglov, V V; Komarov, F F; Shypylenko, A P; Makhmudov, N A; Demyanenko, A A; Baidak, V S; Grudnitskii, V V

    2012-12-01

    Zr-Ti-Si-N coating had high thermal stability of phase composition and remained structure state under thermal annealing temperatures reached 1180 degrees C in vacuum and 830 degrees C in air. Effect of isochronous annealing on phase composition, structure, and stress state of Zr-Ti-Si-N-ion-plasma deposited coatings (nanocomposite coatings) was reported. Below 1000 degrees C annealing temperature in vacuum, changing of phase composition is determined by appearing of siliconitride crystallites (beta-Si3N4) with hexagonal crystalline lattice and by formation of ZrO2 oxide crystallites. Formation of the latter did not result in decay of solid solution (Zr, Ti)N but increased in it a specific content of Ti-component. Vacuum annealing increased sizes of solid solution nanocrystallites from (12 to 15) in as-deposited coatings to 25 nm after annealing temperature reached 1180 degrees C. One could also find macro- and microrelaxations, which were accompanied by formation of deformation defects, which values reached 15.5 vol.%. Under 530 degrees C annealing in vacuum or in air, nanocomposite coating hardness increased. When Ti and Si concentration increased and three phases nc-ZrN, (Zr, Ti)N-nc, and alpha-Si3N4 were formed, average hardness increased to 40.8 +/- 4 GPa. Annealing to 500 degrees C increased hardness and demonstrated lower spread in values H = 48 +/- 6 GPa and E = (456 +/- 78) GPa. Zr-Ti-Si-N coatings has high wear resistance and low friction coefficient in comparison at a temperature of 500 degrees C possess with coatings TiN, Ti-Si-N.

  1. Highly transparent and flexible bio-based polyimide/TiO2 and ZrO2 hybrid films with tunable refractive index, Abbe number, and memory properties

    NASA Astrophysics Data System (ADS)

    Huang, Tzu-Tien; Tsai, Chia-Liang; Tateyama, Seiji; Kaneko, Tatsuo; Liou, Guey-Sheng

    2016-06-01

    The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system, the hybrid materials have a lower LUMO energy level which could facilitate and stabilize the charge transfer complex. Therefore, memory devices derived from these PI hybrid films exhibited tunable memory properties from DRAM, SRAM, to WORM with a different TiO2 or ZrO2 content from 0 wt% to 50 wt% with a high ON/OFF ratio (108). In addition, the different energy levels of TiO2 and ZrO2 revealed specifically unique memory characteristics, implying the potential application of the prepared 4ATA-PI/TiO2 and 4ATA-PI/ZrO2 hybrid films in highly transparent memory devices.The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system

  2. Structural and ferroelectric properties of epitaxial BaZr x Ti1-x O3 thin films

    NASA Astrophysics Data System (ADS)

    Engelhardt, S.; Mietschke, M.; Molin, C.; Gebhardt, S.; Fähler, S.; Nielsch, K.; Hühne, R.

    2016-12-01

    Epitaxial BaZr x Ti1-x O3 (BZTO) thin films with Zr contents of x  =  0, x  =  0.12 and x  =  0.2 were grown by pulsed laser deposition on (0 0 1)-oriented single crystalline SrTiO3 substrates utilizing an additional conducting SrRuO3 buffer layer. It was found that the oxygen pressure during the deposition {{p}{{\\text{O}2}}} heavily influences the lattice constants and the microstructure of BZTO. A low {{p}{{\\text{O}2}}} of 0.01 mbar gives rise to a significant tetragonal distortion. Texture measurements reveal that an undisturbed epitaxial growth is only achieved for BZTO films prepared in 0.01 mbar oxygen. In contrast, the formation of twins was observed for higher {{p}{{\\text{O}2}}} . A detailed microstructural analysis indicates that the sample preparation in low {{p}{{\\text{O}2}}} prevents a preferential growth of columnar grains within the BZTO layers and leads to smoother film surfaces. BZTO thin films deposited with optimized deposition parameters show characteristic ferroelectric polarization behavior. The saturation polarization at room temperature declines with increasing Zr content and the characteristic ferroelectric hysteresis diminishes. Temperature-depended measurements of the relative permittivity reveal the existence of a broad transition range and a significant shift of the phase transition temperature to lower values for increasing Zr content.

  3. Tuning the band gap of mesoporous Zr-doped TiO2 for effective degradation of pesticide quinalphos.

    PubMed

    Goswami, Pallabi; Ganguli, Jatindra Nath

    2013-10-28

    This paper has focused on the synthesis and modification of TiO2 nanomaterial via an acid modified sol-gel process. ZrOCl2 was used as a source of Zr for doping titania. The nanomaterials were characterized by electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, N2 adsorption-desorption isotherms, UV-visible diffuse reflectance spectroscopy, etc. Changes in the band gap of the synthesized nanomaterials were studied with respect to the dopant amount, and the performance of the synthesized nanomaterials was evaluated as a photocatalyst to degrade pesticide quinalphos in aqueous solution under UV light. Anatase TiO2 nanocrystallites with an average size of ca. 8-11 nm were obtained depending on the amount of dopant. The results showed that the amount of dopant significantly altered the band gap as well as the surface properties of the hybrid nanomaterials which resulted in high photocatalytic activity.

  4. Preparation and electrical properties of (Zr,Sn)TiO{sub 4} dielectric thin films by laser ablation

    SciTech Connect

    Nakagawara, Osamu; Toyota, Yuji; Kobayashi, Masato; Yoshino, Yukio; Katayama, Yuzo; Tabata, Hitoshi; Kawai, Tomoji

    1996-11-01

    (Zr,Sn)TiO{sub 4} is considered as a promising dielectric material for microwave devices owing to the temperature stability of capacitance and excellent microwave properties. Preferential (111)-oriented (Zr,Sn)TiO{sub 4} thin film was obtained by an ArF laser ablation. Properties of the crystallized film were as follows; the temperature coefficient of capacitance TCC was 17.6 ppm/C at 3 MHz and the dielectric constant {var_epsilon}{sub r}, 38 in the microwave range of 1GHZ--10GHz. It has turned out that the crystallization of this material is quite effective for improving dielectrical properties. Surface morphologies were observed by atomic force microscope (AFM). Grains grew on the crystallized film at 1 {micro}m x 1 {micro}m size.

  5. Corrosion resistance and in vitro response of a novel Ti35Nb2Ta3Zr alloy with a low Young's modulus.

    PubMed

    Guo, Yongyuan; Chen, Desheng; Lu, Weijie; Jia, Yuhua; Wang, Liqiang; Zhang, Xianlong

    2013-10-01

    β type titanium alloys have attracted much attention in the biomedical field because they consist of non-cytotoxic elements, show high corrosion resistance, and are biologically compatible. In this study, a novel β type titanium alloy (Ti35Nb3Zr2Ta) with a Young's modulus of 48 GPa was fabricated and the alloy's corrosion resistance and in vitro response were determined. The results indicate that the novel alloy exhibits comparable corrosion resistance when compared with Ti6Al4V, but in vitro experiments show that osteoblasts attach, spread, proliferate, and differentiate better on Ti35Nb2Ta3Zr than on Ti6Al4V. The high corrosion resistance and satisfactory biocompatibility make the novel Ti35Nb3Zr2Ta alloy a promising biomaterial for surgical implants.

  6. Highly transparent and flexible bio-based polyimide/TiO2 and ZrO2 hybrid films with tunable refractive index, Abbe number, and memory properties.

    PubMed

    Huang, Tzu-Tien; Tsai, Chia-Liang; Tateyama, Seiji; Kaneko, Tatsuo; Liou, Guey-Sheng

    2016-07-07

    The novel bio-based polyimide (4ATA-PI) and the corresponding PI hybrids of TiO2 or ZrO2 with excellent optical properties and thermal stability have been prepared successfully. The highly transparent 4ATA-PI containing carboxylic acid groups in the backbone could provide reaction sites for organic-inorganic bonding to obtain homogeneous hybrid films. These PI hybrid films showed a tunable refractive index (1.60-1.81 for 4ATA-PI/TiO2 and 1.60-1.80 for 4ATA-PI/ZrO2), and the 4ATA-PI/ZrO2 hybrid films revealed a higher optical transparency and Abbe's number than those of the 4ATA-PI/TiO2 system due to a larger band gap of ZrO2. By introducing TiO2 and ZrO2 as the electron acceptor into the 4ATA-PI system, the hybrid materials have a lower LUMO energy level which could facilitate and stabilize the charge transfer complex. Therefore, memory devices derived from these PI hybrid films exhibited tunable memory properties from DRAM, SRAM, to WORM with a different TiO2 or ZrO2 content from 0 wt% to 50 wt% with a high ON/OFF ratio (10(8)). In addition, the different energy levels of TiO2 and ZrO2 revealed specifically unique memory characteristics, implying the potential application of the prepared 4ATA-PI/TiO2 and 4ATA-PI/ZrO2 hybrid films in highly transparent memory devices.

  7. Giant electrocaloric effect in thin-film PbZr(0.95)Ti(0.05)O3.

    PubMed

    Mischenko, A S; Zhang, Q; Scott, J F; Whatmore, R W; Mathur, N D

    2006-03-03

    An applied electric field can reversibly change the temperature of an electrocaloric material under adiabatic conditions, and the effect is strongest near phase transitions. We demonstrate a giant electrocaloric effect (0.48 kelvin per volt) in 350-nanometer PbZr(0.95)Ti(0.05)O3 films near the ferroelectric Curie temperature of 222 degrees C. A large electrocaloric effect may find application in electrical refrigeration.

  8. Microstructure and Room Temperature Properties of a High-Entropy TaNbHfZrTi Alloy (Preprint)

    DTIC Science & Technology

    2011-07-01

    yielding at 807 MPa. A simple model of solid -solution strengthening is proposed to explain the behavior. 15. SUBJECT TERMS refractory alloy...Ta20Nb20Hf20Zr20Ti20, vacuum arc-melting, hot isostatic pressing 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT: SAR 18. NUMBER OF PAGES... solid -solution strengthening is proposed to explain the behavior. 1 INTRODUCTION Metallic alloys with superior mechanical and functional properties

  9. An experimental study on the mixing behavior of Ti, Zr, V and Mo in the Elbe, Rhine and Weser estuaries

    NASA Astrophysics Data System (ADS)

    Schneider, Alexandre B.; Koschinsky, Andrea; Kiprotich, Joseph; Poehle, Sandra; do Nascimento, Paulo C.

    2016-03-01

    Estuaries are important interfaces between land and ocean, in which the input of trace metals into the ocean via the rivers is often significantly modified along the mixing gradient between freshwater and seawater. In the present study we have carried out mixing experiments using river water from the Rhine, the Elbe and the Weser and seawater from the North Sea with the aim of gaining more insights into the behavior of titanium (Ti), zirconium (Zr), vanadium (V) and molybdenum (Mo) and their distribution between dissolved and particulate forms during mixing in the estuaries. Little is known about the modification of their concentrations in estuaries and these metals increasingly enter the rivers and the ocean due to their application as so-called high-tech metals in industrial activities. Such laboratory experiments at controlled conditions allow the systematic investigation of chemical changes related to the mixing ratios, independent of further influence factors occurring in natural systems. Adsorptive stripping voltammetry was used for the analytical determination of the four metals. Although our data largely confirmed a strong particle-reactive behavior of Ti and Zr and a mostly conservative behavior of Mo, our mixing experiments revealed partial deviation from this behavior. Vanadium mostly does not follow a strict conservative mixing trend but shows both small ad- and desorption effects along the salinity transect. Also Mo shows some deviations from conservative mixing at mid-salinities. The enrichment of dissolved Ti and Zr at about 50:50 river: seawater mixtures agrees with recently published data of similar field studies and appears to be a systematic effect possibly related to charge transitions on particle surfaces or change of the dissolved metal speciation. The observed effects partly differed in experiments with filtered and non-filtered river water samples, especially for Ti and Zr, highlighting the role of riverine particulate matter for the

  10. Site preference of ternary alloying additions to NiTi: Fe, Pt, Pd, Au, Al, Cu, Zr and Hf

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Mosca, Hugo O.

    2004-01-01

    Atomistic modeling of the site substitution behavior of Pd in NiTi (J. Alloys and Comp. (2004), in press) has been extended to examine the behavior of several other alloying additions, namely, Fe, Pt, Au, Al, Cu, Zr and Hf in this important shape memory alloy. It was found that all elements, to a varying degree, displayed absolute preference for available sites in the deficient sublattice. How- ever, the energetics of the different substitutional schemes, coupled with large scale simulations indicate that the general trend in all cases is for the ternary addition to want to form stronger ordered structures with Ti.

  11. Newly developed Ti-Nb-Zr-Ta-Si-Fe biomedical beta titanium alloys with increased strength and enhanced biocompatibility.

    PubMed

    Kopova, Ivana; Stráský, Josef; Harcuba, Petr; Landa, Michal; Janeček, Miloš; Bačákova, Lucie

    2016-03-01

    Beta titanium alloys are promising materials for load-bearing orthopaedic implants due to their excellent corrosion resistance and biocompatibility, low elastic modulus and moderate strength. Metastable beta-Ti alloys can be hardened via precipitation of the alpha phase; however, this has an adverse effect on the elastic modulus. Small amounts of Fe (0-2 wt.%) and Si (0-1 wt.%) were added to Ti-35Nb-7Zr-6Ta (TNZT) biocompatible alloy to increase its strength in beta solution treated condition. Fe and Si additions were shown to cause a significant increase in tensile strength and also in the elastic modulus (from 65 GPa to 85 GPa). However, the elastic modulus of TNZT alloy with Fe and Si additions is still much lower than that of widely used Ti-6Al-4V alloy (115 GPa), and thus closer to that of the bone (10-30 GPa). Si decreases the elongation to failure, whereas Fe increases the uniform elongation thanks to increased work hardening. Primary human osteoblasts cultivated for 21 days on TNZT with 0.5Si+2Fe (wt.%) reached a significantly higher cell population density and significantly higher collagen I production than cells cultured on the standard Ti-6Al-4V alloy. In conclusion, the Ti-35Nb-7Zr-6Ta-2Fe-0.5Si alloy proves to be the best combination of elastic modulus, strength and also biological properties, which makes it a viable candidate for use in load-bearing implants.

  12. Effect of structural evolution on mechanical properties of ZrO2 coated Ti-6Al-7Nb-biomedical application

    NASA Astrophysics Data System (ADS)

    Zalnezhad, E.

    2016-05-01

    Zirconia (ZrO2) nanotube arrays were fabricated by anodizing pure zirconium (Zr) coated Ti-6Al-7Nb in fluoride/glycerol electrolyte at a constant potential of 60 V for different times. Zr was deposited atop Ti-6Al-7Nb via a physical vapor deposition magnetron sputtering (PVDMS) technique. Structural investigations of coating were performed utilizing X-ray diffraction (XRD) analysis. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used to characterize the morphology and microstructure of coatings. Unannealed ZrO2 nanotube arrays were amorphous. Monoclinic and tetragonal ZrO2 appeared when the coated substrates were heat treated at 450 °C and 650 °C, while monoclinic ZrO2 was found at 850 °C and 900 °C. Mechanical properties, including nanohardness and modulus of elasticity, were evaluated at different annealing temperatures using a nanoindentation test. The nanoindentation results show that the nanohardness and modulus of elasticity for Ti-6AL-7Nb increased by annealing ZrO2 coated substrate at 450 °C. The nanohardness and modulus of elasticity for coated substrate decreased with annealing temperatures of 650, 850, and 900 °C. At an annealing temperature of 900 °C, cracks in the ZrO2 thin film coating occurred. The highest nanohardness and elastic modulus values of 6.34 and 218 GPa were achieved at an annealing temperature of 450 °C.

  13. Influence of bilayer period on the characteristics of nanometre-scale ZrN/TiAIN multilayers.

    PubMed

    Vladescu, A; Kiss, A; Popescu, A; Braic, M; Balaceanu, M; Braic, V; Tudor, I; Logofatu, C; Negrila, C C; Rapeanu, R

    2008-02-01

    In the last decade, considerable research effort was directed to the deposition of multilayer films with layer thicknesses in the nanometer range (superlattice coatings), in order to increase the performance of various cutting tools and machine parts. The goal of the present work was to investigate the main microstructural, mechanical and wear resistance characteristics of a superlattice coating, consisting of alternate multilayer ZrN/TiAIN films, with various bilayer periods (5 / 20 nm). The coatings were deposited by the cathodic arc method on Si, plain carbon steel and high speed steel substrates to be used as wear resistance surfaces. The multilayer structures were prepared by using shutters placed in front of each cathode (Zr and Ti+Al). The characteristics of multilayer structures (elemental and phase composition, texture, Vickers microhardness, thickness, adhesion, and wear resistance) were determined by using various techniques (AES, XPS, XRD, microhardness measurements, scratch, and tribological tests). A comparison with the properties of ZrN and TiAIN single-layer coatings was carried out.

  14. Improving iron-enriched basalt with additions of ZrO{sub 2} and TiO{sub 2}

    SciTech Connect

    Reimann, G.A.; Kong, P.C.

    1993-06-01

    The iron-enriched basalt (IEB) waste form, developed at the Idaho National Engineering Laboratory a decade ago, was modified to IEB4 by adding sufficient ZrO{sub 2} and TiO{sub 2} to develop crystals of zirconolite upon cooling, in addition to the crystals that normally form in a cooling basalt. Zirconolite (CaZrTi{sub 2}O{sub 7}) is an extremely leach-resistant mineral with a strong affinity for actinides. Zirconolite crystals containing uranium and thorium have been found that have endured more than 2 billion years of natural processes. On this basis, zirconolite was considered to be an ideal host crystal for the actinides contained in transuranic (TRU)-contaminated wastes. Crystals of zirconolite were developed in laboratory melts of IEB4 that contained 5% each of ZrO{sub 2} and TiO{sub 2} and that were slow-cooled in the 1200--1000{degrees}C range. When actinide surrogates were added to IEB4, these oxides were incorporated into the crystals of zirconolite rather than precipitating in the residual glass phase. Zirconolite crystals developed in IEB4 should stabilize and immobilize the dilute TRUs in heterogeneous, buried low-level wastes as effectively as this same phase does in the various formulations of Synroc used for the more concentrated TRUs encountered in high-level wastes. Synroc requires hot-pressing equipment, while IEB4 precipitates zirconolite from a cooling basaltic melt.

  15. Preparation of Al72Ni8Ti8Zr6Nb3Y3 amorphous powders and bulk materials

    NASA Astrophysics Data System (ADS)

    Wu, Yu; Wang, Xin-fu; Han, Fu-sheng

    2016-10-01

    Amorphous Al72Ni8Ti8Zr6Nb3Y3 powders were successfully fabricated by mechanical alloying. The microstructure, glass-forming ability, and crystallization behavior of amorphous Al72Ni8Ti8Zr6Nb3Y3 powders were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The isothermal crystallization kinetics was analyzed by the Johnson-Mehl-Avrami equation. In the results, the supercooled liquid region of the amorphous alloy is as high as 81 K, as determined by non-isothermal DSC curves. The activation energy for crystallization is as high as 312.6 kJ·mol-1 obtained by Kissinger and Ozawa analyses. The values of Avrami exponent ( n) imply that the crystallization is dominated by interface-controlled three-dimensional growth in the early stage and the end stage and by diffusion-controlled two- or three-dimensional growth in the middle stage. In addition, the amorphous Al72Ni8Ti8Zr6Nb3Y3 powders were sintered under 2 GPa at temperatures of 673 K and 723 K. The results show that the Vickers hardness of the compacted powders is as high as Hv 1215.

  16. Influence of polyetheretherketone coatings on the Ti-13Nb-13Zr titanium alloy's bio-tribological properties and corrosion resistance.

    PubMed

    Sak, Anita; Moskalewicz, Tomasz; Zimowski, Sławomir; Cieniek, Łukasz; Dubiel, Beata; Radziszewska, Agnieszka; Kot, Marcin; Łukaszczyk, Alicja

    2016-06-01

    Polyetheretherketone (PEEK) coatings of 70-90μm thick were electrophoretically deposited from a suspension of PEEK powder in ethanol on near-β Ti-13Nb-13Zr titanium alloy. In order to produce good quality coatings, the composition of the suspension (pH) and optimized deposition parameters (applied voltage and time) were experimentally selected. The as-deposited coatings exhibited the uniform distribution of PEEK powders on the substrate. The subsequent annealing at a temperature above the PEEK melting point enabled homogeneous, semi-crystalline coatings with spherulitic morphology to be produced. A micro-scratch test showed that the coatings exhibited very good adhesion to the titanium alloy substrate. Coating delamination was not observed even up to a maximal load of 30N. The PEEK coatings significantly improved the tribological properties of the Ti-13Nb-13Zr alloy. The coefficient of friction was reduced from 0.55 for an uncoated alloy to 0.40 and 0.12 for a coated alloy in a dry sliding and sliding in Ringer's solution, respectively. The PEEK coatings exhibited excellent wear resistance in both contact conditions. Their wear rate was more than 200 times smaller compared with the wear rate of the uncoated Ti-13Nb-13Zr alloy. The obtained results indicate that electrophoretically deposited PEEK coatings on the near-β titanium alloy exhibit very useful properties for their prospective tribological applications in medicine.

  17. Large irreversible non-180° domain switching after poling treatment in Pb(Zr, Ti)O3 films

    NASA Astrophysics Data System (ADS)

    Ehara, Yoshitaka; Yasui, Shintaro; Oikawa, Takahiro; Shiraishi, Takahisa; Oshima, Naoya; Yamada, Tomoaki; Imai, Yasuhiko; Sakata, Osami; Funakubo, Hiroshi

    2016-05-01

    (11 1 ¯ )/(111)-oriented rhombohedral Pb(Zr0.65Ti0.35)O3 films with different domain fractions were epitaxially grown on various single crystals. The volume fraction of (111)-polar-axis oriented domains in as-deposited films, Vpol.(as-depo.), was controlled by selecting a single crystal substrate with a different thermal expansion coefficient. Applying an electric field, referred to as "poling treatment", resulted in irreversible non-180° domain switching from the (11 1 ¯ )-oriented domain (non-polar-axis) to the (111)-oriented domain (polar-axis), which was observed by synchrotron X-ray diffraction. Remanent polarization (Pr) values were higher than those estimated using the proportional relationship with Vpol.(as-depo.). However, the experimental Pr values were in good agreement with the values estimated using the volume fraction of (111)-oriented domains after applying the poling treatment. In rhombohedral Pb(Zr0.65Ti0.35)O3 films, 30%-50% of the (11 1 ¯ )-oriented domains switched irreversibly to (111)-oriented domains as a result of the poling treatment. The present results show that the domain structures of films may change dramatically after the poling process, and both before and after the poling state should be characterized in order to interpret polarization and piezoelectric behaviors. This study helps to clarify the ferroelectric and piezoelectric properties of Pb(Zr, Ti)O3 films after poling treatment.

  18. Osteogenic differentiation of adipose tissue-derived mesenchymal stem cells on nanostructured Ti6Al4V and Ti13Nb13Zr

    PubMed Central

    Marini, Francesca; Luzi, Ettore; Fabbri, Sergio; Ciuffi, Simone; Sorace, Sabina; Tognarini, Isabella; Galli, Gianna; Zonefrati, Roberto; Sbaiz, Fausto; Brandi, Maria Luisa

    2015-01-01

    Summary Bone tissue engineering and nanotechnology enable the design of suitable substitutes to restore and maintain the function of human bone tissues in complex fractures and other large skeletal defects. Long-term stability and functionality of prostheses depend on integration between bone cells and biocompatible implants. Human adipose tissue-derived mesenchymal stem cells (hAMSCs) have been shown to possess the same ability to differentiate into osteoblasts and to produce bone matrix of classical bone marrow derived stem cells (BMMSCs). Ti6A14V and Ti13Nb13Zr are two different biocompatible titanium alloys suitable for medical bone transplantation. Preliminary results from our Research Group demonstrated that smooth Ti6Al4V surfaces exhibit an osteoconductive action on hAMSCs, granting their differentiation into functional osteoblasts and sustaining bone matrix synthesis and calcification. The purpose of this study is to assay the ability of nanostructured Ti6Al4V and Ti13Nb13Zr alloys to preserve the growth and adhesion of hAMSCs and, mostly, to sustain and maintain their osteogenic differentiation and osteoblast activity. The overall results showed that both nanostructured titanium alloys are capable of sustaining cell adhesion and proliferation, to promote their differentiation into osteoblast lineage, and to support the activity of mature osteoblasts in terms of calcium deposition and bone extracellular matrix protein production. PMID:26811701

  19. Surface characterization of Zr/Ti/Nb tri-layered films deposited by magnetron sputtering on Si(111) and stainless steel substrates

    SciTech Connect

    Tallarico, Denise A.; Gobbi, Angelo L.; Filho, Pedro I. Paulin; Galtayries, Anouk; Nascente, Pedro A. P.

    2012-09-15

    Among metallic materials, commercially pure titanium and titanium alloys are very often used as biomaterials for implants. Among these alloys, titanium-aluminum-vanadium alloy Ti-6 A-4 V is one of the most commonly used due to its excellent biocompatibility and ability to allow bone-implant integration. A new class of Ti alloys employs Zr for solid-solution hardening and Nb as {beta}-phase stabilizer. Metals such as Ti, Nb, and Zr-known as valve metals-usually have their surfaces covered by a thin oxide film that forms spontaneously in air. This oxide film constitutes a barrier between the metal and the medium. The Ti-Nb-Zr alloys have mechanical and corrosion resistance characteristics which make them suitable for use as implants. Tri-layered films of Ti-Nb-Zr were deposited on both Si(111) and stainless steel (SS) substrates using dc magnetron sputtering equipment, under an argon atmosphere according to the following methodology: a 100 nm thick layer of Nb was deposited on the substrate, followed by a 200 nm thick layer of Ti, and finally a 50 nm thick layer of Zr, on top of the multilayer stack. The morphology and chemical composition of the films were analyzed by atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). AFM images showed that the Zr/Ti/Nb tri-layer films presented nanostructured grains and low roughness. The ToF-SIMS depth profiles confirmed the formation of a three-layered film on Si(111) with well-defined and sharp interfaces between the layers, while the deposition on the stainless steel substrate caused slight intermixing at the different alloy/Nb, Nb/Ti and Ti/Zr interfaces, reflecting the greater roughness of the raw substrate. The XPS results for the Zr/Ti/Nb layers deposited on Si(111) and SS confirmed that the outermost layer consisted of Zr only, with a predominance of ZrO{sub 2}, as the metal layer is passivated in air. An oxidation treatment of 1000 Degree

  20. Improvement of bio-corrosion resistance for Ti42Zr40Si15Ta3 metallic glasses in simulated body fluid by annealing within supercooled liquid region.

    PubMed

    Huang, C H; Lai, J J; Wei, T Y; Chen, Y H; Wang, X; Kuan, S Y; Huang, J C

    2015-01-01

    The effects of the nanocrystalline phases on the bio-corrosion behavior of highly bio-friendly Ti42Zr40Si15Ta3 metallic glasses in simulated body fluid were investigated, and the findings are compared with our previous observations from the Zr53Cu30Ni9Al8 metallic glasses. The Ti42Zr40Si15Ta3 metallic glasses were annealed at temperatures above the glass transition temperature, Tg, with different time periods to result in different degrees of α-Ti nano-phases in the amorphous matrix. The nanocrystallized Ti42Zr40Si15Ta3 metallic glasses containing corrosion resistant α-Ti phases exhibited more promising bio-corrosion resistance, due to the superior pitting resistance. This is distinctly different from the previous case of the Zr53Cu30Ni9Al8 metallic glasses with the reactive Zr2Cu phases inducing serious galvanic corrosion and lower bio-corrosion resistance. Thus, whether the fully amorphous or partially crystallized metallic glass would exhibit better bio-corrosion resistance, the answer would depend on the crystallized phase nature.

  1. Role of Hf on Phase Formation in Ti45Zr(38-x)Hf(x)Ni17 Liquids and Solids

    NASA Technical Reports Server (NTRS)

    Wessels, V.; Sahu, K. K.; Gangopadhyay, A. K.; Huett, V. T.; Canepari, S.; Goldman, A. I.; Hyers, R. W.; Kramer, M. J.; Rogers, J. R.; Kelton, K. F.; Robinson, D.

    2008-01-01

    Hafnium and zirconium are very similar, with almost identical sizes and chemical bonding characteristics. However, they behave differently when alloyed with Ti and Ni. A sharp phase formation boundary near 18-21 at.% Hf is observed in rapidly-quenched and as-cast Ti45Zr38-xHfxNi17 alloys. Rapidly-quenched samples that contain less than 18 at.% Hf form the icosahedral quasicrystal phase, whiles samples containing more than 21 at.% form the 3/2 rational approximant phase. In cast alloys, a C14 structure is observed for alloys with Hf lower than the boundary concentration, while a large-cell (11.93 ) FCC Ti2Ni-type structure is found in alloys with Hf concentrations above the boundary. To better understand the role of Hf on phase formation, the structural evolution with supercooling and the solidification behavior of liquid Ti45Zr38-xHfxNi17 alloys (x=0, 12, 18, 21, 38) were studied using the Beamline Electrostatic Levitation (BESL) technique using 125keV x-rays on the 6ID-D beamline at the Advanced Photon Source, Argonne National Laboratory. For all liquids primary crystallization was to a BCC solid solution phase; interestly, an increase in Hf concentration leads to a decrease in the BCC lattice parameter in spite of the chemical similarity between Zr and Hf. A Reitveld analysis confirmed that as in the cast alloys, the secondary phase that formed was the C14 below the phase formation boundary and a Ti2Ni-type structure at higher Hf concentrations. Both the liquidus temperature and the reduced undercooling change sharply on traversing the phase formation boundary concentration, suggesting a change in the liquid structure. Structural information from a Honeycutt-Anderson index analysis of reverse Monte Carlo fits to the S(q) liquid data will be presented to address this issue.

  2. Comparative characteristics of the mineralogical composition of Ti-Zr potential placer district

    NASA Astrophysics Data System (ADS)

    Ovchinnikova, Mary

    2016-04-01

    Russia has a great off-balance reserves of TiO2 and it is ranked fourth in the world after Ukraine, China and Australia. Inferred resources are also very significant. But today Russia produces titanium products only from imported raw materials. Exploration of Ti-raw material is carried out in Russia only as passing on comprehensive deposits. As a result of work conducted in 1959, Stavropolsky elevation was discovered Stavropolsky Ti-Zr alluvial basin. The same mineralogical composition has Ti-Zr Ergeninsky potential alluvial district, which is located north-eastern of Stavropolsky littoral basin. Administratively, Ergeninsky area, basically, covers territory of Kalmikia, and partially Rostovsky and Volgogradsky area. In terms of tectonics, it occupies an area of the junction of the East European platform and Karpinsky Ridge. Alluvial basin holds really magnificent range. There are two hypotheses as to where was the demolition of ore sand. According to the first demolition of the original ore material was from crumbling crystalline rocks southern East European platform. The second hypothesis links the formation of these placers due to the erosion of crystalline basement rocks of the Greater Caucasus, which is explained by the fact of the existence of the Sarmatian paleo sea. There are two productive horizons on the territory of Ergeninsky potential placer district. First - the lower productive horizon it has a capacity of 1.5 to 6.3 m and the total content of titanium and zirconium minerals 12 to 66 kg m³. Second - upper productive horizon. 1.5 to 4.3 m and the total content of titanium and zirconium minerals from 21 to 50 kg m³. Earlier in the study of the area, only samples from the upper productive horizon were considered. At the beginning petrophysical analysis of all available samples, was conducted. Before you choose a basic test, each of the 26 studied several petrophysical properties: 1. Magnetic susceptibility (κ, 10-5 units. C) 2. The density (d, g / cm

  3. Efficiency enhancement of dye-sensitized solar cells by use of ZrO2-doped TiO2 nanofibers photoanode.

    PubMed

    Mohamed, Ibrahim M A; Dao, Van-Duong; Barakat, Nasser A M; Yasin, Ahmed S; Yousef, Ahmed; Choi, Ho-Suk

    2016-08-15

    Due to the good stability and convenient optical properties, TiO2 nanostructures still the prominent photoanode materials in the Dye Sensitized Solar Cells (DSCs). However, the well-known low bandgap energy and weak adsorption affinity for the dye distinctly constrain the wide application. This work discusses the impact of Zr-doping and nanofibrous morphology on the performance and physicochemical properties of TiO2. Zr-doped TiO2 nanofibers (NFs), with various zirconia content (0, 0.5, 1, 1.5 and 2wt%) were prepared by calcination of electrospun mats composed of polyvinyl acetate, titanium isopropoxyl and zirconium n-propoxyl. For all formulations, the results have shown that the prepared materials are continuous, randomly oriented, and good morphology nanofibers. The average diameter decreased from 353.85nm to 210.78nm after calcination without a considerable influence on the nanofibrous structure regardless the zirconia content. XRD result shows that there is no Rutile nor Brookite phases in the obtained material and the average crystallite size of the sample is affected by the presence of Zr-doping and changed from 23.01nm to 37.63nm for TiO2 and Zr-doped TiO2, respectively. Optical studies have shown Zr-doped TiO2 NFs have more absorbance in the visible region than that of pristine TiO2 NFs; the maximum absorbance is corresponding to the NFs having 1wt% zirconia. The improved spectra of Zr-doped TiO2 in the visible region is attributed to the heterostructure composition resulting from Zr-doping. The absorption bandgaps were calculated using Tauc model as 3.202 and 3.217 for pristine and Zr (1wt%)-doped TiO2 NFs, respectively. Furthermore, in Dye-sensitized Solar Cells, utilizing Zr (1wt%)-doped TiO2 nanofibers achieved higher efficiency of 4.51% compared to the 1.61% obtained from the pristine TiO2 NFs.

  4. High-pressure behavior of A2B2O7 pyrochlore (A=Eu, Dy; B=Ti, Zr)

    NASA Astrophysics Data System (ADS)

    Rittman, Dylan R.; Turner, Katlyn M.; Park, Sulgiye; Fuentes, Antonio F.; Yan, Jinyuan; Ewing, Rodney C.; Mao, Wendy L.

    2017-01-01

    In situ high-pressure X-ray diffraction and Raman spectroscopy were used to determine the influence of composition on the high-pressure behavior of A2B2O7 pyrochlore (A = Eu, Dy; B = Ti, Zr) up to ˜50 GPa. Based on X-ray diffraction results, all compositions transformed to the high-pressure cotunnite structure. The B-site cation species had a larger effect on the transition pressure than the A-site cation species, with the onset of the phase transformation occurring at ˜41 GPa for B = Ti and ˜16 GPa B = Zr. However, the A-site cation affected the kinetics of the phase transformation, with the transformation for compositions with the smaller ionic radii, i.e., A = Dy, proceeding faster than those with a larger ionic radii, i.e., A = Eu. These results were consistent with previous work in which the radius-ratio of the A- and B-site cations determined the energetics of disordering, and compositions with more similarly sized A- and B-site cations had a lower defect formation energy. Raman spectra revealed differences in the degree of short-range order of the different compositions. Due to the large phase fraction of cotunnite at high pressure for B = Zr compositions, Raman modes for cotunnite could be observed, with more modes recorded for A = Eu than A = Dy. These additional modes are attributed to increased short-to-medium range ordering in the initially pyrochlore structured Eu2Zr2O7 as compared with the initially defect-fluorite structured Dy2Zr2O7.

  5. Wettability of brazing alloys on molybdenum and TZM (Mo-Ti-Zr alloy)

    SciTech Connect

    McDonald, M.M.; Keller, D.L.; Heiple, C.R.; Hofmann, W.E.

    1988-01-01

    Vacuum brazing studies have been performed on molybdenum and TZM (0.5Ti-0.08Zr-Mo). Wettability tests have been conducted for nineteen braze metal filler alloys on molybdenum and thirty-two braze metal filler alloys on TZM over a wide range of temperatures. A wetting index, which is a function of contact angle and braze alloy contact area, was determined for each filler alloy at each brazing temperature. The nature and extent of interaction between the brazing alloys and the base metals was analyzed by conventional metallography, scanning-electron microscopy, and electron microprobe analysis. A comparison is made between the behavior of filler alloys on molybdenum and TZM -- filler alloys consistently exhibited less wettability on TZM than on molybdenum. The lower wettability of TZM is believed to be due to a small amount of titanium in the surface oxide on TZM. Cracking was observed in the base metal under some of the high temperature braze deposits. The cracking is shown to arise from liquid metal embrittlement from nickel in the high temperature braze alloys. 7 refs., 11 figs., 2 tabs.

  6. Mechanical and corrosion resistance of a new nanostructured Ti-Zr-Ta-Nb alloy.

    PubMed

    Raducanu, D; Vasilescu, E; Cojocaru, V D; Cinca, I; Drob, P; Vasilescu, C; Drob, S I

    2011-10-01

    In this work, a multi-elementary Ti-10Zr-5Nb-5Ta alloy, with non-toxic alloying elements, was used to develop an accumulative roll bonding, ARB-type procedure in order to improve its structural and mechanical properties. The alloy was obtained by cold crucible semi-levitation melting technique and then was ARB deformed following a special route. After three ARB cycles, the total deformation degree per layer is about 86%; the calculated medium layer thickness is about 13 μm. The ARB processed alloy has a low Young's modulus of 46 GPa, a value very close to the value of the natural cortical bone (about 20 GPa). Data concerning ultimate tensile strength obtained for ARB processed alloy is rather high, suitable to be used as a material for bone substitute. Hardness of the ARB processed alloy is higher than that of the as-cast alloy, ensuring a better behaviour as a implant material. The tensile curve for the as-cast alloy shows an elastoplastic behaviour with a quite linear elastic behaviour and the tensile curve for the ARB processed alloy is quite similar with a strain-hardening elastoplastic body. Corrosion behaviour of the studied alloy revealed the improvement of the main electrochemical parameters, as a result of the positive influence of ARB processing. Lower corrosion and ion release rates for the ARB processed alloy than for the as-cast alloy, due to the favourable effect of ARB thermo-mechanical processing were obtained.

  7. Néel-like domain walls in ferroelectric Pb(Zr,Ti)O3 single crystals

    PubMed Central

    Wei, Xian-Kui; Jia, Chun-Lin; Sluka, Tomas; Wang, Bi-Xia; Ye, Zuo-Guang; Setter, Nava

    2016-01-01

    In contrast to the flexible rotation of magnetization direction in ferromagnets, the spontaneous polarization in ferroelectric materials is highly confined along the symmetry-allowed directions. Accordingly, chirality at ferroelectric domain walls was treated only at the theoretical level and its real appearance is still a mystery. Here we report a Néel-like domain wall imaged by atom-resolved transmission electron microscopy in Ti-rich ferroelectric Pb(Zr1−xTix)O3 crystals, where nanometre-scale monoclinic order coexists with the tetragonal order. The formation of such domain walls is interpreted in the light of polarization discontinuity and clamping effects at phase boundaries between the nesting domains. Phase-field simulation confirms that the coexistence of both phases as encountered near the morphotropic phase boundary promotes the polarization to rotate in a continuous manner. Our results provide a further insight into the complex domain configuration in ferroelectrics, and establish a foundation towards exploring chiral domain walls in ferroelectrics. PMID:27539075

  8. Monte Carlo Simulation Study of Diffuse Scattering in PZT, Pb(Zr,Ti)O3

    NASA Astrophysics Data System (ADS)

    Welberry, T. R.; Goossens, D. J.; Withers, R. L.; Baba-Kishi, K. Z.

    2010-05-01

    Transverse polarized diffuse streaks have been observed in diffraction patterns of Pb(Zr1- x Ti x )O3 (PZT) ceramics for compositions ranging from x = 0.3 (rhombohedral phase) to x = 0.7 (tetragonal phase) including the important morphotropic phase boundary (MPB) region ( x = 0.48). The streaks correspond to diffuse planes of scattering in three dimensions, and these are oriented normal to the (cubic) < 111ranglec directions. A Monte Carlo (MC) model has been developed that convincingly reproduces the observed diffraction patterns. In this model, the displacements of Pb ions running in chains along each of the < 111ranglec directions are directed along the chain and are strongly correlated from cell to cell. There is no evidence of lateral correlation. Neighboring chains are essentially independent. At this stage, it is not clear what role the local order revealed by the scattering might play in governing the exceptional piezo-electric properties of the material, but its presence requires the currently accepted models for the average structure to be reassessed.

  9. Preparation of (001)-oriented Pb(Zr,Ti)O3 thin films and their piezoelectric applications.

    PubMed

    Fujii, Eiji; Takayama, Ryoichi; Nomura, Kouji; Murata, Akiko; Hirasawa, Taku; Tomozawa, Atsushi; Fujii, Satoru; Kamada, Takeshi; Torii, Hideo

    2007-12-01

    Preparation of (001)-oriented Pb(Zr,Ti)O(3) (PZT) thin films and their applications to a sensor and actuators were investigated. These thin films, which have a composition close to the morphotropic phase boundary, were epitaxially grown on (100)MgO single-crystal substrates by RF magnetron sputtering. These (001)-oriented PZT thin films could be obtained on various kinds of substrates, such as glass and Si, by introducing (100)-oriented MgO buffer layers. In addition, the (001) oriented PZT thin films could be obtained on Si substrates without buffer layers by optimizing the sputtering conditions. All of these thin films showed excellent piezoelectric properties without the need for poling treatment. The PZT thin films on the MgO substrates had a high piezoelectric coefficient, d(31), of -100 pm/V, and an extremely low relative dielectric constant, epsilon(r), of 240. The PZT thin films on Si substrate had a very high d(31) of -150 pm/V and an epsilon(r) = 700. These PZT thin films were applied to an angular rate sensor with a tuning fork in a car navigation system, to a dual-stage actuator for positioning the magnetic head of a high-density hard disk drive, and to an actuator for an inkjet printer head for industrial on-demand printers.

  10. Ultrasonically assisted turning of Ti-6Al-2Sn-4Zr-6Mo

    NASA Astrophysics Data System (ADS)

    Muhammad, R.; Maurotto, A.; Roy, A.; Silberschmidt, V. V.

    2012-08-01

    Titanium alloys are widely used in the aerospace and offshore industries due to their high strength-to-weight ratio sustained at elevated temperatures, their fracture-resistance features and exceptionally good corrosion-resistance properties. However, poor thermal conductivity and high chemical affinity of these alloys to tool materials severely impair their machinability. As a result the machining processes of titanium alloys are typically characterized by low cutting feeds and speeds making production of components uneconomical. Recently, a non-conventional hybrid machining technique, namely, ultrasonically assisted turning has been shown to significantly improve the machinability of intractable alloys with a concomitant improvement in material removal rates, thus improving machining economics. In the current work, a 3D finite element model of turning of Ti-6Al-2Sn-4Zr-6Mo is developed in the commercial software, MSC Marc/Mentat. A constitutive behaviour of the workpiece material under large deformations and elevated temperatures is adequately represented by a Johnson-Cook material model. For validation of the developed numerical model, experimental tests were carried out. The numerical and experimental results were found to be in good agreement.

  11. Wear and corrosion behavior of oxygen implanted biomedical titanium alloy Ti-13Nb-13Zr

    NASA Astrophysics Data System (ADS)

    Mohan, L.; Anandan, C.

    2013-10-01

    Titanium alloy Ti-13Nb-13Zr was implanted with oxygen ions by plasma immersion ion implantation. The influence of oxygen ion implantation on the growth of apatite on the implanted sample was investigated by immersion in Hanks’ solution and also by potentiodynamic polarization studies in Hanks’ solution. XRD shows the formation of mainly anatase form of oxide. FESEM images of immersion tested samples show that growth of apatite is more with larger sized deposits on oxygen implanted surface as compared to that on the untreated substrate. XPS investigation of corrosion tested and 1 day immersed samples show higher amount of calcium, phosphorous and oxygen in hydroxide/phosphate form on the oxygen implanted sample. EDS results also confirm higher concentration of Ca and P on oxygen implanted sample. Polarization and electrochemical impedance spectroscopy studies show that the oxygen implanted layer behaves like a nearly ideal capacitor with better passivation characteristics. In sliding wear studies, the implanted layers displayed a lower friction coefficient as compared to the substrate one.

  12. Epitaxial PbxZr1-xTiO3 on GaN

    NASA Astrophysics Data System (ADS)

    Paisley, E. A.; Craft, H. S.; Losego, M. D.; Lu, H.; Gruverman, A.; Collazo, R.; Sitar, Z.; Maria, J.-P.

    2013-02-01

    Epitaxial integration of PbxZr1-xTiO3 (PZT) (111) with GaN (0002) presents the possibility of polarity coupling across a functional-oxide/nitride heteropolar interface. This work describes the synthesis and characterization of such thin film heterostructures by magnetron sputtering, with specific attention given to process optimization. Using x-ray diffraction and electrical characterization, the growth of epitaxial PZT (˜250 nm) on GaN and PZT on MgO/GaN stacks was verified. A two-stage growth process was developed for epitaxial PZT with a deposition temperature of 300 °C and an ex-situ anneal at 650 °C, which was effective in mitigating interfacial reactions and promoting phase-pure perovskite growth. Electrical analysis of interdigital capacitors revealed a nonlinear and hysteretic dielectric response consistent with ferroelectric PZT. Piezoresponse force microscopy (PFM) characterization shows clear evidence of ferroelectric switching, and PFM hysteresis loop analysis shows minimal evidence for direct polarity coupling, but suggests that band offsets which accompany the oxide-nitride heterostructures influence switching.

  13. Vacancy related defects in thin film Pb(ZrTi)O{sub 3} materials

    SciTech Connect

    Krishnan, A.; Keeble, D.J.; Ramesh, R.; Warren, W.L.; Tuttle, B.A.; Pfeffer, R.L.; Nielsen, B.; Lynn, K.G.

    1994-12-31

    Positron annihilation techniques have been applied to characterize vacancy-related defects in ferroelectric thin film structures. Variable energy positron beam measurements were carried out on doped and undoped Pb(ZrTi)O{sub 3} (PZT) samples subjected to different post-deposition cool down and anneal conditions. The PZT was deposited by sol-gel with either with platinum or RuO{sub 2} electrodes, or by laser ablation with La{sub 0.5}Sr{sub 0.5}CoO{sub 3} electrodes. The RuO{sub 2} and La{sub 0.5}Sr{sub 0.5}CoO{sub 3} electrode samples showed a smaller S-parameter compared to those deposited with Pt electrodes consistent with an improved PZT layer quality. For laser ablated samples cooled in a reducing ambient an increase in S-parameter for both the PZT and La{sub 0.5}Sr{sub 0.5}CoO{sub 3} layers was observed indicating an increase in neutral or negatively charged open-volume defects.

  14. Subterahertz dielectric relaxation in lead-free Ba(Zr,Ti)O3 relaxor ferroelectrics

    NASA Astrophysics Data System (ADS)

    Wang, D.; Bokov, A. A.; Ye, Z.-G.; Hlinka, J.; Bellaiche, L.

    2016-04-01

    Relaxors are complex materials with unusual properties that have been puzzling the scientific community since their discovery. The main characteristic of relaxors, that is, their dielectric relaxation, remains unclear and is still under debate. The difficulty to conduct measurements at frequencies ranging from ~=1 GHz to ~=1 THz and the challenge of developing models to capture their complex dynamical responses are among the reasons for such a situation. Here, we report first-principles-based molecular dynamic simulations of lead-free Ba(Zr0.5Ti0.5)O3, which allows us to obtain its subterahertz dynamics. This approach reproduces the striking characteristics of relaxors including the dielectric relaxation, the constant-loss behaviour, the diffuse maximum in the temperature dependence of susceptibility, the substantial widening of dielectric spectrum on cooling and the resulting Vogel-Fulcher law. The simulations further relate such features to the decomposed dielectric responses, each associated with its own polarization mechanism, therefore, enhancing the current understanding of relaxor behaviour.

  15. Preparation and characterization of Zr-N-codoped TiO2 nano-photocatalyst and its activity enhanced-mechanism.

    PubMed

    Du, Fengwei; Yu, Shuyu

    2014-09-01

    Zr-N-codoped TiO2 nano-photocatalyst was prepared through sol-gel method using ammonia water and zirconium nitrate as the source of N and Zr, respectively. The resulting materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). XRD results showed that codoping with Zr and N elements could greatly inhibit the phase transformation of TiO2 from anatase to rutile. XPS analysis indicated that Zr4+ was incorporated into the lattice of TiO2 through substituting titanium atoms. Meanwhile, N was also incorporated into the lattice of TiO2 through substituting oxygen atoms and existed in the form of N-Ti-O. DRS revealed that the light absorption edge of Zr-N-TiO2 was significantly red-shifted to visible region, leading to a narrower band gap and higher visible photocatalytic activity. The enhanced visible activity was attributed to the well anatase crystallite, intense light absorbance in visible region and narrow band gap.

  16. Fully ALD-grown TiN/Hf0.5Zr0.5O2/TiN stacks: Ferroelectric and structural properties

    NASA Astrophysics Data System (ADS)

    Zarubin, Sergei; Suvorova, Elena; Spiridonov, Maksim; Negrov, Dmitrii; Chernikova, Anna; Markeev, Andrey; Zenkevich, Andrei

    2016-11-01

    Since the discovery of ferroelectricity (FE) in HfO2-based thin films, they are gaining increasing attention as a viable alternative to conventional FE in the next generation of non-volatile memory devices. In order to further increase the density of elements in the integrated circuits, it is essential to adopt a three-dimensional design. Since atomic layer deposition (ALD) processes are extremely conformal, ALD is the favored approach in the production of 3D ferroelectric random access memory. Here, we report the fabrication of fully ALD-grown capacitors comprising a 10-nm-thick FE Hf0.5Zr0.5O2 layer sandwiched between TiN electrodes, which are subjected to a detailed investigation of the structural and functional properties. The robust FE properties of Hf0.5Zr0.5O2 films in capacitors are established by several alternative techniques. We demonstrate a good scalability of TiN/Hf0.5Zr0.5O2/TiN FE capacitors down to 100-nm size and the polarization retention in the test "one transistor-one capacitor" (1T-1C) cells after 1010 writing cycles. The presence of a non-centrosymmetric orthorhombic phase responsible for FE properties in the alloyed polycrystalline Hf0.5Zr0.5O2 films is established by transmission electron microscopy. Given the ability of the ALD technique to grow highly conformal films and multilayered structures, the obtained results indicate the route for the design of FE non-volatile memory devices in 3D integrated circuits.

  17. Microstructure, mechanical properties, and corrosion resistance of Ti-20Zr alloy in undoped and NaF doped artificial saliva

    NASA Astrophysics Data System (ADS)

    Calderon Moreno, Jose M.; Popa, Monica; Ivanescu, Steliana; Vasilescu, Cora; Drob, Silviu Iulian; Neacsu, Elena Ionela; Popa, Mihai V.

    2014-01-01

    The corrosion behavior of a new, advanced Ti-20Zr alloy with α+β microstructure (determined by optical microscopy, XRD, and SEM) and very good mechanical properties (obtained from the stress-strain curve) is studied in this paper. The composition of the alloy native passive film was determined from a XPS analysis and the long-term corrosion resistance in undoped and doped states with 0.05M NaF artificial Carter-Brugirard saliva of different pH values, simulating the severe functional conditions of a dental implant, was analyzed by electrochemical methods. This alloy possesses an advantageous balance between good mechanical resistance and plasticity and Young's modulus and exhibits more favorable electrochemical parameters and corrosion resistance than CP Ti due to its more resistant passive layer containing Ti2O3, TiO2, and ZrO2 protective oxides. After 1000 h of immersion in saliva, the protective properties of the alloy were enhanced due to the deposited surface layer that incorporated protective phosphates (shown by SEM and XPS).

  18. Corrosion resistance and in vitro response of laser-deposited Ti-Nb-Zr-Ta alloys for orthopedic implant applications.

    PubMed

    Samuel, Sonia; Nag, Soumya; Nasrazadani, Seifollah; Ukirde, Vaishali; El Bouanani, Mohamed; Mohandas, Arunesh; Nguyen, Kytai; Banerjee, Rajarshi

    2010-09-15

    While direct metal deposition of metallic powders, via laser deposition, to form near-net shape orthopedic implants is an upcoming and highly promising technology, the corrosion resistance and biocompatibility of such novel metallic biomaterials is relatively unknown and warrants careful investigation. This article presents the results of some initial studies on the corrosion resistance and in vitro response of laser-deposited Ti-Nb-Zr-Ta alloys. These new generation beta titanium alloys are promising due to their low elastic modulus as well as due the fact that they comprise of completely biocompatible alloying elements. The results indicate that the corrosion resistance of these laser-deposited alloys is comparable and in some cases even better than the currently used commercially-pure (CP) titanium (Grade 2) and Ti-6Al-4V ELI alloys. The in vitro studies indicate that the Ti-Nb-Zr-Ta alloys exhibit comparable cell proliferation but enhanced cell differentiation properties as compared with Ti-6Al-4V ELI.

  19. Influence of boron addition to Ti-13Zr-13Nb alloy on MG63 osteoblast cell viability and protein adsorption.

    PubMed

    Majumdar, P; Singh, S B; Dhara, S; Chakraborty, M

    2015-01-01

    Cell proliferation, cell morphology and protein adsorption on near β-type Ti-13Zr-13Nb (TZN) alloy and Ti-13Zr-13Nb-0.5B (TZNB) composite have been investigated and compared to evaluate the effect of boron addition which has been added to the Ti alloy to improve their poor tribological properties by forming in situ TiB precipitates. MG63 cell proliferation on substrates with different chemistry but the same topography was compared. The MTT assay test showed that the cell viability on the TZN alloy was higher than the boron containing TZNB composite after 36 h of incubation and the difference was pronounced after 7 days. However, both the materials showed substantially higher cell attachment than the control (polystyrene). For the same period of incubation in fetal bovine serum (FBS), the amount of protein adsorbed on the surface of boron free TZN samples was higher than that in the case of boron containing TZNB composite. The presence of boron in the TZN alloy influenced protein adsorption and cell response and they are lower in TZNB than in TZN as a result of the associated difference in chemical characteristics.

  20. Electrocaloric response near room temperature in Zr- and Sn-doped BaTiO3 systems.

    PubMed

    Hou, Ying; Yang, Lu; Qian, Xiaoshi; Zhang, Tian; Zhang, Q M

    2016-08-13

    The electrocaloric effect (ECE) in (1-x)BaZr0.18 Ti0.82O3-(x)BaSn0.11Ti0.89O3 (BZT18-BST11, 0.1≤x≤0.5) ceramics is investigated near room temperature using a calorimetry method. The ceramics exhibit relaxor-like ferroelectric characteristics and by merging phases, a large electrocaloric (EC) response is observed in the system. The largest entropy change is 4.8 Jkg(-1) K(-1) (along with a temperature change of 3.5 K), which is induced under an electric field of 10 MV m(-1) for the 0.8 BaZr0.18Ti0.82O3-0.2 BaSn0.11Ti0.89O3 ceramics. This result reveals that the coexistence of multiple phases improves the ECE of the ceramics, which provides an effective route to achieve a large EC response using a small electric field.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.

  1. Research Update: Magnetic phase diagram of EuTi1-xBxO3 (B = Zr, Nb)

    SciTech Connect

    Li, Ling; Zhou, Haidong; Yan, Jiaqiang; Mandrus, David; Keppens, Veerle

    2014-11-21

    Herein, we report the magnetic phase diagram of EuTi1-xBxO3 (B = Zr, Nb), determined from magnetization and heat capacity measurements. Upon Zr-doping, the antiferromagnetic ordering temperature TN of EuTi1-xZrxO3 gradually decreases from 5.6 K (x = 0) to 4.1 K (x = 1). Whereas a similar decrease in TN is observed for small amounts of Nb doping (x ≤ 0.05), ferromagnetism is induced in EuTi1-xNbxO3 with x > 0.05. Lastly, the ferromagnetic interaction between localized Eu 4f spins mediated by itinerant electrons introduced by Nb doping results in the ferromagnetism in EuTi1-xNbxO3.

  2. Low-temperature synthesis and characterization of TiO2 and TiO2-ZrO2 photocatalytically active thin films.

    PubMed

    Maver, Ksenija; Stangar, Urska Lavrencic; Cernigoj, Urh; Gross, Silvia; Cerc Korosec, Romana

    2009-05-01

    Transparent TiO(2) and TiO(2)-ZrO(2) (molar ratio Zr/Ti = 0.1) thin films were produced by low-temperature sol-gel processing from nanocrystalline aqueous based solutions. The structural features and compositions of the films treated at room temperature, 100 degrees C and 500 degrees C were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and thermal analysis. Addition of zirconia increased specific surface area (140-230 m(2) g(-1)) and hindered the growth of anatase crystallites, exhibiting a constant size of 6-7 nm in the whole temperature range. These significant changes with respect to pure TiO(2) in anatase crystalline form did not result in significantly and systematically different photocatalytic activity, which was evaluated in terms of aqueous pollutant degradation (azo-dye in water) and self-cleaning ability (fatty contaminant deposit). The films treated at only 100 degrees C showed excellent photocatalytic activity towards azo-dye degradation. Contact angle measurements of aged and contaminated surfaces revealed a fast or sharp hydrophilicity gain under UVA illumination. Accordingly, the results of this study confirmed the potential application of advantageous low-temperature films in water treatment as well as for self-cleaning surfaces.

  3. Investigation of the structure stability and superelastic behavior of thermomechanically treated Ti-Nb-Zr and Ti-Nb-Ta shape-memory alloys

    NASA Astrophysics Data System (ADS)

    Sheremetyev, V. A.; Prokoshkin, S. D.; Brailovski, V.; Dubinskiy, S. M.; Korotitskiy, A. V.; Filonov, M. R.; Petrzhik, M. I.

    2015-04-01

    The superelastic parameters of Ti-Nb-Ta and Ti-Nb-Zr alloys, such as Young's modulus, residual strain, and transformation yield stress after thermomechanical treatment (TMT), were determined during cyclic mechanical tests using the tension-unloading scheme (maximum strain 2% per cycle, ten cycles). The superelastic parameters and the alloy structure have been studied by electron microscopy and X-ray diffraction analysis before and after testing and after holding for 40 days, as well as after retesting. The Young's modulus of the Ti-Nb-Ta alloy decreases from 30-40 to 20-25 GPa during mechanocycling after TMT by different modes; however, it returns to its original magnitude during subsequent holding for 40 days, and changes only a little during repeated mechanocycling. The Young's modulus of the Ti-Nb-Zr alloy changes insignificantly during mechanocycling, recovers during holding, and behaves stably upon repeated mechanocycling. Surface tensile stresses arise during mechanocycling, which facilitate the development of martensitic transformation under load, orient it, and thereby promote a decrease in the transformation yield stress and the residual strain. The enhancement of the level of initial strengthening stabilizes the superelastic behavior during mechanocycling.

  4. The evolution of interface microstructure in a ZrO[sub 2]/Ag-Cu-Al-Ti system

    SciTech Connect

    Lee, Youngmin; Yu, Jin )

    1993-08-01

    Among ceramic/metal (C/M) joining technologies, the active filler metal method has been studied extensively due to the simple brazing process and excellent joint strength. Active metal elements, typically Ti, are intentionally added to braze alloys to enhance the formation of reaction products between the ceramic and the braze metal at the C/M interface. In the brazing of Al[sub 2]O[sub 3] with the Ag-Cu-Ti filler metal, reaction products such as [gamma]-TiO, Cu[sub 2](Ti, Al)[sub 4]O, Ti[sub 3](Cu[sub 0.76]Al[sub 0.18]Sn[sub 0.06])[sub 3]O were found, while products such as Ti[sub 5]Si[sub 3] and TiN formed in the brazing of Si[sub 3]N[sub 4]. The presence of reaction layers at the C/M interface influences the interface strength in a complex way. In Cu/Al[sub 2]O[sub 3], Co/Al[sub 2]O[sub 3], Ni/Al[sub 2]O[sub 3], and Cu/diamond systems, maxima of joint strength were observed at some intermediate Ti addition, while the flexural strength decreased substantially with the thickening of the TiO layer in a ZrO[sub 2]/Ag-Cu-Sn-Ti system. Thus, composition of the braze alloy (particularly, the content of the active metal), process conditions such as brazing temperature and time, microstructure and mechanical properties of reaction products at the C/M interfaces, interfacial chemistry, and residual stress are primary factors to be studied in order to understand the strengths of the C/M interfaces systematically. In the present and the following papers, evolutions of interfacial microstructures at various brazing conditions, and corresponding interface strengths are reported, respectively, for a ZrO[sub 2]/Ag-Cu-Al-Ti system.

  5. Ti-Nb-(Zr,Ta) superelastic alloys for medical implants: Thermomechanical processing, structure, phase transformations and functional properties

    NASA Astrophysics Data System (ADS)

    Dubinskiy, Sergey

    The aim of this project is to develop a new class of orthopaedic implant materials that combine the excellent biocompatibility of pure titanium with the outstanding biomechanical compatibility of Ti-Ni-based shape memory alloys. The most suitable candidates for such a role are Ti-Nb-Zr and Ti-Nb-Ta near-beta shape memory alloys. Since this class of materials was developed quite recently, the influence of thermomechanical treatment on their structure and functional properties has not as yet been the subject of any comprehensive study. Consequently, this project is focused on the interrelations between the composition, the microstructure and the functional properties of superelastic Ti-Nb-Zr and Ti-Nb-Ta alloys for biomedical application. The principal objective is to improve the functional properties of these alloys, more specifically their superelastic properties and fatigue resistance, through optimization of the alloys' composition and thermomechanical processing. It is shown in this thesis that the structure and functional properties of Ti-Nb-based shape memory alloys can be effectively controlled by thermomechanical processing including cold deformation with post-deformation annealing and ageing. It is also shown that the formation of nanosubgrain substructure leads to a significant improvement of superelasticity and fatigue resistance in these alloys. The influence of ageing on the ω-phase precipitation kinetics and, consequently, on the functional properties of Ti-Nb-Zr and Ti-Nb-Ta alloys is also observed. Based on the results obtained, optimized regimes of thermomechanical treatment resulting in a best combination of functional properties are recommended for each alloy, from the orthopaedic implant materials standpoint. An original tensile stage for a low-temperature chamber of an X-ray diffractometer is developed and used in this project. A unique low-temperature (-150...+100°C) comparative in situ X-ray study of the transformations' features and crystal

  6. Corrosion resistance of ZrTi alloys with hydroxyapatite-zirconia-silver layer in simulated physiological solution containing proteins for biomaterial applications

    NASA Astrophysics Data System (ADS)

    Mareci, D.; Trincă, L. C.; Căilean, D.; Souto, R. M.

    2016-12-01

    The degradation characteristics of hydroxyapatite-zirconia-silver films (HA-ZrO2-Ag) coatings on three ZrTi alloys were investigated in Ringer's solution containing 10% human albumin protein at 37 °C. Samples were immersed for 7 days while monitored by electrochemical impedance spectroscopy (EIS) and linear potentiodynamic polarization (LPP). The electrochemical analysis in combination with surface analytical characterization by scanning electron microscopy (SEM/EDX) reveals the stability and corrosion resistance of the HA-ZrO2-Ag coated ZrTi alloys. The characteristic feature that describes the electrochemical behaviour of the coated alloys is the coexistence of large areas of the coating presenting pores in which the ZrTi alloy substrate is exposed to the simulated physiological environment. The EIS interpretation of results was thus performed using a two-layer model of the surface film. The blocking effect in the presence the human albumin protein produces an enhancement of the corrosion resistance. The results disclose that the Zr45Ti alloy is a promising material for biomedical devices, since electrochemical stability is directly associated to biocompatibility.

  7. Phase composition, microstructure, and mechanical properties of porous Ti-Nb-Zr alloys prepared by a two-step foaming powder metallurgy method.

    PubMed

    Rao, X; Chu, C L; Zheng, Y Y

    2014-06-01

    Porous Ti-Nb-Zr alloys with different porosities from 6.06 to 62.8% are prepared by a two-step foaming powder metallurgy method using TiH2, Nb, and Zr powders together with 0 to 50wt% of NH4HCO3. The effects of the amounts of Nb and Zr as well as the sintering temperature (1473 to 1673K) on their phase composition, porosity, morphology, and mechanical characteristics are investigated. By controlling the porosity, Nb and Zr concentrations as well as the sintering temperature, porous Ti-Nb-Zr alloys with different mechanical properties can be obtained, for example, the hardness between 290 and 63HV, the compressive strength between 1530.5 and 73.4MPa, and the elastic modulus between 10.8 and 1.2GPa. The mechanical properties of the sintered porous Ti-Nb-Zr alloys can be tailored to match different requirements for the human bones and are thus potentially useful in the hard tissue implants.

  8. Characterization of self-organized TiO2 nanotubes on Ti-4Zr-22Nb-2Sn alloys and the application in drug delivery system.

    PubMed

    Liang, Y Q; Cui, Z D; Zhu, S L; Yang, X J

    2011-03-01

    In this study, the self-organized TiO(2) nanotubes grown by anodization of Ti-4Zr-22Nb-2Sn at different potentials, concentration of NH(4)F and anodization time was investigated. The morphology of nanotubes was observed by FE-SEM. The drug-loaded nanotubes were also fabricated in aqueous media containing minocycline hydrochloride. They were characterized by SEM, XPS and FT-IR. The results showed that the drug of minocycline hydrochloride (MH) was loaded in the nanotubes. The release effects were studied in phosphate buffer solution (PBS). The release rate of MH from TiO(2) nanotubes with shorter tube length in PBS was lower than the one of MH from longer nanotubes. The sustaining release time could last at least 150 h. Hence, it is a promising method to eliminate the harmful reactions by carrying drug in the tubes when the titanium alloys were used as biomedical implants.

  9. Single layer of MX3(M = Ti, Zr; X = S, Se, Te): a new platform for nano-electronics and optics

    NASA Astrophysics Data System (ADS)

    Jin, Yingdi; Li, Xingxing; Yang, Jinlong

    A serial of two dimensional titanium and zirconium trichalcogenides nanosheets MX3 (M=Ti, Zr; X=S, Se, Te) are investigated based on first-principles calculations. The evaluated low cleavage energy indicates that stable two dimensional monolayers can be exfoliated from their bulk crystals in experiment. Electronic studies reveal very rich electronic properties in these monolayers, including metallic TiTe3 and ZrTe3, direct band gap semiconductor TiS3 and indirect band gap semiconductors TiSe3, ZrS3 and ZrSe3. The band gaps of all the semiconductors are between 0.57~1.90 eV, which implies their potential applications in nano-electronics. And the calculated effective masses demonstrate highly anisotropic conduction properties for all the semiconductors. Optically, TiS3 and TiSe3 monolayers exhibit good light absorption in the visible and near-infrared region respectively, indicating their potential applications in optical devices. In particular, the highly anisotropic optical absorption of TiS3 monolayer suggests it could be used in designing nano optical waveguide polarizers.

  10. Influence of N2 partial pressure on structural and microhardness properties of TiN/ZrN multilayers deposited by Ar/N2 vacuum arc discharge

    NASA Astrophysics Data System (ADS)

    Naddaf, M.; Abdallah, B.; Ahmad, M.; A-Kharroub, M.

    2016-08-01

    The influence of N2 partial pressure on structural, mechanical and wetting properties of multilayered TiN/ZrN thin films deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures is investigated. X-ray diffraction (XRD) results show that the average texturing coefficient of (1 1 1) orientation and the grain size of both TiN and ZrN individual layers increase with increasing the N2 partial pressure. The Rutherford back scattering (RBS) measurements and analysis reveal that incorporation of the nitrogen in the film increases with increasing the N2 partial pressure and both TiN and ZrN individual layers have a nitrogen over-stoichiometry for N2 partial pressure ⩾50%. The change in the film micro-hardness is correlated to the changes in crystallographic texture, grain size, stoichiometry and the residual stress in the film as a function of the N2 partial pressure. In particular, stoichiometry of ZrN and TiN individual is found to play the vital role in determining the multilayer hardness. The multilayer film deposited at N2 partial pressure of 25% has the best stoichiometric ratio of both TiN and ZrN layers and the highest micro-hardness of about 32 GPa. In addition, water contact angle (WCA) measurements and analysis show a decrease in the work of adhesion on increasing the N2 partial pressure.

  11. Influence of Zr4+ doping on structural and electrical properties of SrBi4Ti4O15 ceramic

    NASA Astrophysics Data System (ADS)

    Nayak, P.; Badapanda, T.; Panigrahi, S.

    2015-06-01

    This article reports a systematic study of doping effects on the structural and electrical properties of layer structured strontium bismuth titanate ceramic. In this study monophasic SrBi4Ti4-xZrxO15 with x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25 ceramics were synthesized from the solid-state reaction route. X-ray diffraction analysis shows that the Zr-modified SBT ceramics have a pure four-layer Aurivillius phase structure. Dielectric properties revealed that the diffuseness of phase transition increases where as corresponding permittivity value decrease with increasing Zr content. Piezoelectric properties of SBTZ ceramics were improved by the modification of Zirconium ion. Moreover, the reason behind for improvement of piezoelectric properties of modified SBTZ ceramics was also discussed.

  12. On sol-gel derived Au-enriched TiO2 and TiO2-ZrO2 photocatalysts and their investigation in photocatalytic reduction of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Matějová, Lenka; Kočí, Kamila; Reli, Martin; Čapek, Libor; Matějka, Vlastimil; Šolcová, Olga; Obalová, Lucie

    2013-11-01

    Gold-enriched TiO2 and TiO2-ZrO2 and their parent counterparts were prepared by using the sol-gel process controlled within the reverse micelles environment, followed by impregnation in AuCl3 solution. Catalysts were characterized by organic elementary analysis (OEA), inductively coupled plasma mass spectrometry (ICP MS), N2 physisorption, powder X-ray diffraction (XRD), transmission electron microscopy (TEM) combined with electron diffraction, UV-vis spectroscopy, and tested in CO2 photocatalytic reduction. The performance of photocatalysts iluminated by UV-lamp with the wavelenght maximum at 254 nm was decreasing in the order TiO2-ZrO2 > Au/TiO2-ZrO2 > TiO2 > Au/TiO2 > TiO2 Evonic P25. The photocatalytic performance decrease over Au/TiO2-ZrO2 and Au/TiO2, compared to their parent counterparts, can be explained by the presence of too large Au particles, which block the oxide surface and either reduce the light absorption capability of the catalysts, or serve as the recombination centres. Higher photocatalytic performance of the amorphous TiO2-ZrO2 than of the nanocrystalline TiO2 can be ascribed to the enlarged surface area and higher photoactivity of titania-zirconia oxide mixture under the UV lamp with the wavelenght maximum at 254 nm. With regard to crystalline materials the appropriate anatase crystallite-size plays a key role in performance of CO2 photocatalytic reduction. Moreover, correlation between the adsorption edge and the anatase crystallite-size was revealed.

  13. Properties of the Ti40Zr10Cu36Pd14 BMG Modified by Sn and Nb Additions

    NASA Astrophysics Data System (ADS)

    Sypien, Anna; Stoica, Mihail; Czeppe, Tomasz

    2016-03-01

    The results of investigation of the influence of additions of 2 and 3 at.% of Sn and simultaneously of Sn and 3 at.% Nb on microstructure and properties of the bulk metallic glasses of composition (Ti40Cu36- x Zr10Pd14Sn x )100- y Nb y are reported. It was found that the additions of Sn increased the temperatures of glass transition (T g), primary crystallization (T x ), melting, and liquidus as well as supercooled liquid range (Δ T) and glass forming ability (GFA). The nanohardness and elastic modulus decreased in alloys with 2 and 3 at.% Sn additions, revealing similar values. The 3 at.% Nb addition to the Sn-containing amorphous phase decreased as well all the T g, T x , T L, and T m temperatures as Δ T and GFA; however, relatively larger values of this parameters in alloys containing larger Sn content were preserved. In difference to the previously published results, in the case of the amorphous alloys containing small Nb and Sn additions, a noticeable amount of the quenched-in crystalline phases was not confirmed, at least of the micrometric sizes. In the case of the alloys containing Sn or both Sn and Nb, two slightly different amorphous phase compositions were detected, suggesting separation in the liquid phase. Phase composition of the alloys determined after amorphous phase crystallization was similar for all compositions. The phases Cu8Zr3, CuTiZr, and Pd3Zr were mainly identified in the proportions dependent on the alloy compositions.

  14. Effect of Cr, Ti, V, and Zr Micro-additions on Microstructure and Mechanical Properties of the Al-Si-Cu-Mg Cast Alloy

    NASA Astrophysics Data System (ADS)

    Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

    2016-05-01

    Uniaxial static and cyclic tests were used to assess the role of Cr, Ti, V, and Zr additions on properties of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in as-cast and T6 heat-treated conditions. The microstructure of the as-cast alloy consisted of α-Al, eutectic Si, and Cu-, Mg-, and Fe-rich phases Al2.1Cu, Al8.5Si2.4Cu, Al5.2CuMg4Si5.1, and Al14Si7.1FeMg3.3. In addition, the micro-sized Cr/Zr/Ti/V-rich phases Al10.7SiTi3.6, Al6.7Si1.2TiZr1.8, Al21.4Si3.4Ti4.7VZr1.8, Al18.5Si7.3Cr2.6V, Al7.9Si8.5Cr6.8V4.1Ti, Al6.3Si23.2FeCr9.2V1.6Ti1.3, Al92.2Si16.7Fe7.6Cr8.3V1.8, and Al8.2Si30.1Fe1.6Cr18.8V3.3Ti2.9Zr were present. During solution treatment, Cu-rich phases were completely dissolved, while the eutectic silicon, Fe-, and Cr/Zr/Ti/V-rich intermetallics experienced only partial dissolution. Micro-additions of Cr, Zr, Ti, and V positively affected the alloy strength. The modified alloy in the T6 temper during uniaxial tensile tests exhibited yield strength of 289 MPa and ultimate tensile strength of 342 MPa, being significantly higher than that for the Al-Si-Cu-Mg base. Besides, the cyclic yield stress of the modified alloy in the T6 state increased by 23 pct over that of the base alloy. The fatigue life of the modified alloy was substantially longer than that of the base alloy tested using the same parameters. The role of Cr, Ti, V, and Zr containing phases in controlling the alloy fracture during static and cyclic loading is discussed.

  15. TiS2 and ZrS2 single- and double-wall nanotubes: first-principles study.

    PubMed

    Bandura, Andrei V; Evarestov, Robert A

    2014-02-15

    Hybrid density functional theory has been applied for investigations of the electronic and atomic structure of bulk phases, nanolayers, and nanotubes based on titanium and zirconium disulfides. Calculations have been performed on the basis of the localized atomic functions by means of the CRYSTAL-2009 computer code. The full optimization of all atomic positions in the regarded systems has been made to study the atomic relaxation and to determine the most favorable structures. The different layered and isotropic bulk phases have been considered as the possible precursors of the nanotubes. Calculations on single-walled TiS2 and ZrS2 nanotubes confirmed that the nanotubes obtained by rolling up the hexagonal crystalline layers with octahedral 1T morphology are the most stable. The strain energy of TiS2 and ZrS2 nanotubes is small, does not depend on the tube chirality, and approximately obeys to D(-2) law (D is nanotube diameter) of the classical elasticity theory. It is greater than the strain energy of the similar TiO2 and ZrO2 nanotubes; however, the formation energy of the disulfide nanotubes is considerably less than the formation energy of the dioxide nanotubes. The distance and interaction energy between the single-wall components of the double-wall nanotubes is proved to be close to the distance and interaction energy between layers in the layered crystals. Analysis of the relaxed nanotube shape using radial coordinate of the metal atoms demonstrates a small but noticeable deviation from completely cylindrical cross-section of the external walls in the armchair-like double-wall nanotubes.

  16. Structure and electrical properties of sputtered TiO2/ZrO2 bilayer composite dielectrics upon annealing in nitrogen

    PubMed Central

    2012-01-01

    The high-k dielectric TiO2/ZrO2 bilayer composite film was prepared on a Si substrate by radio frequency magnetron sputtering and post annealing in N2 at various temperatures in the range of 573 K to 973 K. Transmission electron microscopy observation revealed that the bilayer film fully mixed together and had good interfacial property at 773 K. Metal-oxide-semiconductor capacitors with high-k gate dielectric TiO2/ZrO2/p-Si were fabricated using Pt as the top gate electrode and as the bottom side electrode. The largest property permittivity of 46.1 and a very low leakage current density of 3.35 × 10-5 A/cm2 were achieved for the sample of TiO2/ZrO2/Si after annealing at 773 K. PMID:22221384

  17. Enhanced photocatalytic activity of S-doped TiO2-ZrO2 nanoparticles under visible-light irradiation.

    PubMed

    Tian, Guohui; Pan, Kai; Fu, Honggang; Jing, Liqiang; Zhou, Wei

    2009-07-30

    Porous nanocrystalline S-doped TiO2-ZrO2 visible-light photocatalysts were prepared through a one-step method. The resulting materials were characterized by X-ray diffraction (XRD), N(2) adsorption-desorption measurements, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS), Fourier transform infrared spectra (FT-IR) and electron paramagnetic resonance (ESR). It was found that modification by ZrO2 could effectively inhibit phase transformation, enhance visible-light absorption, and possess more surface hydroxyl groups. The photocatalytic activity of S-doped TiO2-ZrO2 was higher than that of unmodified S-doped TiO2 and Degussa P25. The enhanced photocatalytic activity could be attributed to the higher specific area, smaller crystal size, porous structure and more surface hydroxyl groups in the catalyst.

  18. (Sm,Zr)(Fe,Co)11.0-11.5Ti1.0-0.5 compounds as new permanent magnet materials

    NASA Astrophysics Data System (ADS)

    Kuno, Tomoko; Suzuki, Shunji; Urushibata, Kimiko; Kobayashi, Kurima; Sakuma, Noritsugu; Yano, Masao; Kato, Akira; Manabe, Akira

    2016-02-01

    We investigated (Sm,Zr)(Fe,Co)11.0-11.5Ti1.0-0.5 compounds as permanent magnet materials. Good magnetic properties were observed in (Sm0.8Zr0.2)(Fe0.75Co0.25)11.5Ti0.5 powder containing a limited amount of the α-(Fe, Co) phase, including saturation polarization (Js) of 1.63 T, an anisotropic field (Ha) of 5.90 MA/m at room temperature, and a Curie temperature (Tc) of about 880 K. Notably, Js and Ha remained above 1.5 T and 3.70 MA/m, respectively, even at 473 K. The high-temperature magnetic properties of (Sm0.8Zr0.2)(Fe0.75Co0.25)11.5Ti0.5 were superior to those of Nd2Fe14B.

  19. On the influence of texture on spall evolution in the HCP materials Ti-6Al-4V and Zr

    NASA Astrophysics Data System (ADS)

    Shackel, James; Appleby-Thomas, Gareth J.; Wood, David C.; Painter, Jonathan; Patel, Arun Kumar; Wielewski, Euan; Hazell, Paul J.; Terzulli, Louis-Pierre

    2017-01-01

    Dynamic tensile failure (spall) is known to be a highly microstructure-dependant phenomena. In particular, spall is greatly influenced by the availability of plastic deformation modes such as slip systems. Significant effort has been put into understanding spall in the common engineering BCC and FCC materials, however there is a relative paucity of data on such behaviour in the highly anisotropic HCP class of materials. Here, preliminary results pertaining to the dynamic behaviour of two important HCP materials, Ti-6Al-4V and Zr, are presented, with the aim of enhancing understanding of this complex class of materials.

  20. Nanoindentation Mechanical Properties of a Bi-phase Cu29Zr32Ti15Al5Ni19 Alloy

    NASA Astrophysics Data System (ADS)

    Pi, JinHong; Wang, ZhangZhong; He, XianCong; Bai, YunQiang

    2016-01-01

    Mechanical properties of cylindrical bi-phasic high-entropy alloy Cu29Zr32Ti15Al5Ni19 (3 mm in diameter) were characterized by nanoindentation test in each phase. The results show that the constituent FCC phase is of low nanohardness (2.35 GPa) and modulus (60.9 GPa), while another constituent phase in the alloy, the HCP phase, shows much higher nanohardness (6.5 GPa) and modulus (115.3 GPa). Creep occurs in both phases during the indentation.

  1. The Study of Complex (Ti, Zr, Cs) Nanopowder Influencing the Effective Ionization Potential of Arc Discharge When Mma Welding

    NASA Astrophysics Data System (ADS)

    Sapozhkov, S. B.; Burakova, E. M.

    2016-08-01

    Strength is one of the most important characteristics of a weld joint. Mechanical properties of a weld metal can be improved in a variety of ways. One of the possibilities is to add a nanopowder to the weld metal. Authors of the paper suggest changing the production process of MMA welding electrodes via adding nanopowder Ti, Zr, Cs to electrode components through liquid glass. Theoretical research into the nanopowder influence on the effective ionization potential (Ueff) of welding arc discharge is also necessitated. These measures support arcing stability, improve strength of a weld joint, as the consequence, ensure quality enhancing of a weld joint and the structure on the whole.

  2. Growth and microstructure formation of isothermally-solidified Zircaloy-4 joints brazed by a Zr-Ti-Cu-Ni amorphous alloy ribbon

    NASA Astrophysics Data System (ADS)

    Kim, K. H.; Lim, C. H.; Lee, J. G.; Lee, M. K.; Rhee, C. K.

    2013-10-01

    The microstructure and growth characteristics of Zircaloy-4 joints brazed by a Zr48Ti16Cu17Ni19 (at.%) amorphous filler metal have been investigated with regard to the controlled isothermal solidification and intermetallic formation. Two typical joints were produced depending on the isothermal brazing temperature: (1) a dendritic growth structure including bulky segregation in the central zone (at 850 °C), and (2) a homogeneous dendritic structure throughout the joint without segregation (at 890 °C). The primary α-Zr phase was solidified isothermally, nucleating to grow into a joint with a cellular or dendritic structure. Also, the continuous Zr2Ni and particulate Zr2Cu phases were formed in the segregated center zone and at the intercellular region, respectively, owing to the different solubility and atomic mobility of the solute elements (Ti, Cu, and Ni) in the α-Zr matrix. A disappearance of the central Zr2Ni phase was also rate-controlled by the outward diffusion of the Cu and Ni elements. When the detrimental Zr2Ni intermetallic phase was eliminated by a complete isothermal solidification at 890 °C, the strengths of the joints were high enough to cause yielding and fracture in the base metal, exceeding those of the bulk Zircaloy-4, at room temperature as well as at elevated temperatures (up to 400 °C).

  3. Comparison of electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb, Ge, Zr-added TiO2 composite electrodes.

    PubMed

    Imahori, Hiroshi; Hayashi, Shinya; Umeyama, Tomokazu; Eu, Seunghun; Oguro, Akane; Kang, Soonchul; Matano, Yoshihiro; Shishido, Tetsuya; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2006-12-19

    Electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were examined to disclose the effects of partial substitution of Ti atom by the other metals in the composite electrodes. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were prepared by sol-gel process using laurylamine hydrochloride as a template for the formation of micellar precursors yielding well-defined mesoporous nanocrystalline structures, as in the cases of the formation of silica and titania tubules and nanoparticles by the templating mechanism. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were characterized by transmission electron microscopy, BET surface area analysis, X-ray diffraction analysis, Raman spectroscopy, and impedance measurements. The TiO2 anatase nanocrystalline structure is retained after doping a small amount (5 mol %) of Nb, Ge, or Zr into the TiO2 structure, suggesting the homogeneous distribution of the doped metals with replacing Ti atom by the doped metal. The power conversion efficiency of the porphyrin-sensitized solar cells increases in the order Zr-added TiO2 (0.8%) < Nb-added TiO2 (1.2%) < TiO2 (2.0%) < Ge-added TiO2 cells (2.4%) under the same conditions. The improvement of cell performance of the Ge-added TiO2 cell results from the negative shift of the conduction band of the Ge-added TiO2 electrode. The Ge-added TiO2 cell exhibited a maximum power conversion efficiency of 3.5% when the porphyrin was adsorbed onto the surface of the Ge-added TiO2 electrode with a thickness of 4 microm in MeOH for 1 h.

  4. Temperature-dependent local structural properties of redox Pt nanoparticles on TiO2 and ZrO2 supports

    DOE PAGES

    Jeong, Eun -Suk; Park, Chang -In; Jin, Zhenlan; ...

    2015-01-21

    This paper examined the local structural properties of Pt nanoparticles on SiO2, TiO2–SiO2, and ZrO2–SiO2 supports to better understand the impact of oxide-support type on the performance of Pt-based catalysts. In situ X-ray absorption fine structure (XAFS) measurements were taken for the Pt L3-edge in a temperature range from 300 to 700 K in He, H2, and O2 gas environments. The XAFS measurements demonstrated that Pt atoms were highly dispersed on TiO2–SiO2 and ZrO2–SiO2 forming pancake-shaped nanoparticles, whereas Pt atoms formed larger particles of hemispherical shapes on SiO2 supports. Contrary to the SiO2 case, the coordination numbers for Pt, Ti,more » and Zr around Pt atoms on the TiO2–SiO2 and ZrO2–SiO2 supports were nearly constant from 300 to 700 K under the different gas environments. These results are consistent with the improvements in thermal stability of Pt nanoparticles achieved by incorporating TiO2 or ZrO2 on the surface of SiO2 supports. XAFS analysis further indicated that the enhanced dispersion and stability of Pt were a consequence of the strong metal support interaction via Pt–Ti and Pt–Zr bonds.« less

  5. Temperature-dependent local structural properties of redox Pt nanoparticles on TiO2 and ZrO2 supports

    SciTech Connect

    Jeong, Eun -Suk; Park, Chang -In; Jin, Zhenlan; Hwang, In -Hui; Son, Jae -Kwan; Kim, Mi -Young; Choi, Jae -Soon; Han, Sang -Wook

    2015-01-21

    This paper examined the local structural properties of Pt nanoparticles on SiO2, TiO2–SiO2, and ZrO2–SiO2 supports to better understand the impact of oxide-support type on the performance of Pt-based catalysts. In situ X-ray absorption fine structure (XAFS) measurements were taken for the Pt L3-edge in a temperature range from 300 to 700 K in He, H2, and O2 gas environments. The XAFS measurements demonstrated that Pt atoms were highly dispersed on TiO2–SiO2 and ZrO2–SiO2 forming pancake-shaped nanoparticles, whereas Pt atoms formed larger particles of hemispherical shapes on SiO2 supports. Contrary to the SiO2 case, the coordination numbers for Pt, Ti, and Zr around Pt atoms on the TiO2–SiO2 and ZrO2–SiO2 supports were nearly constant from 300 to 700 K under the different gas environments. These results are consistent with the improvements in thermal stability of Pt nanoparticles achieved by incorporating TiO2 or ZrO2 on the surface of SiO2 supports. XAFS analysis further indicated that the enhanced dispersion and stability of Pt were a consequence of the strong metal support interaction via Pt–Ti and Pt–Zr bonds.

  6. Direct evidence of flat band voltage shift for TiN/LaO or ZrO/SiO2 stack structure via work function depth profiling

    PubMed Central

    Heo, Sung; Park, Hyoungsun; Ko, Dong-Su; Kim, Yong Su; Kyoung, Yong Koo; Lee, Hyung-Ik; Cho, Eunae; Lee, Hyo Sug; Park, Gyung-Su; Shin, Jai Kwang; Lee, Dongjin; Lee, Jieun; Jung, Kyoungho; Jeong, Moonyoung; Yamada, Satoru; Kang, Hee Jae; Choi, Byoung-Deog

    2017-01-01

    We demonstrated that a flat band voltage (VFB) shift could be controlled in TiN/(LaO or ZrO)/SiO2 stack structures. The VFB shift described in term of metal diffusion into the TiN film and silicate formation in the inserted (LaO or ZrO)/SiO2 interface layer. The metal doping and silicate formation confirmed by using transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) line profiling, respectively. The direct work function measurement technique allowed us to make direct estimate of a variety of flat band voltages (VFB). As a function of composition ratio of La or Zr to Ti in the region of a TiN/(LaO or ZrO)/SiO2/Si stack, direct work function modulation driven by La and Zr doping was confirmed with the work functions obtained from the cutoff value of secondary electron emission by auger electron spectroscopy (AES). We also suggested an analytical method to determine the interface dipole via work function depth profiling. PMID:28252013

  7. Increases in solar conversion efficiencies of the ZrO2 nanofiber-doped TiO2 photoelectrode for dye-sensitized solar cells

    PubMed Central

    2012-01-01

    In this paper, in order to improve the efficiency of dye-sensitized solar cells, we introduced zirconia [ZrO2] nanofibers into a mesoporous titania [TiO2] photoelectrode. The photoelectrode consists of a few weight percent of ZrO2 nanofibers and a mesoporous TiO2 powder. The mixed ZrO2 nanofibers and the mesoporous TiO2 powder possessed a larger surface area than the corresponding mesoporous TiO2 powder. The optimum ratio of the ZrO2 nanofiber was 5 wt.%. The 5 wt.% ZrO2-mixed device could get a short-circuit photocurrent density of 15.9 mA/cm2, an open-circuit photovoltage of 0.69 V, a fill factor of 0.60, and a light-to-electricity conversion efficiency of 6.5% under irradiation of AM 1.5 (100 mW/cm2). PMID:22297154

  8. Increases in solar conversion efficiencies of the ZrO2 nanofiber-doped TiO2 photoelectrode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Jiao; Mei Jin, En; Park, Ju-Young; Wang, Wan Lin; Guan Zhao, Xing; Gu, Hal-Bon

    2012-02-01

    In this paper, in order to improve the efficiency of dye-sensitized solar cells, we introduced zirconia [ZrO2] nanofibers into a mesoporous titania [TiO2] photoelectrode. The photoelectrode consists of a few weight percent of ZrO2 nanofibers and a mesoporous TiO2 powder. The mixed ZrO2 nanofibers and the mesoporous TiO2 powder possessed a larger surface area than the corresponding mesoporous TiO2 powder. The optimum ratio of the ZrO2 nanofiber was 5 wt.%. The 5 wt.% ZrO2-mixed device could get a short-circuit photocurrent density of 15.9 mA/cm2, an open-circuit photovoltage of 0.69 V, a fill factor of 0.60, and a light-to-electricity conversion efficiency of 6.5% under irradiation of AM 1.5 (100 mW/cm2).

  9. Improving High-Temperature Tensile and Low-Cycle Fatigue Behavior of Al-Si-Cu-Mg Alloys Through Micro-additions of Ti, V, and Zr

    NASA Astrophysics Data System (ADS)

    Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

    2015-07-01

    High-temperature tensile and low-cycle fatigue tests were performed to assess the influence of micro-additions of Ti, V, and Zr on the improvement of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in the as-cast condition. Addition of transition metals led to modification of microstructure where in addition to conventional phases present in the Al-7Si-1Cu-0.5Mg base, new thermally stable micro-sized Zr-Ti-V-rich phases Al21.4Si4.1Ti3.5VZr3.9, Al6.7Si1.2TiZr1.8, Al2.8Si3.8V1.6Zr, and Al5.1Si35.4Ti1.6Zr5.7Fe were formed. The tensile tests showed that with increasing test temperature from 298 K to 673 K (25 °C to 400 °C), the yield stress and tensile strength of the present studied alloy decreased from 161 to 84 MPa and from 261 to 102 MPa, respectively. Also, the studied alloy exhibited 18, 12, and 5 pct higher tensile strength than the alloy A356, 354 and existing Al-Si-Cu-Mg alloy modified with additions of Zr, Ti, and Ni, respectively. The fatigue life of the studied alloy was substantially longer than those of the reference alloys A356 and the same Al-7Si-1Cu-0.5Mg base with minor additions of V, Zr, and Ti in the T6 condition. Fractographic analysis after tensile tests revealed that at the lower temperature up to 473 K (200 °C), the cleavage-type brittle fracture for the precipitates and ductile fracture for the matrix were dominant while at higher temperature fully ductile-type fracture with debonding and pull-out of cracked particles was identified. It is believed that the intermetallic precipitates containing Zr, Ti, and V improve the alloy performance at increased temperatures.

  10. Recrystallization temperature influence upon texture evolution of a SPD processed Ti-Nb-Ta-Zr-O alloy

    NASA Astrophysics Data System (ADS)

    Cojocaru, V. D.; Raducanu, D.; Gordin, D. M.; Cinca, I.; Thibon, I.; Caprarescu, A.

    2014-08-01

    The present study investigates the texture features occurred during recrystallization of a Ti-29Nb-9Ta-10Zr-0.2O (wt.%) alloy processed by multi-pass cold-rolling, up to 90% thickness reduction. Data concerning alloy component phases and the lattice parameters of identified phases were obtained and analysed for all thermo-mechanical processing stages. Crystallographic texture changes occurred during alloy thermo-mechanical processing (coldrolling and recrystallization), were investigated using X-ray diffraction; by acquiring the pole figures data of the main β-Ti phase. Data concerning observed texture components and texture fibers was analysed using phi1 - Φ - phi2 Bunge system in phi2 = 0° and 45° sections. The γ textural fiber was analysed for all thermo-mechanical processing stages.

  11. Influence of stresses on structure and properties of Ti and Zr- based alloys from first-principles simulations

    NASA Astrophysics Data System (ADS)

    Barannikova, S. A.; Zharmukhambetova, A. M.; Nikonov, A. Yu; Dmitriev, A. V.; Ponomareva, A. V.; Abrikosov, I. A.

    2015-01-01

    Computer simulations in the framework of the Density Functional Theory have become an established tool for computer simulations of materials properties. In most cases, however, information is obtained at ambient conditions, preventing design of materials for applications at extreme conditions. In this work we employ ab initio calculations to investigate the influence of stresses on structure and stability of Ti-Mo and Zr-Nb alloys, an important class of construction materials. Calculations reproduce known phase stability trends in these systems, and we resolve the controversy regarding the stability of body-centered cubic solid solution in Mo-rich Ti-Mo alloys against the isostructural decomposition. Calculated results are explained in terms of the electronic structure effects, as well as in terms of physically transparent thermodynamic arguments that relate phase stability to deviations of concentration dependence of atomic volume from the linear behavior.

  12. Fabrication of Tetragonal Pb(Zr,Ti)O3 Nanorods by Focused Ion Beam and Characterization of the Domain Structure.

    PubMed

    Ito, Daisuke; Yamada, Tomoaki; Sakata, Osami; Kuroishi, Junki; Namazu, Takahiro; Funakubo, Horoshi; Yoshino, Masahito; Nagasaki, Takanori

    2016-05-19

    It has been widely revealed and discussed that the properties of ferroelectric nanostructures vary with their dimensionality and size. The mechanical substrate clamping and the depolarization field are considered as major factors, which cause their unique properties. In this paper, we fabricated tetragonal {100}-Pb(Zr, Ti)O3 rods with 100 nm - 4 μm widths on Nb-doped SrTiO3 substrates by using focused ion beam, and characterized their domain structure by synchrotron micro X-ray diffraction. It was found that the clapping angle in the a/c-domain structure became larger with decreasing the rod width, which indicates the significant reduction of substrate clamping by fabricating narrow rods.

  13. Room-temperature poling of PbTiO3/Pb(Zr,Ti)O3 sol-gel composite films by pulse discharge

    NASA Astrophysics Data System (ADS)

    Kouyama, Hikaru; Kibe, Taiga; Fujimoto, Shota; Namihira, Takao; Kobayashi, Makiko

    2016-07-01

    The PbTiO3/Pb(Zr,Ti)O3 (PT/PZT) sol-gel composite is a promising piezoelectric material because of its high piezoelectricity and temperature stability up to 360 °C. However, the poling of PT/PZT required high temperature owing to the high coercive field of PT, which made the poling of PT/PZT troublesome. In this research, conventional DC corona poling and pulse discharge at room temperature were attempted for PT/PZT samples. As a result, PT/PZT poled by pulse discharge generation at room temperature showed comparable ultrasonic responses to that poled by DC corona discharge generation at a high temperature. Therefore, room-temperature poling of PT/PZT was successfully carried out by pulse discharge, and poling time was markedly reduced from ˜15 min to 15 s.

  14. High-temperature-immersion ultrasonic probe without delay line using PbTiO3/Pb(Zr,Ti)O3 ultrasonic transducer

    NASA Astrophysics Data System (ADS)

    Kibe, Taiga; Inoue, Takuo; Namihira, Takao; Kobayashi, Makiko

    2015-07-01

    The behavior of a high-temperature-immersion ultrasonic probe without a delay line using a PbTiO3/Pb(Zr,Ti)O3 (PT/PZT) ultrasonic transducer was investigated empirically. A ∼100-µm-thick PT/PZT film was fabricated on a 200-µm-thick stainless steel substrate. After PT/PZT film fabrication, the substrate was bonded to a stainless steel pipe using a high-temperature waterproof adhesive material. The probe was tested in a water bath from room temperature to 100 °C for system verification. During three thermal cycles, the ultrasonic echoes had a high signal-to-noise ratio (SNR) and reasonable repeatability. After that, the same probe was verified by testing it in the silicone oil from room temperature to 200 °C. The test was also repeated three times and the probe successfully demonstrated high-temperature durability, a high SNR, and repeatability throughout the experiments.

  15. Large electrical manipulation of permittivity in BaTiO{sub 3} and Pb(Zr,Ti)O{sub 3} bimorph heterostructure

    SciTech Connect

    Ci, Penghong; Liu, Guoxi; Dong, Shuxiang; Zhang, Li

    2014-08-18

    We report a strain-mediated electric field manipulation of permittivity in BaTiO{sub 3} (barium titanate, BT) ceramic by a Pb(Zr,Ti)O{sub 3} (PZT) bimorph. This BT/PZT heterostructure exhibited a relatively large permittivity tunability of BT up to ±10% in a wide frequency range under an electric field of ±4 kV/cm applied to the PZT bimorph. The permittivity tunability is attributed to the strain in BT produced by the PZT bimorph. Calculations of the relationship between permittivity and applied electric field were developed, and corresponded well with measurements. The BT/PZT heterostructure has potential for applications in broadband field tunable smart electronic devices.

  16. Photocatalytic Hydrogen Formation from Ammonia in an Aqueous Solution Over Pt-Enriched TiO2-ZrO2 Photocatalyst.

    PubMed

    Sihor, Marcel; Kočí, Kamila; Matĕjová, Lenka; Reli, Martin; Ambrožová, Nela; Pavlovský, Jiří; Capek, Libor; Obalová, Lucie

    2015-09-01

    The aim of this study was to remove ammonia from an aqueous solution by its decomposition to valuable products such as H2 and harmless N2 under UV light. The decomposition of ammonia by photocatalytic process represents an emerging and interesting way of its removal since beside the need of its reduction from the drinking and wastewaters with the respect to its negative impact on human and mammals health, it can lead to generation of hydrogen as an alternative fuel. A laboratory-synthesized Pt/TiO2-ZrO2 photocatalyst was studied and its photocatalytic activity was compared with the activity of commercial TiO2 Evonik P25. The Pt/TiO2-ZrO2 photocatalyst was prepared by combining a sol-gel process controlled within reverse micelles of nonionic surfactant Triton X-114 in cyclohexane, impregnation under vacuum and calcination. Explored photocatalysts were characterized by organic elementary analysis, nitrogen physisorption, XRD, FESEM and UV-Vis spectroscopy. The real platinum content in the Pt/TiO2-ZrO2 photocatalyst was determined by ICP-MS. The photocatalytic decomposition of ammonia was investigated in the time range of 0-12 h. During the first two hours the generation of hydrogen was almost negligible. The generation of hydrogen increased after 4 h of irradiation. Based on time dependences of ammonia decomposition the kinetic rate constants for Pt/TiO2-ZrO2 and TiO2 Evonik P25 photocatalysts were calculated. The ammonia photocatalytic decomposition was described well by the first order kinetic equation. The photocatalytic ammonia decomposition over the platinized TiO2-ZrO2 photocatalyst was proving 2 times higher photocatalytic performance than Evonik P25 (1241 μmol/g(cat) and 665 μmol/g(cat), respectively).

  17. Anion Exchange Behavior Of Ti, Zr, Hf, Nb And Ta As Homologues Of Rf And Db In Mixed HF--Acetone Solutions

    SciTech Connect

    Aksenov, N. V.; Bozhikov, G. A.; Starodub, G. Ya.; Dmitriev, S. N.; Filosofov, D. V.; Sun Jin, Jon; Radchenko, V. I.; Lebedev, N. A.; Novgorodov, A. F.

    2010-04-30

    We studied in detail the sorption behavior of Ti, Zr, Hf, Nb and Ta on AG 1 anion exchange resin in HF-acetone mixed solutions as a function of organic cosolvent and acid concentrations. Anion exchange behavior was found to be strongly acetone concentration dependent. The distribution coefficients of Ti, Zr, Hf and Nb increased and those of Ta decreased with increasing content of acetone in HF solutions. With increasing HF concentration anion exchange equilibrium analysis indicated the formation of fluoride complexes of group 4 elements with charge-3 and Ta---2. For Nb the slope of-2 increased up to-5. Optimal conditions for separation of the elements using AIX chromatography were found. Group 4 elements formed MF{sub 7}{sup 3-} (M = Ti, Zr, Hf) complexes whose sorption decreased Ti>Hf>Zr in reverse order of complex stability. This fact is of particular interest for studying ion exchange behavior of Rf compared to Ti. The advantages of studying chemical properties of Rf and Db in aqueous HF solutions mixed with organic solvents are briefly discussed.

  18. Nominal vs Local Shot-Peening Effects on Fatigue Lifetime in Ti-6Al-2Sn-4Zr-6Mo at Elevated Temperature

    DTIC Science & Technology

    2009-11-01

    PROCEDURE A. Material The materia l in this study was tbe IX + /1 titanium aUoy. Ti- 6 -2- 4 - 6 . in the duplex microstructural condition. Two y,;riants of the...ress level and temperature in the turbine engine alloy Ti-6AI-2Sn-4Zr- 6Mo (Ti- 6 -2- 4 - 6 ). The experimental conditions were chosen to target a regime...defects. which are produced during SP by thermally activated pro- cesses.II~.~1J A detailed discussion of these relaxation elTects in Ti- 6 -2- 4 - 6 is

  19. Nominal Versus Local Shot-Peening Effects on Fatigue Lifetime in Ti-6Al-2Sn-4Zr-6Mo at Elevated Temperature (Preprint)

    DTIC Science & Technology

    2008-09-01

    this study was the α+β titanium alloy, Ti- 6 -2- 4 - 6 , in the duplex microstructural condition. Two variants of the microstructure, which differed...condition, at a given stress level and temperature in the turbine engine alloy, Ti-6Al-2Sn-4Zr-6Mo (Ti- 6 -2- 4 - 6 ). The experimental conditions were chosen to...LSG surface. Fig. 1: Microstructures of the Ti- 6 -2- 4 - 6 alloy considered in the study; (a) Microstructure A and (b) Microstructure

  20. Continuous cross-over from ferroelectric to relaxor state and piezoelectric properties of BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} single crystals

    SciTech Connect

    Benabdallah, F.; Veber, P. Prakasam, M.; Viraphong, O.; Maglione, M.; Shimamura, K.

    2014-04-14

    Optimal properties like piezoelectricity can be found in polarizable materials for which the structure changes sharply under small composition variations in the vicinity of their morphotropic phase boundary or the triple point in their isobaric temperature-composition phase diagram. In the latter, lead-free (Ba{sub 0.850}Ca{sub 0.150})(Ti{sub 0.900}Zr{sub 0.100})O{sub 3} ceramics exhibit outstanding piezoelectric coefficients. For the first time, we report the growth of piezoelectric lead-free single crystals in the BaTiO{sub 3}-BaZrO{sub 3}-CaTiO{sub 3} pseudo-ternary system. The stoichiometry control in the CaO-BaO-TiO{sub 2}-ZrO{sub 2} solid solution led to single crystals with various compositions ranging from (Ba{sub 0.857}Ca{sub 0.143})(Ti{sub 0.928}Zr{sub 0.072})O{sub 3} to (Ba{sub 0.953}Ca{sub 0.047})(Ti{sub 0.427}Zr{sub 0.573})O{sub 3}. We evidenced a continuous cross-over from a ferroelectric state at high titanium content to a relaxor one on increasing the zirconium content. Such a property tuning is rather seldom observed in lead-free ferroelectrics and confirms what was already reported for ceramics. Single crystal with (Ba{sub 0.838}Ca{sub 0.162})(Ti{sub 0.854}Zr{sub 0.146})O{sub 3} composition, which has been grown and oriented along [001] crystallographic direction, displayed electromechanical coefficients d{sub 31} and k{sub 31} of 93 pC.N{sup −1} and 0.18, respectively, near the room temperature (T = 305 K)

  1. Continuous cross-over from ferroelectric to relaxor state and piezoelectric properties of BaTiO3-BaZrO3-CaTiO3 single crystals

    NASA Astrophysics Data System (ADS)

    Benabdallah, F.; Veber, P.; Prakasam, M.; Viraphong, O.; Shimamura, K.; Maglione, M.

    2014-04-01

    Optimal properties like piezoelectricity can be found in polarizable materials for which the structure changes sharply under small composition variations in the vicinity of their morphotropic phase boundary or the triple point in their isobaric temperature-composition phase diagram. In the latter, lead-free (Ba0.850Ca0.150)(Ti0.900Zr0.100)O3 ceramics exhibit outstanding piezoelectric coefficients. For the first time, we report the growth of piezoelectric lead-free single crystals in the BaTiO3-BaZrO3-CaTiO3 pseudo-ternary system. The stoichiometry control in the CaO-BaO-TiO2-ZrO2 solid solution led to single crystals with various compositions ranging from (Ba0.857Ca0.143)(Ti0.928Zr0.072)O3 to (Ba0.953Ca0.047)(Ti0.427Zr0.573)O3. We evidenced a continuous cross-over from a ferroelectric state at high titanium content to a relaxor one on increasing the zirconium content. Such a property tuning is rather seldom observed in lead-free ferroelectrics and confirms what was already reported for ceramics. Single crystal with (Ba0.838Ca0.162)(Ti0.854Zr0.146)O3 composition, which has been grown and oriented along [001] crystallographic direction, displayed electromechanical coefficients d31 and k31 of 93 pC.N-1 and 0.18, respectively, near the room temperature (T = 305 K).

  2. Screening on binary Zr-1X (X = Ti, Nb, Mo, Cu, Au, Pd, Ag, Ru, Hf and Bi) alloys with good in vitro cytocompatibility and magnetic resonance imaging compatibility.

    PubMed

    Zhou, F Y; Qiu, K J; Li, H F; Huang, T; Wang, B L; Li, L; Zheng, Y F

    2013-12-01

    In this study, the microstructures, mechanical properties, corrosion behaviors, in vitro cytocompatibility and magnetic susceptibility of Zr-1X alloys with various alloying elements, including Ti, Nb, Mo, Cu, Au, Pd, Ag, Ru, Hf and Bi, were systematically investigated to explore their potential use in biomedical applications. The experimental results indicated that annealed Zr-1X alloys consisted entirely or primarily of α phase. The alloying elements significantly increased the strength and hardness of pure Zr and had a relatively slight influence on elastic modulus. Ru was the most effective enhancing element and Zr-1Ru alloy had the largest elongation. The results of electrochemical corrosion indicated that adding various elements to Zr improved its corrosion resistance, as indicated by the reduced corrosion current density. The extracts of the studied Zr-1X alloys produced no significant deleterious effects on osteoblast-like cells (MG 63), indicating good in vitro cytocompatibility. All except for Zr-1Ag alloy showed decreased magnetic susceptibility compared to pure Zr, and Zr-1Ru alloy had the lowest magnetic susceptibility value, being comparable to that of α' phase Zr-Mo alloy and Zr-Nb alloy and far lower than that of Co-Cr alloy and Ti-6Al-4V alloy. Among the experimental Zr-1X alloys, Zr-1Ru alloy possessing high strength coupled with good ductility, good in vitro cytocompatibility and low magnetic susceptibility may be a good candidate alloy for medical devices within a magnetic resonance imaging environment.

  3. Plasmonic efficiencies of nanoparticles made of metal nitrides (TiN, ZrN) compared with gold

    NASA Astrophysics Data System (ADS)

    Lalisse, Adrien; Tessier, Gilles; Plain, Jérome; Baffou, Guillaume

    2016-12-01

    Metal nitrides have been proposed to replace noble metals in plasmonics for some specific applications. In particular, while titanium nitride (TiN) and zirconium nitride (ZrN) possess localized plasmon resonances very similar to gold in magnitude and wavelength, they benefit from a much higher sustainability to temperature. For this reason, they are foreseen as ideal candidates for applications in nanoplasmonics that require high material temperature under operation, such as heat assisted magnetic recording (HAMR) or thermophotovoltaics. This article presents a detailed investigation of the plasmonic properties of TiN and ZrN nanoparticles in comparison with gold nanoparticles, as a function of the nanoparticle morphology. As a main result, metal nitrides are shown to be poor near-field enhancers compared to gold, no matter the nanoparticle morphology and wavelength. The best efficiencies of metal nitrides as compared to gold in term of near-field enhancement are obtained for small and spherical nanoparticles, and they do not exceed 60%. Nanoparticle enlargements or asymmetries are detrimental. These results mitigate the utility of metal nitrides for high-temperature applications such as HAMR, despite their high temperature sustainability. Nevertheless, at resonance, metal nitrides behave as efficient nanosources of heat and could be relevant for applications in thermoplasmonics, where heat generation is not detrimental but desired.

  4. 3D surface topography study of the biofunctionalized nanocrystalline Ti-6Zr-4Nb/Ca-P

    SciTech Connect

    Jakubowicz, J.; Adamek, G.; Jurczyk, M.U.; Jurczyk, M.

    2012-08-15

    In this work surface of the sintered Ti-6Zr-4Nb nanocrystalline alloy was electrochemically biofunctionalized. The porous surface was produced by anodic oxidation in 1 M H{sub 3}PO{sub 4} + 2%HF electrolyte at 10 V for 30 min. Next the calcium-phosphate (Ca-P) layer was deposited, onto the formed porous surface, using cathodic potential - 5 V kept for 60 min in 0.042 M Ca(NO{sub 3}){sub 2} + 0.025 M (NH{sub 4}){sub 2}HPO{sub 4} + 0.1 M HCl electrolyte. The deposited Ca-P layer anchored in the pores. The biofunctionalized surface was studied by XRD, SEM and EDS. In vitro tests culture of normal human osteoblast (NHOst) cells showed very good cells proliferation, colonization and multilayering. Using optical profiler, roughness and hybrid 3D surface topography parameters were estimated. Correlation between surface composition, morphology, roughness and biocompatibility results was done. It has been shown by us that surface with appropriate chemical composition and topography, after combined electrochemical anodic and cathodic surface treatment, supports osteoblast adhesion and proliferation. 3D topography measurements using optical profiler play a key role in the biomaterials surface analysis. - Highlights: Black-Right-Pointing-Pointer Nanocrystalline Ti-6Zr-4Nb/Ca-P material was produced for hard tissue implant applications. Black-Right-Pointing-Pointer Calcium-phosphate results in surface biofunctionalization. Black-Right-Pointing-Pointer The biofunctionalized surface shows good in-vitro behavior.

  5. Enhancement of the electrochemical behaviour and biological performance of Ti-25Ta-5Zr alloy by thermo-mechanical processing.

    PubMed

    Cimpean, Anisoara; Vasilescu, Ecaterina; Drob, Paula; Cinca, Ion; Vasilescu, Cora; Anastasescu, Mihai; Mitran, Valentina; Drob, Silviu Iulian

    2014-05-01

    A new Ti-25Ta-5Zr alloy based only on non-toxic and non-allergic elements was elaborated in as-cast and thermo-mechanical processed, recrystallized states (XRD and SEM) in order to be used as candidate material for implant applications. Its long-term interactions with Ringer-Brown and Ringer solutions of different pH values and its cytocompatibility were determined. The thermo-mechanically processed alloy has nobler electrochemical behaviour than as-cast alloy due to finer microstructure obtained after the applied treatment. Corrosion and ion release rates presented the lowest values for the treated alloy. Nyquist and Bode plots displayed higher impedance values and phase angles for the processed alloy, denoting a more protective passive film. SEM micrographs revealed depositions from solutions that contain calcium, phosphorous and oxygen ions (EDX analysis), namely calcium phosphate. An electric equivalent circuit with two time constants was modelled. Cell culture experiments with MC3T3-E1 pre-osteoblasts demonstrated that thermo-mechanically processed Ti-25Ta-5Zr alloy supports a better cell adhesion and spreading, and enhanced cell proliferation. Altogether, these data indicate that thermo-mechanical treatment endows the alloy with improved anticorrosion and biological performances.

  6. Development and investigation of the structure and physical and mechanical properties of low-modulus Ti-Zr-Nb alloys

    NASA Astrophysics Data System (ADS)

    Grib, S. V.; Illarionov, A. G.; Popov, A. A.; Ivasishin, O. M.

    2014-06-01

    The criteria for the optimization of chemical composition of Ti-Zr-Nb alloys have been selected that allow for obtaining materials with low elastic moduli and which have been used to melt alloys 50Ti-(50 - x) Zr- xNb, at 15 < x < 20 at %. Transmission electron microscopy and X-ray diffraction analysis have been used to study the phase composition of the as-cast alloys and alloys after homogenizing annealing. The minimum elastic modulus (69 GPa) and minimum microhardness (2440 MPa) have been found in the almost single-β-phase alloy with a maximum niobium content (17.1 at %). An increase in the volume fraction of α″ phase in the alloys with a lower niobium content (to 15 at %) promotes the growth of values of these properties. The phase transformations that occur during the continuous heating of homogenized alloys have been studied. The dependence of the temperature of the polymorphic (α + β)-β transformation on the ratio of the alloying elements in the studied alloys have been shown.

  7. Plasmonic efficiencies of nanoparticles made of metal nitrides (TiN, ZrN) compared with gold

    PubMed Central

    Lalisse, Adrien; Tessier, Gilles; Plain, Jérome; Baffou, Guillaume

    2016-01-01

    Metal nitrides have been proposed to replace noble metals in plasmonics for some specific applications. In particular, while titanium nitride (TiN) and zirconium nitride (ZrN) possess localized plasmon resonances very similar to gold in magnitude and wavelength, they benefit from a much higher sustainability to temperature. For this reason, they are foreseen as ideal candidates for applications in nanoplasmonics that require high material temperature under operation, such as heat assisted magnetic recording (HAMR) or thermophotovoltaics. This article presents a detailed investigation of the plasmonic properties of TiN and ZrN nanoparticles in comparison with gold nanoparticles, as a function of the nanoparticle morphology. As a main result, metal nitrides are shown to be poor near-field enhancers compared to gold, no matter the nanoparticle morphology and wavelength. The best efficiencies of metal nitrides as compared to gold in term of near-field enhancement are obtained for small and spherical nanoparticles, and they do not exceed 60%. Nanoparticle enlargements or asymmetries are detrimental. These results mitigate the utility of metal nitrides for high-temperature applications such as HAMR, despite their high temperature sustainability. Nevertheless, at resonance, metal nitrides behave as efficient nanosources of heat and could be relevant for applications in thermoplasmonics, where heat generation is not detrimental but desired. PMID:27934890

  8. Sintering Of MgO and TiO{sub 2} Doped Al-Zr Oxides Composites by Extended Arc Thermal Plasma

    SciTech Connect

    Ray, M.; Pradhan, S. K.; Dash, S.; Roul, B. K.; Mishra, D. K.; Singh, S. K.; Sahu, D.

    2008-10-23

    MgO and TiO{sub 2} doped Al-Zr oxide composites of Zr{sub 0.95}Al{sub 1.05}Mg{sub x}O with x = 0,0.01,...,0.05,0.75,1 and Zr{sub 0.95}-Al{sub 1.05}-Ti{sub z}-O with z = 0, 0.025,....,1 were sintered to high density by both DC thermal plasma assisted rapid sintering as well as conventional sintering. It is observed that the above mentioned MgO and TiO{sub 2} doped Al-Zr oxide composites were sintered to high density end products by the thermal plasma heating technique within a short sintering time (a few minutes) as compared to a conventional long range resistive heating schedule (a few tens of hours). It is also noticed that there exists a critical limiting point of MgO doping concentration (x = 0.05 in Zr{sub 0.95}Al{sub 1.05}Mg{sub x}O) for maximum physical densification in both conventional as well as plasma sintered samples. Sintered specimens were analyzed by XRD studies. XRD studies revealed the presence of a high density phase, Mg{sub 2}Zr{sub 5}O{sub 12} prominently in x = 0.05 sintered sample which resulted in maximum densification of the sample. With increasing doping concentration of TiO{sub 2}(i.e. z=0 to 1), {rho}{sub s}(sintered density) of both plasma sintered and conventional sintered specimens were found to follow a concavity like variation with well defined critical limit of TiO{sub 2} concentration (i.e. at z=0.05) at which {rho}{sub s} became minimum. However, hardness was found to be maximum at z = 0.05.

  9. Phase transition and electrical properties of highly [1 1 1]-oriented and niobium-modified Pb(ZrxTi1-x)O3 thin films with different Zr/Ti ratios

    NASA Astrophysics Data System (ADS)

    Ruangchalermwong, C.; Li, Jing-Feng; Zhu, Zhi-Xiang; Muensit, S.

    2008-11-01

    Highly [1 1 1]-oriented and niobium-modified Pb(ZrxTi1-x)O3 (PNZT) thin films with different Zr/Ti ratios ranging from 20/80 to 80/20 have been deposited on Pt(1 1 1)/Ti/SiO2/Si substrates by the sol-gel method. The electrical properties as a function of the Zr/Ti ratio were investigated to develop ferroelectric films with enhanced ferroelectric and dielectric properties. The phase transition from tetragonal to rhombohedral was clearly observed by electrical characterization when the Zr/Ti ratios were varied across the morphotropic phase boundary (MPB). The ferroelectric and dielectric properties were found to strongly depend on the Zr/Ti ratio. Among the samples investigated in this work, the film with composition close to MPB exhibited the largest remanent polarization of 80 µC cm-2 and a coercive field as low as 70 kV cm-1. A value of dielectric constant as high as 1550 was also obtained from the MPB-composition film.

  10. Corrosion behavior of novel Ti-24Nb-4Zr-7.9Sn alloy for dental implant applications in vitro.

    PubMed

    Cheng, Yicheng; Hu, Jiang; Zhang, Chunbao; Wang, Zhongyi; Hao, Yulin; Gao, Bo

    2013-02-01

    Ti-24Nb-4Zr-7.9Sn (TNZS) alloy is a newly developed β-titanium alloy considered suitable for dental implant applications due to its low elastic modulus and high strength. The aim of this study was to investigate the corrosion behavior of TNZS alloy through a static immersion test in various simulated physiological solutions, namely, artificial saliva, lactic acid solution, fluoridated saliva, and fluoridated acidified saliva for 7 days. The corrosion behavior of commercially pure titanium and Ti-6Al-4V alloy were also examined for comparison. The elemental release was measured with inductively coupled plasma mass spectroscopy, and the changes of alloy surface were observed with scanning electron microscopy (SEM). The test results showed that the quantity of each metal element released from TNZS alloy into fluoridated solutions was much higher than the solutions without fluoride ions. It was highest in fluoridated acidified saliva and lowest in artificial saliva (p < 0.01). The total elemental release from TNZS alloy was lower than commercially pure titanium and Ti-6Al-4V alloy in the same solution (p < 0.01). SEM micrographs indicated that TNZS alloy possessed better corrosion resistant performance. It can be concluded that fluoridated solutions have a negative influence on the corrosion behavior of TNZS alloy. Compared with commercially pure titanium and Ti-6Al-4V alloy, TNZS alloy demonstrates better corrosion resistance in various simulated physiological solutions, so it has greater potential for dental implant applications.

  11. Electrochemical and surface analyses of nanostructured Ti-24Nb-4Zr-8Sn alloys in simulated body solution.

    PubMed

    Li, J; Li, S J; Hao, Y L; Huang, H H; Bai, Y; Hao, Y Q; Guo, Z; Xue, J Q; Yang, R

    2014-06-01

    The use of nanostructuring to improve the stability of passive thin films on biomaterials can enhance their effectiveness in corrosion resistance and reduce the release of ions. The thickness of the ultrathin films that cover Ti and Ti alloys (only several nanometers) has prevented researchers from establishing systematic methods for their characterization. This study employed a multifunctional biomedical titanium alloy Ti-24Nb-4Zr-8Sn (wt.%) as a model material. Coarse-grained (CG) and nanostructured (NS) alloys were analyzed in 0.9% NaCl solution at 37°C. To reveal the details of the passive film, a method of sample preparation producing a passive layer suitable for transmission electron microscope analysis was developed. Electrochemical corrosion behavior was evaluated by potentiodynamic polarization tests and Mott-Schottky measurements. Surface depth chemical profile and morphology evolution were performed by X-ray photoelectron spectroscopy and in situ atomic force microscopy, respectively. A mechanism was proposed on the basis of the point defect model to compare the corrosion resistance of the passive film on NS and CG alloys. Results showed that the protective amorphous film on NS alloy is thicker, denser and more homogeneous with fewer defects than that on CG alloy. The film on NS alloy contains more oxygen and corrosion-resistant elements (Ti and Nb), as well as their suboxides, compared with the film on CG alloy. These characteristics can be attributed to the rapid, uniform growth of the passive film facilitated by nanostructuring.

  12. Ti insertion in the MTe(5) (M = Zr, Hf) structure type: Hf(0.78)Ti(0.22)Te(5).

    PubMed

    Yu, Jaemin; Yun, Hoseop

    2012-03-01

    The group 5 mixed-metal telluride, Hf(0.78)Ti(0.22)Te(5) (hafnium titanium penta-telluride), is isostructural with the binary phases HfTe(5) and ZrTe(5) and forms a layered structure extending parallel to (010). The layers are made up from chains of bicapped metal-centered trigonal prisms and zigzag Te chains. The metal site (site symmetry m2m) is occupied by statistically disordered Hf [78.1 (5)%] and Ti [21.9 (5)%]. In addition to the regular Te-Te pair [2.7448 (13) Å] forming the short base of the equilateral triangle of the trigonal prism, an inter-mediate Te⋯Te separation [2.9129 (9) Å] is also found. The classical charge balance of the compound can be described as [M(4+)][Te(2-)][Te(2) (2-)][Te(2) (0)] (M = Hf, Ti). The individual metal content can vary in different crystals, apparently forming a random substitutional solid solution (Hf(1-x)Ti(x))Te(5), with 0.15 ≤ x ≤ 0.22.

  13. Modified surface morphology of a novel Ti-24Nb-4Zr-7.9Sn titanium alloy via anodic oxidation for enhanced interfacial biocompatibility and osseointegration.

    PubMed

    Li, Xiang; Chen, Tao; Hu, Jing; Li, Shujun; Zou, Qin; Li, Yunfeng; Jiang, Nan; Li, Hui; Li, Jihua

    2016-08-01

    The Ti-24Nb-4Zr-7.9Sn titanium alloy (Ti2448) has shown potential for use in biomedical implants, because this alloy possesses several important mechanical properties, such as a high fracture strength, low elastic modulus, and good corrosion resistance. In this study, we aimed to produce a hierarchical nanostructure on the surface of Ti2448 to endow this alloy with favorable biological properties. The chemical composition of Ti2448 (64.0wt% Ti, 23.9wt% Nb, 3.9wt% Zr, and 8.1wt% Sn) gives this material electrochemical properties that lead to the generation of topographical features under standard anodic oxidation. We characterized the surface properties of pure Ti (Ti), nanotube-Ti (NT), Ti2448, and nanotube-Ti2448 (NTi2448) based on surface morphology (scanning electron microscopy and atomic force microscopy), chemical and phase compositions (X-ray diffraction and X-ray photoelectron spectroscopy), and wettability (water contact angle). We evaluated the biocompatibility and osteointegration of implant surfaces by observing the behavior of bone marrow stromal cells (BMSCs) cultured on the surfaces in vitro and conducting histological analysis after in vivo implantation of the modified materials. Our results showed that a hierarchical structure with a nanoscale bone-like layer was achieved along with nanotube formation on the Ti2448 surface. The surface characterization data suggested the superior biocompatibility of the NTi2448 surface in comparison with the Ti, NT, and Ti2448 surfaces. Moreover, the NTi2448 surface showed better biocompatibility for BMSCs in vitro and better osteointegration in vivo. Based on these results, we conclude that anodic oxidation facilitated the formation of a nanoscale bone-like structure and nanotubes on Ti2448. Unlike the modified titanium surfaces developed to date, the NTi2448 surface, which presents both mechanical compatibility and bioactivity, offers excellent biocompatibility and osteointegration, suggesting its potential for

  14. Electrochemical characterization of pulsed layer deposited hydroxyapatite-zirconia layers on Ti-21Nb-15Ta-6Zr alloy for biomedical application

    NASA Astrophysics Data System (ADS)

    Izquierdo, Javier; Bolat, Georgiana; Cimpoesu, Nicanor; Trinca, Lucia Carmen; Mareci, Daniel; Souto, Ricardo Manuel

    2016-11-01

    A new titanium base Ti-21Nb-15Ta-6Zr alloy covered with hydroxyapatite-zirconia (HA-ZrO2) by pulsed laser deposition (PLD) technique was characterized regarding its corrosion resistance in simulated physiological Ringer's solution at 37 °C. For the sake of comparison, Ti-6Al-4V standard implant alloy, with and without hydroxyapatite-zirconia coating, was also characterized. Multiscale electrochemical analysis using both conventional averaging electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, and spatially-resolved microelectrochemical techniques (scanning electrochemical microscopy, SECM) were used to investigate the electrochemical behaviour of the materials. In addition, scanning electron microscopy evidenced that no relevant surface morphology changes occurred on the materials upon immersion in the simulated physiological solution, despite variations in their electrochemical behaviour. Although uncoated metals appear to show better performances during conventional corrosion tests, the response is still quite similar for the HA-ZrO2 coated materials while providing superior resistance towards electron transfer due to the formation of a more dense film on the surface, thus effectively behaving as a passive material. It is believed corrosion of the HA-ZrO2 coated Ti-21Nb-15Ta-6Zr alloy will have negligible effect upon biochemical and cellular events at the bone-implant interface and could facilitate osseointegration.

  15. Cellular response of osteoblasts to low modulus Ti-24Nb-4Zr-8Sn alloy mesh structure.

    PubMed

    Nune, K C; Misra, R D K; Li, S J; Hao, Y L; Yang, R

    2017-03-01

    Titanium alloys (Ti-6Al-4V and Ti-6Al-7Nb) are widely used for implants, which are characterized by high elastic modulus (∼110 GPa) with (α + β) structure and that may induce undesirable stress shielding effect and immune responses associated with the presence of toxic elements. In this regard, we have combined the attributes of a new alloy design and the concept of additive manufacturing to fabricate 3D scaffolds with an interconnected porous structure. The new alloy is a β-type Ti-24Nb-4Zr-8Sn (Ti2448) alloy with significantly reduced modulus. In the present study, we explore the biological response of electron beam melted low modulus Ti2448 alloy porous mesh structure through the elucidation of bioactivity and osteoblast functions. The cellular activity was explored in terms of cell-to-cell communication involving proliferation, spreading, synthesis of extracellular and intracellular proteins, differentiation, and mineralization. The formation of fine apatite-like crystals on the surface during immersion test in simulated body fluid confirmed the bioactivity of the scaffold surface, which provided the favorable osteogenic microenvironment for cell-material interaction. The combination of unique surface chemistry and interconnected porous architecture provided the desired pathway for supply of nutrients and oxygen to cells and a favorable osteogenic micro-environment for incorporation (on-growth and in-growth) of osteoblasts. The proliferation and differentiation of pre-osteoblasts and their ability to form a well mineralized bone-like extracellular matrix (ECM) by secreting bone markers (ALP, calcium, etc.) over the struts of the scaffold point toward the determining role of unique surface chemistry and 3D architecture of the Ti2448 alloy mesh structure in modulating osteoblasts functions. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 859-870, 2017.

  16. A three-dimensional extended Sb network in the metallic antimonides (M',Ti)5Sb8 (M' = Zr, Hf, Nb, Mo).

    PubMed

    Kleinke, H

    2001-01-01

    (M',Ti)5Sb8 was prepared from the melt by arc-melting suitable mixtures of Ti, TiSb2, and M'Sb2, respectively. This phase exists at least with M' = Zr, Hf, Nb, and Mo. A significant phase range for Zr delta Ti5 - delta Sb8 was found to be within 1.10(8) < or = delta < or = 3.9(3). All (M',Ti)5Sb8 representatives investigated occur in the same, yet hitherto unknown structure type, as determined by single-crystal analyses. E.g., the lattice dimensions of Zr delta Ti5 - delta Sb8 range from a = 654.49(3) pm, c = 2662.4(2) pm for delta = 1.10(8) to a = 671.06(6), c = 2679.7(4) pm for delta = 3.9(3) (space group I4(1)22, No. 98, Z = 4). The three chemically inequivalent metal sites are statistically occupied by different mixtures of the M atoms M' and Ti, included in a three-dimensional network of Sb atoms on 6- to 8-fold Sb coordinated positions. Sb-Sb bonds of intermediate lengths occur in addition to the predominating heteronuclear M-Sb bonds. Physical property measurements of (Zr,Ti)5Sb8 reveal these phases being metallic exhibiting specific resistances of several m omega.cm and a small Seebeck coefficient at room temperature, in agreement with the results of the electronic structure calculations on the LMTO and extended Hückel levels. The calculations indicate a possible change to semiconducting properties by heavy doping.

  17. Electrochemical properties of melt spun Si-Cu-Ti-Zr-Ni alloy powders for the anode of Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Bae, Seong Min; Sohn, Keun Yong; Park, Won-Wook

    2014-07-01

    The Si-Cu-Ti-Zr-Ni alloys of various compositions were prepared using arc-melting under an argon atmosphere, and the alloys were re-melted several times to ensure chemical homogeneity. The alloyed ingots were melt-spun to produce rapidly solidified ribbons under vacuum in order to prevent oxidation. Finely dispersed silicon particles 50-100 nm in diameter mainly consisting of Cu3Si, NiSi2 and TiSi2 phases were formed in the matrices. The alloy ribbons were then fragmented using ball-milling to produce powders. In order to evaluate the electrochemical properties of the alloys, anode electrodes were fabricated by mixing the active alloy materials (80 wt. %) with Ketjenblack® (2 wt. %) as a conductive material and polyamide imide (PAI, 8 wt. %) binder, and the mixtures were dissolved in N-methyl-2-pyrrolidinone (NMP) and SFG6 (10 wt. %). The anode performances of Si-Cu-Ti-Zr-Ni alloy cells were measured in the range 0.01-1.5 V (versus Li/Li+). The results showed that the Si68(Cu47Ti34Zr11Ni8)32 alloy ribbons had the highest specific discharge capacities, and the Si68(Cu40Ti40Zr10Ni10)32 alloy ribbons had relatively stable electrochemical properties and cycle performances due to the very fine microstructure including partially distributed amorphous phase. The matrix phases of the Si-Cu-Ti-Zr-Ni alloy ribbons effectively accommodated the change in Si particle volume during cycling.

  18. First-Principles Study of the Jahn-Teller Distortion in the Ti1-XVXH2 and Zr1-XNbxH2 Alloys

    NASA Astrophysics Data System (ADS)

    Quijano, Ramiro; de Coss, Romeo; Singh, David

    2008-03-01

    The transition metal dihydrides TiH2 and ZrH2 present the fluorite structure (CaF2) at high temperature but undergoes a tetragonal distortion with c/a<1 at low temperature. Electronic band structure calculations have shown that TiH2 and ZrH2 in the cubic phase display a very flat band at the Fermi level. Thus the low temperature tetragonal distortion has been associated to a Jahn-Teller effect. In order to understand the role of band filling in controlling the structural instability of the transition metal dihydrides, we have performed a first-principles total energy study of the Ti1-XVxH2 and Zr1-xNbxH2 alloys. The calculations were performed using FP-LAPW method within the (DFT) and we use the GGA for exchange correlation functional energy. The critical concentration for which the Jahn-Teller effect is suppressed, was determined from the evolution of the tetragonal-cubic energy barrier. We discuss the electronic mechanism of the structural-instability, in terms of the band filling. From the obtained results we conclude that the tetragonal distortion in TiH2 and ZrH2 is not produced only by a Jahn-Teller Effect. This research was supported by Consejo Nacional de Ciencia y Tecnolog'ia (Conacyt) under Grant No. 43830-F.

  19. Evaluation of AlGaN/GaN high electron mobility transistors grown on ZrTi buffer layers with sapphire substrates

    DOE PAGES

    Ren, Fan; Pearton, Stephen J.; Ahn, Shihyun; ...

    2016-09-21

    Here, AlGaN/GaN high electron mobility transistors (HEMTs) have been grown on sapphire substrates, using ZrTi buffer layers to provide in-plane lattice-matching to hexagonal GaN. X-ray diffraction (XRD) as well as cross-section transmission electron microscopy (TEM) were used to assess the quality of the HEMT structure. The XRD 2θ scans showed full-width-at-half-maximum values of 0.16°, 0.07°, and 0.08° for ZrTi alloy, GaN buffer layer, and the entire HEMT structure, respectively. TEM studies of the GaN buffer layer and the AlN/ZrTi/AlN stack showed the importance of growing thin AlN buffer layers on the ZrTi layer prior to growth of the GaN buffermore » layer. The density of threading dislocations in the GaN channel layer of the HEMT structure was estimated to be in the 108 cm–2 range. The HEMT device exhibited a saturation drain current density of 820 mA/mm, and the channel of the fabricated HEMTs could be well modulated. A cutoff frequency (fT) of 8.9 GHz and a maximum frequency of oscillation (fmax) of 17.3 GHz were achieved for HEMTs with gate dimensions of 1 × 200 μm.« less

  20. Evaluation of AlGaN/GaN high electron mobility transistors grown on ZrTi buffer layers with sapphire substrates

    SciTech Connect

    Ren, Fan; Pearton, Stephen J.; Ahn, Shihyun; Lin, Yi -Hsuan; Machuca, Francisco; Weiss, Robert; Welsh, Alex; McCartney, Martha R.; Smith, David J.; Kravchenko, Ivan I.

    2016-09-21

    Here, AlGaN/GaN high electron mobility transistors (HEMTs) have been grown on sapphire substrates, using ZrTi buffer layers to provide in-plane lattice-matching to hexagonal GaN. X-ray diffraction (XRD) as well as cross-section transmission electron microscopy (TEM) were used to assess the quality of the HEMT structure. The XRD 2θ scans showed full-width-at-half-maximum values of 0.16°, 0.07°, and 0.08° for ZrTi alloy, GaN buffer layer, and the entire HEMT structure, respectively. TEM studies of the GaN buffer layer and the AlN/ZrTi/AlN stack showed the importance of growing thin AlN buffer layers on the ZrTi layer prior to growth of the GaN buffer layer. The density of threading dislocations in the GaN channel layer of the HEMT structure was estimated to be in the 108 cm–2 range. The HEMT device exhibited a saturation drain current density of 820 mA/mm, and the channel of the fabricated HEMTs could be well modulated. A cutoff frequency (fT) of 8.9 GHz and a maximum frequency of oscillation (fmax) of 17.3 GHz were achieved for HEMTs with gate dimensions of 1 × 200 μm.

  1. Tribological and corrosion behaviors of warm-and hot-rolled Ti-13Nb-13Zr alloys in simulated body fluid conditions

    PubMed Central

    Lee, Taekyung; Mathew, Eshaan; Rajaraman, Santhosh; Manivasagam, Geetha; Singh, Ashok Kumar; Lee, Chong Soo

    2015-01-01

    Development of submicrocrystalline structure in biomedical alloy such as Ti-13Nb-13Zr (in wt%) through warm-rolling process has been found to enhance mechanical properties compared to conventional thermomechanical processing routes including hot-rolling process. The present study investigated the tribological and corrosion behaviors of warm-rolled (WR) and hot-rolled Ti-13Nb-13Zr alloys which have not been studied to date. Both tribological and corrosion experiments were carried out in simulated body fluid conditions (Hank’s solution at 37°C) based on the fact that the investigated alloys would be used in a human body as orthopedic implants. The WR Ti-13Nb-13Zr demonstrated a submicrocrystalline structure that provided a significant enhancement in hardness, strength, and corrosion resistance. Meanwhile, there was no notable difference in wear resistance between the WR and hot-rolled samples despite the different microstructure and hardness. The present study confirmed the enormous potential of WR Ti-13Nb-13Zr with not only great mechanical properties but also high corrosion resistance in the simulated body fluid. PMID:26491322

  2. Screening of in vitro cytotoxicity, antioxidant potential and bioactivity of nano- and micro-ZrO2 and -TiO2 particles.

    PubMed

    Karunakaran, Gopalu; Suriyaprabha, Rangaraj; Manivasakan, Palanisamy; Yuvakkumar, Rathinam; Rajendran, Venkatachalam; Kannan, Narayanasamy

    2013-07-01

    Nanometal oxides are used in tissue engineering and implants. The increased use of nanoparticles suggests the need to study their adverse effects on biological systems. The present investigation explores in vitro cytotoxicity, antioxidant potential, and bioactivity of nano- and micro-particles such as zirconia (ZrO2) and titania (TiO2) on biological systems such as National Institute of Health (NIH) 3T3 mouse embryonic fibroblasts cell line, di(phenyl)-(2,4,6-trinitrophenyl) iminoazanium (DPPH) and simulated body fluid (SBF). The cell line viability % indicated that nano ZrO2 and TiO2 were less toxic than microparticles up to 200µgml(-1). DPPH assay revealed that the free radical scavenging potential of tested particles were higher for nano ZrO2 (76.9%) and nano TiO2 (73.3%) at 100mg than that for micron size particles. Calcium deposition percentage of micro- and nano-ZrO2 particles, after SBF study, showed 0.066% and 0.094% respectively, whereas for micro- and nano-TiO2, it was 0.251% and 0.615% respectively. FTIR results showed a good bioactivity through hydroxyapatite formation. The present investigation clearly shows that nanoparticles possess good antioxidant potential and better biocompatibility under in vitro conditions which are dose and size dependent. Hence, cytotoxicity itself is not promising evaluation method for toxicity rather than particles individual characterisation using antioxidant and bioactivity analysis.

  3. Crystal and electronic structure and magnetic properties of divalent europium perovskite oxides EuMO3 (M = Ti, Zr, and Hf): experimental and first-principles approaches.

    PubMed

    Akamatsu, Hirofumi; Fujita, Koji; Hayashi, Hiroyuki; Kawamoto, Takahiro; Kumagai, Yu; Zong, Yanhua; Iwata, Koji; Oba, Fumiyasu; Tanaka, Isao; Tanaka, Katsuhisa

    2012-04-16

    A comparative study of the crystal and electronic structure and magnetism of divalent europium perovskite oxides EuMO(3) (M = Ti, Zr, and Hf) has been performed on the basis of both experimental and theoretical approaches playing complementary roles. The compounds were synthesized via solid-state reactions. EuZrO(3) and EuHfO(3) have an orthorhombic structure with a space group Pbnm at room temperature contrary to EuTiO(3), which is cubic at room temperature. The optical band gaps of EuZrO(3) and EuHfO(3) are found to be about 2.4 and 2.7 eV, respectively, much larger than that of EuTiO(3) (0.8 eV). On the other hand, the present compounds exhibit similar magnetic properties characterized by paramagnetic-antiferromagnetic transitions at around 5 K, spin flop at moderate magnetic fields lower than 1 T, and the antiferromagnetic nearest-neighbor and ferromagnetic next-nearest-neighbor exchange interactions. First-principles calculations based on a hybrid Hartree-Fock density functional approach yield lattice constants, band gaps, and magnetic interactions in good agreement with those obtained experimentally. The band gap excitations are assigned to electronic transitions from the Eu 4f to Mnd states for EuMO(3) (M = Ti, Zr, and Hf and n = 3, 4, and 5, respectively).

  4. Electrical and dielectric properties of ZnO and CeO{sub 2} doped ZrTi{sub 2}O{sub 6} ceramic

    SciTech Connect

    George, Aneesh; Thomas, Jijimon K.; John, Annamma; Solomon, Sam

    2014-01-28

    Zirconium oxide (ZrO{sub 2}) and titanium dioxide (TiO{sub 2}) are the important catalyst supports, since it has acidic and basic properties. The intermediate phase zirconium titanate ZrTi{sub 2}O{sub 6}, which is a solid solution with Zr:Ti ratio 1:2 has outstanding dielectric properties. The effects of doping of ZnO and CeO{sub 2} on the dielectric and electrical properties of ZrTi{sub 2}O{sub 6} ceramic are investigated. On adding 0.5 wt% ZnO, the dielectric constant is increased but, on adding CeO{sub 2}, the dielectric constant is decreased. The bulk density of pure sample sintered at 1530 °C is 91% of theoretical density while that of the doped samples sintered at 1450 °C is more than 94% of theoretical density. Scanning electron micrographs reveal that the samples are well sintered with minimum porosity. The semicircle behavior in the Cole-Cole plots at room temperature reveals that the samples are good ionic conductor. The induced impedance is reduced for doped samples and this can be used as a material for electrolyte in Solid Oxide Fuel Cell.

  5. Tribological and corrosion behaviors of warm-and hot-rolled Ti-13Nb-13Zr alloys in simulated body fluid conditions.

    PubMed

    Lee, Taekyung; Mathew, Eshaan; Rajaraman, Santhosh; Manivasagam, Geetha; Singh, Ashok Kumar; Lee, Chong Soo

    2015-01-01

    Development of submicrocrystalline structure in biomedical alloy such as Ti-13Nb-13Zr (in wt%) through warm-rolling process has been found to enhance mechanical properties compared to conventional thermomechanical processing routes including hot-rolling process. The present study investigated the tribological and corrosion behaviors of warm-rolled (WR) and hot-rolled Ti-13Nb-13Zr alloys which have not been studied to date. Both tribological and corrosion experiments were carried out in simulated body fluid conditions (Hank's solution at 37°C) based on the fact that the investigated alloys would be used in a human body as orthopedic implants. The WR Ti-13Nb-13Zr demonstrated a submicrocrystalline structure that provided a significant enhancement in hardness, strength, and corrosion resistance. Meanwhile, there was no notable difference in wear resistance between the WR and hot-rolled samples despite the different microstructure and hardness. The present study confirmed the enormous potential of WR Ti-13Nb-13Zr with not only great mechanical properties but also high corrosion resistance in the simulated body fluid.

  6. Investigation of short-range structural order in Zr69.5Cu12Ni11Al7.5 and Zr41.5Ti41.5Ni17 glasses, using X-ray absorption spectroscopy and ab initio molecular dynamics simulations.

    PubMed

    Lahiri, Debdutta; Sharma, Surinder M; Verma, Ashok K; Vishwanadh, B; Dey, G K; Schumacher, Gerhard; Scherb, Tobias; Riesemeier, Heinrich; Reinholz, Uwe; Radtke, Martin; Banerjee, S

    2014-11-01

    Short-range order has been investigated in Zr69.5Cu12Ni11Al7.5 and Zr41.5Ti41.5Ni17 metallic glasses using X-ray absorption spectroscopy and ab initio molecular dynamics simulations. While both of these alloys are good glass formers, there is a difference in their glass-forming abilities (Zr41.5Ti41.5Ni17 > Zr69.5Cu12Ni11Al7.5). This difference is explained by inciting the relative importance of strong chemical order, icosahedral content, cluster symmetry and configuration diversity.

  7. Crystal chemistry of the G-phases in the {l_brace}Ti, Zr, Hf{r_brace}-Ni-Si systems

    SciTech Connect

    Grytsiv, A.; Chen Xingqiu; Rogl, P. Podloucky, R.; Schmidt, H.; Giester, G.; Pomjakushin, V.

    2007-02-15

    Ternary compounds M{sub 6}Ni{sub 16}Si{sub 7} (M=Ti, Zr, Hf) have been investigated by X-ray powder/single crystal and neutron powder diffraction. Compounds with Zr and Hf crystallize in the ordered Th{sub 6}Mn{sub 23} type (Mg{sub 6}Cu{sub 16}Si{sub 7}-type, space group Fm3-bar m), whereas Ti{sub 6}Ni{sub 16.7}Si{sub 7} contains an additional Ni atom partially occupying the 24e site (M2 site, x=0.4637,0,0; occ.=0.119) inside a Ti octahedron; Ti atoms occupy a split position. Ti{sub 6}Ni{sub 16.7}Si{sub 7} represents a new variant of the filled Th{sub 6}Mn{sub 23} type structure. Ab initio calculations confirm the structural difference: additional Ni atoms favour the 24e site for Ti{sub 6}Ni{sub 16.7}Si{sub 7}, however, for the Zr and Hf-based compounds the unoccupied site renders an energetically lower ground state. Enthalpies of formation of Ti{sub 6}Ni{sub 17}Si{sub 7}, Zr{sub 6}Ni{sub 16}Si{sub 7}, and Hf{sub 6}Ni{sub 16}Si{sub 7} were calculated to be -68.65, -74.78, and -78.59kJ/(mol of atoms), respectively.

  8. Properties of CaLa4(Zr0.05Ti0.95)4O15 thin films by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hsu, Cheng-Hsing; Liu, Jen-Chieh; Tseng, Ching-Fang; Hsieh, Wan-Yu; Yang, Yu-Han; Chou, Po-Heng; Chang, Chia-Hsien

    2017-01-01

    CaLa4(Zr0.05Ti0.95)4O15 thin films deposited on n-type Si(100) substrates at different substrate temperatures and radio-frequency (RF) powers were investigated. The structural and morphological characteristics analyzed by X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were found to be affected by substrate temperature (150-300 °C) and RF power (200-300 W). Highly oriented CaLa4(Zr0.05Ti0.95)4O15 (110) perpendicular to the substrate surface was identified for all of the deposition conditions. The XRD showed that the deposited films exhibited a polycrystalline microstructure. As the RF power and substrate temperature increased, the quality of the CaLa4(Zr0.05Ti0.95)4O15 thin films improved, and the kinetic energies of the sputtered atoms increased, resulting in a structural improvement of the deposited CaLa4(Zr0.05Ti0.95)4O15 thin films. The optimum conditions for the growth of CaLa4(Zr0.05Ti0.95)4O15 thin films in this study were a RF power of 300 W and substrate temperature of 300 °C. A high dielectric constant of 46.2 (f = 1 MHz), dissipation factor of 0.049 (f = 1 MHz) and a low leakage current density of 7.3 × 10-7 A/cm2 in an electrical field of 100 kV/cm were obtained for the prepared films.

  9. Lead-Free Piezoelectric (Ba,Ca)(Zr,Ti)O3 Thin Films for Biocompatible and Flexible Devices.

    PubMed

    Scarisoreanu, N D; Craciun, F; Ion, V; Birjega, R; Bercea, A; Dinca, V; Dinescu, M; Sima, L E; Icriverzi, M; Roseanu, A; Gruionu, L; Gruionu, G

    2017-01-11

    In this work, we report the synthesis of functional biocompatible piezoelectric (1 - x)Ba(Ti0.8Zr0.2)TiO3-x(Ba0.7Ca0.3)TiO3, x = 0.45 (BCZT45), thin films with high piezoelectric properties. Pulsed-laser-based techniques, classical pulsed-laser deposition and matrix-assisted pulsed-laser evaporation, were used to synthesize the BCZT45 thin films. The second technique was employed in order to ensure growth on polymer flexible Kapton substrates. The BCZT45 thin films grown by both techniques show similar structural properties and high piezoelectric coefficient coupling between the mechanical loading and electrical potential. While it has long been shown that the electrical potential favors biological processes like osteogenesis, the assessment of cell adhesion and osteogenic differentiation onto BCZT materials has not yet been demonstrated. We prove here for the first time that BCZT 45 coatings on Kapton polymer substrates provide optimal support for osteogenic differentiation of mesenchymal stem cells in the bone marrow.

  10. Effect of Pore Structure Regulation on the Properties of Porous TiNbZr Shape Memory Alloys for Biomedical Application

    NASA Astrophysics Data System (ADS)

    Lai, Ming; Gao, Yan; Yuan, Bin; Zhu, Min

    2015-01-01

    Recently, porous Ti-Nb-based shape memory alloys have been considered as promising implants for biomedical application, because of their non-toxic elements, low elastic modulus, and stable superelasticity. However, the inverse relationship between pore characteristics and superelasticity of porous SMAs will strongly affect their clinical application. Until now, there have been few works specifically focusing on the effect of pore structure on the mechanical properties and superelasticity of porous Ti-Nb-based SMAs. In this study, the pore structure, including porosity and pore size, of porous Ti-22Nb-6Zr alloys was successfully regulated by adjusting the amount and size of space-holder particles. XRD and SEM investigation showed that all these porous alloys had homogeneous composition. Compression tests indicated that porosity played an important role in the mechanical properties and superelasticity of these porous alloys. Those alloys with porosity in the range of 38.5%-49.7% exhibited mechanical properties approaching to cortical bones, with elastic modulus, compressive strength, and recoverable strain in the range of 7.2-11.4 GPa, 188-422 MPa, and 2.4%-2.6%, respectively. Under the same porosity, the alloys with larger pores exhibited lower elastic modulus, while the alloys with smaller pores presented higher compressive strength.

  11. Tribological properties of Zr61Ti2Cu25Al12 bulk metallic glass under simulated physiological conditions.

    PubMed

    Wang, Yu; Shi, Ling-ling; Duan, De-li; Li, Shu; Xu, Jian

    2014-04-01

    In this work, wear resistance of a Zr61Ti2Cu25Al12 (ZT1) bulk metallic glass (BMG) in dry-sliding and simulated physiological media was investigated using ball-on-flat tribological approach and Si3N4 ball as counterpart. It was indicated that wear resistance of the BMG in air and deionized water is superior to Ti6Al4V alloy but inferior to 316L stainless steel (316L SS) and Co28Cr6Mo (CoCrMo) alloy. However, under simulated physiological media such as phosphate buffered solution (PBS) and Dulbecco's modified Eagle medium with 10vol.% fetal bovine serum (DMEM+FBS), the ZT1 BMG exhibits decreased wear resistance in comparison with the Ti6Al4V, 316L SS and CoCrMo. This is probably associated with its moderate pitting corrosion resistance in the medium containing chloride ions. The presence of protein in the solution has a significant effect to ruin pitting resistance of the BMG, then causing more severe wear damage. Under the dry-wear condition, abrasive wear is a predominant wear mechanism for the ZT1, whereas under deionized water, deterioration induced by abrasive wear can be mitigated. In simulated physiological media, wear deterioration is a typical tribocorrosion controlled by synergistic effects of the abrasive and corrosive wear. For the four investigated metals, wear resistance does not exhibit distinct correlation with hardness, whereas the material with high Young's modulus possesses better wear resistance.

  12. Enhancement of the Electrical Properties in BaTiO3/PbZr0.52Ti0.48O3 Ferroelectric Superlattices.

    PubMed

    He, Bin; Wang, Zhanjie

    2016-03-01

    In this study, BaTiO3/Pb(Zr0.52Ti0.48)O3 (BTO/PZT) ferroelectric superlattices have been grown on the Nb-doped SrTiO3 (NSTO) single-crystal substrate by pulsed laser deposition, and their electrical properties were investigated in detail. The leakage current was reduced significantly in the BTO/PZT superlattices, and the conduction mechanism could be interpreted as the bulk-limited mechanism. In addition, a more symmetric hysteresis loop was observed in the BTO/PZT superlattices compared with the pure PZT and BTO films. The BTO/PZT superlattices with the modulation thickness of 9.8 nm showed remarkably improved dielectric properties with dielectric constant and loss of 684 and 0.02, respectively, measured at the frequency of 10 kHz. Based on these experimental results, it can be considered that the BTO/PZT interfaces play a very important role for the enhanced electrical properties of the BTO/PZT superlattices.

  13. Enhanced mechanical properties and in vitro corrosion behavior of amorphous and devitrified Ti40Zr10Cu38Pd12 metallic glass.

    PubMed

    Fornell, J; Van Steenberge, N; Varea, A; Rossinyol, E; Pellicer, E; Suriñach, S; Baró, M D; Sort, J

    2011-11-01

    The effects of annealing treatments on the microstructure, elastic/mechanical properties, wear resistance and corrosion behavior of rod-shaped Ti40Zr10Cu38Pd12 bulk glassy alloys, synthesized by copper mold casting, are investigated. Formation of ultrafine crystals embedded in an amorphous matrix is observed for intermediate annealing temperatures, whereas a fully crystalline microstructure develops after heating to sufficiently high temperatures. The glassy alloy exhibits large hardness, relatively low Young's modulus, good wear resistance and excellent corrosion behavior. Nanoindentation measurements reveal that the sample annealed in the supercooled liquid region exhibits a hardness value of 9.4 GPa, which is 20% larger than in the completely amorphous state and much larger than the hardness of commercial Ti-6Al-4V alloy. The Young's modulus of the as-cast alloy (around 100 GPa, as determined from acoustic measurements) increases only slightly during partial devitrification. Finally, the anticorrosion performance of the Ti40Zr10Cu38Pd12 alloy in Hank's solution has been shown to ameliorate as crystallization proceeds and is roughly as good as in the commercial Ti-6Al-4V alloy. The outstanding mechanical and corrosion properties of the Ti40Zr10Cu38Pd12 alloy, both in amorphous and crystalline states, are appealing for its use in biomedical applications.

  14. Comparison of bio-mineralization behavior of Ti-6Al-4V-1Nb and Zr-1Nb nano-tubes formed by anodization

    NASA Astrophysics Data System (ADS)

    Choi, Yong; Hong, Sun I.

    2014-12-01

    Nano-tubes of titanium and zirconium alloys like Ti-6Al-4V-1Nb and Zr-1Nb were prepared by anodization followed by coating with hydroxylapatite (HA) and their bio-mineralization behaviors were compared to develop a bio-compatible material for implants in orthopedics, dentistry and cardiology. Ti-6Al-4V-1Nb weight gain in a simulated body solution increased gradually. The bigger tube diameter was, the heavier HA was deposited. Surface roughness of both alloys increased highly with the increasing diameter of nano-tube. Their surface roughness decreased by HA deposition due to the removal of the empty space of the nano-tubes. Zr-1Nb alloy had faster growth of nano-tubes layers more than Ti-6Al-4V-1Nb alloy.

  15. The effect of the solute on the structure, selected mechanical properties, and biocompatibility of Ti-Zr system alloys for dental applications.

    PubMed

    Correa, D R N; Vicente, F B; Donato, T A G; Arana-Chavez, V E; Buzalaf, M A R; Grandini, C R

    2014-01-01

    New titanium alloys have been developed with the aim of utilizing materials with better properties for application as biomaterials, and Ti-Zr system alloys are among the more promising of these. In this paper, the influence of zirconium concentrations on the structure, microstructure, and selected mechanical properties of Ti-Zr alloys is analyzed. After melting and swaging, the samples were characterized through chemical analysis, density measurements, X-ray diffraction, optical microscopy, Vickers microhardness, and elasticity modulus. In-vitro cytotoxicity tests were performed on cultured osteogenic cells. The results showed the formation essentially of the α' phase (with hcp structure) and microhardness values greater than cp-Ti. The elasticity modulus of the alloys was sensitive to the zirconium concentrations while remaining within the range of values of conventional titanium alloys. The alloys presented no cytotoxic effects on osteoblastic cells in the studied conditions.

  16. AC Hopping Conductance in Nanocomposite Films with Ferromagnetic Alloy Nanoparticles in a PbZrTiO3 Matrix

    NASA Astrophysics Data System (ADS)

    Koltunowicz, T. N.; Zukowski, P.; Boiko, O.; Saad, A.; Fedotova, J. A.; Fedotov, A. K.; Larkin, A. V.; Kasiuk, J.

    2015-07-01

    In this work, the temperature and frequency dependences of the real part of the admittance [ σ( f, T)] of annealed nanocomposite films containing Co45 Fe45Zr10-based nanoparticles covered with native oxides and embedded in a doped PbZrTiO3 ferroelectric matrix were studied. The nanocomposites studied were deposited by ion sputtering a complex target in a mixed Ar/O2 atmosphere followed by a 15-min annealing process (with steps of 25 K) in air in the temperature range of 398 K ≤ T a ≤ 573 K. The σ( f, T) of the annealed samples was measured in the temperature range of 77 K < T p < 373 K at frequencies of 50 Hz < f < 1 MHz. The observed σ( f, T) dependences confirmed that the annealed samples displayed the effects of negative capacitance over the whole frequency and temperature ranges studied because of the pronounced oxidation of the nanoparticles. The σ( f, T) dependences obtained are described using an earlier-developed AC hopping conductance model. Comparisons between experimental and simulation results allow the model parameters to be estimated, such as the activation energies of the hopping conductance and the lifetimes of the electrons in the nanoparticles.

  17. Ab initio calculations of SrTiO3, BaTiO3, PbTiO3, CaTiO3, SrZrO3, PbZrO3 and BaZrO3 (001), (011) and (111) surfaces as well as F centers, polarons, KTN solid solutions and Nb impurities therein

    NASA Astrophysics Data System (ADS)

    Eglitis, R. I.

    2014-03-01

    In this paper, the review of recent results of calculations of surface relaxations, energetics, and bonding properties for ABO3 perovskite (001), (011) and (111) surfaces using mostly a hybrid description of exchange and correlation is presented. Both AO and BO2-terminations of the nonpolar (001) surface and A, BO, and O terminations of the polar (011) surface, as well as B and AO3-terminations of the polar (111) surface were considered. On the AO-terminated (001) surface, all upper-layer A atoms relax inwards, while all second layer atoms relax outwards. For the BO2-terminated (001) surface, in most cases, the largest relaxations are on the second-layer metal atoms. For almost all ABO3 perovskites, the surface rumpling is much larger for the AO-terminated than for the BO2-terminated (001) surface, but their surface energies are always quite similar. In contrast, different terminations of the (011) ABO3 surface lead to very different surface energies for the O-terminated, A-terminated, and BO-terminated (011) surface, respectively. A considerable increase in the Ti-O or Zr-O, respectively, chemical bond covalency near the (011) surface as compared both to the bulk and to the (001) surface in ABO3 perovskites were predicted. According to the results of ab initio calculations for Nb doped SrTiO3, Nb is a shallow donor; six nearest O ions are slightly displaced outwards from the Nb ion. The F center in ABO3 perovskites resembles electron defects in the partially-covalent SiO2 crystal rather than usual F centers in ionic crystals like MgO and alkali halides. The results of calculations for several perovskite KNbxTa1-xO3 (KTN) solid solutions, as well as hole and electron polarons in ABO3 perovskites are analyzed.

  18. Negligible substrate clamping effect on piezoelectric response in (111)-epitaxial tetragonal Pb(Zr, Ti)O{sub 3} films

    SciTech Connect

    Yamada, Tomoaki; Yasumoto, Jun; Ito, Daisuke; Yoshino, Masahito; Nagasaki, Takanori; Sakata, Osami; Imai, Yasuhiko; Kiguchi, Takanori; Shiraishi, Takahisa; Shimizu, Takao; Funakubo, Hiroshi

    2015-08-21

    The converse piezoelectric responses of (111)- and (001)-epitaxial tetragonal Pb(Zr{sub 0.35}Ti{sub 0.65})O{sub 3} [PZT] films were compared to investigate the orientation dependence of the substrate clamping effect. Synchrotron X-ray diffraction (XRD) and piezoelectric force microscopy revealed that the as-grown (111)-PZT film has a polydomain structure with normal twin boundaries that are changed by the poling process to inclined boundaries, as predicted by Romanov et al. [Phys. Status Solidi A 172, 225 (1999)]. Time-resolved synchrotron XRD under bias voltage showed the negligible impact of substrate clamping on the piezoelectric response in the (111)-PZT film, unlike the case for (001)-PZT film. The origin of the negligible clamping effect in the (111)-PZT film is discussed from the viewpoint of the elastic properties and the compensation of lattice distortion between neighboring domains.

  19. Photo-induced and electrooptic properties of (Pb,La)(Zr,Ti) O{sub 3} films for optical memories

    SciTech Connect

    Dimos, D.; Potter, B.G.; Sinclair, M.B.; Tuttle, B.A.; Warren, W.L.

    1993-09-01

    Photo-induced hysteresis changes and electrooptic effects in sol-gel Pb(Zr,Ti)0{sub 3} (PZT) and PLZT films have been studied in an effort to evaluate these materials for optical memory applications. The films exhibit two types of photo-induced changes in their hysteresis behavior which are suitable for optical storage. Both types of photo-induced hysteresis changes are due to trapping of photo-generated charge carriers at sites which minimize internal depolarizing fields. The photo-induced changes are reproducible and stable, which indicates that the charge traps are stable. However, improvements in photosensitivity will be required to develop a competitive technology for optical memories. In addition, polarization-dependent changes in the refractive indices can be the basis of a nondestructive optical readout technique. The index changes of films have been determined using a waveguide refractometry technique, which allows the extraordinary and ordinary index changes to be obtained independently.

  20. Zr and Sn substituted (Na0.5Bi0.5)TiO3 -based solid solutions

    NASA Astrophysics Data System (ADS)

    Ishchuk, V. M.; Gusakova, L. G.; Kisel, N. G.; Kuzenko, D. V.; Spiridonov, N. A.; Sobolev, V. L.

    2016-02-01

    The paper attempts to investigate the phase formation of a Zr- and Sn-substituted [(Na0.5Bi0.5)0.80Ba0.20](Ti1-yBy)O3 system during its solid state synthesis. The synthesis was found to be a multi-step process associated with the formation of a number of intermediate phases which however depended on the compositions and sintering temperatures. Single phase solid solutions were obtained when the sintering temperature was increased to 1000 °C-1100 °C. Increase in the concentration of substituting ions, on the one hand, tends to linearly increase the crystal cell size whereas the tolerance factor, on the other hand, gets reduced bolstering the stability of anti-ferroelectric phase as compared to that of ferroelectric phase’.

  1. Effect of electron count and chemical complexity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor.

    PubMed

    von Rohr, Fabian; Winiarski, Michał J; Tao, Jing; Klimczuk, Tomasz; Cava, Robert Joseph

    2016-11-15

    High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered body-centered cubic (BCC) Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials; e.g., it has a well-defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence electron count dependence of the superconducting transition temperature in the high-entropy alloy falls between those of analogous simple solid solutions and amorphous materials and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellent intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.

  2. Effect of electron count and chemical complexity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor

    NASA Astrophysics Data System (ADS)

    von Rohr, Fabian; Winiarski, Michał J.; Tao, Jing; Klimczuk, Tomasz; Cava, Robert Joseph

    2016-11-01

    High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered body-centered cubic (BCC) Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials; e.g., it has a well-defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence electron count dependence of the superconducting transition temperature in the high-entropy alloy falls between those of analogous simple solid solutions and amorphous materials and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellent intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.

  3. Photo-induced and electrooptic properties of (Pb,La)(Zr,Ti)O3 films for optical memories

    NASA Astrophysics Data System (ADS)

    Dimos, D.; Potter, B. G.; Sinclair, M. B.; Tuttle, B. A.; Warren, W. L.

    Photo-induced hysteresis changes and electro-optic effects in sol-gel Pb(Zr,Ti)03 (PZT) and PLZT films have been studied in an effort to evaluate these materials for optical memory applications. The films exhibit two types of photo-induced changes in their hysteresis behavior which are suitable for optical storage. Both types of photo-induced hysteresis changes are due to trapping of photo-generated charge carriers at sites which minimize internal depolarizing fields. The photo-induced changes are reproducible and stable, which indicates that the charge traps are stable. However, improvements in photosensitivity will be required to develop a competitive technology for optical memories. In addition, polarization-dependent changes in the refractive indices can be the basis of a nondestructive optical readout technique. The index changes of films have been determined using a waveguide refractometry technique, which allows the extraordinary and ordinary index changes to be obtained independently.

  4. Field induced phase transitions and energy harvesting performance of (Pb,La)(Zr,Sn,Ti)O3 single crystal

    NASA Astrophysics Data System (ADS)

    Zhuo, Fangping; Li, Qiang; Li, Yuanyuan; Gao, Jinghan; Yan, Qingfeng; Zhang, Yiling; Xi, Xiaoqing; Chu, Xiangcheng; Cao, Wenwu

    2017-02-01

    (Pb,La)(Zr,Sn,Ti)O3 (PLZST) single crystals with composition close to the morphotropic phase boundary had been grown by the flux method. The antiferroelectric-ferroelectric phase switching electric field was 0.8 kV/mm. Temperature-dependent dielectric and polarization versus electric field hysteresis loops revealed that the electric field induced ferroelectric phase could transform back into the antiferroelectric phase at depolarization temperature (145 °C). An enhanced pyroelectric coefficient value of 1.46 μC/cm2/K was obtained at 145 °C, which is several times larger than that of conventional pyroelectric materials. Furthermore, multiple peak pyroelectric responses and an enhanced harvested energy density value of 0.4 J/cm3 were achieved in the PLZST crystal. The enhanced harvested energy density and multiple peak pyroelectric responses make the PLZST crystal a promising candidate for high sensitive temperature sensors and energy conversion technologies.

  5. 18O tracer diffusion in Pb(Zr,Ti)O3 thin films: A probe of local oxygen vacancy concentration

    NASA Astrophysics Data System (ADS)

    Wang, Ruey-Ven; McIntyre, Paul C.

    2005-01-01

    A series of O18 tracer in-diffusion experiments have been conducted on state-of-the-art metal organic chemical vapor deposition-grown Pb(Zr ,Ti)O3 (PZT) films. Prior to O18 incorporation, samples were preequilibrated in O216 at the same temperature and total pressure used for the following O218 isotope exchange anneal. The final O18 depth profiles were obtained using secondary ion mass spectroscopy (SIMS), which provides a depth resolution of 3-5Å. The SIMS results indicate that the O18 tracer diffusivity varies as a function of depth from the PZT film surface in a way that is inconsistent with a combined grain boundary and lattice diffusion mechanism. Based on a previously-developed model for point defect equilibrium in metal titanate thin films, simulations of O18 tracer diffusion into PZT thin films that are consistent with the experimental results are described.

  6. Stability of the unswitched ferroelectric polarization state in ultrathin epitaxial Pb(Zr,Ti)O3 in large electric fields

    SciTech Connect

    Grigoriev, Alexei; Sichel, Rebecca; Jo, Ji Young; Choudhury, Samrat; Chen, L. Q.; Lee, Ho Nyung; Landahl, Eric C.; Adams, Bernhard; Dufresne, Eric M.; Evans, Paul G.

    2009-01-01

    A series of 50 ns-duration electric field pulses switches the polarization of a 35 nm-thick ferroelectric Pb(Zr,Ti)O3 film only at electric fields greater than 1.5 MV/cm, a factor of three higher than the low-frequency coercive field. There is no switching in response to a large number of pulses with lower fields, even when the total duration reaches several milliseconds. During longer microsecond-duration electric fields, however, switching progresses monotonically in both x-ray microdiffraction images and in electrical measurements. The difference between long and short electric field durations arises from domain nucleation and charge transport. A phase field model shows that the shrinking of the switched domain in the interval between pulses is a less important effect.

  7. Vibrational micro-energy harvesters utilizing Nb-doped Pb(Zr,Ti)O3 films on stainless steel substrates

    NASA Astrophysics Data System (ADS)

    Van Minh, L.; Sano, T.; Fujii, T.; Kuwano, H.

    2016-11-01

    This work presents the micromachined energy harvesters using Nb-doped Pb(Zr,Ti)O3 (PNZT) films grown directly on the stainless steel substrates (SUS430). Piezoelectric materials on metallic substrates have been attracted to practical and robust energy harvesters. Nb-doped PZT films with (001)-preferred orientation grown on SUS substrates provided excellent properties for energy harvesting - high piezoelectric coefficient (e 31 = -10.6 C/m2) and low dielectric permittivity (ɛr = 373). The PNZT-based micro-energy harvester comprising a cantilever of 1.7 mm× 5 mm × 0.05 mm and a proof mass of 3 mm× 5 mm × 47 mm achieved the normalized power density (NPD) of 2.87 mW.g-2.cm-3. It is the highest performance among the published SUS-based energy harvesters, being closer to the best Si- based energy harvesters.

  8. Equilateral triangular ferroelectric closure domains in (111)-oriented epitaxial Pb(Zr,Ti)O3 thin films

    NASA Astrophysics Data System (ADS)

    Yang, Sang Mo; Shin, Y. J.; Noh, T. W.; Ehara, Y.; Funakubo, H.; Yoon, J.-G.; Scott, J. F.

    2013-03-01

    Over 60 years ago, Charles Kittel predicted that intriguing quadrant flux-closure domains could spontaneously form in small ferromagnetic platelets. Such quadrant flux-closure domains are considered as a precursor for the true vortex states, having attracted particular interest for storing memory devices. Although the vortex states are now ubiquitous and rather well understood in ferromagnets, even the flux-closure domains as their precursors are much less established in ferroelectrics (FEs). Here we report the generation of novel equilateral triangular FE closure domains. We generated such intriguing states by using the high crystalline anisotropy energy of a (111)-oriented epitaxial PbZr0.35Ti0.65O3 thin film. Vector piezoresponse force microscopy analysis showed clearly the equilateral triangular closure states, consisting of three stripe domain bundles with three 120 degree orientation differences. Interestingly, the observed two closure states had the different rotation direction around the core, i.e., clockwise and anti-clockwise.

  9. Indium and gallium diffusion through zirconia in the TiN/ZrO{sub 2}/InGaAs stack

    SciTech Connect

    Ceballos-Sanchez, O.; Martinez, E.; Guedj, C.; Veillerot, M.; Herrera-Gomez, A.

    2015-06-01

    Angle-resolved X-ray Photoelectron Spectroscopy (ARXPS) was applied to the TiN/ZrO{sub 2}/InGaAs stack to assess its thermal stability. Through a robust ARXPS analysis, it was possible to observe subtle effects such as the thermally induced diffusion of substrate atomic species (In and Ga) through the dielectric layer. The detailed characterization of the film structure allowed for assessing the depth profiles of the diffused atomic species by means of the scenarios-method. Since the quantification for the amount of diffused material was done at different temperatures, it was possible to obtain an approximate value of the activation energy for the diffusion of indium through zirconia. The result is very similar to the previously reported values for indium diffusion through alumina and through hafnia.

  10. Negligible substrate clamping effect on piezoelectric response in (111)-epitaxial tetragonal Pb(Zr, Ti)O3 films

    NASA Astrophysics Data System (ADS)

    Yamada, Tomoaki; Yasumoto, Jun; Ito, Daisuke; Sakata, Osami; Imai, Yasuhiko; Kiguchi, Takanori; Shiraishi, Takahisa; Shimizu, Takao; Funakubo, Hiroshi; Yoshino, Masahito; Nagasaki, Takanori

    2015-08-01

    The converse piezoelectric responses of (111)- and (001)-epitaxial tetragonal Pb(Zr0.35Ti0.65)O3 [PZT] films were compared to investigate the orientation dependence of the substrate clamping effect. Synchrotron X-ray diffraction (XRD) and piezoelectric force microscopy revealed that the as-grown (111)-PZT film has a polydomain structure with normal twin boundaries that are changed by the poling process to inclined boundaries, as predicted by Romanov et al. [Phys. Status Solidi A 172, 225 (1999)]. Time-resolved synchrotron XRD under bias voltage showed the negligible impact of substrate clamping on the piezoelectric response in the (111)-PZT film, unlike the case for (001)-PZT film. The origin of the negligible clamping effect in the (111)-PZT film is discussed from the viewpoint of the elastic properties and the compensation of lattice distortion between neighboring domains.

  11. Effect of electron count and chemical complexity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor

    DOE PAGES

    von Rohr, Fabian; Winiarski, Michał J.; Tao, Jing; ...

    2016-11-01

    High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered body-centered cubic (BCC) Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials; e.g., it has a well-defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence electron count dependence of the superconducting transition temperature in the high-entropy alloy falls between those of analogous simple solid solutions and amorphous materials and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellentmore » intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.« less

  12. The effects of microstructure on the electrocaloric properties of Pb(Zr, Sn, Ti)O/sub 3/ ceramics

    SciTech Connect

    Tuttle, B.A.; Payne, D.A.

    1981-01-01

    When an electric field is applied to a dielectric material under adiabatic conditions there is a resultant change in temperature, a phenomenon known as the electrocaloric effect. Compositions in the Pb(Zr,Sn,Ti)O/sub 3/ system (PZST) have several phases of nearly equal free energy, allowing antiferroelectric (AFE) to ferroelectric (FE) and paraelectric (PE) to ferroelectric (FE) transitions to occur. Data are presented for electrocaloric measurements on AFE materials in the vicinity of the Curie point. The effect of microstructure is reported, and experimental values are related to dielectric properties through thermodynamic relations. Culmination of this work resulted in the largest electrocaloric effect (2.6/sup 0/K) measured to date for coarse grain material in the PZST system.

  13. Domain structures and piezoelectric properties of Pb(Zr0.2Ti0.8)O3 nanocapacitors

    NASA Astrophysics Data System (ADS)

    Han, Hee; Park, Yong Jun; Baik, Sunggi; Lee, Woo; Alexe, Marin; Hesse, Dietrich; Gösele, Ulrich

    2010-08-01

    Epitaxial ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT) nanoislands and nanocapacitors were fabricated by stencil mask-assisted pulsed laser deposition. By x-ray diffraction reciprocal space mapping it was observed that PZT nanoislands contain mainly c-domains and residual fractions of tilted and nontilted a-domains, while extended thin films contain only c-domains and tilted a-domains. The presence of nontilted a-domains manifests clearly that the misfit strain is significantly reduced in PZT nanoislands, compared to the thin film. Some of the a-domains turned out to be switchable under an external electric field due to the strain relaxation in the PZT nanocapacitors. The piezoresponse of PZT nanocapacitors was higher than that of continuous thin-film capacitors.

  14. Structure and mechanical properties of coatings fabricated by nonvacuum electron beam cladding of Ti-Ta-Zr powder mixtures

    SciTech Connect

    Samoylenko, Vitaliy V. Lenivtseva, Olga G. Polyakov, Igor A. Laptev, Ilya S.

    2015-10-27

    In this paper structural investigations and mechanical tests of Ti-Ta-Zr coatings obtained on surfaces of cp-titanium workpieces were carried out. It was found that the coatings had a dendrite structure; investigations at high-power magnifications revealed a platelet structure. An increase of tantalum concentration led to refinement of structural components. The microhardness level of all coatings, excepting a specimen with the maximum tantalum content, was 370 HV. The microhardness of this coating reached 400 HV. The ultimate tensile strength of cladded layers varied from 697 to 947 MPa. Adhesion tests showed that bimetallic composites were characterized by high bond strength of cladded layers to the substrate, which exceeded cp-titanium strength characteristics.

  15. Highly ordered Pb(Zr0.52Ti0.48)O3 piezoelectric nanorod arrays

    NASA Astrophysics Data System (ADS)

    Yang, Su Chul; Sanghadasa, Mohan; Priya, Shashank

    2013-06-01

    One-dimensional (1D) piezoelectric nanostructures have attracted significant attention for a broad range of applications including optoelectronics, thermoelectrics, electrochemical and electromechanical converters. We demonstrate the synthesis of 1D nanostructures based upon Pb(Zr0.52Ti0.48)O3 (PZT) on conductive substrates via sol-gel template synthesis. The vertically aligned PZT nanostructures with heights around one micron were synthesized by vacuum infiltration of sol-gel precursors into highly ordered cylindrical pores of anodized aluminum oxide templates. The 1D nanostructures were developed on large scale platinized silicon wafers and exhibited dense rod-like structure with a uniform diameter of 90 nm and an aspect ratio of 10. Scanning probe microscopy conducted on individual nanorods demonstrated good electromechanical properties with a high piezoelectric magnitude of 41 pm V-1. We believe that this study opens the possibility of developing high performance nanoscale piezoelectric sensors and transducers.

  16. Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb0.8Sn0.2 system via phase separation.

    PubMed

    Rausch, Elisabeth; Balke, Benjamin; Ouardi, Siham; Felser, Claudia

    2014-12-14

    A novel approach for optimization of the thermoelectric properties of p-type Heusler compounds with a C1b structure was investigated. A successful recipe for achieving intrinsic phase separation in the n-type material based on the TiNiSn system is isoelectronic partial substitution of Ti with its heavier homologues Zr and Hf. We applied this concept to the p-type system MCoSb0.8Sn0.2 by a systematic investigation of samples with different compositions at the Ti position (M = Ti, Zr, Hf, Ti0.5Zr0.5, Zr0.5Hf0.5, and Ti0.5Hf0.5). We thus achieved an approximately 40% reduction of the thermal conductivity and a maximum figure of merit ZT of 0.9 at 700 °C. This is a 80% improvement in peak ZT from 0.5 to 0.9 at 700 °C compared to the best published value of an ingot p-type half-Heusler compound. Thus far, comparable good thermoelectric p-type materials of this structure type have only been realized by a nanostructuring process via ball milling of premelted ingot samples followed by a rapid consolidation method, like hot pressing. The herein-presented simple arc-melting fabrication method reduces the fabrication time as compared to this multi-step nanostructuring process. The high mechanical stability of the Heusler compounds is favorable for the construction of thermoelectric modules. The Vickers hardness values are close to those of the n-type material, leading to good co-processability of both materials.

  17. Synthesis of novel ZrO2&GO@TiO2 nanocomposite as an efficient photoanode in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Mohamed, Ibrahim M. A.; Dao, Van-Duong; Yasin, Ahmed S.; Yassin, Mohamed A.; Barakat, Nasser A. M.; Choi, Ho-Suk

    2017-02-01

    Due to the physicochemical and photo-electro properties, TiO2 nanostructures still being the outstanding photoanode materials in the dye-sensitized solar cells (DSCs). However, it is well known that a low dye-loading and charge recombination constrain the limitation of large-scale application. This work introduces the synthesis of ZrO2&GO@TiO2 nanofibers (NFs) by facile two steps using electrospinning and hydrothermal treatment. Furthermore, the developed materials are applied as an efficient photoanode of DSCs. The synthesized NFs are described in terms of morphology, crystallography and chemistry via FESEM, TEM, XRD, Raman spectra and EDX analysis. As the results, the Ti, Zr, O and C elements are uniformly distributed in the synthesized sample. The percentages of the atomic elements are 10.77, 57.69, 1.45 and 30.09 for C, O, Zr and Ti, respectively. The synthesized composite shows only anatase with crystal size of 25.86 nm and cell volume of 142.39 Å3. The developed material is employed as working electrode of DSCs. The J-V characteristic showed 5.09% efficiency for device using the synthesized material, which is higher than those of cells assembled with TiO2 NFs and ZrO2@TiO2 NFs photoanodes. The obtained result is explained by enhanced dye-loading (1.055 × 1017 molecule/cm2) and improved charge transfer resistance (Rct = 9.18 Ω) of the photoanode substrate. Hence, the presented nanocomposite can be an efficient photoanode towards technology of DSC.

  18. Microstructure and mechanical properties investigation of in situ TiB2 and ZrB2 reinforced Al-4Cu composites

    NASA Astrophysics Data System (ADS)

    Lutfi Anis, Ahmad; Ramli, Rosmamuhammadani; Darham, Widyani; Zakaria, Azlan; Talari, Mahesh Kumar

    2016-02-01

    Conventional Al-Cu alloys exhibit coarse grain structure leading to inferior mechanical properties in as-cast condition. Expensive thermo-mechanical treatments are needed to improve microstructure and corresponding mechanical properties. In situ Al-based composites were developed to improve mechanical properties by dispersion strengthening and grain refinement obtained by the presence of particulates in the melt during solidification. In this work Al-4Cu - 3TiB2 and Al-4Cu-3ZrB2 in situ composites were prepared by liquid casting method. XRD, electron microscopy and mechanical tests were performed on suitably sectioned and metallographically prepared surfaces to investigate the phase distribution, hardness and tensile properties. It was found that the reinforcement particles were segregated along the grain boundaries of Al dendrites. Tensile fracture morphology for both Al-4Cu - 3TiB2 and Al-4Cu-3ZrB2 were analyzed and compared to determine the fracture propagation mechanism in the composites. Al-4Cu-3ZrB2 in situ composites displayed higher strength and hardness compared to Al-4Cu-3TiB2 which could be ascribed to the stronger interfacial bonding between the Al dendrites and ZrB2 particulates as evidenced from fractographs.

  19. Porous TiO2-ZrO2 thin film formed by electrochemical technique to improve the biocompatibility of titanium alloy in physiological environment

    NASA Astrophysics Data System (ADS)

    Benea, L.; Dănăilă, E.; Ponthiaux, P.

    2017-02-01

    Porous Ti and Ti alloys have received increasing research interest for bone tissue engineering, especially for dental and orthopaedic implants because they provide cell ingrowths and vascularization, improving of adhesion and osseointegration. The tribocorrosion process is encountered in orthopaedic and dentistry applications, since it is known that the implants are often exposed to simultaneous chemical/electrochemical and mechanical stresses. The purpose of this study was to carry out a systematic investigation of the tribo-electrochemical performance of porous TiO2–ZrO2 thin film formed by anodization of Ti–10Zr alloy surface in an artificial saliva solution and to compare the resulted performance with that of the untreated Ti–10Zr alloy surface in order to be applied for biomedical use. The in situ electrochemical technique used for investigation of tribo-electrochemical degradation was the open circuit potential (OCP) measurement performed before, during and after sliding tests. The results presented herein show that controlled anodic oxidation method can significantly improve the tribocorrosion and friction performances of Ti–10Zr alloy surface intended for biomedical applications.

  20. Determination of Ti, Zr, Nb, V, W and Mo in seawater by a new online-preconcentration method and subsequent ICP-MS analysis

    NASA Astrophysics Data System (ADS)

    Poehle, Sandra; Schmidt, Katja; Koschinsky, Andrea

    2015-04-01

    We present a new method for the determination of Ti, Zr, Nb, V, W and Mo in seawater by adapting the online-preconcentration procedure with the system SeaFAST and subsequent analysis by ICP-MS to these metals. The trace elements Ti, Zr, Nb and W are present in seawater in ultratrace concentrations in the range of pmol kg-1, whereas Mo and V, which are biologically essential elements, are present in the concentration range of nmol kg-1. The online-preconcentration system we used consists of an autosampler, a sample loop, a preconcentration column and two valves controlling the sample loop and the preconcentration processes. The pre-packed preconcentration column contains a chelating resin with two functional groups, ethylenediamine triacetic acid (EDTriA) and iminodiacetic acid (IDA), immobilized on a polymer backbone. The preconcentration process was optimized for loading the sample and subsequent rinsing to remove residues of seawater matrix prior to elution with the optimized elution acid (0.5 M HNO3-0.002 M HF). We used acidified North Sea seawater (0.02 M HCl-0.002 M HF) for the method development. Samples and calibration standards were loaded onto the preconcentration column and after elution directly transferred to the quadrupole ICP-MS and measured immediately. Best results were achieved with matrix-matched calibration standards (0.6 M NaCl-0.02 M HCl-0.002 M HF) simulating acidified seawater samples. Titanium, Zr, Nb and W are measured simultaneously in one run, whereas V and Mo are determined simultaneously in a separate run. Low procedure blanks were calculated for Ti, Zr, Nb, W (635, 14.5, 1.35, 10.2 pmol kg-1) and for V and Mo, 9.79 and 5.61 nmol kg-1, respectively. Very good spike recoveries achieved with spiked North Sea water demonstrate the applicability for all six elements. Analysis of the seawater standard NASS-6 gave recoveries of 97-99% (0.9-2.2% standard deviation, SD) for Mo and V. We also provide Zr, Nb and W data for this reference standard

  1. Structural characterization of CeO(2)-ZrO(2)/TiO(2) and V(2)O(5)/CeO(2)-ZrO(2)/TiO(2) mixed oxide catalysts by XRD, Raman spectroscopy, HREM, and other techniques.

    PubMed

    Reddy, Benjaram M; Lakshmanan, Pandian; Khan, Ataullah; López-Cartes, Carlos; Rojas, Teresa C; Fernandez, Asunción

    2005-02-10

    Structural characteristics of CeO(2)-ZrO(2)/TiO(2) (CZ/T) and V(2)O(5)/CeO(2)-ZrO(2)/TiO(2) (V/CZ/T) mixed oxide catalysts have been investigated using X-ray diffraction (XRD), BET surface area, Raman spectroscopy (RS), and high-resolution transmission electron microscopy (HREM) techniques. The CeO(2)-ZrO(2) (1:1 mole ratio) solid solution was deposited over a finely powdered TiO(2) support by a deposition precipitation method. A nominal 5 wt % V(2)O(5) was impregnated over the calcined (773 K) CZ/T mixed oxide carrier by a wet impregnation technique. The obtained CZ/T and V/CZ/T samples were further subjected to thermal treatments from 773 to 1073 K to understand the dispersion and temperature stability of these materials. In the case of CZ/T samples, the XRD results suggest the formation of different cubic and tetragonal Ce-Zr-oxide phases, Ce(0.75)Zr(0.25)O(2), Ce(0.6)Zr(0.4)O(2), Ce(0.5)Zr(0.5)O(2), and Ce(0.16)Zr(0.84)O(2) in varying proportions depending on the treatment temperature. With increasing calcination temperature from 773 to 1073 K, the intensity of the lines pertaining to cubic Ce(0.6)Zr(0.4)O(2) and Ce(0.5)Zr(0.5)O(2) phases increased at the expense of cubic Ce(0.75)Zr(0.25)O(2), indicating more incorporation of zirconia into the ceria lattice. The TiO(2) was mainly in the anatase form whose crystallite size also increased with increasing treatment temperature. A better crystallization and more incorporation of zirconia into the ceria lattice was noted when CZ/T was impregnated with V(2)O(5). However, no crystalline V(2)O(5) could be seen from both XRD and RS measurements. In particular, a preferential formation of CeVO(4) compound and an intense tetragonal Ce(0.16)Zr(0.84)O(2) phase were noted beyond 873 K. The HREM results indicate, in the case of CZ/T samples, a well-dispersed Ce-Zr-oxide of the size approximately 5 nm over the bigger crystals ( approximately 40 nm) of TiO(2) when treated at 873 K. The exact structural features of these

  2. The Influence of ZrO2 Concentration in an Yttria-Based Face Coat for Investment Casting a Ti-45Al-2Mn-2Nb-0.2TiB Alloy Using a Sessile Drop Method

    NASA Astrophysics Data System (ADS)

    Cheng, Xu; Yuan, Chen; Blackburn, Stuart; Withey, Paul A.

    2015-03-01

    Investment casting is widely used to cast near-net shape components, reducing material waste and process cost. Due to the high reactivity of titanium and its alloys, in order to reduce the interaction between the mold and molten titanium, very costly materials are used in the mold face coat. In order to reduce the material cost while maintaining the chemical inertness of the face coat, ZrO2 was added into an yttria-based face coat in different concentrations in this study. The face coat properties of the different systems were analyzed using dilatometry and XRD. The chemical inertness of the different face coat systems were tested using a sessile drop test using a Ti-45Al-2Mn-2Nb-0.2TiB alloy, and the interactions between the face coat and the alloy were analyzed by the interfacial microstructures, contact angle, and hardness changes. The results showed that small amounts of ZrO2 can be added into yttria without changing the chemical inertness of the face coat. High amounts of ZrO2 in the face coat can interact with TiAl alloy to form different interaction products. Meanwhile, both Y2O3 and ZrO2 filler materials were observed to dissolve in molten TiAl during the sessile drop test.

  3. Processing, structure and tribological property relations of ternary Zn-Ti-O and quaternary Zn-Ti-Zr-O nanocrystalline coatings

    NASA Astrophysics Data System (ADS)

    Ageh, Victor

    Conventional liquid lubricants are faced with limitations under extreme cyclic operating conditions, such as in applications that require lubrication when changing from atmospheric pressure to ultrahigh vacuum and ambient air to dry nitrogen (e.g., satellite components), and room to elevated (>500°C) temperatures (e.g., aerospace bearings). Alternatively, solid lubricant coatings can be used in conditions where synthetic liquid lubricants and greases are not applicable; however, individual solid lubricant phases usually perform best only for a limited range of operating conditions. Therefore, solid lubricants that can adequately perform over a wider range of environmental conditions are needed, especially during thermal cycling with temperatures exceeding 500°C. One potential material class investigated in this dissertation is lubricious oxides, because unlike other solid lubricant coatings they are typically thermodynamically stable in air and at elevated temperatures. While past studies have been focused on binary metal oxide coatings, such as ZnO, there have been very few ternary oxide and no reported quaternary oxide investigations. The premise behind the addition of the third and fourth refractory metals Ti and Zr is to increase the number of hard and wear resistant phases while maintaining solid lubrication with ZnO. Therefore, the major focus of this dissertation is to investigate the processing-structuretribological property relations of composite ZnO, TiO2 and ZrO2 phases that form ternary (ZnTi)xOy and quaternary (ZnTiZr) xOy nanocrystalline coatings. The coatings were processed by atomic layer deposition (ALD) using a selective variation of ALD parameters. The growth structure and chemical composition of as-deposited and ex situ annealed ternary and quaternary oxide coatings were studied by combined x-ray diffraction/focused ion beam microscopy/cross-sectional transmission electron microscopy, and x-ray photoelectron spectroscopy/Auger electron

  4. Study on the mechanism of NH3-selective catalytic reduction over CuCexZr1-x/TiO2

    NASA Astrophysics Data System (ADS)

    Chen, Xujuan; Sun, Xiaoliang; Gong, Cairong; Lv, Gang; Song, Chonglin

    2016-06-01

    Copper-cerium-zirconium catalysts loaded on TiO2 prepared by a wet impregnation method were investigated for NH3-selective catalytic reduction (SCR) of NOx. The reaction mechanism was proposed on the basis of results from in situ diffuse reflectance infrared transform spectroscopy (DRIFT). When NH3 is introduced, ammonia bonded to Lewis acid sites is more stable over CuCe0.25Zr0.75/TiO2 at high temperature, while Brønsted acid sites are more important than Lewis acid sites at low temperature. For the NH3+NO+O2 co-adsorption, NH3 species occupy most of activity sites on CuCe0.25Zr0.75/TiO2 catalyst, and mainly exist in the forms of NH4 + (at low temperature) and NH3 coordinated (at high temperature), playing a crucial role in the NH3-SCR process. Two different reaction routes, the L-H mechanism at low temperature (< 200°C) and the E-R mechanism at high temperature (> 200°C), are presented for the SCR reaction over CuCe0.25Zr0.75/TiO2 catalyst.

  5. Ultraviolet-accelerated formation of bone-like apatite on oxidized Ti-24Nb-4Zr-7.9Sn alloy

    NASA Astrophysics Data System (ADS)

    Chen, Min-Fang; Zhang, Jing; You, Chen

    2013-12-01

    A novel method has been developed to rapidly deposit bone-like apatite with the assistance of ultraviolet (UV) light irradiation on the nanostructured titania in the simulated body fluid (SBF). The process has three main steps: Ti-24Nb-4Zr-7.9Sn alloy was heated at 650°C for 3 h, UV-light illumination in air for 4 h and soaking in the SBF for 3 d. A titania coating consisted of main rutile formed on the thermal oxidized Ti-24Nb-4Zr-7.9Sn alloy. The UV not only converted the rutile surface from hydrophilic to hydrophobic but also stimulated high surface activity. After 4 h UV illumination, the contents of Ti3+ and hydroxyl groups on the oxidized sample were increased, while that of lattice O decreased. After 3 d of soaking in the SBF, a compact and uniform layer of carbonated hydroxyapatite (CHA) particles was formed on the UV-illuminated rutile surface whereas there was a few of HA to be viewed on the surface of as-oxidized Ti-24Nb-4Zr-7.9Sn alloy. Our study demonstrates a simple, fast and cost-effective technique for growing bone-like apatite on titanium alloys.

  6. Effect of pd and dd reactions enhancement in deuterides TiD2, ZrD2 and Ta2D in the astrophysical energy range

    NASA Astrophysics Data System (ADS)

    Bystritskii, V. M.; Dudkin, G. N.; Filipowicz, M.; Huran, J.; Krylov, A. R.; Nechayev, B. A.; Padalko, V. N.; Pen'kov, F. M.; Philippov, A. V.; Tuleushev, Yu. Zh.

    2016-01-01

    Investigation of the pd-and dd-reactions in the ultralow energy (~keV) range is of great interest in the aspect of nuclear physics and astrophysics for developing of correct models of burning and evolution of stars. This report presents compendium of experimental results obtained at the pulsed plasma Hall accelerator (TPU, Tomsk). Most of those results are new, such as • temperature dependence of the neutron yield in the D( d, n)3He reaction in the ZrD2, Ta2D, TiD2 • potentials of electron screening and respective dependence of astrophysical S-factors in the dd-reaction for the deuteron collision energy in the range of 3-6 keV, with ZrD2, Ta2D temperature in the range of 20-200°C [1] • characteristics of the reaction d( p, γ)3He in the ultralow collision proton-deuterons energy range of 4-13 keV [2, 3] in ZrD2, Ta2D and TiD2 • observation of the neutron yield enhancement in the reaction D( d, n)3He at the ultralow deuteron collision energy due to channeling of deuterons in microscopic TiD2 with a face-centered cubic lattice type TiD1.73, oriented in the [100] direction [4]. The report includes discussion and comparison of the collected experimental results with the global data and calculations.

  7. Variability of impurity doping in the modified Pb(Zr,Ti)O 3 ceramics of type ABO 3

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Liang; Chen, Bing-Huei; Wu, Long

    2004-04-01

    The influence of sintering effects on microstructure, mechanical quality factor Qm and electromechanical coupling factor κ of 1 mol% Nb-doped lead zirconate titanate (PZT) piezoceramics with a composition Zr/Ti=53/47 prepared by the conventional ceramic technology were investigated. Replacement of Ti +4 by Nb +5 in such perovskite type solid solutions was accomplished by the creation of cation vacancies. These created vacancies seemed to facilitate material transport and benefit from sintering. Calcined at 850 °C/2 h and sintered at 1250 °C/2 h, the PZT ceramics had the minimum value of Qm 50 and exhibited maximum electromechanical coupling factor κp 0.62 in accordance with the relationship between mechanical quality factor and electromechanical coupling factor. The measured P- E hysteresis loop illustrated that the remanent polarization ( Pr) and coercive field ( Ec) were 8.63 μC/cm 2 and 17.2 kV/cm, respectively. The fundamental resonance frequency was around 200 kHz, which was suitable for piezoelectric resonator and filter applications.

  8. Promotion of piezoelectric properties of lead zirconate titanate ceramics with (Zr,Ti) partially replaced by Nb 2O 5

    NASA Astrophysics Data System (ADS)

    Chen, Bing-Huei; Huang, Cheng-Liang; Wu, Long

    2004-12-01

    This study investigated the correlation of sintering effects on piezoelectric properties of Nb modified lead zirconate titanate (PZT) piezoceramics produced by the conventional solid reaction sintering. Samples were prepared at a composition Zr/Ti=53/47, contiguous to a morphotropic phase boundary (MPB) for 1 mol% Nb2O5. Replacement of Ti+4 by Nb+5 in such perovskite type solid solutions was accomplished by the creation of cation vacancies. These created vacancies seemed to facilitate material transport and benefit sintering. Calcined at 850 °C/2 h and sintered at 1250 °C/2 h, the PZT ceramics yielded a minimum value of the mechanical quality factor (Qm) 50, and exhibited a maximum electromechanical coupling factor κp 0.62, in accordance with the relationship between the mechanical quality factor and electromechanical coupling factor. In addition, during the sintering process a piezoelectric charge constant at d33 was found to be of 385 pC/N. It was noted that the fundamental resonance frequency was around 200 kHz, which was suitable for piezoelectric nebulizer (fluid atomizer), ultrasonic cleaning transducer applications.

  9. The Mode of Deformation in a Cold-Swaged Multifunctional Ti-Nb-Ta-Zr-O Alloy

    NASA Astrophysics Data System (ADS)

    Guo, W.; Quadir, M. Z.; Ferry, M.

    2013-05-01

    Multifunctional titanium alloys, termed Gum Metal™, are β-phase Ti alloys first developed in 2003. These alloys exhibit many interesting properties including, for example, low rate of work-hardening and superplasticity during cold deformation. The original report described a new plastic deformation mechanism not involving major dislocation activity to explain such deformation behavior. In the current study, a comparable Ti-36.8Nb-2.7Zr-2.0Ta-0.44O (wt pct) alloy to the original investigators was produced by powder sintering, hot forging, solution treatment, and cold swaging with the aim at investigating the microstructural development during swaging. XRD and TEM showed that the forged/solution-treated alloy was β-phase with a small amount of ω-phase. After cold swaging by up to 96 pct area reduction, TEM/HRTEM revealed the existence of dislocations, deformation twins, ω-phase, nanodisturbances, and lattice bending, with EBSD showing the grains to be highly elongated in the swaging direction, fragmented, and distorted. Most notably, swaging also generated a strong <110> fiber texture, even after moderate strains. The foregoing structural analysis provides substantial evidence that dislocations are present in the alloy after cold swaging. The major support of dislocation glide processes acting as the dominant plastic deformation mode in the swaged alloy is the strong <110> fiber texture that develops, which is a characteristic feature of all cold-drawn/swaged body centered cubic metals and alloys.

  10. Influence of fluoride content and pH on corrosion and tribocorrosion behaviour of Ti13Nb13Zr alloy in oral environment.

    PubMed

    Golvano, I; Garcia, I; Conde, A; Tato, W; Aginagalde, A

    2015-09-01

    CpTi and Ti6Al4V alloy are the most widely used materials for implant application, but the release of toxic elements (e.g. Al and V) and the so-called stress-shielding effect are still a concern. In recent years, β and near-β titanium alloys have been developed, which overcome these issues with reduced modulus of elasticity and biocompatible alloying elements. However, literature is scarce studying the tribocorrosion behaviour of these alloys for dental implantology. The present work studies the tribocorrosion behaviour of the near-β Ti13Nb13Zr alloy in oral environment, using CpTi4 for comparison purposes. To that end, the influence of the pH and fluoride concentration in artificial saliva was analysed. Reciprocating sliding corrosion tests were carried out under open circuit potential and potentiostatic conditions. Results reveal a negative influence of the increase of fluoride concentration and the acidified artificial saliva on the material degradation. Moreover, some light has been shed on the different tribocorrosion mechanisms of Ti13Nb13Zr and CpTi4 in simulated oral environment.

  11. Impact of Sr on the performance of BaTi0.9Zr0.1O3-BaTiO3 dielectric powders

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Rong, Guijuan; Wang, Tingwei; Yao, Hao

    2014-06-01

    BaTi0.9Zr0.1O3-Ba1-xSrxTiO3 fine-powders are synthesized by two-step liquid phase method. Phase analysis and microstructure evaluation conducted by X-ray diffraction and scanning electron microscopy confirm the perovskite structure of the ceramic grain. Different Sr content is considered to optimize the density and dielectric performance. The dielectric constant increases and dielectric loss decreases with the rising of Sr content until x = 0.05. At the doping content of 5%, the dielectric constant maximum of 42,430 and excellent Y5V dielectric material can be obtained due to composition inhomogeneity and compact properties. Its dielectric properties are as follows: ɛRT = 36,914, tan δ < 0.09, ΔC/C20°C at -30° C and 80°C are -58.98% and 14.94%, respectively, and the breakdown strength Eb ≥ 5.2 kV ṡ mm-1.

  12. Metastable antiparallel polarization configurations in BaTiO3/PbZr0.2Ti0.8O3 epitaxial bilayer

    NASA Astrophysics Data System (ADS)

    Salev, Pavel; Grigoriev, Alexei

    A combination of LGD and semiconductor theories predicts the electrostatic screening of a large polarization mismatch between BaTiO3 (BTO) and Pb(Zr,Ti)O3 (PZT) ferroelectric layers. The source of this screening is in an increased concentration of interfacial free charge carriers due to the strong bending of electronic bands inside the layers. The enhanced concentration of free charges at the interface can allow for independent polarization reversal in each ferroelectric layer suggesting possible antiparallel polarization configurations in BTO/PZT bilayer. We confirmed these theoretical predictions of layer-by-layer switching by demonstrating double polarization switching in epitaxial BTO/PZT thin films. The layer-by-layer switching leads to formation of head-to-head (H-H) and tail-to-tail (T-T) polarization configurations, which have an enhanced dielectric permittivity when compared to parallel polarization domain configurations. While both H-H and T-T states are unstable at a zero electric field, we found that antiparallel polarization configurations can be stabilized by applying a small bias. Our findings provide a pathway to engineer new multilayer systems with switchable multistate polarizations and dielectric responses.

  13. Resistive Switching and Modulation of Pb(Zr0.4Ti0.6)O3/Nb:SrTiO3 Heterostructures.

    PubMed

    Bai, Yu; Wang, Zhan Jie; Chen, Yan Na; Cui, Jian Zhong

    2016-12-07

    In this work, epitaxial Pb(Zr0.4Ti0.6)O3 (PZT) thin films with different thicknesses were deposited on Nb-doped SrTiO3 (NSTO) single-crystal substrates by chemical solution deposition (CSD), and their ferroelectric resistive switching behaviors were investigated. The results showed that the maximum ON/OFF ratio up to 850 could be obtained in the PZT/NSTO heterostructure with the 150 nm thick PZT film. On the basis of the Schottky-Simmons model and the modified semiconductor theory, we also evaluated the interfacial built-in field and the depletion layer at the PZT/NSTO interface, which can be modulated strongly by the ferroelectric polarization, but are independent of the thickness of the PZT thin films. It is clear that the ferroelectric resistive switching is related to the ferroelectric polarization and modulated by the thickness of ferroelectric films. Therefore, there is an optimal thickness of the PZT film for the maximum ON/OFF ratio due to the ferroelectricity and conductivity mutually restricting. It can be expected that by adjusting the ferroelectricity and conductivity of the ferroelectric thin film and its thickness, the maximum switching ratio can be further improved.

  14. Study of alpha-case depth in Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Gaddam, R.; Sefer, B.; Pederson, R.; Antti, M.-L.

    2013-12-01

    At temperatures exceeding 480°C titanium alloys generally oxidises and forms a hard and brittle layer enriched with oxygen, which is called alpha case. This layer has negative effects on several mechanical properties and lowers the tensile ductility and the fatigue resistance. Therefore any alpha-case formed on titanium alloys during various manufacturing processes, such as heat treatment procedures, must be removed before the final part is mounted in an engine. In addition, long time exposure at elevated temperatures during operation of an engine could possibly also lead to formation of alpha-case on actual parts, therefore knowledge and understanding of the alpha-case formation and its effect on mechanical properties is important. Factors that contribute for growth of alpha-case are: presence of oxygen, exposure time, temperature and pressure. In the present study, isothermal oxidation experiments in air were performed on forged Ti-6Al-2Sn-4Zr-2Mo at 500°C and 593°C up to 500 hours. Similar studies were also performed on Ti-6Al-4V plate at 593°C and 700°C. Alpha-case depth for both alloys was quantified using metallography techniques and compared.

  15. Double hysteresis in BaTiO3/PbZr0.2Ti0.8O3 ferroelectric bilayer thin film

    NASA Astrophysics Data System (ADS)

    Salev, Pavel; Grigoriev, Alexei

    2015-03-01

    We observed two hysteresis loops in BaTiO3/PbZr0.2Ti0.8O3 (BTO/PZT) bilayer thin film. The first loop with polarization of 27 μ C/cm2 was measured in the applied voltage of +/- 20 V. The second hysteresis loop with polarization of 76 μ C/cm2 was measured in the applied voltage of +/- 55 V. Both hysteresis loops showed characteristic shape with concave region followed by saturation region in the broad range of applied voltage frequencies providing strong evidence for ferroelectric origin of both loops. We performed computational analysis of BTO/PZT bilayer based on Landau-Ginzburg-Devonshire model including contributions of electronic band structure. We found an increased concentration of free charge carriers at the interface between BTO and PZT which provides compensation for the bound charge due to polarization mismatch of the layers. Moreover, as the free charge effectively screens polarization in one layer from another, polarization switching of individual layers can be possible. This leads to the conclusion that two hysteresis loops can be a result of polarization switching of the individual layers.

  16. X-ray diffraction and Raman spectroscopic investigations on CaZrTi2O7sbnd Y2Ti2O7 system: Delineation of phase fields consisting of potential ceramic host materials

    NASA Astrophysics Data System (ADS)

    Jafar, M.; Achary, S. N.; Salke, Niliesh P.; Sahu, A. K.; Rao, Rekha; Tyagi, A. K.

    2016-07-01

    Phase evolution from CaZrTi2O7 (zirconolite) to Y2Ti2O7 (pyrochlore) have been delineated by systematic characterization of a series of sample with composition as Ca1-xZr1-xY2xTi2O7 (0.00 ≤ x ≤ 1.00) by powder XRD, Raman spectroscopy, SEM and EDS analyses. Comparative analyses of XRD and Raman spectra revealed sequential evolution of phases with increasing concentration of Y3+ in the compositions. From the XRD studies, three distinct phase fields, namely two layer (2M) and four layer (4M) zirconolite-types and cubic pyrochlore-type are observed in between zirconolite (CaZrTi2O7) and Y2Ti2O7. 4M-zirconolite phase is observed in a narrow range of composition, viz. 0.35 ≤ x ≤ 0.40 while cubic pyrochlore type phase is observed in the compositions with x ≥ 1.20. The unit cell volume of different phases shows a non-linear increasing trend with Y3+ ion concentration which has been attributed to the distribution of cations in different structure and change in their coordination number.

  17. Devitrification of Mechanically Alloyed Zr-Ti-Nb-Cu-Ni-Al Glassy Powders Studied by Time-Resolved X-ray Diffraction

    SciTech Connect

    Scudino, S.; Sordelet, D.J.; Eckert, J.

    2009-04-13

    The crystallization of mechanically alloyed Zr{sub 67}Ti{sub 6.14}Nb{sub 1.92}Cu{sub 10.67}Ni{sub 8.52}Al{sub 5.75} glassy powder is investigated by time-resolved X-ray diffraction. The powder displays a multi-step crystallization behavior characterized by the formation of a metastable nanoscale quasicrystalline phase during the first stage of the crystallization process. At higher temperatures, coinciding with the second crystallization event, the amorphous-to-quasicrystalline transformation is followed by the precipitation of the tetragonal Zr{sub 2}Cu phase (space group I4/mmm) and the tetragonal Zr{sub 2}Ni phase (space group I4/mcm). The transformations are gradual and the quasicrystals and the subsequent phases coexist over a temperature interval of about 25K.

  18. Influence of Zr{sup 4+} doping on structural and electrical properties of SrBi{sub 4}Ti{sub 4}O{sub 15} ceramic

    SciTech Connect

    Nayak, P. Panigrahi, S.; Badapanda, T.

    2015-06-24

    This article reports a systematic study of doping effects on the structural and electrical properties of layer structured strontium bismuth titanate ceramic. In this study monophasic SrBi{sub 4}Ti{sub 4-x}Zr{sub x}O{sub 15} with x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25 ceramics were synthesized from the solid-state reaction route. X-ray diffraction analysis shows that the Zr-modified SBT ceramics have a pure four-layer Aurivillius phase structure. Dielectric properties revealed that the diffuseness of phase transition increases where as corresponding permittivity value decrease with increasing Zr content. Piezoelectric properties of SBTZ ceramics were improved by the modification of Zirconium ion. Moreover, the reason behind for improvement of piezoelectric properties of modified SBTZ ceramics was also discussed.

  19. Sandia octahedral molecular sieves (SOMS): structural and property effects of charge-balancing the M(IV)-substituted (M = Ti, Zr) Niobate framework.

    PubMed

    Nyman, May; Tripathi, Akhilesh; Parise, John B; Maxwell, Robert S; Nenoff, Tina M

    2002-02-27

    Sandia octahedral molecular sieves (SOMS) is an isostructural, variable composition class of ion exchangers with the general formula Na(2)Nb(2-x)M(IV)(x)O (6-x)(OH)(x).H(2)O (M(IV) = Ti, Zr; x = 0.04-0.40) where up to 20% of the framework Nb(V) can be substituted with Ti(IV) or Zr(IV). This class of molecular sieves is easily converted to perovskite through low-temperature heat treatment (500-600 degrees C). This report provides a detailed account of how the charge imbalance of this Nb(V)-M(IV) substitution is compensated. X-ray powder diffraction with Rietveld refinement, infrared spectroscopy, thermogravimetric analysis, (23)Na MAS NMR, and (1)H MAS NMR were used to determine how the framework anionic charge is cation-balanced over a range of framework compositions. All spectroscopic evidence indicated a proton addition for each M(IV) substitution. Evidences for variable proton content included (1) increasing OH observed by (1)H MAS NMR with increasing M(IV) substitution, (2) increased infrared band broadening indicating increased H-bonding with increasing M(IV) substitution, (3) increased TGA weight loss (due to increased OH content) with increasing M(IV) substitution, (4) no variance in population on the sodium sites (indicated by Rietveld refinement) with variable composition, and (5) no change in the (23)Na MAS NMR spectra with variable composition. Also observed by infrared spectroscopy and (23)Na MAS NMR was increased disorder on the Nb(V)/M(IV) framework sites with increasing M(IV) substitution, evidenced by broadening of these spectral features. These spectroscopic studies, along with ion exchange experiments, also revealed the effect of the Nb(V)/M(IV) framework substitution on materials properties. Namely, the temperature of conversion to NaNb(1-x)M(IV)(x)O(3) (M = Ti, Zr) perovskite increased with increasing Ti in the framework and decreased with increasing Zr in the framework. This suggested that Ti stabilizes the SOMS framework and Zr destabilizes

  20. Li2ZrO3-coated Li4Ti5O12 with nanoscale interface for high performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Han; Liu, Yang; Wang, Ting; Yang, Yang; Shi, Shaojun; Yang, Gang

    2016-04-01

    Zr doped sample of Li4Ti4.99Zr0.01O12 (LZTO) and Li2ZrO3 (LZO) coated Li4Ti5O12 (LTO) are prepared by a solid-state method. The lattice structure of LTO is remained after doping element of Zr and coating layer of LZO. The crystal structure and electrochemical performance of the material are investigated by X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM), cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT) and charge-discharge tests, respectively. Zr-doping and LZO coating play the positive role in improving the diffusion ability of lithium cations. LZTO and LZO-LTO show much improved specific capacity and rate capability compared with pristine sample of LTO. LZO-LTO has the smallest voltage differential (ΔV) of the redox peaks because the coating of Li2ZrO3 is helpful for the diffusion ability of lithium ions during charge/discharge processes. LZTO and LZO-LTO as electrode deliver the initial capacities of 164.8, 168.1 mAh g-1, respectively, which are much higher than 150.2 mAh g-1 of intrinsic sample of LTO. Even at the current density of 2 A g-1, LTZO and LZO-LTO offer capacity of 96 and 106 mAh g-1, which are much higher than 33 mAh g-1 of LTO. The improved electrochemical performance is attributed to the improved diffusion ability of lithium. During the whole discharge process, the lowest value of LTO is 5.97 × 10-17 cm2 s-1 that is much lower than 7.80 × 10-16 cm2 s-1 in LZTO and 1.85 × 10-15 cm2 s-1 in LZO-LTO, respectively.

  1. A novel preparation of three-dimensionally ordered macroporous M/Ti (M=Zr or Ta) mixed oxide nanoparticles with enhanced photocatalytic activity.

    PubMed

    Wang, Changhua; Geng, Aifang; Guo, Yihang; Jiang, Shujuan; Qu, Xuesong; Li, Li

    2006-09-01

    Three-dimensionally ordered macroporous (3 DOM) M/Ti (M=Zr or Ta) mixed oxides were prepared by cohydrolysis of a mixture of Zr(n-OC(4)H(9))(4)/TTIP or TaCl(5)/TTIP (TTIP=titanium isopropoxide) combined with a polystyrene (PS) latex sphere templating technique. The resulting products exhibited homogeneous wall compositions, namely, Zr or Ta was uniformly dispersed into the TiO(2) framework with the loading levels of 5, 10, and 20 mol% for Zr and 2.5, 5.0, and 7.5 mol% for Ta, respectively. The estimated macropore diameter, wall thickness, and particle size of the products ranged from 280 to 290 nm, from 30 to 50 nm, and from 10 to 12 nm, respectively. The products showed only anatase phase structure although their starting solitary metal oxides exhibited suitable crystalline structures under the same preparation conditions. Raman scattering spectroscopy showed that the crystal structure of titania had a slight interference due to the incorporation of Zr or Ta, and UV-vis diffuse reflectance spectroscopy (DRS) showed the narrower band gap of the products compared with that of pure anatase TiO(2). The products exhibited mesoporous wall structures, and their BET surface areas were higher than those of the corresponding pure 3 DOM metal oxides. The UV-light photocatalytic activity of the products was assessed by monitoring the photodegradation of two organic molecules including 4-nitrophenol (4-NP) and rhodamine B (RB). Both the photocatalytic reactions confirmed that the presence of the second metal oxide in the titania framework resulted in enhanced photocatalytic activity compared with the pure titania framework.

  2. Zr4+ doping in Li4Ti5O12 anode for lithium-ion batteries: open Li+ diffusion paths through structural imperfection.

    PubMed

    Kim, Jae-Geun; Park, Min-Sik; Hwang, Soo Min; Heo, Yoon-Uk; Liao, Ting; Sun, Ziqi; Park, Jong Hwan; Kim, Ki Jae; Jeong, Goojin; Kim, Young-Jun; Kim, Jung Ho; Dou, Shi Xue

    2014-05-01

    One-dimensional nanomaterials have short Li(+) diffusion paths and promising structural stability, which results in a long cycle life during Li(+) insertion and extraction processes in lithium rechargeable batteries. In this study, we fabricated one-dimensional spinel Li4Ti5O12 (LTO) nanofibers using an electrospinning technique and studied the Zr(4+) doping effect on the lattice, electronic structure, and resultant electrochemical properties of Li-ion batteries (LIBs). Accommodating a small fraction of Zr(4+) ions in the Ti(4+) sites of the LTO structure gave rise to enhanced LIB performance, which was due to structural distortion through an increase in the average lattice constant and thereby enlarged Li(+) diffusion paths rather than changes to the electronic structure. Insulating ZrO2 nanoparticles present between the LTO grains due to the low Zr(4+) solubility had a negative effect on the Li(+) extraction capacity, however. These results could provide key design elements for LTO anodes based on atomic level insights that can pave the way to an optimal protocol to achieve particular functionalities.

  3. Ordered Structures and Thermoelectric Properties of MNiSn (M = Ti, Zr, Hf)-Based Half-Heusler Compounds Affected by Close Relationship with Heusler Compounds

    NASA Astrophysics Data System (ADS)

    Kimura, Yoshisato; Chai, Yaw-Wang

    2015-01-01

    Half-Heusler compounds are excellent thermoelectric materials. A characteristic of the half-Heusler-type ordered structure is the vacancy site that occupies one-fourth of all the lattice points. Therefore, a half-Heusler ABX phase (where A and B are typically transition metal elements, such as Ti, Zr, and Hf, and X represents a half-metal element such as Sn or Sb) has a crystallographically close relationship with a Heusler AB2X phase in the sense that the vacancy site in the half-Heusler phase is filled with B atoms in the Heusler phase. The thermoelectric properties are improved or affected by point lattice defects related to the vacancy site and the B site, such as the antisite atom B in the vacancy site, vacancies in the B site, and vacancy-site occupancy by quaternary C atoms. A modulated-like nanostructure due to point defects regarding vacancies and Ni atoms is formed for an instance in ZrNiSn alloys even close to the stoichiometric composition. Ni-rich nanoclusters are locally formed by excessive Ni antisite atoms in the vacancy site, which work as precursors of Heusler precipitates (TiNi2Sn, ZrNi2Sn, and so forth). The vacancy-site occupation in ZrNiSn with Co and Ir results in the drastic conversion of thermoelectric properties from n type to p type, and the effective reduction of the lattice thermal conductivity.

  4. Highly c-axis-oriented monocrystalline Pb(Zr, Ti)O₃ thin films on si wafer prepared by fast cooling immediately after sputter deposition.

    PubMed

    Yoshida, Shinya; Hanzawa, Hiroaki; Wasa, Kiyotaka; Esashi, Masayoshi; Tanaka, Shuji

    2014-09-01

    We successfully developed sputter deposition technology to obtain a highly c-axis-oriented monocrystalline Pb(Zr, Ti)O3 (PZT) thin film on a Si wafer by fast cooling (~-180°C/min) of the substrate after deposition. The c-axis orientation ratio of a fast-cooled film was about 90%, whereas that of a slow-cooled (~-40°C/min) film was only 10%. The c-axis-oriented monocrystalline Pb(Zr0.5, Ti0.5)O3 films showed reasonably large piezoelectric coefficients, e(31,f) = ~-11 C/m(2), with remarkably small dielectric constants, ϵ(r) = ~220. As a result, an excellent figure of merit (FOM) was obtained for piezoelectric microelectromechanical systems (MEMS) such as a piezoelectric gyroscope. This c-axis orientation technology on Si will extend industrial applications of PZT-based thin films and contribute further to the development of piezoelectric MEMS.

  5. Effect of nitrogen flow ratios on the structure and mechanical properties of (TiVCrZrY)N coatings prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Tsai, Du-Cheng; Huang, Yen-Lin; Lin, Sheng-Ru; Liang, Shih-Chang; Shieu, Fuh-Sheng

    2010-12-01

    This study reports the influence of growth conditions on the characteristics of (TiVCrZrY)N coatings prepared by reactive magnetron sputtering at various N 2-to-total (N 2 + Ar) flow ratio, which is R N. The crystal structures, microstructure, and mechanical properties for different R N were characterized by electron spectroscopy for chemical analysis, X-ray diffraction, atomic force microscopy, field-emission-scanning electron microscopy, transmission electron microscopy, and nanoindentation. The results indicate that the TiVCrZrY alloy and nitride coatings have hexagonal close-packed (hcp)-type and sodium chloride (NaCl)-type solid-solution structures, respectively. The voids in the coatings are eliminated and the growth of the columnar crystal structures is inhibited along with an increasing R N. As a consequence, highly packed equiaxed amorphous structures with smooth surfaces are formed. The coatings accordingly achieved a pronounce hardness of 17.5 GPa when R N = 100%.

  6. Evaluation of micro-abrasion-corrosion on SiO2-TiO2-ZrO2 coatings synthesized by the sol-gel method

    NASA Astrophysics Data System (ADS)

    Bautista Ruiz, J.; Aperador, W.; Caballero Gómez, J.

    2016-02-01

    The medical science and the engineering, work to improve the materials used in the manufacture of joint implants, since they have a direct impact on the quality of people life. The surgical interventions are increasing worldwide with a high probability of a second or even a third intervention. Around these circumstances, it was evaluated the behaviour against microabrasion-corrosion phenomena on SiO2 TiO2 ZrO2 coatings, synthesized by the sol-gel method with concentration of the Si/Ti/Zr precursors: 10/70/20 and 10/20/70. The coatings were deposited on AISI 316 LVM stainless steel substrates. The morphological characterization of the wear was made by AFM techniques. It was observed that the coatings with higher levels of titanium have a good response to the phenomena of microabrasion-corrosion.

  7. Growth of Ba(Ti 1- xZr x)O 3 single crystals by the laser heated pedestal growth technique

    NASA Astrophysics Data System (ADS)

    Zhi, Yu; Guo, Ruyan; Bhalla, A. S.

    2001-12-01

    Single crystals of the ferroelectric Ba(Ti 1- xZr x)O 3 ( x=0.05 and 0.08) were grown by the laser heated pedestal growth (LHPG) technique. The perovskite structure of the crystals was identified by the X-ray diffraction technique. Crystals were examined by Laue patterns and scanning electron microscopy (SEM), which indicated that the single crystals were of good crystallinity and compositional homogeneity. The anisotropic dielectric and piezoelectric behavior was characterized. The Ba(Ti 1- xZr x)O 3 single crystals possessed a high-level hysteresis-free electromechanical strain and are promising lead-free ferroelectric crystals for the piezoelectric transducer applications.

  8. Electrocaloric effect of inorganic low temperature sintering (Pb0.88La0.08)(Zr0.65Ti0.35)O3 ceramics

    NASA Astrophysics Data System (ADS)

    Ra, Cheol-Min; Yoo, Ju-Hyun; Chol, Seung-Hun; Lee, Jie-Young

    2015-07-01

    In this study, in order to develop the composition ceramics with the excellent electrocaloric properties, (Pb0.88La0.08)(Zr0.65Ti0.35)O3 ceramics were fabricated by the conventional solid-state method. Electrocaloric effects of inorganic (Pb0.88La0.08)(Zr0.65Ti0.35)O3 ferroelectric ceramics were investigated and discussed using the characteristics of P-E hysteresis loops at wide temperature range from room temperature to 220 °C. The temperature change ΔT due to the electrocaloric effect was calculated by Maxwell's relations. The temperature change ΔT of ceramics sintered at 950°C reached the maximum of ∼0.19 at 190 °C under applied electric field of 30 kV/cm.

  9. Effect of Zr, Nb and Ti addition on injection molded 316L stainless steel for bio-applications: Mechanical, electrochemical and biocompatibility properties.

    PubMed

    Gulsoy, H Ozkan; Pazarlioglu, Serdar; Gulsoy, Nagihan; Gundede, Busra; Mutlu, Ozal

    2015-11-01

    The research investigated the effect of Zr, Nb and Ti additions on mechanical, electrochemical properties and biocompatibility of injection molded 316L stainless steel. Addition of elemental powder is promoted to get high performance of sintered 316L stainless steels. The amount of additive powder plays a role in determining the sintered microstructure and all properties. In this study, 316L stainless steel powders used with the elemental Zr, Nb and Ti powders. A feedstock containing 62.5 wt% powders loading was molded at different injection molded temperature. The binders were completely removed from molded components by solvent and thermal debinding at different temperatures. The debinded samples were sintered at 1350°C for 60 min. Mechanical, electrochemical property and biocompatibility of the sintered samples were performed mechanical, electrochemical, SBF immersion tests and cell culture experiments. Results of study showed that sintered 316L and 316L with additives samples exhibited high corrosion properties and biocompatibility in a physiological environment.

  10. In vitro bio-functional performances of the novel superelastic beta-type Ti-23Nb-0.7Ta-2Zr-0.5N alloy.

    PubMed

    Ion, Raluca; Gordin, Doina-Margareta; Mitran, Valentina; Osiceanu, Petre; Dinescu, Sorina; Gloriant, Thierry; Cimpean, Anisoara

    2014-02-01

    The materials used for internal fracture fixations and joint replacements are mainly made of metals which still face problems ranging from higher rigidity than that of natural bone to leaching cytotoxic metallic ions. Beta (β)-type titanium alloys with low elastic modulus made from non-toxic and non-allergenic elements are desirable to reduce stress shielding effect and enhance bone remodeling. In this work, a new β-type Ti-23Nb-0.7Ta-2Zr-0.5N alloy with a Young's modulus of approximately 50 GPa was designed and characterized. The behavior of MC3T3-E1 pre-osteoblasts on the new alloy, including adhesion, proliferation and differentiation, was evaluated by examining the cytoskeleton, focal adhesion formation, metabolic activity and extracellular matrix mineralization. Results indicated that the pre-osteoblast cells exhibited a similar degree of attachment and growth on Ti-23Nb-0.7Ta-2Zr-0.5N and Ti-6Al-4V. However, the novel alloy proved to be significantly more efficient in sustaining mineralized matrix deposition upon osteogenic induction of the cells than Ti-6Al-4V control. Further, the analysis of RAW 264.7 macrophages cytokine gene and protein expression indicated no significant inflammatory response. Collectively, these findings suggest that the Ti-23Nb-0.7Ta-2Zr-0.5N alloy, which has an increased mechanical biocompatibility with bone, allows a better osteogenic differentiation of osteoblast precursor cells than Ti-6Al-4V and holds great potential for future clinical prosthetic applications.

  11. Comparative Study of the Optical and Textural Properties of Tetrapyrrole Macrocycles Trapped Within ZrO₂, TiO₂, and SiO₂ Translucent Xerogels.

    PubMed

    Salas-Bañales, Eduardo; Quiroz-Segoviano, R Iris Y; Díaz-Alejo, Luis Antonio; Rojas-González, Fernando; Estrella-González, Alberto; Campero, Antonio; García-Sánchez, Miguel A

    2015-10-23

    The entrapping of physicochemical active molecules inside mesoporous networks is an appealing field of research due to the myriad of potential applications in optics, photocatalysis, chemical sensing, and medicine. One of the most important reasons for this success is the possibility of optimizing the properties that a free active species displays in solution but now trapped inside a solid substrate. Additionally it is possible to modulate the textural characteristics of substrates, such as pore size, specific surface area, polarity and chemical affinity of the surface, toward the physical or chemical adhesion of a variety of adsorbates. In the present document, two kinds of non-silicon metal alkoxides, Zr and Ti, are employed to prepare xerogels containing entrapped tetrapyrrolic species that could be inserted beforehand in analogue silica systems. The main goal is to develop efficient methods for trapping or binding tetrapyrrole macrocycles inside TiO₂ and ZrO₂ xerogels, while comparing the properties of these systems against those of the SiO₂ analogues. Once the optimal synthesis conditions for obtaining translucent monolithic xerogels of ZrO₂ and TiO₂ networks were determined, it was confirmed that these substrates allowed the entrapment, in monomeric form, of macrocycles that commonly appear as aggregates within the SiO₂ network. From these experiments, it could be determined that the average pore diameters, specific surface areas, and water sorption capacities depicted by each one of these substrates, are a consequence of their own nature combined with the particular structure of the entrapped tetrapyrrole macrocycle. Furthermore, the establishment of covalent bonds between the intruding species and the pore walls leads to the obtainment of very similar pore sizes in the three different metal oxide (Ti, Zr, and Si) substrates as a consequence of the templating effect of the encapsulated species.

  12. Microstructure and Properties of a Refractory NbCrMo0.5Ta0.5TiZr Alloy (Postprint)

    DTIC Science & Technology

    2014-04-01

    phases was con- ucted with the use of an EDS detector attached to the field mission gun SEM. The results are given in Table 2. It is found that he...Microstruc- ture and properties of a refractory TaNbHfZrTi alloy, Unpublished paper, 2011. 10] J.-W. Yeh, S.-K. Chen, S.-J. Lin, J.-Y. Gan, T.-S. Chin , T

  13. Effect of martensitic transformation on magnetoelectric properties of Ni2MnGa/PbZr0.52Ti0.48O3 composite

    NASA Astrophysics Data System (ADS)

    Zhao, K.; Chen, K.; Dai, Y. R.; Wan, J. G.; Zhu, J. S.

    2005-10-01

    The magnetoelectric (ME) coefficient was measured as a function of temperature, from room temperature to 100°C, in a bilayer composite of Ni2MnGa/PbZr0.52Ti0.48O3. A distinct peak of the ME coefficient was observed near the martensitic transformation temperature of the Ni2MnGa alloy. The effect of martensitic transition on the ME coefficient and the multiferroic properties were discussed.

  14. Acetylene adsorption on δ-MoC(001), TiC(001) and ZrC(001) surfaces: a comprehensive periodic DFT study.

    PubMed

    Jimenez-Orozco, Carlos; Florez, Elizabeth; Moreno, Andres; Liu, Ping; Rodriguez, Jose A

    2017-01-04

    A comprehensive study of acetylene adsorption on δ-MoC(001), TiC(001) and ZrC(001) surfaces was carried out by means of calculations based on periodic density functional theory, using the Perdew-Burke-Ernzerhof exchange-correlation functional. It was found that the bonding of acetylene was significantly affected by the electronic and structural properties of the carbide surfaces. The adsorbate interacted with metal and/or carbon sites of the carbide. The interaction of acetylene with the TiC(001) and ZrC(001) surfaces was strong (binding energies higher than -3.5 eV), while moderate acetylene adsorption energies were observed on δ-MoC(001) (-1.78 eV to -0.66 eV). Adsorption energies, charge density difference plots and Mulliken charges suggested that the binding of the hydrocarbon to the surface had both ionic and covalent contributions. According to the C-C bond lengths obtained, the adsorbed molecule was modified from acetylene-like into ethylene-like on the δ-MoC(001) surface (desired behavior for hydrogenation reactions) but into ethane-like on TiC(001) and ZrC(001). The obtained results suggest that the δ-MoC(001) surface is expected to have the best performance in selective hydrogenation reactions to convert alkynes into alkenes. Another advantage of δ-MoC(001) is that, after C2H2 adsorption, surface carbon sites remain available, which are necessary for H2 dissociation. However, these sites were occupied when C2H2 was adsorbed on TiC(001) and ZrC(001), limiting their application in the hydrogenation of alkynes.

  15. Impact of cyclic plasma treatment on oxygen vacancy defects in TiN/HfZrO/SiON/Si gate stacks

    SciTech Connect

    Bhuyian, Md Nasir Uddin Misra, D.; Poddar, S.; Tapily, K.; Clark, R. D.; Consiglio, S.; Wajda, C. S.; Nakamura, G.; Leusink, G. J.

    2015-05-11

    This work evaluates the defects in HfZrO as a function of Zr addition into HfO{sub 2} and when the dielectric was subjected to a slot-plane-antenna (SPA) plasma treatment in a cyclic process to form TiN/HfZrO/SiON/Si gate stacks. The defect energy levels, estimated by temperature-dependent current-voltage measurements, suggest that Zr addition in HfO{sub 2} modifies the charge state of the oxygen vacancy formation, V{sup +}. The influence of electron affinity variation of Hf and Zr ions on the charged oxygen vacancy levels seems to have contributed to the increase in defect activation energy, E{sub a}, from 0.32 eV to 0.4 eV. The cyclic SPA plasma exposure further reduces the oxygen vacancy formation because of the film densification. When the dielectric was subjected to a constant voltage stress, the charge state oxygen vacancy formation changes to V{sup 2+} and improvement was eliminated. The trap assisted tunneling behavior, as observed by the stress induced leakage current characteristics, further supports the oxygen vacancy formation model.

  16. Impact of cyclic plasma treatment on oxygen vacancy defects in TiN/HfZrO/SiON/Si gate stacks

    NASA Astrophysics Data System (ADS)

    Bhuyian, Md Nasir Uddin; Poddar, S.; Misra, D.; Tapily, K.; Clark, R. D.; Consiglio, S.; Wajda, C. S.; Nakamura, G.; Leusink, G. J.

    2015-05-01

    This work evaluates the defects in HfZrO as a function of Zr addition into HfO2 and when the dielectric was subjected to a slot-plane-antenna (SPA) plasma treatment in a cyclic process to form TiN/HfZrO/SiON/Si gate stacks. The defect energy levels, estimated by temperature-dependent current-voltage measurements, suggest that Zr addition in HfO2 modifies the charge state of the oxygen vacancy formation, V+. The influence of electron affinity variation of Hf and Zr ions on the charged oxygen vacancy levels seems to have contributed to the increase in defect activation energy, Ea, from 0.32 eV to 0.4 eV. The cyclic SPA plasma exposure further reduces the oxygen vacancy formation because of the film densification. When the dielectric was subjected to a constant voltage stress, the charge state oxygen vacancy formation changes to V2+ and improvement was eliminated. The trap assisted tunneling behavior, as observed by the stress induced leakage current characteristics, further supports the oxygen vacancy formation model.

  17. Microstructure, mechanical properties and machining performance of hot-pressed Al2O3 - ZrO2 - TiC composites

    NASA Astrophysics Data System (ADS)

    Grigoriev, M.; Kotelnikov, N.; Buyakova, S.; Kulkov, S.

    2016-02-01

    The effect of adding nanocrystalline ZrO2 and submicron TiC to ultrafine Al2O3 on mechanical properties and the microstructure of the composites developed by hot pressing was investigated. It was shown that by means of hot pressing in an argon atmosphere at a sintering temperature of 1500 °C one can obtain the composites Al2O3 - ZrO2 - TiC with a fine structure and minimal porosity. It has been shown that in material a multi-scale hierarchical structure is formed, which possesses high physical and mechanical properties: the hardness and fracture toughness was 21.5 GPa and 5.2 MPa*m1/2 respectively, the modulus of elasticity was 500 GPa and bending strength was 390 MPa. Tests on composites’ cutting properties were carried out on interrupted cutting of hardened steel. All samples had wear of the cutting edge in the form of chips of the grain rear working surface of the tool, but the cutting tool which was made by Al2O3 - 10% ZrO2 - 10% TiC had a minimum width of wear.

  18. Speculation of equilibrium pressure of Ti{sub 36}Zr{sub 40}Ni{sub 20}Pd{sub 4} icosahedral quasicrystal

    SciTech Connect

    Huang, Huogen; Chen, Liang

    2015-08-17

    Ti-Zr-Ni quasicrystals have been demonstrated to store a large number of hydrogen atoms, which implies strong potential application in hydrogen energy field for them. However, the desorption of hydrogen atoms in the quasicrystals is quite difficult, with the indication of high desorption temperature and slow desorption rate. The shortage limits their use in the field to a large extent. But this kind of quasicrystals might be used in nuclear fusion energy field, because tritium as a coral fuel for nuclear fusion needs tight storage. However, equilibrium pressure at room temperature of Ti-Zr-Ni quasicrystals, important for their application in fusion energy field, has not been clear yet. In this work, we designed a gas-solid reaction system with the pressure resolution of 10{sup −8}Pa and carried out hydrogen desorption investigation at different temperatures on Ti{sub 36}Zr{sub 40}Ni{sub 20}Pd{sub 4} icosahedral quasicrystal. Based on three Pressure-Composition-Temperature desorption curves, we speculate according to Van’t Hoff theory about hydrogen storage that its equilibrium pressure at room temperature could be at the magnitude of 10{sup −6}Pa, displaying good stability of hydrogen in the quasicrystal and also implying application prospects in fusion energy field for quasicrystals of this type.

  19. Photoluminescence: A probe for short, medium and long-range self-organization order in ZrTiO{sub 4} oxide

    SciTech Connect

    Lucena, Poty R. de . E-mail: poty@liec.ufscar.br; Roberto Leite, Edson; Pontes, Fenelon M.; Longo, Elson; Pizani, Paulo S.; Arana Varela, Jose

    2006-12-15

    Photoluminescent disordered ZrTiO{sub 4} powders were obtained by the polymeric precursor soft-chemical method. This oxide system (ordered and disordered) was characterized by photoluminescence, Raman spectroscopy, X-ray diffraction, differential scanning calorimetry and UV-vis absorption experiments. The UV absorption tail formation in the disordered oxides was related to the diminution of optical band gap. In the disordered phase, this oxide displayed broad band photoluminescence caused by change in coordination number of titanium and zirconium with oxygen atoms. The gap decreased from 3.09eV in crystalline oxide to 2.16 eV in disordered oxide. The crystalline oxide presented an orthorhombic {alpha}-PbO{sub 2}-type structure in which Zr{sup 4+} and Ti{sup 4+} were randomly distributed in octahedral coordination polyhedra with oxygen atoms. The amorphous-crystalline transition occurred at almost 700 deg. C, at which point the photoluminescence vanished. The Raman peak at close to 80-200cm{sup -1} indicated the presence of locally ordered Ti-O{sub n} and Zr-O{sub n} polyhedra in disordered photoluminescent oxides.

  20. Non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 bulk metallic glass investigated by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Gong, Pan; Zhao, Shaofan; Wang, Xin; Yao, Kefu

    2015-07-01

    The non-isothermal crystallization kinetics and glass-forming ability of Ti41Zr25Be28Fe6 glassy alloy were investigated by differential scanning calorimetry. The activation energies corresponding to the characteristic temperatures have been calculated by Kissinger and Ozawa equations. Based on Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall models, it has been found that the local activation energy is higher at the beginning of the crystallization process for the first exothermic peak. The local Avrami exponent indicates that the first-step crystallization is mainly a high-dimensional nucleation and growth with an increasing nucleation rate. According to the calculated fragility index, Ti41Zr25Be28Fe6 alloy can be classified as "strong glass former." The studied alloy also possesses a critical size up to centimeter order, and the high glass-forming ability is probably related to the relatively low Gibbs energy difference between the liquid and crystalline states. The critical cooling rate of Ti41Zr25Be28Fe6 glassy alloy has also been determined using Barandiaran-Colmenero's method.

  1. Electrical and structural properties of group-4 transition-metal nitride (TiN, ZrN, and HfN) contacts on Ge

    SciTech Connect

    Yamamoto, Keisuke; Nakashima, Hiroshi; Noguchi, Ryutaro; Wang, Dong; Mitsuhara, Masatoshi; Nishida, Minoru; Hara, Toru

    2015-09-21

    Electrical and structural properties were investigated for group-4 transition-metal nitride contacts on Ge (TiN/Ge, ZrN/Ge, and HfN/Ge), which were prepared by direct sputter depositions using nitride targets. These contacts could alleviate the intrinsic Fermi-level pinning (FLP) position toward the conduction band edge. It was revealed that this phenomenon is induced by an amorphous interlayer (a-IL) containing nitrogen atoms at the nitride/Ge interfaces. The strength of FLP alleviation positively depended on the thickness of a-IL. TiN/Ge and ZrN/Ge contacts with ∼2 nm-thick a-ILs showed strong FLP alleviations with hole barrier heights (Φ{sub BP}) in the range of 0.52–56 eV, and a HfN/Ge contact with an ∼1 nm-thick a-IL showed a weaker one with a Φ{sub BP} of 0.39 eV. However, TaN/Ge contact without a-IL did not show such FLP alleviation. Based on the results of depth distributions for respective elements, we discussed the formation kinetics of a-ILs at TiN/Ge and ZrN/Ge interfaces. Finally, we proposed an interfacial dipole model to explain the FLP alleviation.

  2. The effect of oxygen vacancy on holes-induced d0 magnetism in CaTiO3 and CaZrO3

    NASA Astrophysics Data System (ADS)

    Zheng, Xiao-Xi; Wang, Dan; Tang, Li-Ming; Chen, Ke-Qiu

    2015-08-01

    Using the first-principles calculations, the holes-induced d0 magnetism associated with oxygen vacancy (VO) in CaTiO3 and CaZrO3 has been investigated. To obtain holes, the divalent calcium and tetravalent IVB-group ions are replaced respectively by the monovalent alkali, IB-group and trivalent III-group ions. It is found that the VO can enhance the magnetic moment of few acceptors-doped CaTiO3, whereas it enhances the magnetic moment in most acceptor-doped CaZrO3 except for La doping. Mainly, it is because the VO gives rise to no gap-states in CaTiO3 but generates gap-states in CaZrO3. Based on the similar effect of VO on the band structure in XTiO3 or in XZrO3 (X = Ca, Sr, Ba), we suggest that there exists a similar effect of VO on d0 magnetism in acceptor-doped alkaline titanium (zirconium) perovskites.

  3. Microstructures and mechanical properties of metastable Ti-30Zr-(Cr, Mo) alloys with changeable Young's modulus for spinal fixation applications.

    PubMed

    Zhao, Xiaoli; Niinomi, Mitsuo; Nakai, Masaaki; Miyamoto, Goro; Furuhara, Tadashi

    2011-08-01

    In order to develop a novel alloy with a changeable Young's modulus for spinal fixation applications, we investigated the microstructures, Young's moduli, and tensile properties of metastable Ti-30Zr-(Cr, Mo) alloys subjected to solution treatment (ST) and cold rolling (CR). All the alloys comprise a β phase and small athermal ω phase, and they exhibit low Young's moduli after ST. During CR, deformation-induced phase transformation occurs in all the alloys. The change in Young's modulus after CR is highly dependent on the type of deformation-induced phase. The increase in Young's modulus after CR is attributed to the deformation-induced ω phase on {3 3 2} mechanical twinning. Ti-30Zr-3Cr-3Mo (3Cr3Mo), which exhibits excellent tensile properties and a changeable Young's modulus, shows a smaller springback than Ti-29Nb-13Ta-4.6Zr, a β-type titanium alloy expected to be useful in spinal fixation applications. Thus, 3Cr3Mo is a potential candidate for spinal fixation applications.

  4. Effect of Surface Modifications of Ti40Zr10Cu38Pd12 Bulk Metallic Glass and Ti-6Al-4V Alloy on Human Osteoblasts In Vitro Biocompatibility

    PubMed Central

    Blanquer, Andreu; Hynowska, Anna; Nogués, Carme; Ibáñez, Elena; Sort, Jordi; Baró, Maria Dolors; Özkale, Berna; Pané, Salvador; Pellicer, Eva

    2016-01-01

    The use of biocompatible materials, including bulk metallic glasses (BMGs), for tissue regeneration and transplantation is increasing. The good mechanical and corrosion properties of Ti40Zr10Cu38Pd12 BMG and its previously described biocompatibility makes it a potential candidate for medical applications. However, it is known that surface properties like topography might play an important role in regulating cell adhesion, proliferation and differentiation. Thus, in the present study, Ti40Zr10Cu38Pd12 BMG and Ti6-Al-4V alloy were surface-modified electrochemically (nanomesh) or physically (microscratched) to investigate the effect of material topography on human osteoblasts cells (Saos-2) adhesion, proliferation and differentiation. For comparative purposes, the effect of mirror-like polished surfaces was also studied. Electrochemical treatments led to a highly interconnected hierarchical porous structure rich in oxides, which have been described to improve corrosion resistance, whereas microscratched surfaces showed a groove pattern with parallel trenches. Cell viability was higher than 96% for the three topographies tested and for both alloy compositions. In all cases, cells were able to adhere, proliferate and differentiate on the alloys, hence indicating that surface topography plays a minor role on these processes, although a clear cell orientation was observed on microscratched surfaces. Overall, our results provide further evidence that Ti40Zr10Cu38Pd12 BMG is an excellent candidate, in the present two topographies, for bone repair purposes. PMID:27243628

  5. First-principles study on magnetism and half-metallicity in bulk and various (001) surfaces of Heusler alloy Zr2VSn with Hg2CuTi-type structure

    NASA Astrophysics Data System (ADS)

    Deng, Zun-Yi; Zhang, Jian-Min

    2016-07-01

    Structural, electronic and magnetic properties in the bulk and five different (001) surfaces (ZrV-, ZrSn-, VV-, ZrZr- and SnSn-terminations) of Zr2 VSn Heusler alloy with Hg2 CuTi -type structure are studied by using first-principles calculations based on density-functional theory. The bulk Zr2 VSn Heusler alloy is ferrimagnetic half-metallicity with equilibrium lattice constant 6.815 Å and total magnetic moment -1.000 μB / f.u . , following the Slater-Pauling rule μt =Zt - 18 . The atoms on different surface layers exhibit different displacements, electronic and magnetic properties. All five (001) surfaces lose the half-metallicity and are not usable in spintronics devices.

  6. Characterizing Sintered Nano-Hydroxyapatite Sol-Gel Coating Deposited on a Biomedical Ti-Zr-Nb Alloy

    NASA Astrophysics Data System (ADS)

    Jafari, Hassan; Hessam, Hamid; Shahri, Seyed Morteza Ghaffari; Assadian, Mahtab; Shairazifard, Shahin Hamtaie Pour; Idris, Mohd Hasbullah

    2016-03-01

    In this study, sol-gel dip-coating method was used to coat nano-hydroxyapatite on specimens of Ti-14Zr-13Nb alloy for orthopedic applications. The coated specimens were sintered at three different temperatures and time spans to evaluate the impact of sintering process on microstructure, mechanical, bio-corrosion, and bioactivity properties of the coating. Field-emission scanning electron microscopy and x-ray diffraction were used to analyze the coating microstructure. Coating adhesion and mechanical performance were also investigated by scratch testing. Besides, electrochemical corrosion and immersion tests were performed in simulated body fluid to examine the sintering effect on corrosion performance and bioactivity of the coatings, respectively. The evaluations of coated specimens displayed that sintering at elevated temperatures leads to higher surface integrity and improves crystallinity of the nano-hydroxyapatite to approximately 89% which brings about distinctively enhanced mechanical properties. Similarly, it improved the corrosion rate for about 17 times through sintering at 700 °C. Immersion test proved that the coating increased the bioactivity resulted from the dissolution of calcium phosphates into the corresponding environment. It is noticeable that sintering the dip-coated specimens in the nano-hydroxyapatite improves corrosion performance and maintains bioactive behaviors as well.

  7. Evolution of Microstructure and Texture during Recrystallization of the Cold-Swaged Ti-Nb-Ta-Zr-O Alloy

    NASA Astrophysics Data System (ADS)

    Guo, W. Y.; Xing, H.; Sun, J.; Li, X. L.; Wu, J. S.; Chen, R.

    2008-03-01

    The deformed microstructure and evolution of microstructure and texture during recrystallization of the cold-swaged multifunctional Ti-23Nb-0.7Ta-2Zr-1.2O (TNTZO, at. pct) alloy were investigated by optical microscope, electron backscatter diffraction, and transmission electron microscope. This alloy has been reported, by Saito et al., to possess a specific dislocation-free plastic deformation mechanism. In this study, the results show a curly grain or swirled structure and a pronounced fibrous {left< {110} rightrangle } texture along the swaging axis in the cold-swaged TNTZO alloy. The normal to the swirled grain surface is near {left< {001} rightrangle } in the cross section of the rod. This characteristic microstructure can be considered to arise from the plane strain deformation of the grains under applied stress, which is similar to that in ordinary bcc metals after heavily drawing or swaging. It is also shown that recovery involves the redistribution and partial annihilation of dislocations within the deformation bands, and recrystallization proceeds by a typical new grain nucleation-growth mechanism during annealing of the TNTZO alloy. The fibrous {left< {110} rightrangle } deformation texture is gradually replaced by random orientations with increasing annealing time. Thus, it could be concluded that the TNTZO alloy deforms by the traditional dislocation glide on {left< {111} rightrangle }{left\\{ {110} right\\}} , {112}, or {123} slip systems, rather than the dislocation-free mechanism.

  8. Coexistence of multiple positive and negative electrocaloric responses in (Pb, La)(Zr, Sn, Ti)O3 single crystal

    NASA Astrophysics Data System (ADS)

    Zhuo, Fangping; Li, Qiang; Gao, Jinghan; Wang, Yujie; Yan, Qingfeng; Zhang, Yiling; Xi, Xiaoqing; Chu, Xiangcheng; Cao, Wenwu

    2016-02-01

    The electrocaloric effect has been investigated in antiferroelectric (Pb, La)(Zr, Sn, Ti)O3 (PLZST) single crystals grown by the flux method. The measurements of polarization versus electric field loops on unpoled crystals revealed that at room temperature, a critical electric field of 1.8 kV/mm is needed to induce a ferroelectric phase from an antiferroelectric phase. The dielectric properties demonstrated that the induced ferroelectric phase recovers to antiferroelectric phase when temperature is above the depolarization temperature (70 °C-100 °C). Coexistence of the negative and positive electrocaloric effect has been achieved in ⟨001⟩-oriented PLZST single crystals. Multiple electrocaloric response values of -0.054 °C at room temperature, 0.17 °C near the depolarization temperature, -0.14 °C at 125 °C, and 0.75 °C around Curie temperature have been observed under an electric field of 3 kV/mm. The coexistence of multiple negative and positive electrocaloric effects in one material provides a possibility to design solid-state refrigerator technologies to enhance the electrocaloric efficiency.

  9. Improving tribological properties of Ti-5Zr-3Sn-5Mo-15Nb alloy by double glow plasma surface alloying

    NASA Astrophysics Data System (ADS)

    Guo, Lili; Qin, Lin; Kong, Fanyou; Yi, Hong; Tang, Bin

    2016-12-01

    Molybdenum, an alloying element, was deposited and diffused on Ti-5Zr-3Sn-5Mo-15Nb (TLM) substrate by double glow plasma surface alloying technology at 900, 950 and 1000 °C. The microstructure, composition distribution and micro-hardness of the Mo modified layers were analyzed. Contact angles on deionized water and wear behaviors of the samples against corundum balls in simulated human body fluids were investigated. Results show that the surface microhardness is significantly enhanced after alloying and increases with treated temperature rising, and the contact angles are lowered to some extent. More importantly, compared to as-received TLM alloy, the Mo modified samples, especially the one treated at 1000 °C, exhibit the significant improvement of tribological properties in reciprocating wear tests, with lower specific wear rate and friction coefficient. To conclude, Mo alloying treatment is an effective approach to obtain excellent comprehensive properties including optimal wear resistance and improved wettability, which ensure the lasting and safety application for titanium alloys as the biomedical implants.

  10. Evaluation of Osseointegration around Tibial Implants in Rats by Ibandronate-Treated Nanotubular Ti-32Nb-5Zr Alloy

    PubMed Central

    Nepal, Manoj; Li, Liang; Bae, Tae Sung; Kim, Byung Il; Soh, Yunjo

    2014-01-01

    Materials with differing surfaces have been developed for clinical implant therapy in dentistry and orthopedics. This study was designed to evaluate bone response to titanium alloy containing Ti-32Nb-5Zr with nanostructure, anodic oxidation, heat treatment, and ibandronate coating. Rats were randomly assigned to two groups for implantation of titanium alloy (untreated) as the control group and titanium alloy group coated with ibandronate as the experimental group. Then, the implants were inserted in both tibiae of the rats for four weeks. After implantation, bone implant interface, trabecular microstructure, mechanical fixation was evaluated by histology, micro-computed tomography (μCT) and the push-out test, respectively. We found that the anodized, heat-treated and ibandronate-coated titanium alloy triggered pronounced bone implant integration and early bone formation. Ibandronate-coated implants showed elevated values for removal torque and a higher level of BV/TV, trabecular thickness and separation upon analysis with μCT and mechanical testing. Similarly, higher bone contact and a larger percentage bone area were observed via histology compared to untreated alloy. Furthermore, well coating of ibandronate with alloy was observed by vitro releasing experiment. Our study provided evidences that the coating of bisphosphonate onto the anodized and heat-treated nanostructure of titanium alloy had a positive effect on implant fixation. PMID:25489426

  11. Possible contribution of low shear modulus C44 to the low Young's modulus of Ti-36Nb-5Zr alloy

    NASA Astrophysics Data System (ADS)

    Meng, Qingkun; Guo, Shun; Ren, Xiaobing; Xu, Huibin; Zhao, Xinqing

    2014-09-01

    Despite the importance of single-crystal elastic constants of β-phase titanium alloys in understanding their low Young's modulus—a property crucial for many applications, such data are often difficult to obtain when the alloy composition is close to the instability limit of the β phase, where the presence of α" martensite precludes the fabrication of β-phase single crystal. In the present study, we extracted the single-crystal elastic constants of such a β-phase titanium alloy with low Young's modulus, Ti-36Nb-5Zr (wt. %), from polycrystalline specimens by using an in-situ synchrotron X-ray diffraction technique. It is indicated that the low Young's modulus of the alloy originates from the anomalously low shear modulus C44 as well as the low shear modulus C', which is different from a common viewpoint that the Young's modulus of β-phase titanium alloys is dominantly controlled by the C'. This suggests that low C44 is an important contributor to low Young's modulus for instable β-phase titanium alloys.

  12. Effect of molybdenum on structure, microstructure and mechanical properties of biomedical Ti-20Zr-Mo alloys.

    PubMed

    Kuroda, Pedro Akira Bazaglia; Buzalaf, Marília Afonso Rabelo; Grandini, Carlos Roberto

    2016-10-01

    Titanium has an allotropic transformation around 883°C. Below this temperature, the crystalline structure is hexagonal close-packed (α phase), changing to body-centered cubic (β phase). Zirconium has the same allotropic transformation around 862°C. Molybdenum has body-centered cubic structure, being a strong β-stabilizer for the formation of titanium alloys. In this paper, the effect of substitutional molybdenum was analyzed on the structure, microstructure and selected mechanical properties of Ti-20Zr-Mo (wt%) alloys to be used in biomedical applications. The samples were prepared by arc-melting and characterized by x-ray diffraction with subsequent refinement by the Rietveld method, optical and scanning electron microscopy. The mechanical properties were analyzed by Vickers microhardness and dynamic elasticity modulus. X-ray measurements and Rietveld analysis revealed the presence of α' phase without molybdenum, α'+α″ phases with 2.5wt% of molybdenum, α″+β phases with 5 and 7.5wt% of molybdenum, and only β phase with 10wt% of molybdenum. These results were corroborated by microscopy results, with a microstructure composed of grains of β phase and lamellae and needles of α' and α″ phase in intra-grain the region. The hardness of the alloy was higher than the commercially pure titanium, due to the action of zirconium and molybdenum as hardening agents. The samples have a smaller elasticity modulus than the commercially pure titanium.

  13. BaZr0.5Ti0.5O3 : Lead-free relaxor ferroelectric or dipolar glass

    NASA Astrophysics Data System (ADS)

    Filipič, C.; Kutnjak, Z.; Pirc, R.; Canu, G.; Petzelt, J.

    2016-06-01

    Glassy freezing dynamics was investigated in BaZr0.5Ti0.5O3 (BZT50) ceramic samples by means of dielectric spectroscopy in the frequency range 0.001 Hz-1 MHz at temperatures 10

  14. Band bending at copper and gold interfaces with ferroelectric Pb(Zr,Ti)O3 investigated by photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Apostol, Nicoleta G.; Ştoflea, Laura E.; Tănase, Liviu C.; Bucur, Ioana Cristina; Chirilă, Cristina; Negrea, Raluca F.; Teodorescu, Cristian M.

    2015-11-01

    Interfaces formed by gold and copper on single crystal layers of (0 0 1) PbZr0.2Ti0.8O3 (PZT) produced by pulsed laser deposition and exhibiting outwards polarization are analyzed by X-ray photoelectron spectroscopy. The stoichiometry of the layers reproduces reasonably that of the PZT target. The band bending occurring at the interface between PZT and the metals is investigated by analyzing the core level shifts as function on the metal deposition. It is found that for Au/PZT(0 0 1) the gold layer is not continuous and the observed band bendings can be attributed to a Schottky mechanism, whereas for Cu/PZT(0 0 1) the copper layer is continuous; in this latter case, the observed band bendings towards higher energies (lower binding energies) can be attributed to a concomitant bending due to the Schottky effect together with the disappearance of the initial bending due to the outwards polarization of the samples. Metal Pb is observed to segregate only in the case of Cu/PZT(0 0 1), therefore the surface self-reduction might also be connected to the presence of a metal with lower work function, which for larger coverage forms a continuous metal layer, able to provide electrons to the surface. High resolution transmission electron spectroscopy yielded the disappearance of the tetragonal distortion in the case of Cu/PZT(0 0 1), in line with the assumption of disappearance of the polarization-induced band bending.

  15. Influence of annealing temperature on Pb(Zr,Ti)O3 nanoparticles growth on multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jeon, Do Hyun; Han, Jin Kyu; Bu, Sang Don

    2015-01-01

    We report the influence of annealing temperature on Pb(Zr,Ti)O3 nanoparticles (PZT NPs) grown on multi-walled carbon nanotubes (MWCNTs). The nanocomposites consist of PZT NPs and MWCNTs that were successfully prepared by using a sol-gel process, followed by an injection using a syringe filter and then by rapid thermal annealing. Field-emission transmission electron microscopy (FETEM) indicated that as the annealing temperature was increased, the shape and the crystallinity of the PZT NPs on the MWCNTs changed from an amorphous structure to the perovskite phase of PZT. Raman spectroscopy showed that the ratio of the intensity of G band to that of the D band, which indicates the crystal purity of the MWCNTs, decreased from 0.57 to 0.55 when the annealing temperature was increased from 500 to 700 °C. A separate distribution of elemental C in the PZT NPs on the MWCNTs annealed at 600 °C was directly observed via energy dispersive X-ray spectroscopy.

  16. Structure-property relationships of antiferroelectric Pb(Zr, Ti)O{sub 3} based materials: Hydrostatic depoling characteristics

    SciTech Connect

    Tuttle, B.; Voigt, J.; Moore, R.

    1997-09-01

    A novel technique has been developed for the synthesis of homogeneous, weakly agglomerated highly filterable Pb(Zr, Ti)O{sub 3} (PZT) powders. PZT 95/5 based ceramics were fabricated from these powders to determine interrelationships among microstructure, dielectric properties and pressure induced ferroelectric (FE) to antiferroelectric (AFE) phase transitions. Initial measurements indicate that microstructure has a substantial effect on hydrostatic depoling characteristics. While smaller grain size materials and higher switching pressures, subtleties in microstructure, which may include entrapped porosity, resulted in a more diffuse depoling characteristic. In addition, greater than 90% dense materials were obtained at process temperatures as low at 900{degrees}C. were only 30% of the values of PZT 95/5 fired at 1300{degrees}C, the dielectric constants of the 900{degrees}C materials were almost a factor of two higher. Backscattered electron Kikuchi pattern analysis determined that adjacent, nonlinear, irregularly shaped domain structures observed by electron channel imaging were 109{degrees} domains.

  17. Flash Memory Featuring Low-Voltage Operation by Crystalline ZrTiO4 Charge-Trapping Layer

    NASA Astrophysics Data System (ADS)

    Shen, Yung-Shao; Chen, Kuen-Yi; Chen, Po-Chun; Chen, Teng-Chuan; Wu, Yung-Hsien

    2017-03-01

    Crystalline ZrTiO4 (ZTO) in orthorhombic phase with different plasma treatments was explored as the charge-trapping layer for low-voltage operation flash memory. For ZTO without any plasma treatment, even with a high k value of 45.2, it almost cannot store charges due the oxygen vacancies-induced shallow-level traps that make charges easy to tunnel back to Si substrate. With CF4 plasma treatment, charge storage is still not improved even though incorporated F atoms could introduce additional traps since the F atoms disappear during the subsequent thermal annealing. On the contrary, nevertheless the k value degrades to 40.8, N2O plasma-treated ZTO shows promising performance in terms of 5-V hysteresis memory window by ±7-V sweeping voltage, 2.8-V flatband voltage shift by programming at +7 V for 100 μs, negligible memory window degradation with 105 program/erase cycles and 81.8% charge retention after 104 sec at 125 °C. These desirable characteristics are ascribed not only to passivation of oxygen vacancies-related shallow-level traps but to introduction of a large amount of deep-level bulk charge traps which have been proven by confirming thermally excited process as the charge loss mechanism and identifying traps located at energy level beneath ZTO conduction band by 0.84 eV~1.03 eV.

  18. Unusual Changes in Electronic Band-Edge Energies of the Nanostructured Transparent n-Type Semiconductor Zr-Doped Anatase TiO2 (Ti1-xZrxO2; x < 0.3).

    PubMed

    Mieritz, Daniel G; Renaud, Adèle; Seo, Dong-Kyun

    2016-07-05

    By the establishment of highly controllable synthetic routes, electronic band-edge energies of the n-type transparent semiconductor Zr-doped anatase TiO2 have been studied holistically for the first time up to 30 atom % Zr, employing powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen gas sorption measurements, UV/vis spectroscopies, and Mott-Schottky measurements. The materials were produced through a sol-gel synthetic procedure that ensures good compositional homogeneity of the materials, while introducing nanoporosity in the structure, by achieving a mild calcination condition. Vegard's law was discovered among the homogeneous samples, and correlations were established between the chemical compositions and optical and electronic properties of the materials. Up to 20% Zr doping, the optical energy gap increases to 3.29 eV (vs 3.19 eV for TiO2), and the absolute conduction band-edge energy increases to -3.90 eV (vs -4.14 eV). The energy changes of the conduction band edge are more drastic than what is expected from the average electronegativities of the compounds, which may be due to the unnatural coordination environment around Zr in the anatase phase.

  19. Systematic theoretical study of ethylene adsorption on δ-MoC(001), TiC(001), and ZrC(001) surfaces

    DOE PAGES

    Jimenez-Orozco, Carlos; Florez, Elizabeth; Moreno, Andres; ...

    2016-05-31

    A systematic study of ethylene adsorption over δ-MoC(001), TiC(001), and ZrC(001) surfaces was conducted by means of calculations based on periodic density functional theory. The structure and electronic properties of each carbide pristine surface had a strong influence in the bonding of ethylene. It was found that the metal and carbon sites of the carbide could participate in the adsorption process. As a consequence of this, very different bonding mechanisms were seen on δ-MoC(001) and TiC(001). The bonding of the molecule on the TMC(001) systems showed only minor similarities to the type of bonding found on a typical metal likemore » Pt(111). In general, the ethylene binding energy follow the trend in stability: ZrC(001) < TiC(001) < δ-MoC(001) < Pt(111). The van der Waals correction to the energy produces large binding energy values, modifies the stability orders and drives the ethylene closer to the surface but the adsorbate geometry parameters remain unchanged. Ethylene was activated on clearly defined binding geometries, changing its hybridization from sp2 to sp3 with an elongation (0.16–0.31 Å) of the C=C bond. As a result, on the basis of this theoretical study, δ-MoC(001) is proposed as a potential catalyst for the hydrogenation of olefins, whereas TiC(001) could be useful for their hydrogenolysis.« less

  20. Systematic theoretical study of ethylene adsorption on δ-MoC(001), TiC(001), and ZrC(001) surfaces

    SciTech Connect

    Jimenez-Orozco, Carlos; Florez, Elizabeth; Moreno, Andres; Liu, Ping; Rodriguez, José A.

    2016-05-31

    A systematic study of ethylene adsorption over δ-MoC(001), TiC(001), and ZrC(001) surfaces was conducted by means of calculations based on periodic density functional theory. The structure and electronic properties of each carbide pristine surface had a strong influence in the bonding of ethylene. It was found that the metal and carbon sites of the carbide could participate in the adsorption process. As a consequence of this, very different bonding mechanisms were seen on δ-MoC(001) and TiC(001). The bonding of the molecule on the TMC(001) systems showed only minor similarities to the type of bonding found on a typical metal like Pt(111). In general, the ethylene binding energy follow the trend in stability: ZrC(001) < TiC(001) < δ-MoC(001) < Pt(111). The van der Waals correction to the energy produces large binding energy values, modifies the stability orders and drives the ethylene closer to the surface but the adsorbate geometry parameters remain unchanged. Ethylene was activated on clearly defined binding geometries, changing its hybridization from sp2 to sp3 with an elongation (0.16–0.31 Å) of the C=C bond. As a result, on the basis of this theoretical study, δ-MoC(001) is proposed as a potential catalyst for the hydrogenation of olefins, whereas TiC(001) could be useful for their hydrogenolysis.

  1. Thermoelectric properties and electronic structure of substituted Heusler compounds: NiTi0.3-xScxZr0.35Hf0.35Sn

    NASA Astrophysics Data System (ADS)

    Ouardi, Siham; Fecher, Gerhard H.; Balke, Benjamin; Schwall, Michael; Kozina, Xeniya; Stryganyuk, Gregory; Felser, Claudia; Ikenaga, Eiji; Yamashita, Yoshiyuki; Ueda, Shigenori; Kobayashi, Keisuke

    2010-12-01

    The effect of Ti substitution by Sc on the thermoelectric properties of the Heusler compounds NiTi0.3-xScxZr0.35Hf0.35Sn (where 0Ti by Sc. The pure compound NiTi0.3Zr0.35Hf0.35Sn showed n-type conductivity with a Seebeck coefficient of -288 μV/K at 350 K, while under Sc substitution the system switched to p-type behavior. A maximum Seebeck coefficient of +230 μV/K (350 K) was obtained by 4% Sc substitution, which is the highest value for p-type thermoelectric compounds based on Heusler alloys. The electronic structure was studied by photoelectron spectroscopy excited by hard x-ray synchrotron radiation. Massive in gap states are observed for the parent compound. This proves that the electronic states close to the Fermi energy play a key role on the behavior of the transport properties. Especially, they are responsible for the high, negative Seebeck coefficient of the parent compound.

  2. Biological Behaviour and Enhanced Anticorrosive Performance of the Nitrided Superelastic Ti-23Nb-0.7Ta-2Zr-0.5N Alloy

    PubMed Central

    Mitran, Valentina; Vasilescu, Cora; Drob, Silviu Iulian; Osiceanu, Petre; Calderon-Moreno, Jose Maria; Tabirca, Mariana-Cristina; Gordin, Doina-Margareta; Gloriant, Thierry; Cimpean, Anisoara

    2015-01-01

    The influence of gas nitriding surface treatment on the superelastic Ti-23Nb-0.7Ta-2Zr-0.5N alloy was evaluated. A thorough characterization of bare and nitrided Ti-based alloy and pure Ti was performed in terms of surface film composition and morphology, electrochemical behaviour, and short term osteoblast response. XPS analysis showed that the nitriding treatment strongly influenced the composition (nitrides and oxynitrides) and surface properties both of the substrate and of the bulk alloy. SEM images revealed that the nitrided surface appears as a similar dotted pattern caused by the formation of N-rich domains coexisting with less nitrided domains, while before treatment only topographical features could be observed. All the electrochemical results confirmed the high chemical stability of the nitride and oxynitride coating and the superiority of the applied treatment. The values of the corrosion parameters ascertained the excellent corrosion resistance of the coated alloy in the real functional conditions from the human body. Cell culture experiments with MG63 osteoblasts demonstrated that the studied biomaterials do not elicit any toxic effects and support cell adhesion and enhanced cell proliferation. Altogether, these data indicate that the nitrided Ti-23Nb-0.7Ta-2Zr-0.5N alloy is the most suitable substrate for application in bone implantology. PMID:26583096

  3. [Selective catalytic reduction of NOx over Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalysts].

    PubMed

    Sun, Hong; Quan, Xie; Zhang, Yao-bin; Zhao, Ya-zhi

    2008-06-01

    Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalyst was prepared by sol-gel and impregnation. Furthermore, selective catalytic reduction of NOx over Pd/CeZr/TiO2/Al2O3 wire-mesh honeycomb catalyst with propylene under lean burn condition was studied. The effects of the concentration of tetra-n-butyl titanate and dipcoat cycles on TiO2 washcoat were studied by SEM, and the effects of Pd concentration, O2 concentration and gas velocity on catalytic activity were investigated. The experimental results showed that the TiO2 washcoat on wire-mesh support is even and crack-free when the support is impregnated in 20.0% tetra- n-butyl titanate sol for 2 cycles. The NOx conversion decreases with Pd concentration increase. When Pd concentration is 0.23%, NOx conversion is highest. NOx conversion increases with oxygen concentration increase in the range of 1.5%-6.0%. However, when oxygen concentration is higher than 6.0%, NOx conversion decreases with increasing oxygen concentration. The NOx conversion decreases with gas velocity increase and its effect is severer at high temperature than low temperature.

  4. Ferroelectric and conductivity behavior of multilayered PbZr0.52Ti0.48O3/Pb(Mg1/3Ta2/3)0.7Ti0.3O3/PbZr0.52Ti0.48O3 thin films

    NASA Astrophysics Data System (ADS)

    Li, Fang; Zhou, Zhaohui; Wang, John

    2006-08-01

    Ferroelectric and impedance behavior of sandwich-structured PbZr0.52Ti0.48O3/Pb(Mg1/3Ta2/3)0.7Ti0.3O3/PbZr0.52Ti0.48O3 thin films was studied as a function of temperature (23-300°C ) and frequency (0.1-104Hz). A change in the controlling mechanism of the electrical behavior from grain interior to grain boundary occurred in the temperature range studied. A low-frequency dielectric relaxation was observed in the temperature range of 200-300°C, the activation energy of which was calculated to be 0.90eV. This suggests that oxygen vacancies are the most likely charge carriers at high temperatures. The change in fatigue behavior of the sandwich-structured thin film with temperature can be accounted for by the increased mobility of oxygen vacancies at elevated temperatures. Frequency dependent conductivities were analyzed with an augmented Jonscher relation. The activation energies for dc conductivity and hopping frequency were calculated to be 0.90 and 0.89eV, respectively.

  5. Synthesis of the ferroelectric solid solution, Pb(Zr{sub 1-x}Ti{sub x})O{sub 3} on a single substrate using a modified molecular beam epitaxy technique

    SciTech Connect

    Anderson, P. S.; Guerin, S.; Hayden, B. E.; Khan, M. A.; Bell, A. J.; Han, Y.; Pasha, M.; Whittle, K. R.; Reaney, I. M.

    2007-05-14

    High-throughput synthesis of the ferroelectric solid solution Pb(Zr{sub 1-x}Ti{sub x})O{sub 3} (PZT) on single Pt/Ti/SiO{sub 2}/Si substrates was demonstrated using a modified molecular beam epitaxy (MBE) system. The PZT films exhibited a phase transition from rhombohehdral to tetragonal symmetry as a function of Zr:Ti ratio, across the substrate diagonal. This was consistent with the presence of a morphotropic phase boundary at Zr:Ti ratio of 0.64:0.36, different from the value of 0.53:0.47 observed for bulk ceramics. All points on the films exhibited ferroelectric hysteresis. Results demonstrate the feasibility of high-throughput MBE for deposition of complex ferroelectric oxides, and pave the way for further materials discovery.

  6. Effect of ZrO2 Source Variations on PbZrO3 - PbTiO3 Piezoelectric Properties.

    DTIC Science & Technology

    1980-01-15

    produced from 27 various ZrO2. vi IT 1 List of Tables Table Page 1 Batch additions for reprecipitation of zirconium hydroxide. 7 2 Batch formulations using...chemical solutions of zirconium . 9 3 Within batch chemical uniformity for six samples of wet blended 10 PZ-PT using Florida precipitate( ZrO. 4...decomposition of zircon sand ( zirconium silicate). By using an optimum ratio of 1.1 parts by weight of caustic soda to 1 part of unground zircon sand and a

  7. Microhardness and lattice parameter calibrations of the oxygen solid solutions of unalloyed alpha-titanium and Ti-6Al-2Sn-4Zr-2Mo

    NASA Technical Reports Server (NTRS)

    Wiedemann, K. E.; Shenoy, R. N.; Unnam, J.

    1987-01-01

    Standards were prepared for calibrating microanalyses of dissolved oxygen in unalloyed alpha-Ti and Ti-6Al-2Sn-4Zr-2Mo. Foils of both of these materials were homogenized for 120 hours in vacuum at 871 C following short exposures to the ambient atmosphere at 854 C that had partially oxidized the foils. The variation of Knoop microhardness with oxygen content was calibrated for both materials using 15-g and 5-g indentor loads. The unit-cell lattice parameters were calibrated for the unalloyed alpha-Ti. Example analyses demonstrate the usefulness of these calibrations and support an explanation of an anomaly in the lattice parameter variation. The results of the calibrations have been tabulated and summarized using predictive equations.

  8. Chromium-free conversion coatings based on inorganic salts (Zr/Ti/Mn/Mo) for aluminum alloys used in aircraft applications

    NASA Astrophysics Data System (ADS)

    Santa Coloma, P.; Izagirre, U.; Belaustegi, Y.; Jorcin, J. B.; Cano, F. J.; Lapeña, N.

    2015-08-01

    Novel chromium-free conversion coatings based on Zr/Ti/Mn/Mo compounds were developed at a pilot scale to improve the corrosion resistance of the AA2024-T3 and AA7075-T6 aluminum alloys for aircraft applications. The influence of the presence of Zr and Ti in the Zr/Ti/Mn/Mo conversion bath's formulation on the corrosion resistance of the coated alloys was investigated. The corrosion resistance provided by the conversion coatings was evaluated by salt spray exposure and potentiodynamic sweeps. Optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and atomic force microscopy (AFM) operating in the Kelvin Probe mode (SKPFM) were used to provide microstructural information of the coated samples that achieved the best results in the corrosion tests. The salt spray test evidenced the higher corrosion resistance of the coated samples compared to the bare surfaces for both alloys. The potentiodynamic tests showed that the corrosion current density decreased for coated AA7075-T6 and AA2024-T3 alloys, which indicated an obvious improvement of the corrosion resistance with all the processes for both alloys. Although the corrosion resistance of the coated samples appeared to be higher for the alloy AA7075-T6 than for the alloy AA2024-T3, both alloys achieved the best corrosion protection with the coatings deposited from conversion bath formulations containing no titanium salts. The microscopy analysis on the coated AA7075-T6 samples revealed that a local deposition of Zr compounds and, possibly, an oxidation process occurred in the vicinity of the alloy's intermetallic particles. The amount of the Zr deposits at these locations increased with coating's formulations without Ti, which provided the best corrosion resistance. The Cr-free conversion coatings developed in this study for the AA7075-T6 and AA2024-T3 alloys do not meet yet the strict requirements of the aircraft industry. However, they significantly improved the corrosion

  9. Wear studies on ZrO2-filled PEEK as coating bearing materials for artificial cervical discs of Ti6Al4V.

    PubMed

    Song, Jian; Liu, Yuhong; Liao, Zhenhua; Wang, Song; Tyagi, Rajnesh; Liu, Weiqiang

    2016-12-01

    Polyetheretherketone (PEEK) and its composite coatings are believed to be the potential candidates' bio-implant materials. However, these coatings have not yet been used on the surface of titanium-based orthopedics and joint products and very few investigations on the tribological characteristics could be found in the published literature till date. In this study, the wettabilities, composition and micro-hardness were characterized using contact angle measurement, scanning electron microscopy (SEM) and hardness tester. The tribological tests were conducted using a ball-on-disc contact pair under 25% newborn calf serum (NCS) lubricated condition. For comparison, bare Ti6Al4V was studied. The obtained results revealed that those PEEK/ZrO2 composite coatings could improve the tribological properties of Ti6Al4V significantly. Adhesive wear and mild abrasive wear might be the dominant wear and failure mechanisms for PEEK/ZrO2 composite coatings in NCS lubricated condition. After comprehensive evaluation in the present study, 5wt.% ZrO2 nanoparticles filled PEEK coating displayed the optimum tribological characteristics and could be taken as a potential candidate for the bearing material of artificial cervical disc.

  10. Effect of Misfit Strain on Pyroelectric Properties of (111) Oriented Pb(Zr1-x Ti x ) O3 Thin Films

    NASA Astrophysics Data System (ADS)

    Qiu, Jian-Hua; Chen, Zhi-Hui; Wang, Xiu-Qin; Yuan, Ning-Yi; Ding, Jian-Ning

    2016-10-01

    Based on the Landau-Dovenshire theory, the thermodynamic potential of (111) oriented films is constructed to investigate the pyroelectric properties of Pb(Zr1-xTix) O3 thin films. Due to the presence of nonlinear coupling terms resulted from the (111) epitaxy with substrates, the effects of misfit strain and electric field on the phase transitions at room temperature are more complex than that of (001) and (110) oriented films. Pb(Zr0.5Ti0.5) O3 thin films with the Ti composition around the morphotropic phase boundary (MPB) have the giant dielectric and pyroelectric properties. Moreover, Pb(Zn1-xTix) O3 thin films grown on the tensile substrates which induce the triclinic γ phase have the larger dielectric and pyroelectric properties than that on the compressive substrates. Therefore, the physical properties of (111) oriented Pb(Zr1-xTix) O3 thin films can be adjusted by choosing the suitable substrates. Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions, the research fund of Jiangsu Province Cultivation base for State Key Laboratory of Photovoltaic Science and Technology, Major Projects of Natural Science Research in Jiangsu Province under Grant Nos. 15KJA43002, 16KJD430006, and also sponsored by Qing Lan Project of Education Department of Jiangsu Province

  11. Examination of Multiphase (Zr,Ti)(V,Cr,Mn,Ni)2 Ni-MH Electrode Alloys: Part I. Dendritic Solidification Structure

    NASA Astrophysics Data System (ADS)

    Boettinger, W. J.; Newbury, D. E.; Wang, K.; Bendersky, L. A.; Chiu, C.; Kattner, U. R.; Young, K.; Chao, B.

    2010-08-01

    The solidification microstructures of three nine-element Zr-Ni-based AB2 type C14/C15 Laves hydrogen storage alloys are determined. The selected compositions represent a class of alloys being examined for usage as an MH electrode in nickel metal-hydride batteries that often have their best properties in the cast state. Solidification is accomplished by dendritic growth of hexagonal C14 Laves phase, peritectic solidification of cubic C15 Laves phase, and formation of cubic B2 phase in the interdendritic regions. The B2 phase decomposes in the solid state into a complex multivariate platelike structure containing Zr-Ni-rich intermetallics. The observed sequence C14/C15 upon solidification agrees with predictions using effective compositions and thermodynamic assessments of the ternary systems, Ni-Cr-Zr and Cr-Ti-Zr. Experimentally, the closeness of the compositions of the C14 and C15 phases required the use of compositional mapping with an energy dispersive detector capable of processing a very high X-ray flux to locate regions in the microstructure for quantitative composition measurement and transmission electron microscope examination.

  12. Designing new biocompatible glass-forming Ti75-x Zr10 Nbx Si15 (x = 0, 15) alloys: corrosion, passivity, and apatite formation.

    PubMed

    Abdi, Somayeh; Oswald, Steffen; Gostin, Petre Flaviu; Helth, Arne; Sort, Jordi; Baró, Maria Dolors; Calin, Mariana; Schultz, Ludwig; Eckert, Jürgen; Gebert, Annett

    2016-01-01

    Glass-forming Ti-based alloys are considered as potential new materials for implant applications. Ti75 Zr10 Si15 and Ti60 Zr10 Nb15 Si15 alloys (free of cytotoxic elements) can be produced as melt-spun ribbons with glassy matrix and embedded single β-type nanocrystals. The corrosion and passivation behavior of these alloys in their homogenized melt-spun states have been investigated in Ringer solution at 37°C in comparison to their cast multiphase crystalline counterparts and to cp-Ti and β-type Ti-40Nb. All tested materials showed very low corrosion rates as expressed in corrosion current densities icorr  < 50 nA/cm(2). Electrochemical and surface analytical studies revealed a high stability of the new alloys passive states in a wide potential range. This corresponds to low passive current densities ipass  = 2 ± 1 µA/cm(2) based on the growth of oxide films with thickness d <10 nm. A homogeneous constituent distribution in the melt-spun alloys is beneficial for stable surface passivity. The addition of Nb does not only improve the glass-forming ability and the mechanical properties but also supports a high pitting resistance even at extreme anodic polarization up to 4V versus SCE were oxide thickness values of d ∼35 nm are reached. With regard to the corrosion properties, the Nb-containing nearly single-phase glassy alloy can compete with the β-type Ti-40Nb alloy. SBF tests confirmed the ability for formation of hydroxyapatite on the melt-spun alloy surfaces. All these properties recommend the new glass-forming alloys for application as wear- and corrosion-resistant coating materials for implants.

  13. Effect of Ce/Zr molar ratio on the performance of Cu–Ce{sub x}–Zr{sub 1−x}/TiO{sub 2} catalyst for selective catalytic reduction of NO{sub x} with NH{sub 3} in diesel exhaust

    SciTech Connect

    Sun, Xiaoliang; Gong, Cairong; Lv, Gang; Bin, Feng; Song, Chonglin

    2014-12-15

    Graphical abstract: The Cu–Ce{sub 0.25}–Zr{sub 0.75}/TiO{sub 2} catalyst exhibited excellent SCR activity at 165–450 °C within the range of exhaust temperatures of diesel engines. - Highlights: • Cu–Ce{sub x}–Zr{sub 1−x}/TiO{sub 2} catalysts were prepared by a wet impregnation method. • The property for NH{sub 3}-selective catalytic reduction of NO{sub x} were investigated. • The Ce/Zr molar ratio had effects on the performance of Cu–Ce–Zr/TiO{sub 2} catalysts. • The Cu–Ce{sub 0.25}–Zr{sub 0.75}/TiO{sub 2} sample exhibited 100% NO{sub x} conversion between 165 °C and 450 °C. • The factors that govern the activity enhancement were extensively investigated. - Abstract: Copper–cerium–zirconium catalysts loaded on TiO{sub 2} prepared by a wet impregnation method were investigated for NH{sub 3}-selective catalytic reduction of NO{sub x}, aiming to study the effects of the Ce/Zr molar ratio on the performance of Cu–Ce–Zr/TiO{sub 2} catalysts. The Cu–Ce{sub 0.25}–Zr{sub 0.75}/TiO{sub 2} sample exhibited nearly 100% NO{sub x} conversion over a wide temperature range (165–450 °C), which is strikingly superior to that of Cu/TiO{sub 2} (210–389 °C) within the range of exhaust temperatures of diesel engines. The factors that govern the activity enhancement were extensively investigated by using a series of characterization techniques, namely X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction by hydrogen (H{sub 2}-TPR). The results showed that the addition of zirconium and/or cerium refined the copper dispersion, prevented copper crystallization and partially incorporated the copper ions into the zirconia (ceira) lattice, which led to enhance the redox abilities of Cu–Ce–Zr/TiO{sub 2} catalysts.

  14. Strong piezoelectric response in stable TiZnN2, ZrZnN2, and HfZnN2 found by ab initio high-throughput approach

    NASA Astrophysics Data System (ADS)

    Tholander, C.; Andersson, C. B. A.; Armiento, R.; Tasnádi, F.; Alling, B.

    2016-12-01

    The phase diagrams of the Ti-Zn-N, Zr-Zn-N, and Hf-Zn-N systems are determined using large-scale high-throughput density functional calculations. Thermodynamically stable ordered phases of TiZnN2, ZrZnN2, and HfZnN2 have been found to be promising candidates in piezoelectric devices/applications for energy harvesting. The identified stable phase of TiZnN2 is an ordered wurtzite superstructure, and the stable phases of ZrZnN2 and HfZnN2 have a layered structure with alternating tetrahedral ZnN and octahedral (Zr, Hf)N layers. All of the TMZnN2 (TM = Ti, Zn, Hf) structures exhibit electronic bandgaps and large piezoelectric constants, d33TiZnN2=14.21 , d24ZrZnN2=-26.15 , and d24HfZnN2=-21.99 pC/N . The strong piezoelectric responses and their thermodynamical stability make materials with these phases promising candidates for piezoelectric applications.

  15. Low-temperature MOCVD growth of oriented PbZr{sub x}Ti{sub 1-x}O{sub 3} thin films on Si substrates.

    SciTech Connect

    Chen, N.

    1998-05-08

    Polycrystalline Pb(Zr{sub 0.6}Ti{sub 0.4})O{sub 3} (PZT) thin films, 3000-6000 {angstrom} thick, have been grown by metal-organic chemical vapor deposition (MOCVD) on (111)Pt/Ti/SiO{sub 2}/Si substrates at temperatures as low as 450-525 C. Random and (111)-oriented, or occasionally (100)-oriented, PZT films can be deposited directly on (111)Pt/Ti/SiO{sub 2}/Si. In addition, highly (100)-oriented films can be deposited consistently by using 150-250 {angstrom} thick (100)-oriented PbTiO{sub 3} (PT) or TiO{sub 2} as a template. Films were characterized by X-ray diffraction, electron microscopy, and electrical measurements. The as-grown (100)-oriented films on (111)Pt/TiSiO{sub 2}/Si substrates exhibited dielectric constants ({var_epsilon}{sub r}) of up to 600, remnant polarization (P{sub r}) of 40 {micro}C/cm{sup 2}, coercive field of 55 kV/cm, and breakdown field of 2-6 x 10{sub 7} V/m.

  16. Fabrication of nano ZrO2 dispersed novel W79Ni10Ti5Nb5 alloy by mechanical alloying and pressureless sintering

    NASA Astrophysics Data System (ADS)

    Sahoo, R. R.; Patra, A.; Karak, S. K.

    2017-02-01

    A high energy planetary ball-mill was employed to synthesize tungsten (W) based alloy with nominal composition of W79Ni10Ti5Nb5(ZrO2)1 (in wt. %) for 20 h with chrome steel as grinding media, toluene as process control agent (PCA) along with compaction at 500 MPa pressure for 5 mins and sintering at 1500°C for 2 h using Ar atmosphere. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), elemental mapping and Transmission electron microscopy (TEM) was used to study the phase formation, microstructure of both milled powder and consolidated alloy. The crystallite size of W in W79Ni10Ti5Nb5(ZrO2)1 powder was 37 nm, 14.7 nm at 10 h and 20 h of milling respectively and lattice strain enhances to 0.54% at 20 h of milling. The crystallite size reduction is more at 10 h of milling and the rate drop beyond 10 to 20 h of milling. The intense improvement in dislocation density was evident upto 10 h of milling and the rate decreases between 10 to 20 h of milling. Increase in the lattice parameter of tungsten in W79Ni10Ti5Nb5(ZrO2)1 alloy upto 0.09% was observed at 10 h of milling owing to severe stress assisted deformation followed by contraction upto 0.07% at 20 h of milling due to formation of solid solution. The large spherical particles at 0 h of milling transformed to elongated shape at 10 h of milling and finer morphology at 20 h of milling. The average particle size reduced from 100 µm to 4.5 µm with the progress of milling from 0 to 20 h. Formation of fine polycrystallites of W was revealed by bright field TEM analysis and the observed crystallite size from TEM study was well supported by the evaluated crystallite size from XRD. XRD pattern and SEM micrograph of sintered alloy revealed the formation of NbNi, Ni3Ti intermetallic phases. Densification of 91.5% was attained in the 20 h milled and sintered alloy. Mechanical behaviour of the sintered product was evaluated by hardness and wear study. W79Ni10Ti5Nb5(ZrO2)1 alloy

  17. Pb(Zr,Ti)O3 ceramic thick films for optical device applications

    NASA Astrophysics Data System (ADS)

    Cardin, J.; Leduc, D.; Boisrobert, C.; Gundel, Hartmut W.

    2003-08-01

    Ferroelectric PbxZryTi1-yO3 (PZT) has been prepared by chemical solution deposition (CSD) and spin-coating technique, using acetate and alkoxide precursors. Rapid thermal annealing has been employed in order to obtain crystallization in the perovskite phase. Aiming to study the optical properties of the films, PZT was deposited on different glass substrates. Structural characterization of the films was done by X-ray diffraction, morphology was investigated by SEM micrography. Using standard photography analysis, the films were qualified in terms of crack density, their appearance strongly depending on the type of substrate. Using a visible to the near infrared spectrophotometer, the transmittance normal to the surface of the films was studied. Coupling of laser light into the films by the M-lines technique allowed the determination of the refractive index and the thickness of the ferroelectric layer. A waveguiding interferometer structure of Mach-Zehnder type was realized by photolithography and wet chemical etching.

  18. Hierarchical surface patterning of Ni- and Be-free Ti- and Zr-based bulk metallic glasses by thermoplastic net-shaping.

    PubMed

    Sarac, Baran; Bera, Supriya; Balakin, Sascha; Stoica, Mihai; Calin, Mariana; Eckert, Jürgen

    2017-04-01

    In order to establish a strong cell-material interaction, the surface topography of the implant material plays an important role. This contribution aims to analyze the formation kinetics of nickel and beryllium-free Ti- and Zr-based Bulk Metallic Glasses (BMGs) with potential biomedical applications. The surface patterning of the BMGs is achieved by thermoplastic net-shaping (TPN) into anisotropically etched cavities of silicon chips. The forming kinetics of the BMG alloys is assessed by thermal and mechanical measurements to determine the most suitable processing temperature and time, and load applied. Array of pyramidal micropatterns with a tip resolution down to 50nm is achievable for the Zr-BMG, where the generated hierarchical features are crucial for surface functionalization, acting as topographic cues for cell attachment. The unique processability and intrinsic properties of this new class of amorphous alloys make them competitive with the conventional biomaterials.

  19. Synthesis and structural investigations of gel metal oxide composites WO₃-ZrO₂, WO₃-TiO₂, WO₃-ZrO₂-SiO₂, and their evaluation as materials for the preparation of ¹⁸⁸W/¹⁸⁸Re generator.

    PubMed

    Iller, Edward; Wawszczak, Danuta; Konior, Marcin; Polkowska-Motrenko, Halina; Milczarek, Jacek J; Górski, Ludwik

    2013-05-01

    The gel composites of WO3-ZrO2, WO3-TiO2, WO3-ZrO2-SiO2 at different molar ratios of oxides were synthesized. The elution profiles of the generator columns packed with gel samples activated at the Polish nuclear research reactor MARIA were studied. The best results of elution were found for WO3-ZrO2 and WO3-TiO2 both at 1:2M ratio annealed at 500°C and 650°C, respectively. Their structure determined with X-ray and neutron diffraction is completely amorphous with spherical grains of ∼23nm diameter. The efficiency of (188)W/(188)Re generators with WO3-ZrO2 gel of natural isotope composition as well as enriched in (186)W were investigated.

  20. Bio-corrosion and cytotoxicity studies on novel Zr55Co30Ti15 and Cu60Zr20Ti20 metallic glasses

    SciTech Connect

    Vincent, S.; Daiwile, A.; Devi, S. S.; Kramer, M. J.; Besser, M. F.; Murty, B. S.; Bhatt, Jatin

    2014-09-26

    Metallic glasses are a potential and compatible implant candidate for biomedical applications. In the present investigation, a comparative study between novel Zr55Co30Ti15 and Cu60Zr20Ti20 metallic glasses is carried out to evaluate in vitro biocompatibility using simulated body fluids. The bio-corrosion behavior of Zr- and Cu-based metallic glasses in different types of artificial body fluids such as artificial saliva solution, phosphate-buffered saline solution, artificial blood plasma solution, and Hank’s balanced saline solution is evaluated using potentiodynamic polarization studies at a constant body temperature of 310.15 K (37 °C). Surface morphology of samples after bio-corrosion experiments was observed by scanning electron microscopy. In vitro cytotoxicity test on glassy alloys were performed using human osteosarcoma cell line as per 10993-5 guidelines from International Organization for Standardization. As a result, the comparative study between Zr- and Cu-based glassy alloys provides vital information about the effect of elemental composition on biocompatibility of metallic glasses.

  1. A-site- and/or B-site-modified PbZrTiO3 materials and (Pb, Sr, Ca, Ba, Mg) (Zr, Ti, Nb, Ta)O3 films having utility in ferroelectric random access memories and high performance thin film microactuators

    NASA Technical Reports Server (NTRS)

    Roeder, Jeffrey F. (Inventor); Chen, Ing-Shin (Inventor); Bilodeau, Steven (Inventor); Baum, Thomas H. (Inventor)

    2001-01-01

    A modified PbZrTiO.sub.3 perovskite crystal material thin film, wherein the PbZrTiO.sub.3 perovskite crystal material includes crystal lattice A-sites and B-sites at least one of which is modified by the presence of a substituent selected from the group consisting of (i) A-site substituents consisting of Sr, Ca, Ba and Mg, and (ii) B-site substituents selected from the group consisting of Nb and Ta. The perovskite crystal thin film material may be formed by liquid delivery MOCVD from metalorganic precursors of the metal components of the thin film, to form PZT and PSZT, and other piezoelectric and ferroelectric thin film materials. The thin films of the invention have utility in non-volatile ferroelectric memory devices (NV-FeRAMs), and in microelectromechanical systems (MEMS) as sensor and/or actuator elements, e.g., high speed digital system actuators requiring low input power levels.

  2. Electric field tuning of magnetic properties in FeGa films on ferroelastic Pb(Zr,Ti)O3 thin films probed by ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Luykx, Arun; Lofland, Samuel; Anbusathaiah, Varatharajan; Nagarajan, Valanoor; Kartawidjaja, Fransiska; Wang, John; Takeuchi, Ichiro

    2009-03-01

    In order to investigate the possibility of fabricating electric field tunable thin film magnetic devices using a multiferroic transduction effect, we have patterned Fe0.7Ga0.3 (FeGa) films sputter-deposited on PbZr0.3Ti0.7O3 (PZT(30/70))/PbZr0.7Ti0.3O3 (PZT(70/30)) tetragonal/rhombohedral bilayers on Pt/Ti/SiO2/Si wafers. Previous piezoforce microscopy studies have shown that the PZT bilayers exhibit presence of ferroelastic domains where the fraction of the local c/a domain ratio can be tuned by an applied electric field. The FeGa top layer was patterned into 20 μm x 20 μm capacitor devices in order to apply electric field to the multilayers, and ferromagnetic resonance (FMR) measurements at 9.2 GHz were performed. Typically, a relatively sharp FMR signal observed before application of the electric field would get substantially broadened after initial application of +4 kV/cm. Angular dependent FMR indicates that magnetic anisotropy in the FeGa is indeed affected by application of electric field.

  3. Ag-TiO2 nanoparticle codoped SiO2 films on ZrO2 barrier-coated glass substrates with antibacterial activity in ambient condition.

    PubMed

    Mukhopadhyay, Anindita; Basak, Sujit; Das, Jugal Kishore; Medda, Samar Kumar; Chattopadhyay, Krishnananda; De, Goutam

    2010-09-01

    Anatase TiO2 and Ag nanoparticles (NPs) codoped SiO2 films were prepared by the sol-gel method. Proportionate amounts of 3-(glycidoxypropyl)trimethoxysilane (GLYMO), tetraethylorthosilicate (TEOS) and 3-(methacryloxypropyl)trimethoxysilane (MEMO) derived inorganic-organic silica sol, commercially available dispersed anatase TiO2 NPs, and AgNO3 were used to prepare the sols. The films were prepared on ZrO2 (cubic) precoated soda-lime glass substrates by a single-dipping technique and heat-treated at 450 °C in air and H2/Ar atmosphere to obtain hard, relatively porous, and transparent coatings of thickness>600 nm. The ZrO2 barrier layer was previously applied on soda-lime glass to restrict the diffusion of Ag into the substrate. The Ag-TiO2 NPs incorporated SiO2 films were intense yellow in color and found to be fairly stable at ambient condition for several days under fluorescent light. These films show a considerable growth inhibition on contact with the gram negative bacteria E. coli.

  4. Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN2 (TM = Ti, Zr, and Hf)

    NASA Astrophysics Data System (ADS)

    Zhang, Meiguang; Cheng, Ke; Yan, Haiyan; Wei, Qun; Zheng, Baobing

    2016-11-01

    Motivated by recent successful synthesis of transition metal dinitride TiN2, the electronic structure and mechanical properties of the discovered TiN2 and other two family members (ZrN2 and HfN2) have been thus fully investigated by using first-principles calculations to explore the possibilities and provide guidance for future experimental efforts. The incompressible nature of these tetragonal TMN2 (TM = Ti, Zr, and Hf) compounds has been demonstrated by the calculated elastic moduli, originating from the strong N-N covalent bonds that connect the TMN8 units. However, as compared with traditional fcc transition metal mononitride (TMN), the TMN2 possess a larger elastic anisotropy may impose certain limitations on possible applications. Further mechanical strength calculations show that tetragonal TMN2 exhibits a strong resistance against (100)[010] shear deformation prevents the indenter from making a deep imprint, whereas the peak stress values (below 12 GPa) of TMN2 along shear directions are much lower than those of TMN, showing their lower shear resistances than these known hard wear-resistant materials. The shear deformation of TMN2 at the atomic level during shear deformation can be attributed to the collapse of TMN8 units with breaking of TM-N bonds through the bonding evolution and electronic localization analyses.

  5. Electronic bonding analyses and mechanical strengths of incompressible tetragonal transition metal dinitrides TMN2 (TM = Ti, Zr, and Hf)

    PubMed Central

    Zhang, Meiguang; Cheng, Ke; Yan, Haiyan; Wei, Qun; Zheng, Baobing

    2016-01-01

    Motivated by recent successful synthesis of transition metal dinitride TiN2, the electronic structure and mechanical properties of the discovered TiN2 and other two family members (ZrN2 and HfN2) have been thus fully investigated by using first-principles calculations to explore the possibilities and provide guidance for future experimental efforts. The incompressible nature of these tetragonal TMN2 (TM = Ti, Zr, and Hf) compounds has been demonstrated by the calculated elastic moduli, originating from the strong N-N covalent bonds that connect the TMN8 units. However, as compared with traditional fcc transition metal mononitride (TMN), the TMN2 possess a larger elastic anisotropy may impose certain limitations on possible applications. Further mechanical strength calculations show that tetragonal TMN2 exhibits a strong resistance against (100)[010] shear deformation prevents the indenter from making a deep imprint, whereas the peak stress values (below 12 GPa) of TMN2 along shear directions are much lower than those of TMN, showing their lower shear resistances than these known hard wear-resistant materials. The shear deformation of TMN2 at the atomic level during shear deformation can be attributed to the collapse of TMN8 units with breaking of TM-N bonds through the bonding evolution and electronic localization analyses. PMID:27830728

  6. Modification of the Ti40Cu36Zr10Pd14 BMG Crystallization Mechanism with Heating Rates 10-140 K/min

    NASA Astrophysics Data System (ADS)

    Czeppe, T.; Sypien, A.; Wierzbicka-Miernik, A.

    2016-12-01

    The article presents investigations of Ti40Cu36Zr10Pd14 bulk metallic glass crystallization process heated with the rates of 10, 60, 100 and 140 K/min. High heating rates experiments were performed in a new type of differential scanning calorimeter equipped with a fast responding thermal sensor. Phase composition and microstructure were studied with x-ray diffraction and transmission electron microscopy. The observed crystallization proceeded in two separate steps. Applied high rates of heating/cooling resulted in the crystallization of only one CuTi phase, replacing typical multi-phase crystallization. The microstructure after crystallization was polycrystalline with some amount of amorphous phase retained. Kinetic parameters were determined with the use of the Kissinger and Friedman iso-conversional analysis and Matusita-Sakka iso-kinetic model. The kinetic analysis supplies results concerning autocatalytically activated mechanism of primary crystallization with decreasing activation energy and small density of quenched-in nuclei, in good agreement with previous structural investigations. The mechanism of secondary crystallization required dense nuclei site, increasing activation energy and large nucleation frequency. The amorphous phase of Ti40Cu36Zr10Pd14 BMG revealed high thermal stability against crystallization. Application of high heating rates in DSC experiments might be useful for the determination of mechanism and kinetic parameters in investigations of metallic glasses crystallization, giving reasonable results.

  7. Bone integration capability of alkali- and heat-treated nanobimorphic Ti-15Mo-5Zr-3Al.

    PubMed

    Tsukimura, Naoki; Ueno, Takeshi; Iwasa, Fuminori; Minamikawa, Hajime; Sugita, Yoshihiko; Ishizaki, Ken; Ikeda, Takayuki; Nakagawa, Kaori; Yamada, Masahiro; Ogawa, Takahiro

    2011-12-01

    The role of nanofeatured titanium surfaces in a number of aspects of in vivo bone-implant integration, and, in particular, their potential advantages over microfeatured titanium surfaces, as well as their specific contribution to osteoconductivity, is largely unknown. This study reports the creation of a unique nanobimorphic titanium surface comprised of nanotrabecular and nanotuft-like structures and determines how the addition of this nanofeature to a microroughened surface affects bone-implant integration. Machined surfaces without microroughness, sandblasted microroughened surfaces, and micro-nano hybrid surfaces created by sandblasting and alkali and heat treatment of Ti-15Mo-5Zr-3Al alloy were subjected to biomechanical, interfacial and histological analyses in a rat model. The presence of microroughness enabled accelerated establishment of biomechanical implant fixation in the early stages of healing compared to the non-microroughened surfaces; however, it did not increase the implant fixation at the late stages of healing. The addition of nanobimorphic features to the microroughened surfaces further increased the implant fixation by as much as 60-100% over the healing time. Bone area within 50 μm of the implant surface, but not beyond this distance, was significantly increased by the presence of nanobimorphic features. Although the percentage of bone-implant contact was also significantly increased by the addition of nanobimorphic features, the greatest improvement was found in the soft tissue intervention between the bone and the implant, which was reduced from >30% to <5%. Mineralized tissue densely deposited with calcium-binding globular proteins was observed in an extensive area of nanobimorphic surfaces after biomechanical testing. This study clearly demonstrates the nanofeature-enhanced osteoconductivity of titanium by an alkali- and heat-treated nanobimorphic surface compared to that by microfeatured surfaces, which results not only in an

  8. Flash Memory Featuring Low-Voltage Operation by Crystalline ZrTiO4 Charge-Trapping Layer

    PubMed Central

    Shen, Yung-Shao; Chen, Kuen-Yi; Chen, Po-Chun; Chen, Teng-Chuan; Wu, Yung-Hsien

    2017-01-01

    Crystalline ZrTiO4 (ZTO) in orthorhombic phase with different plasma treatments was explored as the charge-trapping layer for low-voltage operation flash memory. For ZTO without any plasma treatment, even with a high k value of 45.2, it almost cannot store charges due the oxygen vacancies-induced shallow-level traps that make charges easy to tunnel back to Si substrate. With CF4 plasma treatment, charge storage is still not improved even though incorporated F atoms could introduce additional traps since the F atoms disappear during the subsequent thermal annealing. On the contrary, nevertheless the k value degrades to 40.8, N2O plasma-treated ZTO shows promising performance in terms of 5-V hysteresis memory window by ±7-V sweeping voltage, 2.8-V flatband voltage shift by programming at +7 V for 100 μs, negligible memory window degradation with 105 program/erase cycles and 81.8% charge retention after 104 sec at 125 °C. These desirable characteristics are ascribed not only to passivation of oxygen vacancies-related shallow-level traps but to introduction of a large amount of deep-level bulk charge traps which have been proven by confirming thermally excited process as the charge loss mechanism and identifying traps located at energy level beneath ZTO conduction band by 0.84 eV~1.03 eV. PMID:28272529

  9. Soft-rubber-packaged Pb(Zr,Ti)O3 MEMS touch sensors for human–machine interface applications

    NASA Astrophysics Data System (ADS)

    Takeshita, Toshihiro; Kobayashi, Takeshi; Takei, Ryohei; Itoh, Toshihiro; Takamatsu, Seiichi

    2017-04-01

    We proposed and developed soft-rubber-packaged Pb(Zr,Ti)O3 (PZT) microelectromechanical systems (MEMS) force sensors as human–machine interface sensors of human touch and input. To achieve small and highly sensitive sensors with low-power-consumption, a small PZT MEMS cantilever was used as the sensing element, and it was covered with soft rubber, poly(dimethylsiloxane) (PDMS), to prevent the cracking of the brittle PZT film when touching the sensor. The PDMS packaging does not affect the ferroelectric characteristics of the sensing PZT film, because the hysteresis and impedance changes of the PZT are less than 5%. The sensor dimensions are 5 × 5 × 1.1 mm3. The sensor generated charges without requiring voltage supply. The sensor generated an electric charge of 7.8 pC under an applied force of 1 N. The sensitivity was adjusted by changing the hardness of the soft rubber package: hard rubber provides high sensitivity, but the sensor is easily cracks. Hence, a sensor with a durometer hardness A of 35.6 was found to be optimal as a human–machine interface sensors of human touch of approximately 5–7 N because it has a linear sensitivity at force smaller than 5 N and the bending is small at forces larger than 5 N, which leads to a highly durable sensor. The sensor with a durometer hardness A of 35.6 did not break or crack until the applied force reached 40 N. By packaging brittle PZT MEMS cantilevers with soft rubber, small-force sensors can be constructed, leading to small, low-energy-consumption human–machine interface sensors.

  10. Characterization of solid-phase welds between Ti-6Al-2Sn-4Zr-2Mo-0. 01Si and Ti-13. 5A1-21. 5Nb titanium aluminide

    SciTech Connect

    Baeslack, W.A. III; Juhas, M.; Fraser, H.L. ); Broderick, T.F. . Materials Directorate)

    1994-12-01

    Dissimilar-alloy welds have been produced between Ti-6Al-2Sn-4Zr-2Mo-0.1Si (wt.%) and Ti-13.5Al-21.5Nb (wt.%) titanium aluminide using three different solid-phase welding processes that create significantly different thermo-mechanical conditions at the weld interface. Exposure to supertransus temperatures, appreciable deformation and rapid cooling of the weld interface region during linear-friction welding promote dynamic recrystallization of beta grains and beta decomposition to fine martensitic products. In contrast, diffusion welding at temperatures below the base metal beta transus temperatures and at relatively low pressures minimizes deformation and microstructural variations in the weld interface region relative to the unaffected base metal. During capacitor-discharge resistance spot welding, extremely rapid heating of the weld interface region to near-solidus temperatures, and subsequent rapid cooling, result in the formation of a metastable, ordered-beta microstructure in the Ti-13.5ASl-21.5Nb and fine alpha-prime martensite in the Ti-6Al-2Sn-4Zr-2Mo-0.1Si.

  11. Elastic properties of amorphous T 0.75Y0.75B14 (T  =  Sc, Ti, V, Y, Zr, Nb) and the effect of O incorporation on bonding, density and elasticity (T'  =  Ti, Zr).

    PubMed

    Hunold, Oliver; Keuter, Philipp; Bliem, Pascal; Music, Denis; Wittmers, Friederike; Ravensburg, Anna L; Primetzhofer, Daniel; Schneider, Jochen M

    2017-03-01

    We have systematically studied the effect of transition metal valence electron concentration (VEC) of amorphous T 0.75Y0.75B14 (a-T 0.75Y0.75B14, T  =  Sc, Ti, V, Y, Zr, Nb) on the elastic properties, bonding, density and electronic structure using ab initio molecular dynamics. As the transition metal VEC is increased in both periods, the bulk modulus increases linearly with molar- and mass density. This trend can be understood by a concomitant decrease in cohesive energy. T'  =  Ti and Zr were selected to validate the predicted data experimentally. A-Ti0.74Y0.80B14 and a-Zr0.75Y0.75B14 thin films were synthesized by high power pulsed magnetron sputtering. Chemical composition analysis revealed the presence of up to 5 at.% impurities, with O being the largest fraction. The measured Young's modulus values for a-Ti0.74Y0.80B14 (301  ±  8 GPa) and a-Zr0.75Y0.75B14 (306  ±  9 GPa) are more than 20% smaller than the predicted ones. The influence of O incorporation on the elastic properties for these selected systems was theoretically studied, exemplarily in a-Ti0.75Y0.75B12.75O1.25. Based on ab initio data, we suggest that a-Ti0.75Y0.75B14 exhibits a very dense B network, which is partly severed in a-Ti0.75Y0.75B12.75O1.25. Upon O incorporation, the average coordination number of B and the molar density decrease by 9% and 8%, respectively. Based on these data the more than 20% reduced Young's modulus obtained experimentally for films containing impurities compared to the calculated Young's modulus for a-Ti0.75Y0.75B14 (without incorporated oxygen) can be rationalized. The presence of oxygen impurities disrupts the strong B network causing a concomitant decrease in molar density and Young's modulus. Very good agreement between the measured and calculated Young's modulus values is obtained if the presence of impurities is considered in the calculations. The implications of these findings are that prediction efforts regarding the

  12. Wear transition of solid-solution-strengthened Ti-29Nb-13Ta-4.6Zr alloys by interstitial oxygen for biomedical applications.

    PubMed

    Lee, Yoon-Seok; Niinomi, Mitsuo; Nakai, Masaaki; Narita, Kengo; Cho, Ken; Liu, Huihong

    2015-11-01

    In previous studies, it has been concluded that volume losses (V loss) of the Ti-29Nb-13Ta-4.6Zr (TNTZ) discs and balls are larger than those of the respective Ti-6Al-4V extra-low interstitial (Ti64) discs and balls, both in air and Ringer's solution. These results are related to severe subsurface deformation of TNTZ, which is caused by the lower resistance to plastic shearing of TNTZ than that of Ti64. Therefore, it is necessary to further increase the wear resistance of TNTZ to satisfy the requirements as a biomedical implant. From this viewpoint, interstitial oxygen was added to TNTZ to improve the plastic shear resistance via solid-solution strengthening. Thus, the wear behaviors of combinations comprised of a new titanium alloy, TNTZ with high oxygen content of 0.89 mass% (89O) and a conventional titanium alloy, Ti64 were investigated in air and Ringer's solution for biomedical implant applications. The worn surfaces, wear debris, and subsurface damage were analyzed using a scanning electron microscopy and an electron probe microanalysis. V loss of the 89O discs and balls are smaller than those of the respective TNTZ discs and balls in both air and Ringer's solution. It can be concluded that the solid-solution strengthening by oxygen effectively improves the wear resistance for TNTZ materials. However, the 89O disc/ball combination still exhibits higher V loss than the Ti64 disc/ball combination in both air and Ringer's solution. Moreover, V loss of the disc for the 89O disc/Ti64 ball combination significantly decreases in Ringer's solution compared to that in air. This decrease for the 89O disc/Ti64 ball combination in Ringer's solution can be explained by the transition in the wear mechanism from severe delamination wear to abrasive wear.

  13. Thickness dependence of magnetoelectric response for composites of Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} films on CoFe{sub 2}O{sub 4} ceramic substrates

    SciTech Connect

    Wang, Jing Zhu, Kongjun; Wu, Xia; Deng, Chaoyong; Peng, Renci; Wang, Jianjun

    2014-08-15

    Using chemical solution spin-coating we grew Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} films of different thicknesses on highly dense CoFe{sub 2}O{sub 4} ceramics. X-ray diffraction revealed no other phases except Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} and CoFe{sub 2}O{sub 4}. In many of these samples we observed typical ferroelectric hysteresis loops, butterfly-shaped piezoelectric strains, and the magnetic-field-dependent magnetostriction. These behaviors caused appreciable magnetoelectric responses based on magnetic-mechanical-electric coupling. Our results indicated that the thickness of the Pb(Zr{sub 0.52}Ti{sub 0.48})O{sub 3} film was important in obtaining strong magnetoelectric coupling.

  14. Thickness dependence of magnetoelectric response for composites of Pb(Zr0.52Ti0.48)O3 films on CoFe2O4 ceramic substrates

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Wu, Xia; Peng, Renci; Wang, Jianjun; Deng, Chaoyong; Zhu, Kongjun

    2014-08-01

    Using chemical solution spin-coating we grew Pb(Zr0.52Ti0.48)O3 films of different thicknesses on highly dense CoFe2O4 ceramics. X-ray diffraction revealed no other phases except Pb(Zr0.52Ti0.48)O3 and CoFe2O4. In many of these samples we observed typical ferroelectric hysteresis loops, butterfly-shaped piezoelectric strains, and the magnetic-field-dependent magnetostriction. These behaviors caused appreciable magnetoelectric responses based on magnetic-mechanical-electric coupling. Our results indicated that the thickness of the Pb(Zr0.52Ti0.48)O3 film was important in obtaining strong magnetoelectric coupling.

  15. Mechanical Properties of Low-Density, Refractory Multi-Principal Element Alloys of the Cr-Nb-Ti-V-Zr System (Postprint)

    DTIC Science & Technology

    2014-04-01

    of high temperature properties, including reduced density, superior to existing Ni base superalloys or refractory alloys . Recently a high entropy ...CrMo0.5NbTa0.5TiZr [8,9]. The first three alloys are single phase with a BCC crystal structure, probably due to high entropy of mixing and similar atomic radii of...design strategies used to predict stable high entropy alloys suggest [10,11] that this is the result of adding an element, Cr, which has a much

  16. Influence of residual pressure and ion implantation on the structure, elemental composition, and properties of (TiZrAlYNb)N nitrides

    NASA Astrophysics Data System (ADS)

    Pogrebnjak, A. D.; Yakushchenko, I. V.; Sobol', O. V.; Beresnev, V. M.; Kupchishin, A. I.; Bondar, O. V.; Lisovenko, M. A.; Amekura, H.; Kono, K.; Oyoshi, K.; Takeda, Y.

    2015-08-01

    The nitrides of high-entropy alloys, (TiZrAlYNb)N, fabricated by cathodic vacuum arc evaporation are studied with electron microscopy, atomic force microscopy, laser scanning microscopy; energy-dispersive X-ray analysis, X-ray phase analysis, time-of-flight secondary-ion mass spectrometry; and hardness measurements. It is found that the deposition parameters influence the structure, surface morphology, element distribution, and mechanical properties. The structural—phase state of the coatings before and after the ion implantation of heavy negative gold ions Au- are compared.

  17. Influence of the shot-peening intensity on the structure and near-surface mechanical properties of Ti40Zr10Cu38Pd12 bulk metallic glass

    NASA Astrophysics Data System (ADS)

    González, S.; Fornell, J.; Pellicer, E.; Suriñach, S.; Baró, M. D.; Greer, A. L.; Belzunce, F. J.; Sort, J.

    2013-11-01

    Shot-peening (SP) changes the near-surface structure and mechanical properties of a Ti40Zr10Cu38Pd12 bulk metallic glass. Near the surface, the hardness, Young's modulus, and elastic strain limit are all reduced. Measurements of the heat of relaxation show that an exceptionally high stored energy of cold work can be induced, implying a large increase in free volume. At the highest SP intensity there is partial nanocrystallization enabled by the increased free volume and not by the increase in temperature.

  18. Effect of samarium and iron substitution on the structural and magnetic properties of BaZr0.05Ti0.95O3 ceramics

    NASA Astrophysics Data System (ADS)

    Kaur, Randeep; Kaur, Anumeet; Singh, Anupinder; Singh, Mandeep; Singh, Lakhwant

    2016-05-01

    Samarium and Iron doped barium zirconate titanate (SF-BZT) ceramics with general formula (SmFeO3)x - (BaZr0.05Ti0.95O3)1-x (x = 0, 0.21, 0.22, 0.23) were prepared by solid state reaction route. X-Ray Diffraction revealed the proper phase formation and the profile matching with constant scale factor confirmed phase change from tetragonal to pseudo cubic with increase in samarium and iron content. The SEM micrographs show proper grain growth in samples. The magnetic data confirmed the presence of ferromagnetic character in the SF-BZT solid solutions.

  19. Effect of shock front geometry on shock depolarization of Pb(Zr(0.52)Ti(0.48))O3 ferroelectric ceramics.

    PubMed

    Shkuratov, Sergey I; Baird, Jason; Talantsev, Evgueni F

    2012-07-01

    By use of experimentation, we detected a shock wave geometry effect on the depolarization of poled Pb(Zr(0.52)Ti(0.48))O(3) (PZT 52/48) ferroelectrics. It follows from the experimental results that shock front geometry is one of key parameters in the shock depolarization of PZT 52/48 ferroelectrics. This shock depolarization effect forms a fundamental limit to miniaturization of explosive-driven shock-wave ferroelectric generators (FEGs). Based on obtained experimental results, we developed miniature generators that reliably produce pulsed voltages exceeding 140 kV.

  20. Deformation Mechanisms and Biocompatibility of the Superelastic Ti-23Nb-0.7Ta-2Zr-0.5N Alloy

    NASA Astrophysics Data System (ADS)

    Castany, P.; Gordin, D. M.; Drob, S. I.; Vasilescu, C.; Mitran, V.; Cimpean, A.; Gloriant, T.

    2016-03-01

    In this study, we have synthesized a new Ti-23Nb-0.7Ta-2Zr-0.5N alloy composition with the aim to obtain useful mechanical properties to be used in medicine such as high strength, good superelastic property, low modulus, and large ductility. Thus, mechanical properties including superelasticity and plasticity were investigated in relation with the different deformation mechanisms observed (stress-induced martensitic transformation, twinning and dislocation slip). On the other hand, the corrosion resistance in simulated body fluid (Ringer solution) and the in vitro cell behavior (MG63 human osteoblasts) of such biomedical alloy were also evaluated in order to assess its biocompatibility.

  1. Effect of oxygen barrier coatings on oxidation and embrittlement of Ti-6Al-2Sn-4Zr-2Mo foil in heat shield applications

    NASA Technical Reports Server (NTRS)

    Clark, R. K.; Unnam, J.; Wiedemann, K. E.

    1986-01-01

    Because of the loss of ductility with exposure to oxidizing conditions, long time applications of titanium alloys have been limited to temperatures below 700 K and short time applications have been limited to temperatures below 815 K. Oxygen barrier coatings for shielding Ti-6Al-2Sn-4Zr-2Mo alloy from oxidation during exposure to high temperatures were studied using foil gage specimens. The coatings included micrometer-thick sputtered SiO2 and chemical-vapor-deposited silicate layers both with and without an aluminum basecoat. The oxidation rates and resistance to embrittlement of the coated specimens were significantly better than those of the uncoated specimens.

  2. Effects of a rotating electric field on the properties of epitaxial (001) Pb(Zr,Ti)O3 ultrathin film: a first-principles-based study.

    PubMed

    Sichuga, D; Bellaiche, L

    2014-01-15

    Pb(Zr,Ti)O3 ultrathin films under open-circuit electrical boundary conditions and subjected to an electric field rotating in the (1¯10) plane are investigated via the use of an effective Hamiltonian, for different magnitudes of this field. Varying the direction and magnitude of the electric field leads to specific reorganization of dipoles into original configuration states, whose microstructures and macroscopic properties are revealed. In particular, a novel (direction of the electric field-versus-magnitude of the electric field) phase diagram is reported here. The field-induced correlation between the polar distortions and the oxygen octahedral tilting is also discussed.

  3. Revised structural phase diagram of (Ba{sub 0.7}Ca{sub 0.3}TiO{sub 3})-(BaZr{sub 0.2}Ti{sub 0.8}O{sub 3})

    SciTech Connect

    Keeble, Dean S.; Thomas, Pam A.; Benabdallah, Feres; Maglione, Mario; Kreisel, Jens

    2013-03-04

    The temperature-composition phase diagram of barium calcium titanate zirconate (x(Ba{sub 0.7}Ca{sub 0.3}TiO{sub 3})-(1 - x)(BaZr{sub 0.2}Ti{sub 0.8}O{sub 3}); BCTZ) has been reinvestigated using high-resolution synchrotron x-ray powder diffraction. Contrary to previous reports of an unusual rhombohedral-tetragonal phase transition in this system, we have observed an intermediate orthorhombic phase, isostructural to that present in the parent phase, BaTiO{sub 3}, and we identify the previously assigned T-R transition as a T-O transition. We also observe the O-R transition coalescing with the previously observed triple point, forming a phase convergence region. The implication of the orthorhombic phase in reconciling the exceptional piezoelectric properties with the surrounding phase diagram is discussed.

  4. The structural, electronic, magnetic and mechanical properties of quaternary Heusler alloys ZrTiCrZ (Z  =  Al, Ga, In, Si, Ge, Sn): a first-principles study

    NASA Astrophysics Data System (ADS)

    Yan, Peng-Li; Zhang, Jian-Min; Zhou, Bo; Xu, Ke-Wei

    2016-06-01

    The structural, electronic, magnetic and mechanical properties of the quaternary Heusler alloys ZrTiCrZ (Z  =  Al, Ga, In, Si, Ge, Sn) have been investigated firstly by using the first-principles calculations. The preferred configurations of the ZrTiCrZ alloys are all Y-type (I). At their equilibrium lattice constants, the ZrTiCrZ alloys are half-metallic (HM) ferrimagnets for Z  =  Al, Ga and In, while spin-gapless semiconductor (SGS) antiferromagnets (AFM) for Z  =  Si, Ge and Sn. The total magnetic moments {μt} of the ZrTiCrZ alloys are  -1 {μ\\text{B}}/\\text{f}\\text{.u}\\text{.} for Z  =  Al, Ga and In, while 0 {μ\\text{B}}/\\text{f}\\text{.u}\\text{.} for Z  =  Si, Ge and Sn, both linearly scaled with the total number of valence electrons {{Z}\\text{t}} by Slater-Pauling rule {μ\\text{t}}={{Z}\\text{t}}-18 . The elastic constants {{C}11} , {{C}12} and {{C}44} of the single crystal and the related elastic moduli G , B , E , \\upsilon and A of the polycrystalline aggregates are also calculated and used to study the mechanical stability of these alloys. Although the Curie temperatures {{T}\\text{C}} of the ZrTiCrZ alloys are overestimated by using the mean field approximation (MFA), they can be better estimated by including the exchange interactions. Finally, the HM stabilities as well as the total and atomic magnetic moments of the ZrTiCrZ alloys (Z  =  Al, Ga, In) under either hydrostatic strain or tetragonal strain are also discussed.

  5. Phase Composition of a CrMo0.5NbTa0.5TiZr High Entropy Alloy: Comparison of Experimental and Simulated Data (Postprint)

    DTIC Science & Technology

    2014-04-01

    COMPOSITION OF A CrMo0 5NbTa0 5TiZr HIGH ENTROPY ALLOY : COMPARISON OF EXPERIMENTAL AND SIMULATED DATA (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT...e15093796. 14. ABSTRACT Microstructure and phase composition of a CrMo0 5NbTa0 5TiZr high entropy alloy were studied in the as-solidified and heat...15. SUBJECT TERMS refractory high entropy alloy , microstructure and phase analysis, CALPHAD 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

  6. Structural characterization and optical properties of Sol-gel-derived polycrystalline Pb(Zr0.35Ti0.65)O3 thin films

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Zhang, Rong Jun; Wang, Zi Yi; Zheng, Yu Xiang; Wang, Song You; Zhao, Hai Bin; Chen, Liang Yao; Liu, Xiao Bin; Jiang, An Quan

    2013-07-01

    Polycrystalline Pb(Zr0.35Ti0.65)O3 thin films prepared on Pt/Ti/SiO2/Si substrate by using solgel technique were characterized by using X-ray diffraction (XRD) and atomic force microscopy (AFM). The optical properties of the films were investigated by using spectroscopic ellipsometry (SE) with a four-phase optical model, air/roughness layer/PZT layer/Pt layer in the spectral range of 300-800 nm. The optical band gap of the films calculated following the Tauc's Law was smaller than that of an amorphous PZT thin film with some microcrystals existing on the surface. The result indicates that the quantum-size effect leads to an increase in band gap when the crystalline dimensions become very small.

  7. Evidence of Eu{sup 2+} 4f electrons in the valence band spectra of EuTiO{sub 3} and EuZrO{sub 3}

    SciTech Connect

    Kolodiazhnyi, T.; Valant, M.; Williams, J. R.; Bugnet, M.; Botton, G. A.; Ohashi, N.; Sakka, Y.

    2012-10-15

    We report on optical band gap and valence electronic structure of two Eu{sup 2+}-based perovskites, EuTiO{sub 3} and EuZrO{sub 3} as revealed by diffuse optical scattering, electron energy loss spectroscopy, and valence-band x-ray photoelectron spectroscopy. The data show good agreement with the first-principles studies in which the top of the valence band structure is formed by the narrow Eu 4f{sup 7} electron band. The O 2p band shows the features similar to those of the Ba(Sr)TiO{sub 3} perovskites except that it is shifted to higher binding energies. Appearance of the Eu{sup 2+} 4f{sup 7} band is a reason for narrowing of the optical band gap in the title compounds as compared to their Sr-based analogues.

  8. Evidence of Eu2+ 4f electrons in the valence band spectra of EuTiO3 and EuZrO3

    NASA Astrophysics Data System (ADS)

    Kolodiazhnyi, T.; Valant, M.; Williams, J. R.; Bugnet, M.; Botton, G. A.; Ohashi, N.; Sakka, Y.

    2012-10-01

    We report on optical band gap and valence electronic structure of two Eu2+-based perovskites, EuTiO3 and EuZrO3 as revealed by diffuse optical scattering, electron energy loss spectroscopy, and valence-band x-ray photoelectron spectroscopy. The data show good agreement with the first-principles studies in which the top of the valence band structure is formed by the narrow Eu 4f7 electron band. The O 2p band shows the features similar to those of the Ba(Sr)TiO3 perovskites except that it is shifted to higher binding energies. Appearance of the Eu2+ 4f7 band is a reason for narrowing of the optical band gap in the title compounds as compared to their Sr-based analogues.

  9. Enhanced photocatalytic activity of nanocomposites of TiO2 doped with Zr, Y or Ce polyoxometalates for degradation of methyl orange dye.

    PubMed

    Khoshnavazi, Roushan; Fereydouni, Shler; Bahrami, Leila

    2016-01-01

    The synergistic effect of polyoxometalate (POM) and metal-doped TiO2 (metal = Zr, Y and Ce) was examined, to fabricate nanocomposites with enhanced photocatalytic activities toward the degradation of methyl orange (MO), as a model textile dye. A series of new nanocomposites, containing different loading amounts of H9Na3[WZn3(H2O)2(ZnW9O34)2].24H2O (HZnW) (10-30%) on each of the metal-doped TiO2 nanoparticles, were synthesized using impregnation method. The morphology and crystal phase of the as-prepared nanocomposites were investigated by various characterization techniques: Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray analysis and diffuse reflectance spectroscopy, indicating that the HZnW and metal-doped TiO2 had been successfully incorporated into the nanocomposite structure. The effects of parameters such as loading amount of HZnW, catalyst dose, pH and initial concentration of dye solution were investigated on the degradation kinetics and it was interestingly found that the prepared nanocomposites could efficiently degrade the MO dye in 5-7 min under UV light irradiation. The best results were obtained for the HZnW-Zr-TiO2 among the different nanocomposites. Also, control studies showed the superior photocatalytic properties of composites compared to that of the individual components. The facile preparation and their improved photocatalytic activities suggest that these materials can have a promising future for water and wastewater purifications.

  10. Preparation and properties of highly (100)-oriented Pb(Zr0.2Ti0.8)O3 thin film prepared by rf magnetron sputtering with a PbOx buffer layer

    NASA Astrophysics Data System (ADS)

    Wu, Jiagang; Zhu, Jiliang; Xiao, Dingquan; Zhu, Jianguo; Tan, Junzhe; Zhang, Qinglei

    2007-05-01

    A method for fabrication of highly (100)-oriented Pb(Zr0.2Ti0.8)O3 (PZT) thin films by rf magnetron sputtering with a special buffer of PbOx (RFMS-SBP) was developed. With this method, highly (100)-oriented Pb(Zr0.2Ti0.8)O3 thin films were prepared on the PbOx/Pt(111)/Ti/SiO2/Si(100) substrates, and the preferential (100) orientation of the Pb(Zr0.2Ti0.8)O3 film is 92%. The (100) orientation of the PbOx buffer layer leads to the (100) orientation of the PZT thin films, and the thickness of the buffer layer plays a significant role on the phase purity and electrical properties of the films. Highly (100)-oriented Pb(Zr0.2Ti0.8)O3 thin films with proper thickness of PbOx buffer layer possess good electrical properties with larger remnant polarization Pr (69.7 μC/cm2), lower coercive field Ec (92.4 kV/cm), and good pyroelectric coefficient at room temperature (2.6×10-8 C/cm2 K). The butterfly-shaped ɛ-E characteristic curve gives the evidence of the improved in-plane ferroelectric property in the films.

  11. Effect of Thermal Treatments on Ni-Mn-Ga and Ni-Rich Ni-Ti-Hf/Zr High-Temperature Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Santamarta, Ruben; Evirgen, Alper; Perez-Sierra, Aquilina M.; Pons, Jaume; Cesari, Eduard; Karaman, Ibrahim; Noebe, Ron D.

    2015-11-01

    Among all the promising high-temperature shape memory alloys (HTSMAs), the Ni-Mn-Ga and the Ni-Ti-Hf/Zr systems exhibit interesting shape memory and superelastic properties that may place them in a good position for potential applications. The present work shows that thermal treatments play a crucial role in controlling the martensitic phase transformation characteristics of both systems, but in different ways. On one hand, the equilibrium phase diagram of the Ni-Mn-Ga family allows selecting compositions with high transformation temperatures and outstanding thermal stability at relatively high temperatures in air, showing no significant changes in the transformation behavior for continuous aging up to ˜5 years at 500 °C. Moreover, the excellent thermal stability correlates with a good thermal cyclic stability and an exceptional oxidation resistance of the parent phase. On the other hand, precipitation processes controlled by thermal treatments are needed to manipulate the transformation temperatures, mechanical properties, and thermal stability of Ni-rich Ni-Ti-Hf/Zr alloys to become HTSMAs. These changes in the functional properties are a consequence of the competition between the mechanical and compositional effects of the precipitates on the martensitic transformation.

  12. Phase, crystal struture and sintering behavior of shock-synthesized Pb(Zr 0.95Ti 0.05)O 3 powders

    NASA Astrophysics Data System (ADS)

    Wang, Junxia; Yang, Shiyuan; Wang, Jin; He, Hongliang; Xiong, Ying; Chen, Feng

    2010-12-01

    With a cylindrical shock-wave-loading technique, the single perovskite-phase Pb(Zr 0.95Ti 0.05)O 3 powders (PZT 95/5) were synthesized by shock-induced chemical reactions in heterogeneous multi-material powder mixtures of Pb 3O 4, ZrO 2 and TiO 2. The phase and crystal structure of as-synthesized powders were characterized by X-ray diffraction (XRD) and fourier transform infrared (FT-IR) analysis. And the microstructure and electrical properties of PZT 95/5 ceramics prepared with as-synthesized PZT powders at different sintering temperature were analyzed. The results showed that the shock-wave-induced a large quantity of lattice defects and distortion of the crystal structure in the shock-synthesized PZT powders, which could enhance the sintering activity. Thus, the optimal density and electrical properties of PZT ceramics prepared with as-synthesized powders could be obtained at a sintering temperature of 1200-1225 °C for 3 h, significantly lower than the sintering temperature of PZT 95/5 ceramics prepared by conventional solid-state reaction.

  13. Toxicity of TiO₂, ZrO₂, Fe⁰, Fe₂O₃, and Mn₂O₃ nanoparticles to the yeast, Saccharomyces cerevisiae.

    PubMed

    Otero-González, Lila; García-Saucedo, Citlali; Field, James A; Sierra-Álvarez, Reyes

    2013-10-01

    The growing application of engineered nanomaterials is leading to an increased occurrence of nanoparticles (NPs) in the environment. Thus, there is a need to better understand their potential impact on the environment. This study evaluated the toxicity of nanosized TiO₂, ZrO₂, Fe(0), Fe₂O₃, and Mn₂O₃ towards the yeast Saccharomyces cerevisiae based on O₂ consumption and cell membrane integrity. In addition, the state of dispersion of the nanoparticles in the bioassay medium was characterized. All the nanomaterials showed high tendency to aggregate in the bioassay medium. A non-toxic polyacrylate dispersant was used to improve the NP dispersion stability and test the influence of the aggregation state in their toxicity. Mn₂O₃ NPs showed the highest inhibition of O₂ consumption (50% at 170 mg L(-1)) and cell membrane damage (approximately 30% of cells with compromised membrane at 1000 mg L(-1)), while the other NPs caused low (Fe(0)) or no toxicity (TiO₂, ZrO₂, and Fe₂O₃) to the yeast. Dispersant supplementation decreased the inhibition caused by Mn₂O₃ NPs at low concentrations, which could indicate that dispersant association with the particles may have an impact on the interaction between the NPs and the cells.

  14. Multiferroic CoFe2O4-Pb(Zr0.52Ti0.48)O3 core-shell nanofibers and their magnetoelectric coupling

    NASA Astrophysics Data System (ADS)

    Xie, Shuhong; Ma, Feiyue; Liu, Yuanming; Li, Jiangyu

    2011-08-01

    Multiferroic CoFe2O4-Pb(Zr0.52Ti0.48)O3 core-shell nanofibers have been synthesized by coaxial electrospinning in combination with a sol-gel process. The core-shell configuration of nanofibers has been verified by scanning electron microscopy and transmission electron microscopy, and the spinel structure of CoFe2O4 and perovskite structure of Pb(Zr0.52Ti0.48)O3 have been confirmed by X-ray diffraction and selected area electron diffraction. The multiferroic properties of core-shell nanofibers have been demonstrated by magnetic hysteresis and piezoresponse force microscopy, and their magnetoelectric coupling has been confirmed by evolution of piezoresponse under an external magnetic field, showing magnetically induced ferroelectric domain switching and changes in switching characteristics. The lateral magnetoelectric coefficient is estimated to be 2.95 × 104 mV/cmOe, two orders of magnitude higher than multiferroic thin films of similar composition.

  15. Manipulation of electronic and magnetic properties of M2C (M = Hf, Nb, Sc, Ta, Ti, V, Zr) monolayer by applying mechanical strains

    NASA Astrophysics Data System (ADS)

    Zhao, Shijun; Kang, Wei; Xue, Jianming

    2014-03-01

    Tuning the electronic and magnetic properties of a material through strain engineering is an effective strategy to enhance the performance of electronic and spintronic devices. In this paper, first-principles calculations based on density functional theory are carried out to investigate the electronic and magnetic properties of M2C(M = Hf, Nb, Sc, Ta, Ti, V, Zr, known as MXenes) subjected to biaxial symmetric mechanical strains. At the strain-free state, all these MXenes exhibit no spontaneous magnetism except for Ti2C and Zr2C which show a magnetic moment of 1.92 and 1.25 μB/unit, respectively. As the tensile strain increases, the magnetic moments of MXenes are greatly enhanced and a transition from nonmagnetism to ferromagnetism is observed for those nonmagnetic MXenes at zero strains. The most distinct transition is found in Hf2C, in which the magnetic moment is elevated to 1.5 μB/unit at a strain of 1.80%. We further show that the magnetic properties of Hf2C are attributed to the band shift mainly composed of Hf(5d) states.

  16. Enhanced photocathodic behaviors of Pb(Zr{sub 0.20}Ti{sub 0.80})O{sub 3} films on Si substrates for hydrogen production

    SciTech Connect

    Cheng, Xiaorong; Dong, Wen; Zheng, Fengang; Fang, Liang; Shen, Mingrong

    2015-06-15

    Wide bandgap ferroelectric Pb(Zr{sub 0.20}Ti{sub 0.80})O{sub 3} films were deposited on indium tin oxide (ITO) coated Si-pn{sup +} substrates with an intention to form efficient Si-pn{sup +}/ITO/Pb(Zr,Ti)O{sub 3} (PZT) photocathode for hydrogen production. Depolarization electric field generated in PZT film due to poling can drive the photogenerated electrons from Si-pn{sup +} junction to PZT film, resulting in enhanced photoelectrochemical activity of the photocathode. Comparing the electrode with as-prepared PZT film, the photocurrent increased from −100 μA cm{sup −2} to −1.2 mA cm{sup −2} at 0 V vs. reversible hydrogen electrode (RHE) and the onset potential from 0.36 V to 0.7 V vs. RHE under 100 mW cm{sup −2} illumination, manifesting the great advantage of depolarization electric field in driving the photogenerated carriers not only in the ferroelectric film but also on the interface of different semiconductors.

  17. Theoretical study of phase stability and elastic properties of T 0.75Y0.75B14 (T = Sc, Ti, V, Y, Zr, Nb, Si).

    PubMed

    Hunold, Oliver; Music, Denis; Schneider, Jochen M

    2016-03-16

    In this study the phase stability, elastic properties, and plastic behaviour of icosahedral transition metal borides T 0.75Y0.75B14 (T = Sc, Ti, V, Y, Zr, Nb, Si) have been investigated using density functional theory. Phase stability critically depends on the charge transferred by T and Y to the B icosahedra. For the metal sublattice occupancy investigated here, the minimum energy of formation is identified at an effective B icosahedra charge of - 1.8 ± 0.1. This charge corridor encompasses the highest phase stability among all the reported icosahedral transition metal boride systems so far. This data provides guidance for future experimental efforts: from a wear-resistance point of view, Sc0.75Y0.75B14, Ti0.75Y0.75B14, and Zr0.75Y0.75B14 exhibit a rather unique and attractive combination of large Young's modulus values ranging from 488 to 514 GPa with the highest phase stability for icosahedral transition metals borides reported so far.

  18. Note: utilizing Pb(Zr(0.95)Ti(0.05))O3 ferroelectric ceramics to scale down autonomous explosive-driven shock-wave ferroelectric generators.

    PubMed

    Shkuratov, Sergey I; Baird, Jason; Talantsev, Evgueni F

    2012-07-01

    Further miniaturization of recently designed autonomous ferroelectric generators (FEGs) [S. I. Shkuratov, J. Baird, and E. F. Talantsev, Rev. Sci. Instrum. 82, 086107 (2011)], which are based on the effect of explosive-shock-wave depolarization of poled ferroelectrics is achieved. The key miniaturization factor was the utilization of high-energy density Pb(Zr(0.95)Ti(0.05))O(3) (PZT 95/5) ferroelectric ceramics as energy-carrying elements of FEGs instead of the previously used Pb(Zr(0.52)Ti(0.48))O(3) (PZT 52/48). A series of experiments demonstrated that FEGs based on smaller PZT 95/5 ferroelectric elements are capable of producing the same output voltage as those based on PZT 52/48 elements twice as large. It follows from the experimental results that the FEG output voltage is directly proportional to the thickness of PZT 95/5 samples. A comparison of the operation of FEGs based on PZT 95/5 and on PZT 52/48 ferroelectrics is presented.

  19. Influence of an MgO interfacial layer on the properties of Pb(Zr,Ti)O3/ZnO ferroelectric-semiconductor heterostructures

    NASA Astrophysics Data System (ADS)

    Xiao, Bo; Walker, Brandon; Pradhan, Aswini K.

    2014-05-01

    We report on the study of high quality Pb(Zr,Ti)O3 thin films grown by radio-frequency magnetron sputtering on (0 0 0 1) ZnO with an MgO interfacial seed layer. A systematic investigation of the heterostructures has been performed by x-ray diffraction, atomic force microscopy (AFM) and ultraviolet-visible spectroscopy for the structural and optical properties, along with the electrical characterization and simulation. (0 1 1)-oriented perovskite phase was observed in Pb(Zr,Ti)O3 thin films which used the MgO seed layer, whereas the pyrochlore phase was dominant in the films deposited directly on ZnO. The surface morphology measured by AFM indicated that the introduction of the MgO interfacial seed layer promoted formation of a smooth surface and uniform grain structures in the thin films. The transmission spectra also showed an increase of the optical transmittance measured by ultraviolet-visible spectroscopy. The capacitance-voltage measurements exhibited butterfly-shaped capacitance curves which bear a resemblance to those of the typical metal-ferroelectric-metal structures. The characteristics of the polarization versus electric field were investigated by a simulation to understand the behaviour of the hysteresis loops in this metal-ferroelectric-insulator-semiconductor structure.

  20. Polarization induced self-doping in epitaxial Pb(Zr0.20Ti0.80)O3 thin films

    PubMed Central

    Pintilie, Lucian; Ghica, Corneliu; Teodorescu, Cristian Mihail; Pintilie, Ioana; Chirila, Cristina; Pasuk, Iuliana; Trupina, Lucian; Hrib, Luminita; Boni, Andra Georgia; Georgiana Apostol, Nicoleta; Abramiuc, Laura Elena; Negrea, Raluca; Stefan, Mariana; Ghica, Daniela

    2015-01-01

    The compensation of the depolarization field in ferroelectric layers requires the presence of a suitable amount of charges able to follow any variation of the ferroelectric polarization. These can be free carriers or charged defects located in the ferroelectric material or free carriers coming from the electrodes. Here we show that a self-doping phenomenon occurs in epitaxial, tetragonal ferroelectric films of Pb(Zr0.2Ti0.8)O3, consisting in generation of point defects (vacancies) acting as donors/acceptors. These are introducing free carriers that partly compensate the depolarization field occurring in the film. It is found that the concentration of the free carriers introduced by self-doping increases with decreasing the thickness of the ferroelectric layer, reaching values of the order of 1026 m−3 for 10 nm thick films. One the other hand, microscopic investigations show that, for thicknesses higher than 50 nm, the 2O/(Ti+Zr+Pb) atomic ratio increases with the thickness of the layers. These results suggest that the ratio between the oxygen and cation vacancies varies with the thickness of the layer in such a way that the net free carrier density is sufficient to efficiently compensate the depolarization field and to preserve the outward direction of the polarization. PMID:26446442

  1. Effects of silicon content on the structure and mechanical properties of (AlCrTaTiZr)-Six-N coatings by reactive RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Cheng, Keng-Hao; Tsai, Che-Wei; Lin, Su-Jien; Yeh, Jien-Wei

    2011-05-01

    Multi-component (AlCrTaTiZr)-Six-N films were deposited on silicon wafers by reactive RF magnetron co-sputtering. The effect of silicon content on the structure, morphology and mechanical properties of the nitride films was investigated. Nitride films with lower silicon content remained as a simple NaCl-type face-centred cubic (FCC) structure. As the silicon content reached 7.9 at%, thermodynamically driven phase separation occurred, leading to a nanocomposite structure consisting of an FCC solid-solution nitride and an amorphous SiNx phase. These nitride films exhibited a high hardness of 34 GPa and remained at a constant level up to 7.9 at% Si. The reduced hardness at a silicon content of 10.2 at% was attributed to the appreciable amounts of softer amorphous segregation. The silicon incorporation significantly improved the oxidation resistance of (AlCrTaTiZr)N films. The film containing 7.9 at% Si annealed at 1000 °C for 2 h in air only had a 330 nm-thick oxide layer. The optimum Si content is 7.9 at% since it gives the best combination of hardness and oxidation resistance.

  2. Liquid-to-glass transition in bulk glass-forming Cu60Ti20Zr20 alloy by molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Han, X. J.; Teichler, H.

    2007-06-01

    We report results from molecular dynamics studies concerning the microscopic structure and dynamics of the ternary, bulk metallic glass-forming Cu60Ti20Zr20 alloy. In detail we consider the partial radial distribution functions, nearest-neighbor numbers, specific heat, simulated glass temperature, diffusion coefficients, and incoherent intermediate scattering function (ISF). The applied atomic model reproduces well experimental x-ray data of the total radial distribution function. It provides for Cu60Ti20Zr20 a structure with marked intermediate-range order. The ISF is analyzed within an extension of mode-coupling theory, where the effective memory kernel is evaluated from the Laplace transform of the ISF. The dynamics of the system fulfills in most respects the predictions of mode-coupling theory (MCT), up to an absence of the algebraic t-a decay in the early β range. Comparison with the calculated memory kernel shows that this absence can be traced back to deviations of the kernel from its approximate form analyzed in MCT. As by-product, our investigation provides a method to reconstruct around the critical temperature major parts of the memory kernel from λ and the plateau value fc of the ISF, and it indicates why the critical dynamics predicted by mode-coupling theory can be observed in a temperature interval of more than 500K .

  3. Structural, stability and electronic properties of C15-AB2 (A = Ti, Zr; B = Cr) intermetallic compounds and their hydrides: An ab initio study

    NASA Astrophysics Data System (ADS)

    Sarhaddi, Reza; Arabi, Hadi; Pourarian, Faiz

    2014-05-01

    The structural, stability and electronic properties of C15-AB2 (A = Ti, Zr; B = Cr) isomeric intermetallic compounds were systematically investigated by using density functional theory (DFT) and plane-wave pseudo-potential (PW-PP) method. The macroscopic properties including the lattice constant, bulk modulus and stability for these compounds were studied before and after hydrogenation. For parent compounds, the enthalpy of formation was evaluated with regard to their bulk modules and electronic structures. After hydrogenation of compounds at different interstitial tetrahedral sites (A2B2, A1B3, B4), a volume expansion was found for hydrides. The stability properties of hydrides characterized the A2B2 sites as the site preference of hydrogen atoms for both compounds. The Miedema's "reverse stability" rule is also satisfied in these compounds as lower the enthalpy of formation for the host compound, the more stable the hydride. Analysis of microscopic properties (electronic structures) after hydrogenation at more stable interstitial site (A2B2) shows that the H atoms interact stronger with the weaker (or non) hydride forming element B (Cr) than the hydride forming element A (Ti/Zr). A correlation was also found between the stability of the hydrides and their electronic structure: the deeper the hydrogen band, the less stable the hydride.

  4. Synthesis and Characterization of Ba(Zr{sub x}Ti{sub 1-x})O{sub 3} Solid Solutions Using Impedance Spectroscopic Techniques

    SciTech Connect

    Bajpai, P. K.; Mohan, C. R. K.

    2011-11-22

    Technologically important solid solutions of Ba(Zr{sub x}Ti{sub 1-x})O{sub 3} are synthesized using conventional solid state route. Relatively dense and single phase ceramics are confirmed using X-ray diffraction. Homogeneous and micron size grain growth is characterized using SEM. Impedance spectroscopy is used to study the electrical properties of ceramics. Broad and diffuse impedance loss peak is observed above 250 deg. C, which shifts towards higher frequency with increase in temperature. The distribution of relaxation frequency may be associated with the B-site cationic disorder due to the random distribution of (Zr{sup 4+}/Ti{sup +4}) having different ionic radii. Impedance relaxation obeys the Arrhenius relation with activation energy, E{tau} is 0.31 eV and 0.48 eV for BZT compositions with x = 0.10 and 0.15 respectively. Equivalent circuit representation using two RC element coupled in parallel is used to analyse the impedance response.

  5. The structural and in-plane dielectric/ferroelectric properties of the epitaxial (Ba, Sr)(Zr, Ti)O{sub 3} thin films

    SciTech Connect

    Chan, N. Y. Wang, Y.; Chan, H. L. W.; Wang, D. Y.; Dai, J. Y.

    2014-06-21

    Epitaxial (Ba{sub 1-x}Sr{sub x})(Zr{sub 0.1}Ti{sub 0.9})O{sub 3} (BSZT, x = 0 – 0.45) thin films were deposited on (LaAlO{sub 3}){sub 0.3}(Sr{sub 2}AlTaO{sub 6}){sub 0.35} (LSAT) substrates by pulsed laser deposition. The experimental results demonstrate that the structural, dielectric, and ferroelectric properties of the BSZT thin films were greatly dependent on the strontium content. The BSZT thin films transformed from tetragonal to cubic phase when x ≥ 0.35 at room temperature. The Curie temperature and room-temperature remnant polarization decrease with increasing strontium concentration. The optimal dielectric properties were found in (Ba{sub 0.55}Sr{sub 0.45})(Zr{sub 0.1}Ti{sub 0.9})O{sub 3} thin films which is in paraelectric state, having tunability of 47% and loss tangent of 0.0338 under an electric field of 20 MV/m at 1 MHz. This suggests that BSZT thin film is a promising candidate for tunable microwave device applications.

  6. Novel Neo-Pentoxide Precursors for MOCVD Thin Films of TiO(2) and ZrO(2).[1

    SciTech Connect

    Boyle, Timothy J.; Francisco, Laila P.; Gallegos, Jesus J.; Rodriguez, Mark A.; Ward, Timothy L.

    1999-07-14

    Two novel Group IV precursors, titanium (IV) neo-pentoxide, [Ti({mu}-ONep)(ONep){sub 3}]{sub 2} (l), and zirconium (IV) neo-pentoxide, [Zr({mu}-ONep)(ONep){sub 3}]{sub 2} (2), were reported to possess relatively high volatility at low temperatures. These compounds were therefore investigated as MOCVD precursors using a lamp-heated cold-wall CVD reactor and direct sublimation without carrier gas. The ONep derivatives proved to be competitive precursors for the production of thin films of the appropriate MO{sub 2} (M = Ti or Zr) materials in comparison to other metallo-organic precursors. Compound 1 was found to sublime at 120 C with a deposition rate of {approximately}0.350 {mu}m/min onto a substrate at 330 C forming the anatase phase with < 1% residual C found in the final film. Compound 2 was found to sublime at 160 C and deposited as crystalline material at 300 C with < 1% residual C found in the final film. A comparison to standard alkoxide and {beta}-diketonates is presented where appropriate.

  7. Sonophotocatalytic degradation of 4-chlorophenol using Bi2O3/TiZrO4 as a visible light responsive photocatalyst.

    PubMed

    Neppolian, Bernaurdshaw; Ciceri, Luca; Bianchi, Claudia L; Grieser, Franz; Ashokkumar, Muthupandian

    2011-01-01

    The oxidative degradation of 4-chlorophenol (4-CP) by sonolytic, photocatalytic and sonophotocatalytic processes was studied in aqueous solutions using Bi(2)O(3)/TiZrO(4) as a visible light driven photocatalyst and with 20 kHz ultrasound. The results reveal that Bi(2)O(3)/TiZrO(4) is an efficient photocatalyst capable of degrading 4-CP by both photocatalytic and sonophotocatalytic processes. During the sonolysis of 4-CP solutions, HPLC results showed the formation of a number of intermediate products, whereas, no such intermediates were formed during the sonophotocatalytic degradation of 4-CP. TOC results showed rapid mineralization of 4-CP during the sonophotocatalytic degradation process, relative to that observed with sonolysis alone. The results reveal a clear advantage in using a coupled method for the oxidation of 4-CP and a cumulative effect was observed. Further, the solution pH had no specific influence on the sonophotocatalytic degradation of 4-CP, unlike the situation for sonolysis alone where the degradation rate decreased as the pH was raised from acidic to basic conditions. The combined sonophotocatalytic degradation process was found to be simple to apply and has the potential to be a powerful method for the remediation of organic contaminants present in water and wastewater.

  8. Dynamic hysteresis scaling of ferroelectric Pb(0.9)Ba(0.1)(Zr(0.52)Ti(0.48))O(3) thin films.

    PubMed

    Guo, Y Y; Wei, T; He, Q Y; Liu, J-M

    2009-12-02

    We measure systematically the intrinsic scaling behavior of dynamic hysteresis for Pb(0.9)Ba(0.1)(Zr(0.52)Ti(0.48))O(3) (PBZT) ferroelectric thin films with Pt electrodes on Si substrates, utilizing the Sawyer-Tower technique. For the as-prepared thin films of similar thickness and microstructure, over the low frequency range, the scaling follows the power law [Formula: see text] under low E(0) and the power law [Formula: see text] under high E(0), where ⟨A⟩ is the hysteresis area, and f and E(0) are the frequency and amplitude of the external electric field. In the high- f range, the power law for low E(0) takes the form of [Formula: see text], while that for high E(0) takes the form of [Formula: see text]. It is identified that the dynamic behaviors at low frequency mainly come from the intrinsic domain reversal instead of others like the leakage current, while the depolarization field may influence the frequency exponents at high frequency. We study the temperature scaling of the hysteresis, indicating that the scaling under low E(0) is roughly consistent with the (Φ(2))(2) model. Finally, we argue that experimentally obtained power law scaling for Pb(Zr(0.52)Ti(0.48))O(3) thin films prepared under the given conditions may not be reliable due to the polarization fatigue effect.

  9. Manipulation of electronic and magnetic properties of M{sub 2}C (M = Hf, Nb, Sc, Ta, Ti, V, Zr) monolayer by applying mechanical strains

    SciTech Connect

    Zhao, Shijun; Kang, Wei; Xue, Jianming

    2014-03-31

    Tuning the electronic and magnetic properties of a material through strain engineering is an effective strategy to enhance the performance of electronic and spintronic devices. In this paper, first-principles calculations based on density functional theory are carried out to investigate the electronic and magnetic properties of M{sub 2}C(M = Hf, Nb, Sc, Ta, Ti, V, Zr, known as MXenes) subjected to biaxial symmetric mechanical strains. At the strain-free state, all these MXenes exhibit no spontaneous magnetism except for Ti{sub 2}C and Zr{sub 2}C which show a magnetic moment of 1.92 and 1.25 μ{sub B}/unit, respectively. As the tensile strain increases, the magnetic moments of MXenes are greatly enhanced and a transition from nonmagnetism to ferromagnetism is observed for those nonmagnetic MXenes at zero strains. The most distinct transition is found in Hf{sub 2}C, in which the magnetic moment is elevated to 1.5 μ{sub B}/unit at a strain of 1.80%. We further show that the magnetic properties of Hf{sub 2}C are attributed to the band shift mainly composed of Hf(5d) states.

  10. The catalytic performance and characterization of ZrO2 support modification on CuO-CeO2/TiO2 catalyst for the simultaneous removal of Hg0 and NO

    NASA Astrophysics Data System (ADS)

    Wang, Teng; Li, Caiting; Zhao, Lingkui; Zhang, Junyi; Li, Shanhong; Zeng, Guangming

    2017-04-01

    The different addition amounts of ZrO2 on CuO-CeO2/TiO2 catalyst synthesized by co-precipitation method were investigated to research the simultaneous removal of Hg0 and NO in simulated flue gas. Results indicated that the CuCe/TiZr0.15 catalyst exhibited the superior Hg0 removal efficiency (72.7%) and prominent NO conversion (83.3%). Hg0 slightly restrained the NO conversion. Except for the effect of the separate NH3 and NO on Hg0 removal, significances of the increased NH3/NO ratio on Hg0 removal and NO conversion were detected. The lower GHSV could give rise to the significant acceleration of Hg0 and NO removal. With the existence of SO2 and H2O, the slightly prohibitive effect on Hg0 and NO removal was displayed. BET, XRD, SEM, H2-TPR, XPS, FTIR analysis were applied to characterize catalysts and the results revealed the ZrO2 modified support on CuO-CeO2/TiO2 resulted in strong redox ability, great mobility of surface oxygen and growing total amount of chemisorbed oxygen and lattice oxygen, which favorably impacted on Hg0 and NO removal. The introduction of Zr benefited great surface area, weakened crystallinity of TiO2 and then improved the dispersion of metal oxide species. More stable Lewis acid sites to form coordinated NH3 were generated due to ZrO2 additive. The synergetic effect through redox equilibrium of Ce3+ + Cu2+ ↔ Ce4+ + Cu+ contributed to Hg0 removal and NO conversion. In addition, the simultaneous removal of Hg0 and NO on CuCe/TiZr0.15 in terms of detailed mechanism was discussed.

  11. Nanoscale polarisation switching and leakage currents in (Ba0.955Ca0.045)(Zr0.17Ti0.83)O3 epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Sreenivas Puli, Venkata; Pradhan, Dhiren K.; Adireddy, Shiva; Martínez, R.; Silwal, Punam; Scott, J. F.; Ramana, C. V.; Chrisey, Douglas B.; Katiyar, Ram S.

    2015-09-01

    This paper investigates the crystal structure, ferroelectric, temperature-dependent leakage current conduction mechanism and the piezoresponse force microscopy (PFM) behaviours of (Ba0.955Ca0.045) (Zr0.17Ti0.83)O3-BZT-BCT (x=0.15 ) films at the vicinity of the morphotropic phase boundary (MPB) of the [(1  -  x) BaZr0.20Ti0.80O3-xBa0.70Ca0.30TiO3] (x=0.50 ) composition. Epitaxial BZT-BCT thin films were grown on conductive La0.5Sr0.5CoO3 (LSCO) layers coated onto MgO (1 0 0) single-crystal substrates by pulsed laser deposition (PLD). High resolution x-ray diffraction (HR-XRD) reciprocal space maps (RSMs) confirmed the epitaxy with in-plane tetragonal symmetry (c  <  a), and Raman spectra also revealed a tetragonal perovskite crystalline lattice structure. Polarisation studies demonstrate that BZT-BCT films exhibit a high saturation polarisation of 148 µC cm-2 and a high recoverable (discharged) energy-storage density of 39.11 J cm-3 at 2.08 MV cm-1. Temperature-dependent P-E hysteresis loops resulted in a decrease in polarisation. Temperature-dependent leakage current behaviour was obtained and possible conduction mechanism is discussed. PPFM images revealed switchable ferroelectric piezoelectric contrasts after the application of a  ±9 V dc voltage on the conductive tip of the piezoresponse force microscope.

  12. PHASE TRANSITION, DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF NaNbO3-Ba0.85Ca0.15(Ti0.9Zr0.1)O3 LEAD-FREE CERAMICS

    NASA Astrophysics Data System (ADS)

    Lei, Yuqing; Wu, Hong; Lin, Dunmin; Zheng, Qiaoji; Wu, Xiaochun; Fan, Ximing

    2012-09-01

    A new lead-free solid solution of (1-x)NaNbO3-xBa0.85Ca0.15(Ti0.9Zr0.1)O3 was prepared by a traditional sintering method and its phase transition, dielectric and piezoelectric properties were studied. Ba0.85Ca0.15(Ti0.9Zr0.1)O3 diffuses into NaNbO3 lattices to form a new solid solution with perovskite structure. The addition of Ba0.85Ca0.15(Ti0.9Zr0.1)O3(x≥0.025) transforms NaNbO3 from antiferroelectric to ferroelectric. The diffusive ferroelectric-paraelectric phase transition is induced in the ceramics with high concentration of Ba0.85Ca0.15(Ti0.9Zr0.1)O3. The ceramics with x = 0.05-0.125 possess large Pr values of 18.6-25.5 μC/cm2. A morphotropic phase boundary between tetragonal and orthorhombic phases is formed at 0.05 < x < 0.15, leading to a significant enhancement of piezoelectric properties. The ceramic with x = 0.125 situated near the morphotropic phase boundary exhibits the optimum piezoelectric properties: d33 = 151 pC/N and kp = 31.6%.

  13. Half-metallic and magnetic properties of full-Heusler alloys Zr2CrZ (Z=Ga, In) with Hg2CuTi-type structure: A first-principles study

    NASA Astrophysics Data System (ADS)

    Deng, Zun-Yi; Zhang, Jian-Min

    2016-01-01

    The half-metallic and magnetic properties of Heusler alloys Zr2 CrZ (Z=Ga, In) with Hg2 CuTi -type structure have been investigated by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA). The equilibrium lattice constants are 6.635 and 6.875 Å for Zr2 CrGa and Zr2 CrIn, respectively. Under compression and expansion deformations within lattice constant ranges of 6.515-7.100 and 6.371-7.126 Å for Zr2 CrGa and Zr2 CrIn, respectively, the Zr2 CrZ (Z=Ga, In) maintain a half-metallic nature with a fixed total magnetic moment of -1 μB / f.u ., following the Slater-Pauling rule μt = Zt - 18, but the absolute values of the local magnetic moments on Zr and Cr atoms increase with increasing lattice constant.

  14. Diffusion-barrier contacts based on the TiN and Ti(Zr)B{sub x} interstitial phases in the microwave diodes for the range of 75-350 GHz

    SciTech Connect

    Boltovets, N. S. Ivanov, V. N.; Belyaev, A. E.; Konakova, R. V. Kudrik, Ya. Ya.; Milenin, V. V.; Arsent'ev, I. N.; Bobyl, A. V. Brunkov, P. N.; Tarasov, I. S.; Tonkikh, A. A.; Ulin, V. P.; Ustinov, V. V.; Cirlin, G. E.

    2006-06-15

    A new technology for thermally stable ohmic contacts with diffusion barriers based on the amorphous TiN and Ti(Zr)B{sub x} interstitial phases is used in the development of microwave diodes for the millimeter region (with the frequency higher than 100 GHz) based on GaAs, InP, and Si. It became possible to increase the reliability of the GaAs-and InP-based Gunn diodes that operate at the frequency of 200 GHz by using the epitaxial layers formed on porous III-V substrates by gas-phase, molecular-beam, and liquid-phase epitaxy as the initial device structures. The range of emission from the avalanche transit-time diodes based on Si is extended to 350 GHz. To this end, the technology of forming the active element on the silicon metallized diaphragm is used for the first time.

  15. Effect of shock-wave loading on mechanical and thermomechanical characteristics of shape-memory alloys 45Ti-45Ni-10Nb and 43Ti-46Ni-8Nb-3Zr

    NASA Astrophysics Data System (ADS)

    Popov, N. N.; Lar'kin, V. F.; Ogorodnikov, V. A.; Presnyakov, D. V.; Lar'kina, Yu. A.; Aushev, A. A.; Sysoyeva, T. I.; Suvorova, E. B.; Kostyleva, A. A.

    2016-09-01

    This work was performed to study the behavior of 45Ti-45Ni-10Nb and 43Ti-46Ni-8Nb-3Zr (at %) shape-memory alloys (SMAs) under the effect of severe dynamic deformation to use the obtained results to develop technologies based on SMAs. Cast alloys were used for the tests. The elemental and phase compositions of the alloys in the initial state, as well as the phase composition, kinetics, and temperatures of phase transformations after heat treatment (annealing in a vacuum at 850°C for 4 h, furnace cooling) have been determined. The mechanical and thermomechanical characteristics of these alloys before and after shock-wave loading have been determined.

  16. Prediction of the quantum spin Hall effect in monolayers of transition-metal carbides MC (M = Ti, Zr, Hf)

    NASA Astrophysics Data System (ADS)

    Zhou, Liujiang; Shao, Bin; Shi, Wujun; Sun, Yan; Felser, Claudia; Yan, Binghai; Frauenheim, Thomas

    2016-09-01

    We report the existence of the quantum spin Hall effect (QSHE) in monolayers of transition-metal carbides MC (M = Zr, Hf). Under ambient conditions, the ZrC monolayer exhibits QSHE with an energy gap of 54 meV, in which topological helical edge states exist. Enhanced d xy -d xy interaction induces band inversion, resulting in nontrivial topological features. By applying in-plane strain, the HfC monolayer can be tuned from a trivial insulator to a quantum spin Hall insulator with an energy gap of 170 meV, three times that of the ZrC monolayer. The strong stability of MC monolayers provides a new platform for QSHE and spintronic applications.

  17. Bond dissociation energies of diatomic transition metal selenides: TiSe, ZrSe, HfSe, VSe, NbSe, and TaSe

    NASA Astrophysics Data System (ADS)

    Sorensen, Jason J.; Persinger, Thomas D.; Sevy, Andrew; Franchina, Jordan A.; Johnson, Eric L.; Morse, Michael D.

    2016-12-01

    Predissociation thresholds have been observed in the resonant two-photon ionization spectra of TiSe, ZrSe, HfSe, VSe, NbSe, and TaSe. It is argued that the sharp onset of predissociation corresponds to the bond dissociation energy in each of these molecules due to their high density of states as the ground separated atom limit is approached. The bond dissociation energies obtained are D0(TiSe) = 3.998(6) eV, D0(ZrSe) = 4.902(3) eV, D0(HfSe) = 5.154(4) eV, D0(VSe) = 3.884(3) eV, D0(NbSe) = 4.834(3) eV, and D0(TaSe) = 4.705(3) eV. Using these dissociation energies, the enthalpies of formation were found to be Δf,0 KHo(TiSe(g)) = 320.6 ± 16.8 kJ mol-1, Δf,0 KHo(ZrSe(g)) = 371.1 ± 8.5 kJ mol-1, Δf,0 KHo(HfSe(g)) = 356.1 ± 6.5 kJ mol-1, Δf,0 KHo(VSe(g)) = 372.9 ± 8.1 kJ mol-1, Δf,0 KHo(NbSe(g)) = 498.9 ± 8.1 kJ mol-1, and Δf,0 KHo(TaSe(g) ) = 562.9 ± 1.5 kJ mol-1. Comparisons are made to previous work, when available. Also reported are calculated ground state electronic configurations and terms, dipole moments, vibrational frequencies, bond lengths, and bond dissociation energies for each molecule. A strong correlation of the measured bond dissociation energy with the radial expectation value, ⟨r⟩nd, for the metal atom is found.

  18. Preparing Pb(Zr,Ti)O3 films less than 100 nm thick by low-temperature metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Nagai, A.; Morioka, H.; Asano, G.; Funakubo, H.; Saiki, A.

    2005-04-01

    Polycrystalline Pb(Zr ,Ti)O3 (PZT) films 70-80nm thick on (111)Ir/TiO2/SiO2/Si substrates were prepared at 415°C by metalorganic chemical vapor deposition (MOCVD). At 3V, the remanent polarization (Pr) of the as-deposited films was approximately 22μC/cm2. Inserting PbTiO3 seeds between the PZT films and Ir bottom electrodes improved the crystallinity of the films markedly but improved their ferroelectric properties only slightly. Low-temperature postannealing, on the other hand, even at 400°C (i.e., below the deposition temperature), improved Pr values and hysteresis loop shapes without obviously improving the crystallinity of the films. The electrical properties were improved even more when the films were annealed at 500°C. These results suggest that the low-temperature processing and sub-100-nm film thickness needed for making three-dimensionally structured ferroelectric capacitors can be obtained by using low-temperature MOCVD to deposit PZT films, and then annealing those films at a temperature no greater than 500°C.

  19. Effect of fluorine additive on CeO2(ZrO2)/TiO2 for selective catalytic reduction of NO by NH3.

    PubMed

    Jin, Qijie; Shen, Yuesong; Zhu, Shemin

    2017-02-01

    A series of CeO2(ZrO2)/TiO2 catalysts with fluorine additive were prepared by impregnation method and tested for selective catalytic reduction (SCR) of NO by NH3. These samples were characterized by XRD, N2-BET, Raman spectra, SEM, TEM, NH3-TPD, H2-TPR and XPS, respectively. Results showed that the optimal catalyst with the appropriate HF exhibited excellent performance for NH3-SCR and more than 96% NO conversion at 360°C under GHSV of 71,400h(-1). It was found that the grain size of TiO2 increased and the specific surface area reduced with the modulation of HF, which was not good for the adsorption of gas molecule. However, the modulation of HF exposed the high energy (001) facets of TiO2 and increased the surface chemisorbed oxygen concentration, oxygen storage capacity and Ce(3+) concentration of catalyst. In addition, the synergy of (101) and (001) facets was beneficial to the improvement of catalytic activity.

  20. Electronic structure, transport properties, and excited states in CoTiSb, CoZrSb, and CoHfSb half-Heusler compounds

    NASA Astrophysics Data System (ADS)

    Janotti, Anderson; Gui, Zhigang; Kawasaki, Jason; Palmstrom, Chris; Himmetoglu, Burak

    CoTiSb is a member of a large family of half-Heusler compounds with 18 valence electrons. CoTiSb is semiconductor material with a band gap a little over 1 eV, and it has been considered promising for thermoelectric applications. It can be grown on conventional III-V semiconductors, and could potentially be integrated in III-V devices. Here we present results of first-principles calculations of electronic structure, transport properties, and excited states in CoTiSb, as well as CoZrSb and CoHfSb. Electronic structures are studied using density functional theory within the local density approximation, hybrid functional and quasiparticle GW methods. Both room-temperature Seebeck coefficient and carrier mobility are calculated from first-principles. We also determine the band alignments to III-V semiconductors, and all the results are presented and discussed in the light of available experimental data. This work was supported by the DOE.

  1. Dielectric relaxation analysis of Pb(Zr{sub 0.54},Ti{sub 0.46})O{sub 3} thin films: Electric field dependence

    SciTech Connect

    Ponchel, F. Rémiens, D.; Sama, N.; Lasri, T.

    2014-12-28

    350 nm-thick Perovskite PbZr{sub 0.54}Ti{sub 0.46}O{sub 3} (PZT) thin films were deposited on Al{sub 2}O{sub 3} substrates by sputtering with and without an additional 10-nm-thick TiO{sub x} buffer layer. X-ray diffraction patterns showed that in presence of TiO{sub x} buffer layer, PZT film was highly oriented along the (111) direction film, whereas the unbuffered, counterpart was polycrystalline. A full wave electromagnetic analysis using a vector finite element method was performed to determine the tunability and the complex permittivity up to 67 GHz. A comparison between the electromagnetic analysis and Cole-Cole relaxation model was proposed. Through an original study of the relaxation time as a function of the electric field, values, such as 2 ps and 0.6 ps, were estimated for E{sub DC} = 0 kV/cm and 235 kV/cm, respectively, and in both cases (111)-PZT and polycrystalline-PZT. The distribution of relaxation times is found to be larger for (111)-PZT film, which is probably related to the film microstructure.

  2. The in vitro and in vivo performance of a strontium-containing coating on the low-modulus Ti35Nb2Ta3Zr alloy formed by micro-arc oxidation.

    PubMed

    Liu, Wei; Cheng, Mengqi; Wahafu, Tuerhongjiang; Zhao, Yaochao; Qin, Hui; Wang, Jiaxing; Zhang, Xianlong; Wang, Liqiang

    2015-07-01

    The β-titanium alloy is thought to be a promising alloy using as orthopedic or dental implants owing to its characteristics, which contains low elastic modulus, high corrosion resistance and well biocompatibility. Our previous study has reported that a new β-titanium alloy Ti35Nb2Ta3Zr showed low modulus close to human bone, equal tissue compatibility to a traditional implant alloy Ti6Al4V. In this study, micro-arc oxidation (MAO) was applied on the Ti35Nb2Ta3Zr alloy to enhance its surface characteristics and biocompatibility and osseointegration ability. Two different coatings were formed, TiO2 doped with calcium-phosphate coating (Ca-P) and calcium-phosphate-strontium coating (Ca-P-Sr). Then we evaluated the effects of the MAO coatings on the Ti35Nb2Ta3Zr alloy through in vitro and in vivo tests. As to the characteristics of the coatings, the morphology, chemical composition, surface roughness and contact angle of MAO coatings were tested by scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, and video contact-angle measurement system respectively. Besides, we performed MTT assay, ALP test and cell morphology-adhesion test on materials to evaluate the MAOed coating materials' biocompatibility in vitro. The in vivo experiment was performed through rabbit model. Alloys were implanted into rabbits' femur shafts, then we performed micro-CT, histological and sequential fluorescent labeling analysis to evaluate implants' osseointegration ability in vivo. Finally, the Ca-P specimens and Ca-P-Sr specimens exhibited a significant enhancement in surface roughness, hydrophilicity, cell proliferation, cell adhesion. More new bone was found around the Ca-P-Sr coated alloy than Ca-P coated alloy and Ti35Nb2Ta3Zr alloy. In conclusion, the MAO treatment improved in vitro and in vivo performance of Ti35Nb2Ta3Zr alloy. The Ca-P-Sr coating may be a promising modified surface formed by MAO for the novel β-titanium alloy Ti35Nb2Ta3Zr.

  3. Assessing the performance and longevity of Nb, Pt, Ta, Ti, Zr, and ZrO₂-sputtered Havar foils for the high-power production of reactive [18F]F by proton irradiation of [18O]H2O.

    PubMed

    Gagnon, K; Wilson, J S; Sant, E; Backhouse, C J; McQuarrie, S A

    2011-10-01

    As water-soluble ionic contaminants, which arise following proton irradiation of [18O]H2O have been associated with decreased [18F]FDG yields, the minimization of these contaminants is an asset in improving the [18F]F reactivity. To this end, we have previously demonstrated that the use of Nb-sputtered Havar foils results in decreased radionuclidic and chemical impurities in proton irradiated [18O]H2O, improved [18F]FDG yields, and improved [18F]FDG yield consistency when compared with non-sputtered Havar. Resulting from the highly reactive chemical microenvironment within the target however, this niobium layer is observed to degrade over time. To find a material that displays increased longevity with regards to maintaining high [18F]F reactivity, this project extensively investigated and compared Havar foils sputtered with Nb, Pt, Ta, Ti, Zr and ZrO₂. Of the materials investigated, the results of this study suggest that Ta-sputtered Havar foil is the preferred choice. For similar integrated currents (~1,000,000 μA min), when comparing the Ta-sputtered Havar with Nb-sputtered Havar we observed: (i) greater than an order of magnitude decrease in radionuclidic impurities, (ii) a 6.4 percent increase (p=0.0025) in the average TracerLab MX [18F]FDG yield, and (iii) an overall improvement in the FDG yield consistency. Excellent performance of the Ta-sputtered foil was maintained throughout its ~1,500,000 μA min lifetime.

  4. Zr partitioning and kinetics and mechanism

    NASA Technical Reports Server (NTRS)

    Taylor, L. A.

    1973-01-01

    The results of investigations concerning the cooling histories of lunar rocks are reported. Publications resulting from this research are listed. Studies discussed include the partitioning of Zr between FeTi03 and Fe2Ti04 in the presence of Fe + Zr02, and ulvospinel reduction.

  5. A new titanium based alloy Ti-27Nb-13Zr produced by powder metallurgy with biomimetic coating for use as a biomaterial.

    PubMed

    Mendes, Marcio W D; Ágreda, Carola G; Bressiani, Ana H A; Bressiani, José C

    2016-06-01

    Titanium alloys are widely used in biomedical applications due to their excellent properties such as high strength, good corrosion resistance and biocompatibility. Titanium alloys with alloying elements such as Nb and Zr are biocompatible and have Young's modulus close to that of human bone. To increase the bioactivity of titanium alloy surfaces is used chemical treatment with NaOH followed by immersion in simulated body fluid (SBF). The purpose of this study was to produce the alloy Ti-27Nb-13Zr with low Young's modulus by powder metallurgy using powders produced by the HDH process. The formation of biomimetic coatings on samples immersed in SBF for 3, 7, 11 and 15 days was evaluated. Characterization of the coating was performed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and scanning electron microscope. The microstructure and composition of the alloy were determined using SEM and XRD, while the mechanical properties were evaluated by determining the elastic modulus and the Vickers microhardness. The sintered alloys were composed of α and β phases, equiaxed grains and with density around 97.8% of its theoretical density. The Vickers microhardness and elasticity modulus of the alloy were determined and their values indicate that this alloy can be used as a biomaterial. Analysis of the coating revealed the presence of calcium phosphate layers on samples immersed for >3 days in the SBF solution.

  6. Ab initio phonon properties of half-Heusler NiTiSn, NiZrSn and NiHfSn.

    PubMed

    Andrea, Luc; Hug, Gilles; Chaput, Laurent

    2015-10-28

    A theoretical investigation of phonon properties from first-principles calculations is carried out for the half-Heusler compounds NiXSn, [Formula: see text], Zr and Hf. The crystal structures are optimised via ab initio calculations within the framework of density functional theory. The phonon properties are retrieved from harmonic and anharmonic interatomic force constants calculations using the finite size displacements method and many-body perturbation theory. A solution to the linearized phonon Boltzmann transport equation is then used to compute the ab initio thermal conductivities. For X   =   Ti, Zr and Hf, we found 15.4, 13.3 and 15.8 W m(-1) K(-1) at 300 K, respectively. Thanks to a spectral analysis of the velocities and lifetimes we were able appreciate the differences in the thermal conductivities between the three compounds under study. Our results provide insights to understand the behaviour of the thermal conductivity and therefore to improve the thermoelectric figure of merit for such materials.

  7. Structural, dielectric and electrocaloric properties in lead-free Zr-doped Ba0.8Ca0.2TiO3 solid solution

    NASA Astrophysics Data System (ADS)

    Asbani, B.; Gagou, Y.; Dellis, J.-L.; Lahmar, A.; Amjoud, M.; Mezzane, D.; Kutnjak, Z.; El Marssi, M.

    2016-07-01

    We investigate in the present work the additional data points (x=0.02, 0.06 and 0.08) to the previous reported paper (Asbani et al., 2015) [21] that sufficiently enrich to understand the EC properties and underlying phase diagram of the lead-free Ba0.8Ca0.2Ti(1-x)ZrxO3 (xBCTZ) system. X-ray diffraction analysis performed at room temperature, confirms a continuous tetragonal solid solution with P4mm (No. 99) space group that evolved to pseudo-cubic symmetry for the high Zr-content compounds. Ferroelectric and paraelectric behaviors were highlighted using P-E hysteresis data versus temperature. Phase transition was confirmed by dielectric permittivity measurements versus temperature showing a decrease of the Curie temperature when Zr-content increases. From P-E hysteresis recording the electrocaloric temperature change (ΔT) was calculated that ranged in between 0.12 and 0.27 K and the electrocaloric responsivity (ξ) in 0.15 to 0.34×10-6 K·m/V under 7.95 kV/cm applied electric field. The zero-field entropy is compared to electrocaloric isothermal entropy to estimate the extent the EC is being under-driven.

  8. Corrosion Protection of Copper Using Al2O3, TiO2, ZnO, HfO2, and ZrO2 Atomic Layer Deposition.

    PubMed

    Daubert, James S; Hill, Grant T; Gotsch, Hannah N; Gremaud, Antoine P; Ovental, Jennifer S; Williams, Philip S; Oldham, Christopher J; Parsons, Gregory N

    2017-02-01

    Atomic layer deposition (ALD) is a viable means to add corrosion protection to copper metal. Ultrathin films of Al2O3, TiO2, ZnO, HfO2, and ZrO2 were deposited on copper metal using ALD, and their corrosion protection properties were measured using electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV). Analysis of ∼50 nm thick films of each metal oxide demonstrated low electrochemical porosity and provided enhanced corrosion protection from aqueous NaCl solution. The surface pretreatment and roughness was found to affect the extent of the corrosion protection. Films of Al2O3 or HfO2 provided the highest level of initial corrosion protection, but films of HfO2 exhibited the best coating quality after extended exposure. This is the first reported instance of using ultrathin films of HfO2 or ZrO2 produced with ALD for corrosion protection, and both are promising materials for corrosion protection.

  9. Characterization of oxygen vacancies and their migration in Ba-doped Pb(Zr0.52Ti0.48)O3 ferroelectrics

    NASA Astrophysics Data System (ADS)

    Zhang, M. F.; Wang, Y.; Wang, K. F.; Zhu, J. S.; Liu, J.-M.

    2009-03-01

    We investigate in detail the migration kinetics of oxygen vacancies (OVs) in Ba-doped Pb(Zr0.52Ti0.48)O3 (PZT) ferroelectrics by complex impedance spectroscopy. The temperature dependent dc-electrical conductivity σdc suggests that Ba doping into PZT can lower significantly the density of OVs, leading to the distinctly decreased σdc and slightly enhanced activation energy U for the migration of OVs, thus benefiting the polarization fatigue resistance. Furthermore, the polarization fluctuation induced by the relaxation of OVs is reduced by the Ba doping. The Cole-Cole fitting to the dielectric loss manifests strong correlation among OVs, and the migration of OVs appears to be a collective behavior.

  10. New dielectric ceramics Pb(Cd)BiM/sup IV/SbO/sub 7/ (M/sup IV/ = Ti, Zr, Sn) with the pyrochlore structure

    SciTech Connect

    Lambachri, A.; Monier, M.; Mercurio, J.P.; Frit, B.

    1988-04-01

    Dielectric ceramics have been obtained by natural sintering of pyrochlore phases with general formula Pb(Cd)BiM/sup IV/SbO/sub 7/ (M/sup IV/ = Ti, Zr, Sn). Low frequency dielectric characteristics have been studied with respect to the processing conditions: sintering without additive and in the presence of some low melting compounds (PbO, Pb/sub 5/Ge/sub 3/O/sub 11/, Bi/sub 12/PbO/sub 19/ and Bi/sub 12/CdO/sub 19/). The dielectric constants of these ceramics lie between 30 and 60, the dielectric losses range from 10 to 30.10/sup -4/ and the temperature coefficient of the dielectric constants (20 - 100/sup 0/C) can be tailored by means of additives in the +- 30 ppm K/sup -1/ range.

  11. Large magnetoelectric effect in mechanically mediated structure of TbFe{sub 2}, Pb(Zr,Ti)O{sub 3}, and nonmagnetic flakes

    SciTech Connect

    Bi, K.; Wang, Y. G.; Wu, W.; Pan, D. A.

    2011-03-28

    Magnetoelectric (ME) effect has been studied in a structure of a magnetostrictive TbFe{sub 2} alloy, two piezoelectric Pb(Zr,Ti)O{sub 3} (PZT) ceramics, and two nonmagnetic flakes. The ME coupling originates from the magnetic-mechanical-electric transform of the magnetostrictive effect in TbFe{sub 2} and the piezoelectric effect in PZT by end bonding, instead of interface bonding. Large ME coefficients of 10.5 and 9.9 V cm{sup -1} Oe{sup -1} were obtained at the first planar acoustic and third bending resonance frequencies, which are larger than that of conventional layered TbFe{sub 2}/PZT composites. The results show that the large ME coupling can be achieved without interface coupling.

  12. Preparation and investigation of ferroelectric Pb(Zr0.53Ti0.47)O3 by modified Pechini method

    NASA Astrophysics Data System (ADS)

    Van Chuong, Truong; Duy Nhan, Huynh; Tien Dung, Le Quang; Tuan, Nguyen Duy Anh

    2009-09-01

    This paper describes a new method, namely modified Pechini for one, for the preparation of nano-sized ferroelectric Pb(Zr0.53Ti0.47)O3 (PZT (53/47)) from low cost precursors. With this method, PZT (53/47) was prepared by microwave-assisted dissolving a pre-calcinated mixture of component oxides in dilute HNO3 for a short time and precipitating in NH4OH solution (pH = 9-10). On the other hand, the ferroelectric thin films PZT (53/47) on Al substrates were also prepared. The films and the ceramic powders of PZT (53/47) were obtained with high quality in terms of structure and microstructure. The ferroelectric properties of thin films have also been investigated.

  13. Rate-dependent serrated flow and plastic deformation in Ti45Zr16Be20Cu10Ni9 bulk amorphous alloy during nanoindentation

    PubMed Central

    Kumar Misra, Dinesh; Woo Sohn, Sung; Tae Kim, Won; Hyang Kim, Do

    2008-01-01

    The plastic deformation of Ti45Zr16Be20Cu10Ni9 bulk metallic glass has been investigated by nanoindentation performed with loads ranging from 10 to 200 mN in a wide range of loading rates. The plastic flow in the alloy exhibited conspicuous serrations at low loading rates. The serrations, however, became less prominent as the rate of indentation increased. Atomic force microscopy showed a significant pile-up of materials around the indents, indicating that a highly localized plastic deformation occurred under nanoindentation. The possible mechanism governing the plastic deformation in bulk metallic glass specimens is tentatively discussed in terms of strain-induced free volume. PMID:27878032

  14. Enhancement of optical properties of hydrothermally synthesized TiO{sub 2}/ZrO{sub 2} nanoparticles by Al, Ce Co-doping

    SciTech Connect

    Tomar, Laxmi J.; Bhatt, Piyush J. Desai, Rahul K.; Chakrabarty, Bishwajit S.

    2015-06-24

    Al, Ce co-doped TiO{sub 2}/ZrO{sub 2} (TZ) nano composites have been prepared by hydrothermal method. The structural and optical properties of the obtained samples were investigated by X –ray diffraction (XRD) and UV-Visible spectroscopy respectively. It has been found that the crystallite size of all the samples was distributed in the range 9.19 to 17.41 nm. The content of anatase phase varied in the range 48.71 to 100% depending on doping. The dopant produced lattice strain in material and it was found between 0.027 - 0.069. A clear shift of absorption edge for different dopant has been observed from UV-Visible absorption spectra. The change in optical bandgap, refractive index, absorption co efficient and optical conductivity was also evaluated from absorption spectra.

  15. X-ray scattering evidence for the structural nature of fatigue in epitaxial Pb(Zr, Ti)O{sub 3} films.

    SciTech Connect

    Thompson, C.; Munkholm, A.; Streiffer, S. K.; Stephenson, G. B.; Ghosh, K.; Eastman, J. A.; Auciello, O.; Bai, G.-R.; Lee, M. K.; Eom, C. B.; Northern Illinois Univ.; Univ. of Wisconsin at Madison

    2001-05-28

    We have probed the microscopic distribution of 180{sup o} domains as a function of switching history in 40 nm epitaxial films of Pb(Zr{sub 0.30}Ti{sub 0.70})O{sub 3} by analyzing interference effects in the x-ray scattering profiles. These as-grown films exhibit voltage offsets (imprint) in the polarization hysteresis loops, coupled with a strongly preferred polarization direction in the virgin state. Our x-ray results are consistent with models attributing the loss of switchable polarization to the inhibition of the formation of oppositely polarized domains in a unipolar matrix. Using such model epitaxial films, we demonstrate that different microscopic ensembles of domains resulting from, for example, fatigue, may be resolved by this technique.

  16. Self-biased and wide resonance band magnetoelectric effect in series-connected SrFe12O19/Metglas/Pb(Zr, Ti)O3 composites

    NASA Astrophysics Data System (ADS)

    Ma, J. N.; Xin, C. Z.; Ma, J.; Lin, Y. H.; Nan, C. W.

    2016-12-01

    Self-biased and wide resonance band magnetoelectric (ME) response is realized in the series-connected SrFe12O19/Metglas/ Pb(Zr, Ti)O3 composites. Both ME composites fabrication and series-connecting method are optimized in this paper. It is found that 2/5—length ratio between SFO ribbon and PZT plate is proposed to maintain the ME resonance property in the ME composites, and that series-connecting the ME components by opposite polarizations with each other is the proposal method to achieve wide resonance band ME response. Without external magnetic field, the self-biased ME composites show a resonance enhanced ME response of over 117 mV Oe-1 in a 30 kHz bandwidth frequency window. Our ME composites present a good potential for application in broadband magnetic field sensors and energy harvesters.

  17. Theoretical investigations on vibrational properties and thermal conductivities of ternary antimonides TiXSb, ZrXSb and HfXSb (X = Si, Ge)

    NASA Astrophysics Data System (ADS)

    Deligoz, E.; Ozyar, U. F.; Ozisik, H. B.

    2016-06-01

    We have performed density functional calculations of the vibrational and thermodynamic properties of the ternary antimonides TiXSb, ZrXSb and HfXSb (X = Si, Ge). The direct method is used to calculate the phonon dispersion relation and phonon density of states for these compounds as well as their infrared and Raman active mode frequencies for the first time. Their dynamical stability is confirmed by phonon spectra. The lattice thermal conductivities of these compounds have been calculated from third-order force constants and plotted as a function of temperature. We have also evaluated the high temperature thermal conductivity by means of the Clarke's model and Cahill's model. Some selected thermodynamical properties, e.g. Gibbs free energy, entropy and heat capacity at constant volume are predicted theoretically and discussed. We have showed the relationships between thermodynamical properties and temperature. The numerical calculations reported in this paper were partially performed at Aksaray University, Science and Technology Application and Research Center.

  18. Deuterium dynamics in the icosahedral and amorphous phases of the Ti40Zr40Ni20 hydrogen-absorbing alloy studied by 2H NMR

    NASA Astrophysics Data System (ADS)

    Gradišek, A.; Kocjan, A.; McGuiness, P. J.; Apih, T.; Kim, Hae Jin; Dolinšek, J.

    2008-11-01

    The Ti40Zr40Ni20 hydrogen-absorbing alloy was prepared in the icosahedral and amorphous phases by controlling the rotation speed of the melt-spinning method of sample preparation, and the deuterium dynamics was investigated by 2H NMR dynamic lineshape and spin-lattice relaxation. The results were analysed by the lineshape and relaxation models that assume deuterium thermally activated hopping within a manifold of different chemical environments. The observed 8% larger activation energy for the deuterium hopping over the interstitial sites and the 10% larger static spectrum width of the amorphous phase, as compared to the icosahedral phase, can be accounted for by the larger deuterium content of the investigated amorphous sample. From the deuterium dynamics point of view, the icosahedral phase is not special with respect to the amorphous modification of the same material.

  19. Phase transformation and its effect on mechanical characteristics in warm-deformed Ti-29Nb-13Ta-4.6Zr alloy

    NASA Astrophysics Data System (ADS)

    Lee, Taekyung; Nakai, Masaaki; Niinomi, Mitsuo; Park, Chan Hee; Lee, Chong Soo

    2015-01-01

    Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy has been extensively studied as it is promising for use in biomedical applications. Despite its potential, the effects of warm plastic deformation on the alloy have not yet been revealed. This study investigated the differences in phase constitution of two warm-deformed TNTZ alloys and revealed relevant mechanisms with particular attention to martensitic transformation. The influence of phase constituents on mechanical characteristics was discussed as well. The TNTZ alloy deformed at 823 K possessed α, β, and ω phases as well as α″ martensite, and demonstrated a low Young's modulus and double-yielding phenomenon. In contrast, the alloy deformed at 723 K had no martensite but more ω phase, leading to increased strength, hardness, and Young's modulus. The absence of α″ martensite in the alloy deformed at 723 K was interpreted in light of β-stability of the parent phase and reduced M s temperature.

  20. A-site stoichiometry and piezoelectric response in thin film PbZr1-xTixO3

    SciTech Connect

    Marincel, Dan; Jesse, Stephen; Belianinov, Alex; Okatan, Mahmut Baris; Kalinin, Sergei V.; Jackson, T. N.; Randall, Clive; Trolier-McKinstry, Susan E

    2015-05-29

    Lead zirconate titanate (PZT) films with Zr/Ti ratios of 52/48 and 30/70 annealed at varying partial pressures of PbO within the perovskite phase field exhibited permittivities of 1150 and 600, respectively, with loss tangents of 0.02. Many of the functional properties, including the permittivity, piezoelectricity as indicated via the Rayleigh coefficients, and the aging rates were found to be weakly dependent of the lead content in the single phase field. Minor polarization electric field hysteresis loops and piezoelectric coefficient e31,f values after a hot poling process suggest that the point defect helps stabilize the aligned domain states. Measurements of the local nonlinear response show an increased low response cluster size with decreasing PbO content, indicating that PbO deficiency acts to reduce domain wall motion where it is already low