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Sample records for rastvorov karbidov ti

  1. PIIID-formed (Ti, O)/Ti, (Ti, N)/Ti and (Ti, O, N)/Ti coatings on NiTi shape memory alloy for medical applications.

    PubMed

    Sun, Tao; Wang, Lang-Ping; Wang, Min; Tong, Ho-Wang; Lu, William W

    2012-08-01

    (Ti, O)/Ti, (Ti, N)/Ti and (Ti, O, N)/Ti composite coatings were fabricated on NiTi shape memory alloy via plasma immersion ion implantation and deposition (PIIID). Surface morphology of samples was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Cross-sectional morphology indicated that the PIIID-formed coatings were dense and uniform. X-ray diffraction (XRD) was used to characterize the phase composition of samples. X-ray photoelectron spectroscopy (XPS) results showed that the surface of coated NiTi SMA samples was Ni-free. Nanoindentation measurements and pin-on-disc tests were carried out to evaluate mechanical properties and wear resistance of coated NiTi SMA, respectively. For the in vitro biological assessment of the composite coatings in terms of cell morphology and cell viability, osteoblast-like SaOS-2 cells and breast cancer MCF-7 cells were cultured on NiTi SMA samples, respectively. SaOS-2 cells attached and spread better on coated NiTi SMA. Viability of MCF-7 cells showed that the PIIID-formed composite coatings were noncytotoxic and coated samples were more biocompatible than uncoated samples.

  2. Dissolution rate measurements of TiN in Ti-6242

    SciTech Connect

    Bewlay, B.P.; Gigliotti, M.F.X.

    1997-01-01

    This paper describes measurements of the dissolution rate of nitrided Ti sponge and monolithic TiN rod in molten Ti-6242. The dissolution rate is described in terms of an interface recession rate that was 2.2 {micro}m/s for a Ti-6242 temperature of 1,725 C and dissolution times between 1 and 100 min. Similar dissolution rates were measured for nitrided sponge and monolithic rod. This report also descries the microstructural and chemical interdiffusion phenomena that occur during dissolution of solid {delta}TiN in molten Ti-6242. There is a N-containing solid {alpha}Ti layer and a N-solidified {beta}Ti layer between the solid {delta}TiN and liquid Ti-6242 during dissolution. Microprobe measurements indicate that diffusion of Al, Zr, Sn and Mo into {delta}TiN did not occur. Steep N concentration profiles were observed in the {alpha}Ti layer. Al, Zr, Sn and Mo were observed in the N-solidified {beta}Ti layer contained <1% N. Similar microstructural and interdiffusional behaviors were observed during dissolution of nitrided sponge and monolithic {delta}TiN rod in molten Ti-6242.

  3. (Ti, O)/Ti and (Ti, O, N)/Ti composite coatings fabricated via PIIID for the medical application of NiTi shape memory alloy.

    PubMed

    Sun, Tao; Wang, Lang-Ping; Wang, Min

    2011-02-01

    In this investigation, the plasma immersion ion implantation and deposition (PIIID) technique was used to fabricate (Ti, O)/Ti or (Ti, O, N)/Ti coatings on a NiTi shape memory alloy (SMA, 50.8 at.% Ni) to improve its corrosion, wear resistance, and bioactivity. After coating fabrication, the structure and properties of composite coatings were studied, and the coated and uncoated NiTi SMA samples were compared with each other. Scanning electron microscopic (SEM) examination of coating surfaces and cross-sections showed that (Ti, O)/Ti and (Ti, O, N)/Ti composite coatings were dense and uniform, having thickness values of 1.16 ± 0.08 μm and 0.95 ± 0.06 μm, respectively. X-ray diffraction (XRD) results revealed that there were no diffraction peaks corresponding to TiO(2) or TiN for (Ti, O)/Ti and (Ti, O, N)/Ti composite coatings, suggesting that after the PIIID treatment, TiO(2) and TiN were amorphous or nanosized in the coatings. Energy dispersive X-ray (EDX) analysis indicated that the interface between the coating and NiTi SMA substrate was gradual rather than sharp. In addition, EDX elemental mapping of coating cross-sections showed that Ni was depleted from the surface. Differential scanning calorimetry (DSC) curves revealed that the shape memory ability of NiTi SMA was not degraded by the PIIID treatment. The width of wear tracks on (Ti, O, N)/Ti coated NiTi SMA samples was reduced 6.5-fold, in comparison with that on uncoated samples. The corrosion potential (E(corr) ) was improved from -466.20 ± 37.82 mV for uncoated samples to 125.50 ± 21.49 mV and -185.40 ± 37.05 mV for (Ti, O)/Ti coated and (Ti, O, N)/Ti coated samples, respectively. Both types of coatings facilitated bone-like apatite formation on the surface of NiTi SMA in simulated body fluid (SBF), indicating their in vitro bioactivity.

  4. Preparation of overdamped NbTiN Josephson junctions with bilayered Ti-TiN barriers

    NASA Astrophysics Data System (ADS)

    Yamamori, Hirotake; Sasaki, Hitoshi; Kohjiro, Satoshi

    2010-12-01

    Overdamped NbTiN Josephson junctions with Ti-TiN bilayered normal-metal barrier are proposed for metrological applications. Binary arrays consisting of 32 768 NbTiN/Ti-TiN/NbTiN junctions were fabricated for quantum voltage standards, and a Shapiro step at 1 V with the step height of about 0.5 mA was generated at around 8 K. The Ti layer was added to protect the base NbTiN electrode from nitrogen plasma during the deposition of the TiN layer. While the critical current Ic and the junction resistance Rn are mainly dominated by the thickness of the TiN barrier, Ic can be also adjusted by changing the thickness of the Ti barrier to maximize the operating margin for voltage standard circuits. An optimization of the NbTiN film in terms of film stress is also described for fabrication of circuits containing such a large number of junctions.

  5. Ti site occupancy in zircon

    NASA Astrophysics Data System (ADS)

    Tailby, N. D.; Walker, A. M.; Berry, A. J.; Hermann, J.; Evans, K. A.; Mavrogenes, J. A.; O'Neill, H. St. C.; Rodina, I. S.; Soldatov, A. V.; Rubatto, D.; Sutton, S. R.

    2011-02-01

    Ti site occupancy in zircon (ZrSiO 4) is fundamental to thermobarometry because substitution mechanisms control Ti content-temperature relations. Here we describe the results of three independent methods used to demonstrate that Ti substitutes for Si and not Zr in zircon. Zircon grains were synthesized from oxide powders held in a Na 2WO 4 flux at 1 bar and 1300 °C. Zircon grains equilibrated with rutile + cristobalite show Ti contents (1201 ppm) nearly half that of zircon grains equilibrated with srilankite ((Ti,Zr)O 2) + tetragonal zirconia (2640 ppm). The lower Ti content of zircon grains produced at silica-saturated conditions indicates that Ti substitution predominately occurs on the Si site. Moreover, the higher Ti contents of silica-saturated experiments at 1 bar (1201 ppm), relative to those at 1 GPa (457 ppm, Ferry and Watson, 2007), indicates a substantial pressure effect on Ti solubility in zircon. Measured Ti K-α edge X-ray Absorption Near Edge Structure (XANES) spectra of synthetic zircon grains show energies and normalized intensities akin to those seen among tetrahedrally coordinated Ti-bearing standard minerals, strongly suggesting that Ti occupies the Si site. Density functional theory (DFT) calculations confirm that Ti substitution is most likely to occur on the Si site and predict a Ti-O bond length of 1.797 Å (compared to an average of 2.160 Å for substitution on the Zr site), in excellent agreement with X-ray Absorption Fine Structure (EXAFS) spectra of experimentally grown zircon grains which indicate a value of 1.76(1) Å. The software FEFF 8.4 was used to simulate XANES spectra from the defect structures determined by DFT for Ti substituting on both the Si and Zr sites. The predicted spectrum for Ti on the Si site reproduces all the key features of the experimental zircon spectra, whereas Ti on the Zr site is markedly different. All applied methods confirm that Ti substitutes for Si in zircon. Consequently, the Ti content of zircon at a

  6. Electronic Structure of Ti substituted hydroxyapatite: TiHap

    NASA Astrophysics Data System (ADS)

    Yin, Shuxia; Ellis, Donald

    2009-03-01

    Hydroxyapatite (Hap), with the chemical formula Ca10(PO4)6(OH)2, is the main mineral constituent of mammal tooth enamel and bone and has become an important biomaterial with medical applications. Hap also attracts increasing interest for use in environmental adsorbents and catalysts due to its porous nature and highly active ion-exchange character. Ti-modified Hap (TiHap) has been proved to possess high affinity to organic molecules and bacteria as well as high photocatalytic activity for their oxidative decomposition. The concentration of Ti^4+ is a key factor controlling TiHap crystallinity and catalytic efficiency. Here we studied the sorption mechanism of Ti^4+ on Hap using Density Functional Theory within periodic slab models. Ti^4+ or (Ti(OH)2)^2+, as the most likely ion exchange species with Ca^2+, were first considered in bulk Hap. A second charge compensated model considered includes both surface Ca ion vacancies and substitutional Ti^4+. To obtain insight of the energetic stability and microscopic crystal structure of TiHap, Ti substitution on different Ca sites and distributions at different atomic ratios are investigated in both bulk and surface models.

  7. Characteristics of laser clad α-Ti/TiC+(Ti,W)C1-x/Ti2SC+TiS composite coatings on TA2 titanium alloy

    NASA Astrophysics Data System (ADS)

    Zhai, Yong-Jie; Liu, Xiu-Bo; Qiao, Shi-Jie; Wang, Ming-Di; Lu, Xiao-Long; Wang, Yong-Guang; Chen, Yao; Ying, Li-Xia

    2017-03-01

    TiC reinforced Ti matrix composite coating with Ti2SC/TiS lubricant phases in-situ synthesized were prepared on TA2 titanium alloy by laser cladding with different powder mixtures: 40%Ti-19.5%TiC-40.5%WS2, 40%Ti-25.2%TiC-34.8%WS2, 40%Ti-29.4%TiC-30.6%WS2 (wt%). The phase compositions, microstructure, microhardness and tribological behaviors and wear mechanisms of coatings were investigated systematically. Results indicate that the main phase compositions of three coatings are all continuous matrix α-Ti, reinforced phases of (Ti,W)C1-x and TiC, lubricant phases of Ti2SC and TiS. The microhardness of the three different coatings are 927.1 HV0.5, 1007.5 HV0.5 and 1052.3 HV0.5, respectively. Compared with the TA2 titanium alloy (approximately 180 HV0.5), the microhardness of coatings have been improved dramatically. The coefficients of friction and the wear rates of those coatings are 0.41 and 30.98×10-5 mm3 N-1 m-1, 0.30 and 18.92×10-5 mm3 N-1 m-1, 0.34 and 15.98×10-5 mm3 N-1 m-1, respectively. Comparatively speaking, the coating fabricated with the powder mixtures of 40%Ti-25.2%TiC-34.8%WS2 presents superior friction reduction and anti-wear properties and the main wear mechanisms of that are slight plastic deformation and adhesive wear.

  8. The Agrobacterium Ti Plasmids.

    PubMed

    Christie, Peter J; Gordon, Jay E

    2014-12-01

    Agrobacterium tumefaciens is a plant pathogen with the capacity to deliver a segment of oncogenic DNA carried on a large plasmid called the tumor-inducing or Ti plasmid to susceptible plant cells. A. tumefaciens belongs to the class Alphaproteobacteria, whose members include other plant pathogens (Agrobacterium rhizogenes), plant and insect symbionts (Rhizobium spp. and Wolbachia spp., respectively), human pathogens (Brucella spp., Bartonella spp., Rickettsia spp.), and nonpathogens (Caulobacter crescentus, Rhodobacter sphaeroides). Many species of Alphaproteobacteria carry large plasmids ranging in size from ∼100 kb to nearly 2 Mb. These large replicons typically code for functions essential for cell physiology, pathogenesis, or symbiosis. Most of these elements rely on a conserved gene cassette termed repABC for replication and partitioning, and maintenance at only one or a few copies per cell. The subject of this review is the ∼200-kb Ti plasmids carried by infectious strains of A. tumefaciens. We will summarize the features of this plasmid as a representative of the repABC family of megaplasmids. We will also describe novel features of this plasmid that enable A. tumefaciens cells to incite tumor formation in plants, sense and respond to an array of plant host and bacterial signal molecules, and maintain and disseminate the plasmid among populations of agrobacteria. At the end of this review, we will describe how this natural genetic engineer has been adapted to spawn an entire industry of plant biotechnology and review its potential for use in future therapeutic applications of plant and nonplant species.

  9. Wear resistance of TiN(Ti2N)/Ti composite layer formed on C17200 alloy by plasma surface Ti-alloying and nitriding

    NASA Astrophysics Data System (ADS)

    Liu, L.; Shen, H. H.; Liu, X. Z.; Guo, Q.; Meng, T. X.; Wang, Z. X.; Yang, H. J.; Liu, X. P.

    2016-12-01

    The duplex treatment of plasma Ti-alloying and plasma nitriding was applied on the surface of C17200 alloy to improve its wear resistance. C17200 substrate was alloyed with Ti using double glow plasma alloying to form a Ti-alloyed layer in its surface, and then treated by plasma nitriding to make a TiN(Ti2N) alloying layer based on the Ti-alloyed surface. The microstructure and formation mechanism were studied by using GDOES, XRD and SEM. The hardness, tribological property and electrical conductivity of C17200 alloy after plasma alloying and nitriding were investigated by mean of micro-hardness tester, friction and wear testers as well as impedance analyzers. Modulus of elasticity and the adhesive strength of TiN(Ti2N)/Ti composite layer were evaluated by nano-indenter and scratch tester. The result shows that a TiN(Ti2N)-Ti-Be-Cu composite layer with a thickness of 27 μm is formed in the C17200 surface and is mainly composed of TiN, Ti2N, Cu(Ti) solid solution, etc. The composite alloying surface consists of the hard TiN(Ti2N)-rich layer on the top surface and Ti-Cu-Be diffusion layer, showing a strong adhesive strength with the C17200 substrate and a little decrease in the modulus of elasticity. A certain amount of Cu and Be together with TiN/Ti2N exists in the outmost, resulting in a better combination of wear resistance and conductive performance.

  10. Microstructure and Properties of (TiB2 + NiTi)/Ti Composite Coating Fabricated by Laser Cladding

    NASA Astrophysics Data System (ADS)

    Lin, Yinghua; Lei, Yongping; Fu, Hanguang; Lin, Jian

    2015-10-01

    Agglomerated TiB2 particle and network-like structure-reinforced titanium matrix composite coatings were prepared by laser cladding of the Ni + TiB2 + Ti preplaced powders on Ti-6Al-4V alloy. The network-like structure mainly consisted of NiTi and Ni3Ti. Through the experiment, it was found that the size of agglomerated particle gradually decreased with the increase of Ti content, but the number of the network-like structure first increased and then disappeared. In-situ reaction competition mechanism and the formation of network-like structure were discussed. The average micro-hardness gradually decreased with the increase of Ti content, but the average fracture toughness gradually increased. Meanwhile, the wear resistance of the coatings is higher than that of the substrate, but the wear loss of the coatings is gradually increased with the increase of Ti content.

  11. Brazing of zirconia to Ti and Ti6Al4V

    SciTech Connect

    Agathopoulos, S.; Moretto, P.; Peteves, S.D.

    1997-11-01

    The interface microstructure of tetragonal zirconia (Y{sub 2}O{sub 3}-stab.), (TZP), brazed to itself, Ti and Ti6Al4V with a commercial Ag35Cu1.65Ti filler alloy at 900{degrees}C in vacuum was investigated. TiO formed in the reaction zone in TZP/TZP joints irrespectively the brazing time. In TZP/Ti joints, a complex interface microstructure comprising Ti{sub 2}O, Cu{sub 2}Ti{sub 4}O and Cu-Ti-intermetallics was time dependent. High joint strengths of over 400 MPa were obtained for short brazing times. In TZP/Ti6Al4V joints, the evolution of the microstructure with brazing time depends on diffusion of Ti, Al and V to the interface forming Cu{sub 2}(Ti,A1,V){sub 4}O.

  12. Electronic Conduction in Ti/Poly-TiO2/Ti Structures

    PubMed Central

    Hossein-Babaei, Faramarz; Alaei-Sheini, Navid

    2016-01-01

    Recent intensive investigations on metal/metal oxide/metal structures have targeted nanometric single grain oxides at high electric fields. Similar research on thicker polycrystalline oxide layers can bridge the results to the prior literature on varistors and may uncover novel ionic/electronic features originating from the conduction mechanisms involving grain boundaries. Here, we investigate electronic conduction in Ti/poly-TiO2−x/Ti structures with different oxygen vacancy distributions and describe the observed features based on the motion and rearrangement of the ionized oxygen vacancies (IOVs) on the grain facets rather than the grain interiors. Containing no interface energy barrier, Ti/poly-TiO2/Ti devices demonstrate high resistance ohmic conduction at biasing fields below 5 × 106 V.m−1; higher fields drive the samples to a distinctly nonlinear and hysteretic low resistance status. The observed threshold is two orders of magnitude smaller than the typical resistance switching fields reported for the nanosized single grain memristors. This is consistent with the smaller activation energies reported for the IOV motion on the rutile facets than its interior. The presented model describes the observed dependence of the threshold field on the relative humidity of the surrounding air based on the lower activation energies reported for the hydroxyl-assisted IOV motion on the rutile facets. PMID:27404085

  13. LASE Ti: Sapphire Laser

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the photo, Messrs. Leroy F. Matthews (left) and Frank J. Novak (Lockheed Engineering & Sciences Co.) are preparing the Lidar Atmospheric Sensing Experiment (LASE) Instrument for integration into a NASA/ER-2 aircraft for a field mission. LASE is the first fully- engineered, autonomous differential Absorption Lidar (DIAL) System for the measurement of water vapor, aerosol and cloud in the troposphere. LASE uses a double-pulsed Ti:Sapphire laser for the transmitter with a 30 ns pulse length and 150 mJ/pulse. The laser beam is seeded to operate on a selected water vapor absorption line in the 815-nm region using a laser diode and an onboard absorption reference cell. A 40 cm diameter telescope collects the backscattered signals and directs them onto two detectors. LASE collects DIAL data at 5 Hz while flying at altitudes from 16-21 km. LASE was designed to operate autonomously within the environment and physical constraints of the ER-2 aircraft and to make water vapor profile measurements across the troposphere with accuracy having less than 6% of error. No other instrument can provide the spatial coverage and accuracy of LASE. Water vapor is the most radiative active gas in the troposphere, and the lack of understanding about its distribution provides one of the largest uncertainties in modeling climate change. LASE has demonstrated the necessary potential in providing high resolution water vapor measurements that can advance the studies of tropospheric water vapor distributions. LASE has flown 19 times during the development of the instrument and the validation of the science data. A joint international field mission was completed in the summer of 1996; adding 9 more successful flights. The LASE Instrument is being adapted to other aircraft platforms to support planned missions and to increase its utility.

  14. LASE Ti: Sapphire Laser

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the photo, Mr. Leroy F. Matthews (Lockheed Engineering & Sciences Co.) is connecting the Thermal Control Unit cables in preparing the Lidar Atmospheric Sensing Experiment (LASE) Instrument for integration into a NASA/ER-2 aircraft for a field mission. LASE is the first fully-engineered, autonomous differential Absorption Lidar (DIAL) System for the measurement of water vapor, aerosol and cloud in the troposphere. LASE uses a double-pulsed Ti:Sapphire laser for the transmitter with a 30 ns pulse length and 150 mJ/pulse. The laser beam is seeded to operate on a selected water vapor absorption line in the 815-nm region using a laser diode and an onboard absorption reference cell. A 40 cm diameter telescope collects the backscattered signals and directs them onto two detectors. LASE collects DIAL data at 5 Hz while flying at altitudes from 16-21 km. LASE was designed to operate autonomously within the environment and physical constraints of the ER-2 aircraft and to make water vapor profile measurements across the troposphere with accuracy having less than 6% of error. No other instrument can provide the spatial coverage and accuracy of LASE. Water vapor is the most radiative active gas in the troposphere, and the lack of understanding about its distribution provides one of the largest uncertainties in modeling climate change. LASE has demonstrated the necessary potential in providing high resolution water vapor measurements that can advance the studies of tropospheric water vapor distributions. LASE has flown 19 times during the development of the instrument and the validation of the science data. A joint international field mission was completed in the summer of 1996; adding 9 more successful flights. The LASE Instument is being adapted to other aircraft platforms to support planned missions and to increase its utility.

  15. 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.

  16. TiTaN Reconsidered

    NASA Astrophysics Data System (ADS)

    Natland, J. H.

    2008-12-01

    Strongly positive TiO2, Ta, and Nb (TiTaN) anomalies (1) in a Samoan ankaramite from Ofu Island have been attributed to the presence of refractory yet titanian eclogite in the mantle source. From chemical compositions, however, the anomalies could instead result from concentration of phenocrysts in magmas produced by mixing between a highly differentiated alkalic basalt and a crystal sludge carrying abundant olivine, clinopyroxene and especially titanomagnetite phenocrysts, the latter producing much of the TiTaN anomalies, and behaving much like rutile in eclogite. This is consistent with petrography. The distinctive effects of addition of each mineral are well illustrated on major-oxide variation diagrams. Separation of these minerals from liquids (to concentrate in ankaramites and dunite-wehrlite-pyroxenite cumulates) beginning at about 0.15 GPa in the mantle produces residual felsic differentiates (hawaiites, mugearites) with low TiTan anomalies (<1), exemplified by samples dredged elsewhere in Samoa from Savai'i (2). The Ofu samples have a low EMII signature (high 3He/4He), whereas the Savai'i samples have a high EMII signature (low 3He/4He), the extremes at Samoa. This gives a coincidental positive correlation at Samoa overall between TiTan anomalies and 3He/4He, TiTan anomalies being accentuated at the two places by the contrasting effects of phenocryst addition and subtraction during differentiation. High 3He/4He beneath several eastern Samoan volcanoes appears to be an attribute of near-FOZO mantle sources with minimal EM2 signature. (1) Jackson, M., et al., 2008. G-Cubed 9: doi:1029/2007GC001876 (2) Jackson, M., et al., 2007, Nature 448: 684-687, doi:10.1038/nature060488

  17. Analysis of the Coupling Effects of TiB Whiskers and TiC Particles on the Fracture Toughness of (TiB + TiC)/TC4 Composites: Experiment and Modeling

    NASA Astrophysics Data System (ADS)

    Lu, Weijie; Guo, Xianglong; Meng, Jialin; Wang, Fangqiu; Wang, Liqiang; Zhang, Di

    2015-08-01

    (TiB + TiC)/TC4 composites reinforced with different amounts of TiB whiskers and TiC particles are produced by common casting and hot forging technology. Then the fracture toughness of (TiB + TiC)/TC4 composites is analyzed by experiment and modeling. The experimental results indicate that not only reinforcement volume fraction but also the mole ratio between TiB whiskers and TiC particles can influence the fracture toughness of (TiB + TiC)/TC4 composites. Microstructure observations are carried out to examine the behavior of TiB whiskers and TiC particles in the fracture process. An analytical expression for predicting the fracture toughness of (TiB + TiC)/TC4 composites is built up. In particular, the coupling influences of TiB whiskers and TiC particles on the elastic modulus, yield strength, and fracture strain of TMCs are revealed in the modeling process. The results indicate that when TiB and TiC particles are coexisting in the TMCs, the fracture toughness of (TiB + TiC)/TC4 composites increases with the increase of the TiB whiskers aspect ratio, TiC particles volume fraction and size; however, with the increase of TiB whiskers volume fraction, the fracture toughness decreases. The breakage of TiB whiskers is the main reason for the fracture of TMCs. The acting mechanism of TiC particles on the fracture of TMCs transfers from blocking crack propagation and interfacial debonding to breakage with the increase of size, which can decrease the fracture toughness of (TiB + TiC)/TC4 composites. Considering the broken fraction of TiB whiskers, the fracture toughness of (TiB + TiC)/TC4 composites can be reasonably predicted.

  18. On the Nucleation and Growth of Alpha-Ti Off of TiB Precipitates (PREPRINT)

    DTIC Science & Technology

    2010-01-01

    that a dispersion of thermally stable titanium- boride particles, formed by trace boron additions, was effective in restricting the grain growth...reinforced by the TiB phase [6-13]. The boride particles act as the pinning sites for the grain boundaries. In the TiB reinforced Ti-6Al-4V alloy...these titanium- boride particles provide additional nucleation sites for the -Ti precipitates in addition to the -Ti precipitates that form along

  19. Biomineralisation with Saos-2 bone cells on TiSiN sputtered Ti alloys.

    PubMed

    V V, Anusha Thampi; Bendavid, Avi; Martin, P J; Vaithilingam, Vijay; Bean, Penelope A; Evans, Margaret D M; Subramanian, B

    2017-03-18

    Surface modifications of metallic implants are important in order to protect the underlying metals from the harsh corrosive environment inside the human body and to minimize the losses caused by wear. Recently, researches are carried out in developing bioactive surfaces on metallic implants, which supports the growth and proliferation of cells on to these surfaces. Titanium silicon nitride (TiSiN) hard nanocomposites thin films were fabricated on Ti alloys (Ti-6Al-4V) by pulsed direct current (DC) reactive magnetron sputtering. The films were characterized for its microstructural and electrochemical behavior. The higher charge transfer resistance (Rct) and positive shift in Ecorr value of TiSiN/Ti alloys than the bare Ti-alloys indicates a better corrosion resistance offered by the TiSiN thin films to the underlying substrates. The biological response to TiSiN/Ti alloys and control bare Ti-alloys was measured in vitro using cell-based assays with two main outcomes. Firstly, neither the Ti alloy nor the TiSiN thin film was cytotoxic to cells. Secondly, the TiSiN thin film promoted differentiation of human bone cells above the bare control Ti alloy as measured by alkaline phosphatase and calcium production. TiSiN thin films provide better corrosion resistance and protect the underlying metal from the corrosive environment. The thin film surface is both biocompatible and bioactive as indicated from the cytotoxicity and biomineralization studies.

  20. Study of preparation of TiB{sub 2} by TiC in Al melts

    SciTech Connect

    Ding Haimin; Liu Xiangfa; Nie Jinfeng

    2012-01-15

    TiB{sub 2} particles are prepared by TiC in Al melts and the characteristics of them are studied. It is found that TiC particles are unstable when boron exists in Al melts with high temperature and will transform to TiB{sub 2} and Al{sub 4}C{sub 3}. Most of the synthesized TiB{sub 2} particles are regular hexagonal prisms with submicron size. The diameter of the undersurfaces of these prisms is ranging from 200 nm to 1 {mu}m and the height is ranging from 100 nm to 300 nm. It is considered that controlling the transformation from TiC to TiB{sub 2} is an effective method to prepare small and uniform TiB{sub 2} particles. - Highlights: Black-Right-Pointing-Pointer TiC can easily transform into TiB{sub 2} in Al melts. Black-Right-Pointing-Pointer TiB{sub 2} formed by TiC will grow into regular hexagonal prisms with submicron size. Black-Right-Pointing-Pointer Controlling the transformation from TiC to TiB{sub 2} is an effective method to prepare small and uniform TiB{sub 2} particles.

  1. 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.

  2. Dynamics of Ti, N, and TiNx (x=1-3) admolecule transport on TiN(001) surfaces

    NASA Astrophysics Data System (ADS)

    Sangiovanni, D. G.; Edström, D.; Hultman, L.; Chirita, V.; Petrov, I.; Greene, J. E.

    2012-10-01

    We use classical molecular dynamics and the modified embedded atom method formalism to investigate the dynamics of atomic-scale transport on a low-index model compound surface, TiN(001). Our simulations, totaling 0.25 μs for each case study, follow the pathways and migration kinetics of Ti and N adatoms, as well as TiNx complexes with x=1-3, which are known to contribute to the growth of TiN thin films by reactive deposition from Ti, N2, and N precursors. The simulations are carried out at 1000 K, within the optimal range for TiN(001) epitaxial growth. We find Ti adatoms to be the highest-mobility species on TiN(001), with the primary migration path involving jumps of one nearest-neighbor distance dNN between adjacent fourfold hollow sites along in-plane <100> channels. Long jumps, 2dNN, are also observed, but at much lower frequency. N adatoms, which exhibit significantly lower migration rates than Ti, diffuse along in-plane <110> directions and, when they intersect other N atoms, associatively form N2 molecules, which desorb at kinetic rates. As expected, TiN and TiN3 complexes migrate at even lower rates with complex diffusion pathways involving rotations, translations, and rototranslations. TiN2 trimers, however, are shown to have surprisingly high diffusion rates, above that of N adatoms and almost half that of Ti adatoms. TiN3 motion is dominated by in-place rotation with negligible diffusion.

  3. Fibonacci Meets the TI-82.

    ERIC Educational Resources Information Center

    Dion, Gloria S.

    1995-01-01

    Presents the Fibonacci sequence in a format that is readily implemented using the table and list features of the Texas Instruments TI-82 graphing calculator or a spreadsheet. Includes questions and investigations that can be explored using these tables and lists. (MKR)

  4. One-step synthesis of TiO₂ nanorod arrays on Ti foil for supercapacitor application.

    PubMed

    Zheng, Zhi; Chen, Jiajun; Yoshida, Ryuji; Gao, Xiang; Tarr, Kayla; Ikuhara, Yumi H; Zhou, Weilie

    2014-10-31

    Titanium dioxide (TiO2) nanorod arrays grown directly on Ti metal foil were prepared by a facile one-step hydrothermal method, in which the Ti foil serves as both substrate and precursor. The nanorods are tetragonal rutile single crystal with growth orientation along the [001] direction. The electrochemical properties of the TiO2 nanorod arrays were systematically investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy using a three-electrode system. As a result, the TiO2 nanorod arrays exhibit good areal specific capacitance and excellent cyclic stability by retaining more than 98% of the initial specific capacitance after 1000 cycles. In addition, a good flexibility of the Ti foil with TiO2 nanorod arrays was demonstrated by the stable electrochemical performance under different bending angles, which indicates that TiO2 nanorod arrays grown on Ti foil could be a promising electrode material for flexible supercapacitor application.

  5. 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.

  6. Synthesis and characterization of TiO2 and Ag/TiO2 nanostructure

    NASA Astrophysics Data System (ADS)

    Gahlot, Swati; Thakur, Amit Kumar; Kulshrestha, Vaibhav; Shahi, V. K.

    2013-02-01

    Single phase anatase TiO2 nanoparticles were prepared using Titanium tertachloride (TiCl4) as precursor through an inexpensive method. Well dispersed nanocomposites of silver at TiO2 were synthesized successfully by photochemical route. Both TiO2 and Ag/TiO2 were characterized using X-Ray Diffraction (XRD) and transmission electron microscopy (TEM). The particle size of TiO2 is found to be ˜ 11 nm and ˜ 22 nm for Ag/TiO2, by XRD and confirmed by TEM. TEM micrographs also show the single phase crystal of TiO2 and confirm the deposition of silver among TiO2.

  7. Layered Composite of TiC-TiB2 to Ti-6Al-4V in Graded Composition by Combustion Synthesis in High-gravity Field

    NASA Astrophysics Data System (ADS)

    Huang, Xuegang; Zhao, Zhongmin; Zhang, Long

    2013-03-01

    By taking combustion synthesis to prepare solidified TiB2 matrix ceramic in high-gravity field, the layered composite of TiC-TiB2 ceramic to Ti-6Al-4V substrate in graded composition was achieved. XRD, FESEM and EDS results showed that the bulk full-density solidified TiC-TiB2 composite was composed of fine TiB2 platelets, TiC irregular grains, a few of α-Al2O3 inclusions and Cr alloy phases, and α'-Ti phases alternating with Ti-enriched carbides constituted the matrix of the joint in which fine TiB platelets were embedded, whereas some C, B atoms were also detected at the heat-affected zone of Ti-6A1-4V substrate. The layered composite of the solidified ceramic to Ti-6Al-4V substrate in graded composition with continuous microstructure was considered a result of fused joint and inter-diffusion between liquid ceramic and surface-molten Ti alloy, followed by TiB2-Ti peritectic reaction and subsequent eutectic reaction in TiC-TiB-Ti ternary system.

  8. Investigation on W/Fe diffusion bonding using Ti foil and Ti powder interlayer by SPS

    NASA Astrophysics Data System (ADS)

    Chen, Hong-Yu; Luo, Lai-Ma; Zhang, Jun; Zan, Xiang; Zhu, Xiao-Yong; Luo, Guang-Nan; Wu, Yu-Cheng

    2015-12-01

    W/steel composites are being developed for potential application in He gas-cooled divertors and plasma-facing components in fusion reactors. In this study, the dissimilar metal joints between W and Fe were fabricated at 950 °C via spark plasma sintering method with Ti foil (Ti-F) and Ti powder (Ti-P) as the interlayer under Ar atmosphere for 5 min at 57 MPa. Microscopic structures of the W/Fe diffusion joints with Ti-F and Ti-P were investigated and compared via field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. Thermal cycling tests were employed to measure the thermal stability of different types of W/Ti/Fe samples. The hardness distribution across joining interfaces was also determined. After thermal cycling tests, a crack occurred along the W/Ti-P interface in the W/Ti-P/Fe samples, whereas the W/Ti-F/Fe samples were intact at the interfaces. Results revealed that Ti-F is more suitable as an interlayer than Ti-P, and the interfaces of the W/Ti-F/Fe samples have better thermal stability than those of the W/Ti-P/Fe ones.

  9. Experimental study on the osseointegration of foam TiC/Ti composites.

    PubMed

    Jingyu, Wang; Lin, Wu; Yong, Gao; Jinsong, Zhang; Cuicui, Zhang

    2013-08-01

    Macroporous ceramics have demonstrated osteoconductive properties because of their biocompatibility and 3D macroporous structure, and these materials have recently been widely studied as bone replacement materials. The foam TiC/Ti composites discussed in this study have good mechanical properties, balancing out metallic toughness and ceramic strength. Furthermore, because of the high porosity and pore connectivity of these TiC/Ti composites, they have the potential to be a new bone replacement material. The purpose of this study was to evaluate the osseointegration of foam TiC/Ti composites, preliminarily discuss the TiC/Ti ossification mechanism, and to obtain reliable data on the use of foam TiC/Ti composites as bone replacement materials. The foam TiC/Ti composites were sited in 40 Japanese white rabbits for 4, 8, 12 and 24 weeks. The foam TiC/Ti composites were compared to foam SiC. M-CT (micro-computed tomography) analysis, histological analysis, SEM (scanning electron microscopy) observation and EDS (energy-dispersive x-ray spectrometer) analysis were conducted to estimate the osseointegration of the materials. The histological observations and quantitative analysis exhibited significantly more ossification area (volume), trabeculae maturity, and calcium and phosphorus content in the foam TiC/Ti composites compared to the foam SiC (p < 0.05). The results from this study suggest that the foam TiC/Ti composites possess good osseointegration capacity and have the potential to be a new bone replacement material.

  10. Reactive sintering of TiAl–Ti5Si3 in situ composites

    SciTech Connect

    Alman, David E.

    2005-06-01

    TiAl with between 0 and 20 vol%Ti5Si3 was produced by reactive sintering (700 °C for 15 min in vacuum) of cold pressed compacts of elemental Ti, Al and Si powder. The results show that adding Si to Ti and Al reduces the swelling associated with reactive sintering of TiAl, as composites containing more than 5 vol%Ti5Si3 densified during reactive sintering. However, composites containing more than 10 vol%Ti5Si3 did not retain their shape and the TiAl+20 vol%Ti5Si3 composite completely melted during the sintering process. A thermodynamic analysis indicated that the simultaneous formation of TiAl and Ti5Si3 increases the adiabatic flame temperature during the reaction between the powders. In fact, the analysis predicted that the maximum temperature of the reaction associated with the formation TiAl+20 vol%Ti5Si3 should exceed the melting point of TiAl, and this was observed experimentally. Differential thermal analysis (DTA) revealed that an Al–Si eutectic reaction occurred in mixtures of Ti, Al and Si powders prior to the formation of the TiAl and Ti5Si3 phases. There was no such pre-reaction formation of a eutectic liquid in Ti and Al powder mixtures. The formation of the pre-reaction liquid and the increase in adiabatic flame temperature resulted in the melting that occurred and the enhanced densification (minimization of swelling) during reactive sintering of the in situ composites.

  11. 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.

  12. Study and characterization of the irreversible transformation of electrically stressed planar Ti/TiO{sub x}/Ti junctions

    SciTech Connect

    Guillaume, N.; Puyoo, E. Le Berre, M.; Albertini, D.; Baboux, N.; Chevalier, C.; Ayadi, K.; Grégoire, J.; Gautier, B.; Calmon, F.

    2015-10-14

    We investigate the properties and characteristics of planar Ti/TiO{sub x}/Ti junctions, which consist of transverse TiO{sub x} lines drawn on Ti test patterns. Junctions are elaborated by means of local anodic oxidation using atomic force microscopy. An irreversible morphological transformation occurring in a reproducible manner is observed when these planar junctions are electrically stressed under ambient atmosphere. Structural and chemical analyses based on transmission electron microscopy techniques reveal the extension of the initial amorphous TiO{sub x} into a crystalline rutile phase. This irreversible transformation is proven to vanish completely if the electrical stress occurs under vacuum atmosphere. Finally, we carry out temperature dependent electrical measurements in order to elucidate their conduction mechanism: Schottky emission above an ultra-low potential barrier is assumed to dominate under vacuum atmosphere whereas ionic conduction seems to prevail in air.

  13. Ultrasound assisted combustion synthesis of TiC in Al-Ti-C system.

    PubMed

    Liu, Zhiwei; Rakita, Milan; Xu, Wilson; Wang, Xiaoming; Han, Qingyou

    2015-11-01

    This research investigated the effects of high-intensity ultrasound on the combustion synthesis of TiC particles in Al-Ti-C system. The process involved that high-intensity ultrasound was applied on the surface of a compacted Al-Ti-C pellet directly through a Nb probe during the thermal explosion reaction. By comparing with the sample without ultrasonic treatment, it was found that the thermal explosion reaction for synthesizing TiC phase could take place thoroughly in the ultrasonically treated sample. During the process of synthesizing TiC phase, the dissolution of solid graphite particles into the Al-Ti melt, as well as the nucleation and growth of TiC particles could be promoted effectively due to the effects of ultrasound, leading to an enhancement of the formation of TiC particles. Ultrasound assisted combustion synthesis as a simple and effective approach was proposed for synthesizing materials in this research.

  14. Investigation of TiC/Si{sub 3}N{sub 4} and TiN-coated TiC/Si{sub 3}N{sub 4} composites

    SciTech Connect

    Jow-Lay Huang; Boy-Yuan Shew; Ding-Fwu Lii

    1996-12-31

    Silicon nitride containing various compositions of as received TiC and TiN-coated TiC were hot pressed at 1800{degrees}C for 1 h in a nitrogen atmosphere. In TiN-coated TiC/Si{sub 3}N{sub 4} composites, TiC reacted firstly with the TiN coating to form a titanium carbonitride interlayer at 1450{degrees}C, which essentially reduced further reactions between TiC and Si{sub 3}N{sub 4} and enhanced densification. TiN-coated TiC/Si{sub 3}N{sub 4} composites exhibited better densification, flexural strength and fracture toughness than those of as received TiC/Si{sub 3}N{sub 4}.

  15. B-Ni-Ti (164)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 2 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from B-Be-Fe to Co-W-Zr' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'B-Ni-Ti (164)' with the content:

  16. TiC reinforced cast chromium steels

    SciTech Connect

    Dogan, Omer N.; Rawers, James C.; Hawk, Jeffrey A.; Schrems, Karol K.

    2003-11-01

    A series of new titanium carbide reinforced cast chromium steels were developed for wear applications. Objective of the program was to enhance wear resistant alloys and, if possible, improve mechanical properties. The new steels which were melted in a vacuum induction furnace contained 12 Cr, 3-5 Ti, 1-2 C in weight percent. Alloying with Ti changed the precipitate microstructure from Cr carbide to TiC dispersed in a martensitic matrix. Yield strength and impact resistance improved with Ti alloying. Wear rates of the cast Cr/TiC steels, (determined from high- and low-stress abrasion tests, erosion test, and scratch tests) were generally lower than both the as-cast and heat-treated AISI type 440°C steel and were often further reduced by increasing the Ti alloy concentration. The exceptions were the erosion test for which all materials had similar wear rate.

  17. Oxide Scales Formed on NiTi and NiPtTi Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Garg, Anita; Rogers, Richard B.; Noebe, Ronald D.

    2011-01-01

    Ni-49Ti and Ni-30Pt-50Ti (at.%) shape memory alloys were oxidized isothermally in air over the temperature range of 500 to 900 C. The microstructure, composition, and phase content of the scales were studied by SEM, EDS, XRD, and metallography. Extensive plan view SEM/EDS identified various features of intact or spalled scale surfaces. The outer surface of the scale was a relatively pure TiO2 rutile structure, typified by a distinct highly striated and faceted crystal morphology. Crystal size increased significantly with temperature. Spalled regions exhibited some porosity and less distinct features. More detailed information was obtained by correlation of SEM/EDS studies of 700 C/100 hr cross-sections with XRD analyses of serial or taper-polishing of plan surfaces. Overall, multiple layers exhibited graded mixtures of NiO, TiO2, NiTiO3, Ni(Ti) or Pt(Ni,Ti) metal dispersoids, Ni3Ti or Pt3Ti depletion zones, and substrate, in that order. The NiTi alloy contained a 3 at.% Fe impurity that appeared in embedded localized Fe-Ti-rich oxides, while the NiPtTi alloy contained a 2 v/o dispersion of TiC that appeared in lower layers. The oxidation kinetics of both alloys (in a previous report) indicated parabolic growth and an activation energy (250 kJ/mole) near those reported in other Ti and NiTi studies. This is generally consistent with TiO2 existing as the primary scale constituent, as described here.

  18. Deformation and fracture of Ti- and Ti3Al-matrix composites

    SciTech Connect

    Yang, J.M.; Jeng, S.M. )

    1992-06-01

    Continuous fiber-reinforced composites having Ti-alloy or Ti aluminide matrices are under consideration for refractory aerospace structural applications. An account is presently given of microscopic damage mechanisms, flaw evolution, and fracture behavior of fiber-reinforced Ti alloy and Ti aluminide matrices under various loading conditions. Attention is given to representative levels of tensile behavior, low-cycle fatigue and fatigue-crack propagation, and creep and environmentally-assisted damage. 40 refs.

  19. CO gas-sensing properties of CuO-TiN and CuO-TiN-TiO2 prepared by controlled oxidation of Cu-TiN composites

    NASA Astrophysics Data System (ADS)

    Park, Je-Shin; Lim, Chae-Hun; Cho, Young-Ki; Yu, Yeon-Tae

    2015-03-01

    P-type Cu-TiN composites sensitive to CO gas, CuO-TiN and CuO-TiN-TiO2, were synthesized by ball milling Cu33Ti67 and Cu15Ti85 alloys for 25 h in a pressurized N2 atmosphere. The sensing materials of CuO-TiN and CuO-TiN-TiO2 were prepared via a two-step oxidation process following an investigation of their CO gas-sensing properties. Their sensing responses for CO gas were compared; typical for p-type semiconductors, the resistances of both sensing materials increased as CO was introduced. The CuO-TiN-TiO2 powder had a greater response than the CuO-TiN powder at all temperatures tested. The highest responses shown by the two materials were to 1000 ppm CO at 250 °C: a response of 5.4 by CuO-TiN-TiO2 and 3.1 by CuO-TiN. During the first oxidation step of CuO-TiN-TiO2, micropores were formed that significantly increased this material's specific surface area. Therefore, we believe that the superior response of the CuO-TiN-TiO2 sensing material was due to this surface area enlargement during the oxidation treatment.

  20. Controllable Synthesis and Tunable Photocatalytic Properties of Ti(3+)-doped TiO2.

    PubMed

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-06-05

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti(3+)-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti(4+) on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti(3+)-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity.

  1. Controllable Synthesis and Tunable Photocatalytic Properties of Ti3+-doped TiO2

    PubMed Central

    Ren, Ren; Wen, Zhenhai; Cui, Shumao; Hou, Yang; Guo, Xiaoru; Chen, Junhong

    2015-01-01

    Photocatalysts show great potential in environmental remediation and water splitting using either artificial or natural light. Titanium dioxide (TiO2)-based photocatalysts are studied most frequently because they are stable, non-toxic, readily available, and highly efficient. However, the relatively wide band gap of TiO2 significantly limits its use under visible light or solar light. We herein report a facile route for controllable synthesis of Ti3+-doped TiO2 with tunable photocatalytic properties using a hydrothermal method with varying amounts of reductant, i.e., sodium borohydride (NaBH4). The resulting TiO2 showed color changes from light yellow, light grey, to dark grey with the increasing amount of NaBH4. The present method can controllably and effectively reduce Ti4+ on the surface of TiO2 and induce partial transformation of anatase TiO2 to rutile TiO2, with the evolution of nanoparticles into hierarchical structures attributable to a high pressure and strong alkali environment in the synthesis atmosphere; in this way, the photocatalytic activity of Ti3+-doped TiO2 under visible-light can be tuned. The as-developed strategy may open up a new avenue for designing and functionalizing TiO2 materials for enhancing visible light absorption, narrowing band gap, and improving photocatalytic activity. PMID:26044406

  2. TiCl, TiH and TiH+ Bond Energies, a Test of a Correlation Consistent Ti Basis Set

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1999-01-01

    Correlation consistent basis sets are developed for Ti atom. The polarization functions are optimized for the average of the 3F and 5F states. One series of correlation consistent basis sets is for 3d and 4s correlation, while the second series includes 3s and 3p correlation as well as 3d and 4s correlation. These basis sets are tested using the Ti 3F-5F separation and the dissociation energies of TiCl X4Phi, TiH X4Phi, and TiH(+) X3Phi. The CCSD(T) complete basis set limit values are determined by extrapolation. The Douglas Kroll approach is used to compute the scalar relativistic effect. Spin-orbit effects are taken from experiment and/or computed at the CASSCF level. The Ti 3F-5F separation is in excellent agreement with experiment, while the TiCl, TiH, and TiH(+) bond energies are in good agreement with experiment. Extrapolation with the valence basis set is consistent with other atoms, while including 3s and 3p correlation appears to make extrapolation.

  3. Porous NiTi shape memory alloys produced by SHS: microstructure and biocompatibility in comparison with Ti2Ni and TiNi3.

    PubMed

    Bassani, Paola; Panseri, Silvia; Ruffini, Andrea; Montesi, Monica; Ghetti, Martina; Zanotti, Claudio; Tampieri, Anna; Tuissi, Ausonio

    2014-10-01

    Shape memory alloys based on NiTi have found their main applications in manufacturing of new biomedical devices mainly in surgery tools, stents and orthopedics. Porous NiTi can exhibit an engineering elastic modulus comparable to that of cortical bone (12-17 GPa). This condition, combined with proper pore size, allows good osteointegration. Open cells porous NiTi was produced by self propagating high temperature synthesis (SHS), starting from Ni and Ti mixed powders. The main NiTi phase is formed during SHS together with other Ni-Ti compounds. The biocompatibility of such material was investigated by single culture experiment and ionic release on small specimen. In particular, NiTi and porous NiTi were evaluated together with elemental Ti and Ni reference metals and the two intermetallic TiNi3, Ti2Ni phases. This approach permitted to clearly identify the influence of secondary phases in porous NiTi materials and relation with Ni-ion release. The results indicated, apart the well-known high toxicity of Ni, also toxicity of TiNi3, whilst phases with higher Ti content showed high biocompatibility. A slightly reduced biocompatibility of porous NiTi was ascribed to combined effect of TiNi3 presence and topography that requires higher effort for the cells to adapt to the surface.

  4. Understanding the Magnesiothermic Reduction Mechanism of TiO2 to Produce Ti

    NASA Astrophysics Data System (ADS)

    Choi, Kyunsuk; Choi, Hanshin; Sohn, Il

    2017-04-01

    Titanium dioxide (TiO2) powders in the mineral form of rutile were reduced to metallic and an intermediate phase via a magnesiothermic reaction in molten Mg at temperatures between 973 K and 1173 K (700 °C and 900 °C) under high-purity Ar atmosphere. The reaction behavior and pathway indicated intermediate phase formation during the magnesiothermic reduction of TiO2 using XRD (X-ray diffraction), SEM (scanning electron microscope), and TEM (transmission electron microscope). Mg/TiO2 = 2 resulted in various intermediate phases of oxygen containing titanium, including Ti6O, Ti3O, and Ti2O, with metallic Ti present. MgTi2O4 ternary intermediate phases could also be observed, but they were dependent on the excess Mg present in the sample. Nevertheless, even with excessive amounts of Mg at Mg/TiO2 = 10, complete reduction to metallic Ti could not be obtained and some Ti6O intermediate phases were present. Although thermodynamics do not predict the formation of the MgTi2O4 spinel phase, detailed phase identification through XRD, SEM, and TEM showed significant amounts of this intermediate ternary phase even at excess Mg additions. Considering the stepwise reduction of TiO2 by Mg and the pronounced amounts of MgTi2O4 phase observed, the rate-limiting reaction is likely the reduction of MgTi2O4 to the TitO phase. Thus, an additional reduction step beyond thermodynamic predictions was developed.

  5. Understanding the Magnesiothermic Reduction Mechanism of TiO2 to Produce Ti

    NASA Astrophysics Data System (ADS)

    Choi, Kyunsuk; Choi, Hanshin; Sohn, Il

    2017-01-01

    Titanium dioxide (TiO2) powders in the mineral form of rutile were reduced to metallic and an intermediate phase via a magnesiothermic reaction in molten Mg at temperatures between 973 K and 1173 K (700 °C and 900 °C) under high-purity Ar atmosphere. The reaction behavior and pathway indicated intermediate phase formation during the magnesiothermic reduction of TiO2 using XRD (X-ray diffraction), SEM (scanning electron microscope), and TEM (transmission electron microscope). Mg/TiO2 = 2 resulted in various intermediate phases of oxygen containing titanium, including Ti6O, Ti3O, and Ti2O, with metallic Ti present. MgTi2O4 ternary intermediate phases could also be observed, but they were dependent on the excess Mg present in the sample. Nevertheless, even with excessive amounts of Mg at Mg/TiO2 = 10, complete reduction to metallic Ti could not be obtained and some Ti6O intermediate phases were present. Although thermodynamics do not predict the formation of the MgTi2O4 spinel phase, detailed phase identification through XRD, SEM, and TEM showed significant amounts of this intermediate ternary phase even at excess Mg additions. Considering the stepwise reduction of TiO2 by Mg and the pronounced amounts of MgTi2O4 phase observed, the rate-limiting reaction is likely the reduction of MgTi2O4 to the TitO phase. Thus, an additional reduction step beyond thermodynamic predictions was developed.

  6. Ti-O-N/Ti composite coating on Ti-6Al-4V: surface characteristics, corrosion properties and cellular responses.

    PubMed

    Cao, Xiao-Lin; Sun, Tao; Yu, Yonghao

    2015-03-01

    To enhance the corrosion resistance of Ti-6Al-4V and extend its lifetime in medical applications, Ti-O-N/Ti composite coating was synthesized on the surface via plasma immersion ion implantation and deposition (PIIID). Surface morphology and cross sectional morphology of the composite coating were characterized using atomic force microscopy and scanning electron microscopy, respectively. Although X-ray photoelectron spectroscopic analysis revealed that the Ti-O-N/Ti composite coating was composed of non-stoichiometric titanium oxide, titanium nitride and titanium oxynitride, no obvious characteristic peak corresponding to the crystalline phases of them was detected in the X-ray diffraction pattern. In accordance with Owens-Wendt equation, surface free energy of the uncoated and coated samples was calculated and compared. Moreover, the corrosion behavior of uncoated and coated samples was evaluated by means of electrochemical impedance spectroscopy measurement, and an equivalent circuit deriving from Randles model was used to fit Bode plots and describe the electrochemical processes occurring at the sample/electrolyte interface. On the basis of the equivalent circuit model, the resistance of the composite coating was 4.7 times higher than that of the passive layer on uncoated samples, indicating the enhanced corrosion resistance after PIIID treatment. Compared to uncoated Ti-6Al-V, Ti-O-N/Ti-coated samples facilitated ostoblast proliferation within 7 days of cell culture, while there was no statistically significant difference in alkaline phosphate activity between uncoated and coated samples during 21 days of cell culture.

  7. Effects of Ti content on the structural and the magnetic properties of ZnCrO:Ti (Cr: 1 at.%, Ti: 0 - 0.8 at.%) thin films

    NASA Astrophysics Data System (ADS)

    Lee, Youngmin; Shon, Yoon; Yoon, Im Taek; Kim, Deuk Young; Lee, Sejoon

    2016-12-01

    We investigated the effects of the Ti content on the structural and the magnetic properties of ZnCrO:Ti thin films (Cr: 1.0 at.%, Ti: 0 - 0.8 at.%). The samples were prepared by co-sputtering of ZnCrO and Ti and showed the Ti solution limit to be 0.3 at.%. When the Ti additives were doped with an appropriate concentration less than the solution limit, the magnetic properties of the films were improved due to the increased magnetic moments from Ti2+ ions ( i.e., 3d24s0). For the samples doped with large amounts of Ti dopants over the solution limit, however, the magnetization was gradually degraded due to the formation of metastable TiO2 and ZnCrTiO having no spins ( i.e., 3d04s0).

  8. Creep behavior of alloys based on TiAl containing TiB sub 2 and TiN particulates

    SciTech Connect

    Martin, P.L.; Carter, D.H.; Aikin, R.M. Sr. ); Aikin, R.M. Jr.; Christodoulou, L. )

    1990-01-01

    Ordered alloys based on the L1{sub 0} crystal structure compound TiAl were tested in constant stress creep. The alloys ranged from 45 to 47 at. % Al with and without V substitutions. The ingot processing, utilizing the XD{trademark} technique, incorporated 1 to 5 {mu}m diameter particles of boride or nitride compounds. Emphasis was placed on characterizing the initial stages of creep using digital data acquisition and analysis in the range 70 to 280 MPa stress and 760 to 850{degrees}C temperature. When TiN (converting to Ti{sub 2}AlN in processing) and TiB{sub 2} are both added to the matrix, the creep properties are significantly improved. Fine particles were observed to decorate dislocations and to have nucleated homogeneously within the TiAl grains. 16 refs., 7 figs., 3 tabs.

  9. Influence of TiN coating on the biocompatibility of medical NiTi alloy.

    PubMed

    Jin, Shi; Zhang, Yang; Wang, Qiang; Zhang, Dan; Zhang, Song

    2013-01-01

    The biocompatibility of TiN coated nickel-titanium shape memory alloy (NiTi-SMA) was evaluated to compare with that of the uncoated NiTi-SMA. Based on the orthodontic clinical application, the surface properties and biocompatibility were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), wettability test, mechanical test and in vitro tests including MTT, cell apoptosis and cell adhesion tests. It was observed that the bonding between the substrate and TiN coating is excellent. The roughness and wettability increased as for the TiN coating compared with the uncoated NiTi-SMA. MTT test showed no significant difference between the coated and uncoated NiTi-SMA, however the percentage of early cell apoptosis was significantly higher as for the uncoated NiTi alloy. SEM results showed that TiN coating could enhance the cell attachment, spreading and proliferation on NiTi-SMA. The results indicated that TiN coating bonded with the substrate well and could lead to a better biocompatibility.

  10. Laser processing of in situ TiN/Ti composite coating on titanium.

    PubMed

    Sahasrabudhe, Himanshu; Soderlind, Julie; Bandyopadhyay, Amit

    2016-01-01

    Laser remelting of commercially pure titanium (CP-Ti) surface was done in a nitrogen rich inert atmosphere to form in situ TiN/Ti composite coating. Laser surface remelting was performed at two different laser powers of 425 W and 475 W. At each power, samples were fabricated with one or two laser scans. The resultant material was a nitride rich in situ coating that was created on the surface. The cross sections revealed a graded microstructure. There was presence of nitride rich dendrites dispersed in α-Ti matrix at the uppermost region. The structure gradually changed with lesser dendrites and more heat affected α-Ti phase maintaining a smooth interface. With increasing laser power, the dendrites appeared to be larger in size. Samples with two laser scans showed discontinuous dendrites and more α-Ti phase as compared to the samples with one laser scan. The resultant composite of TiN along with Ti2N in α-Ti showed substantially higher hardness and wear resistance than the untreated CP-Ti substrate. Coefficient of friction was also found to reduce due to surface nitridation. Leaching of Ti(4+) ions during wear test in DI water medium was found to reduce due to laser surface nitriding.

  11. Preparation, characterization and photocatalytic activities of TiO2-SrTiO3 composites

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Zhu, Lianjie; Gao, Fubo; Xie, Hanjie

    2017-01-01

    Series of TiO2-SrTiO3 composites were synthesized by hydrothermal method, using TiO2 nanotube array as a precursor and Sr(OH)2 as a Sr source material. TiO2-SrTiO3 products with various composition were obtained by simply changing the reaction time. The as-synthesized products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The optical properties were studied by means of UV-Vis absorption spectroscopy and photoluminescence (PL) spectra. Their photocatalytic activities were assessed by photodegradation of rhodamine B (RhB) solution and the photocatalytic reaction mechanism was discussed. The TiO2-SrTiO3 composites obtained at 2 h exhibits the highest activity for photodegradation of RhB.

  12. Controllable hydrothermal synthesis of rutile TiO{sub 2} hollow nanorod arrays on TiCl{sub 4} pretreated Ti foil for DSSC application

    SciTech Connect

    Xi, Min; Zhang, Yulan; Long, Lizhen; Li, Xinjun

    2014-11-15

    Rutile TiO{sub 2} nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl{sub 4} pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO{sub 2} nanorod arrays (H-TNRs). The TiCl{sub 4} pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl{sub 4} concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of ∼1.5 μm and diameter of ∼200 nm, obtained on 0.15 M TiCl{sub 4} pretreated Ti foil with 0.6 mL TTB, exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 °C-H-TNRs photoanode obtained from the 0.15-TiCl{sub 4}-TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode. - Graphical abstract: Rutile hollow TiO{sub 2} nanorod array photoanode obtained from original TiO{sub 2} nanorod array photoanode by hydrothermal etching demonstrates enhanced photoelectric efficiency of DSSC. - Highlights: • TiO{sub 2} nanorods are prepared via hydrothermal process on TiCl{sub 4}-pretreated Ti foil. • Hollow TiO{sub 2} nanorods are obtained by hydrothermal etching of TiO{sub 2} nanorods. • TiCl{sub 4} pretreatment plays a key role in protecting Ti foil from chemical corrosion. • Hollow TiO{sub 2} nanorods photoanode shows enhanced photoelectric efficiency for DSSC.

  13. Durability Assessment of TiAl Alloys

    NASA Technical Reports Server (NTRS)

    Draper, Susan L.; Lerch, Bradley A.

    2008-01-01

    The durability of TiAl is a prime concern for the implementation of TiAl into aerospace engines. Two durability issues, the effect of high temperature exposure on mechanical properties and impact resistance, have been investigated and the results are summarized in this paper. Exposure to elevated temperatures has been shown to be detrimental to the room temperature ductility of gamma alloys with the most likely mechanisms being the ingress of interstitials from the surface. Fluorine ion implantation has been shown to improve the oxidation resistance of gamma alloys, and ideally it could also improve the environmental embrittlement of high Nb content TiAl alloys. The effect of F ion implantation on the surface oxidation and embrittlement of a third generation, high Nb content TiAl alloy (Ti-45Al-5Nb-B-C) were investigated. Additionally, the ballistic impact resistance of a variety of gamma alloys, including Ti-48Al-2Cr- 2Nb, Ti-47Al-2Cr-2Nb, ABB-2, ABB-23, NCG359E, 95A and Ti-45Al-5Nb-B-C was accessed. Differences in the ballistic impact properties of the various alloys will be discussed, particularly with respect to their manufacturing process, microstructure, and tensile properties.

  14. Fabrication of Powder Metallurgy Pure Ti Material by Using Thermal Decomposition of TiH2

    NASA Astrophysics Data System (ADS)

    Mimoto, Takanori; Nakanishi, Nozomi; Umeda, Junko; Kondoh, Katsuyoshi

    Titanium (Ti) and titanium alloys have been interested as an engineering material because they are widely used across various industrial applications, for example, motorcycle, automotive and aerospace industries, due to their light weight, high specific strength and superior corrosion resistance. Ti materials are particularly significant for the aircraft using carbon/carbon (C/C) composites, for example, carbon fiber reinforced plastics (CFRP), because Ti materials are free from the problem of contact corrosion between C/C composites. However, the applications of Ti materials are limited because of their high cost. From a viewpoint of cost reduction, cost effective process to fabricate Ti materials is strongly required. In the present study, the direct consolidation of titanium hydride (TiH2) raw powders in solid-state was employed to fabricate pure Ti bulk materials by using thermal decomposition of TiH2. In general, the production cost of Ti components is expensive due to using commercially pure (CP) Ti powders after dehydrogenation. On the other hand, the novel process using TiH2 powders as starting materials is a promising low cost approach for powder metallurgy (P/M) Ti products. Furthermore, this new process is also attractive from a viewpoint of energy saving because the dehydrogenation is integrated into the sintering process. In this study, TiH2 raw powders were directly consolidated by conventional press technique at 600 MPa to prepare TiH2 powder compacted billets. To thermally decompose TiH2 and obtain sintered pure Ti billets, the TiH2 powder billets were heated in the integrated sintering process including dehydrogenation. The hot-extruded pure Ti material, which was heat treated at 1273 K for 180 min in argon gas atmosphere, showed tensile strength of 701.8 MPa and elongation of 27.1%. These tensile properties satisfied the requirements for JIS Ti Grade 4. The relationship between microstructures, mechanical properties response and heat treatment

  15. TiC reinforced cast Cr steels

    SciTech Connect

    Dogan, O.N.; Hawk, J.A.; Schrems, K.K.

    2006-06-01

    A new class of materials, namely TiC-reinforced cast chromium (Cr) steels, was developed for applications requiring high abrasion resistance and good fracture toughness. The research approach was to modify the carbide structure of commercial AISI 440C steel for better fracture resistance while maintaining the already high abrasion resistance. The new alloys contained 12Cr, 2.5–4.5Ti, and 1–1.5C (wt.%) and were melted in a vacuum induction furnace. Their microstructure was composed primarily of a martensitic matrix with a dispersion of TiC precipitates. Modification of TiC morphology was accomplished through changing the cooling rate during solidification. Wear rates of the TiC-reinforced Cr steels were comparable to that of AISI 440C steel, but the impact resistance was much improved.

  16. Structural inheritance and difference between Ti2AlC, Ti3AlC2 and Ti5Al2C3 under pressure from first principles

    NASA Astrophysics Data System (ADS)

    Gao, Qing-He; Du, An; Yang, Ze-Jin

    2017-01-01

    The structural inheritance and difference between Ti2AlC, Ti3AlC2 and Ti5Al2C3 under pressure from first principles are studied. The results indicate that the lattice parameter a are almost the same within Ti2AlC, Ti3AlC2 and Ti5Al2C3, and the value of c in Ti5Al2C3 is the sum of Ti2AlC and Ti3AlC2 which is revealed by the covalently bonded chain in the electron density difference: Al-Ti-C-Ti-Al for Ti2AlC, Al-Ti2-C-Ti1-C-Ti2-Al for Ti3AlC2 and Al-Ti3-C2-Ti3-Al-Ti2-C1-Ti1-C1-Ti2-Al for Ti5Al2C3. The calculated axial compressibilities, volumetric shrinkage, elastic constant c11, c33/c11 ratio, bulk modulus, shear modulus, and Young’s modulus of Ti5Al2C3 are within the range of the end members (Ti2AlC and Ti3AlC2) in a wide pressure range of 0-100 GPa. Only Ti2AlC is isotropic crystal at about 50 GPa within the Ti-Al-C compounds. All of the Ti 3d density of states curves of the three compounds move from lower energy to higher energy level with pressure increasing. The similarities of respective bond length, bond overlap population (Ti-C, Ti-Al and Ti-Ti), atom Mulliken charges under pressure as well as the electron density difference for the three compounds are discovered. Among the Ti-Al-C ternary compounds, Ti-Ti bond behaves least compressibility, whereas the Ti-Al bond is softer than that of Ti-C bonds, which can also been confirmed by the density of states and electron density difference. Bond overlap populations of Ti-Ti, Ti-C and Ti-Al indicate that the ionicity interaction becomes more and more stronger in the three structures as the pressure increasing. Mulliken charges of Ti1, Ti2, Ti3, C and Al are 0.65, 0.42, 0.39, ‑0.73, ‑0.04 at 0 GPa, respectively, which are consistent with the Pauling scale.

  17. Fabrication and nanoindentation properties of TiN/NiTi thin films and their applications in electrochemical sensing.

    PubMed

    Kumar, Ashvani; Singh, Devendra; Goyal, Rajendra N; Kaur, Davinder

    2009-05-15

    Nanocrystalline TiN/NiTi thin films have been grown on silicon substrate by dc magnetron sputtering to improve the corrosion and mechanical properties of NiTi based shape memory alloys without sacrificing the phase transformation effect. Interestingly, the preferential orientation of the TiN films was observed to change from (1 1 1) to (2 0 0) with change in nature of sputtering gas from 70% Ar+30% N(2) to 100% N(2). In present study the influence of crystallographic orientation of TiN on mechanical and corrosion properties of TiN/NiTi thin films was investigated. TiN (2 0 0)/NiTi films were found to exhibit high hardness, high elastic modulus, and thereby better wear resistance as compared to pure NiTi and TiN (1 1 1)/NiTi films. Electrochemical test revealed that TiN coated NiTi film exhibits better corrosion resistance in 1M NaCl solution as compared to uncoated NiTi film. The application of TiN/NiTi films in the electrochemical sensing of dopamine, which has a critical physiological importance in Parkinson's disease, has been demonstrated. A comparison of voltammetric response of dopamine at silicon based electrodes modified with different nanocrystalline coatings indicated that these films catalyze the oxidation of dopamine.

  18. Deformation twinning in metals and ordered intermetallics-Ti and Ti-aluminides

    NASA Astrophysics Data System (ADS)

    Yoo, M. H.; Fu, C. L.; Lee, J. K.

    1991-06-01

    The role of deformation twinning in the strength and ductility of metals and ordered intermetallic alloys is examined on the basis of crystallography, energetics and kinetics of deformation twinning. A systematic analysis is made by taking Ti, Ti3AI, TiAl, and A13Ti as four model systems. In comparison with profuse twinning in Ti, the intrinsic difficulty of twinning in Ti3A1 is rationalized in terms of the interchange shuffling mechanism. A fault (SISF) dragging mechanism based on the interaction torque explains the physical source for the low mobility of screw superdislocations in TiAl, which may lead to (111) [ 11bar{2}] twin nucleation. In TiAl and A13Ti alloys, the twin-slip (ordinary) conjugate relationship makes an important contribution to the strain compatibility for high-temperature plasticity. Potentially beneficial alloying additions to promote twinning are discussed. Les conséquences de la déformation par maclage sur la fracture et la ductilité des métaux et alliages intermétalliques ordonnés sont étudiées en fonction de la cristallographie, de l'énergie et de la cinétique des déformations par maclage. Une analyse systématique a été faite en considérant Ti, Ti3AI, TiAl et A13Ti comme quatre systèmes modèles. En comparaison avec le nombre important de maclages observés dans Ti, la difficulté intrinsèque des maclages dans Ti3AI est rationalisée en terme de mécanisme d'“interchange shuffling”. Un mécanisme de “dragging fault” basé sur l'interaction “torque” explique l'origine physique de la faible mobilité des superdislocations vissées dans TiAl qui peuvent conduire à la nucléation des macles (111) 112. Dans les alliages tels TiAl et A13Ti, la relation conjuguée entre la macle et le glissement (ordinaire) contribue de façon importante à la compatibilité des contraintes lors de la déformation plastique à haute température. Des effets bénéfiques potentiels liés à des éléments d'addition sur le processus

  19. Calculation of defect properties of NiTi and FeTi

    SciTech Connect

    Lutton, R.T.; Sabochick, M.J. . Dept. of Engineering Physics); Lam, N.Q. )

    1990-12-01

    The energies and configurations of interstitials and vacancies in the B2 ordered compounds NiTi and FeTi were calculated using atomistic simulation. The stable configuration of a vacancy after the removal of an Ni atom was a vacant Ni site; similarly, the removal of an Fe atom in FeTi resulted in a vacant Fe site. Removal of a Ti atom in both compounds, however, resulted in a vacant Ni or Fe site and an adjacent antisite defect. The effective vacancy formation energies in NiTi and FeTi were calculated to be 1.48 and 1.07 eV, respectively. Interstitials in NiTi formed split {l angle}111{r angle} configurations consisting of a Ni-Ni dumbbell oriented in the {l angle}111{r angle} direction with one or two adjacent antisite defects. The Fe interstitial in FeTi had a similar configuration, except the dumbbell contained Fe atoms. The Ti interstitial in FeTi formed an {l angle}110{r angle} Fe-Fe dumbbell. 8 refs., 2 tabs.

  20. Laser-assisted atom probe tomography of Ti/TiN films deposited on Si.

    PubMed

    Sanford, N A; Blanchard, P T; White, R; Vissers, M R; Diercks, D R; Davydov, A V; Pappas, D P

    2017-03-01

    Laser-assisted atom probe tomography (L-APT) was used to examine superconducting TiN/Ti/TiN trilayer films with nominal respective thicknesses of 5/5/5 (nm). Such materials are of interest for applications that require large arrays of microwave kinetic inductance detectors. The trilayers were deposited on Si substrates by reactive sputtering. Electron energy loss microscopy performed in a scanning transmission electron microscope (STEM/EELS) was used to corroborate the L-APT results and establish the overall thicknesses of the trilayers. Three separate batches were studied where the first (bottom) TiN layer was deposited at 500°C (for all batches) and the subsequent TiN/Ti bilayer was deposited at ambient temperature, 250°C, and 500°C, respectively. L-APT rendered an approximately planar TiN/Si interface by making use of plausible mass-spectral assignments to N3(1+), SiN(1+), and SiO(1+). This was necessary since ambiguities associated with the likely simultaneous occurrence of Si(1+) and N2(1+) prevented their use in rendering the TiN/Si interface upon reconstruction. The non-superconducting Ti2N phase was also revealed by L-APT. Neither L-APT nor STEM/EELS rendered sharp Ti/TiN interfaces and the contrast between these layers diminished with increased film deposition temperature. L-APT also revealed that hydrogen was present in varying degrees in all samples including control samples that were composed of single layers of Ti or TiN.

  1. Hydrolysis of TiCl₄: Initial Steps in the Production of TiO₂

    SciTech Connect

    Wang, Tsang-Hsiu; Navarrete-Lopez, Alejandra M.; Li, Shenggang; Dixon, David A.; Gole, James L.

    2010-06-24

    The hydrolysis of titanium tetrachloride (TiCl{sub 4}) to produce titanium dioxide (TiO{sub 2})nanoparticles has been studied to provide insight into the mechanism for forming these nanoparticles. We provide calculations of the potential energy surfaces, the thermochemistry of the intermediates, and the reaction paths for the initial steps in the hydrolysis of TiCl{sub 4}. We assess the role of the titanium oxychlorides (Ti{sub x}O{sub y}Cl{sub z}; x = 2-4, y = 1,3-6, and z = 2, 4, 6) and their viable reaction paths. Using transition-state theory and RRKM theory, we predicted rate constants including the effect of tunneling. Heats of formation at 0 and 298 K are predicted for TiCl{sub 4}, TiCl{sub 3}OH, TiOCl{sub 2}, TiOClOH, TiCl{sub 2}(OH){sub 2}, TiCl(OH){sub 3}, Ti(OH){sub 4}, and TiO{sub 2} using the CCSD(T) method with correlation consistent basis sets extrapolated to the complete basis set limit and compared with the available experimental data. Clustering energies and heats of formation are calculated for neutral clusters. The calculated heats of formation were used to study condensation reactions that eliminate HCl or H{sub 2}O. The reaction energy is substantially endothermic if more than two HCl molecules are eliminated. The results show that the mechanisms leading to formation of TiO{sub 2} nanoparticles and larger ones are complicated and will have a strong dependence on the experimental conditions.

  2. Mechanical properties and microstructures of dental cast Ti-6Nb-4Cu, Ti-18Nb-2Cu, and Ti-24Nb-1Cu alloys.

    PubMed

    Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo

    2016-01-01

    The mechanical properties -tensile strength, yield strength, elongation after fracture, and Vickers hardness- and alloy phases of the dental cast alloys Ti-6%Nb-4%Cu, Ti-18%Nb-2%Cu, and Ti-24%Nb-1%Cu were investigated. Ti-6%Nb-4%Cu consisted of a single α-phase, while Ti-18%Nb-2%Cu and Ti-24%Nb-1%Cu consisted of α- and β-phases. The tensile strengths, yield strengths, and hardnesses of these alloys were higher than those of Ti-5%Cu and Ti-30%Nb; however, their breaking elongations were smaller. These differences in the mechanical properties are attributable to solid-solution strengthening or to precipitation strengthening by the dual-phase (α+β) structure. Thus, Ti-Nb-Cu alloys are suitable for use in high-strength dental prostheses, such as implantretained superstructures and narrow-diameter implants.

  3. The effect of site geometry, Ti content and Ti oxidation state on the Ti K-edge XANES spectrum of synthetic hibonite

    NASA Astrophysics Data System (ADS)

    Doyle, P. M.; Berry, A. J.; Schofield, P. F.; Mosselmans, J. F. W.

    2016-08-01

    The Al-rich oxide hibonite (CaAl12O19) is modeled to be the second mineral to condense from a gas of solar composition and is found within calcium-aluminum-rich inclusions and the matrix of chondritic meteorites. Both Ti3+ and Ti4+ are reported in meteoritic hibonite, so hibonite has been proposed as a single mineral oxybarometer that could be used to elucidate conditions within the first 0.2 Myrs of the Solar System. Synthetic hibonites with Ti3+/(Ti3+ + Ti4+) (hereafter Ti3+/ΣTi) ranging between 0 and 1 were prepared as matrix-matched standards for meteoritic hibonite. The largest yield of both Ti-free and Ti-bearing hibonite at ∼1300 and ∼1400 °C was obtained by a single sinter under reducing conditions. In situ micro-beam Ti K-edge X-ray absorption near edge structure (XANES) spectra were recorded from the synthetic hibonites, as well as from terrestrial hibonite. Spectral features in the post-crest region were shown to correlate with the Ti4+ content. Furthermore, Ti4+ on the M2 trigonal bipyramidal and the adjoining M4 octahedral sites appears to cause variability in the post-crest region as a function of orientation. For this suite of synthetic hibonites it was observed that the pre-edge peak region is not influenced by orientation, but is controlled by Ti3+/ΣTi, site geometry and/or Ti concentration. In particular, the pre-edge peak intensities reflect Ti coordination environment and distortion of the M4 octahedral site. Therefore, although pre-edge peak intensities have previously been used to determine Ti3+/ΣTi in meteoritic minerals, we excluded use of the pre-edge peak intensities for quantifying Ti valence states in hibonite. The energy of the absorption edge at a normalized intensity of 0.8 (E0.8) and the energy of the minimum between the pre-edge region and the absorption edge (Em1) were found to vary systematically with Ti3+/ΣTi. Ti3+/ΣTi in hibonite as a function of Em1 was modeled by a quadratic function that may be used to quantify Ti3

  4. Anatase TiO2 sheet-assisted synthesis of Ti(3+) self-doped mixed phase TiO2 sheet with superior visible-light photocatalytic performance: Roles of anatase TiO2 sheet.

    PubMed

    Zhang, Xiaojie; Zuo, Guoqing; Lu, Xin; Tang, Changqing; Cao, Shuo; Yu, Miao

    2017-03-15

    On the basis of measurements, such as field emission scanning electron microscope, UV-Vis diffuse reflectance spectra, X-ray diffraction, electron paramagnetic resonance, photoluminescence spectra, and photocurrent measurements, the roles of anatase TiO2 sheet on synthesizing Ti(3+) self-doped mixed phase TiO2 nanosheets (doped TiO2 (A/R, TiO2 (A))) and on improving the performance for photocatalytic CO2 reduction were explored systematically. High surface area anatase TiO2 nanosheets (TiO2 (A)) as a substrate, structure directing agent, and inhibitor, mediated the synthesis of Ti(3+) self-doped mixed phase TiO2 nanosheets. Addition of TiO2 (A) significantly improved not only visible light absorption of doped TiO2 (A/R, TiO2 (A)), but also the efficiency of photo-excited charges separations due to the existence of interfacial regions of anatase-rutile TiO2 junctions. Finally, a possible mechanism for interfacial charge transfer at the anatase-rutile TiO2 interface and for photocatalytic CO2 reduction over Pt loaded doped TiO2 (A/R, TiO2 (A)) were proposed.

  5. The permeation behavior of deuterium through 1Cr18Ni9Ti stainless steel with TiN+TiC-TiN multiple films

    SciTech Connect

    Xiong, Y.; Song, J.; Luo, D.; Lei, Q.; Chen, C.

    2015-03-15

    The prevention of tritium losses via permeation through structure components is an important issue in fusion technology. The production of thin layers on materials with low diffusivity and/or low surface recombination constants (so-called permeation barriers) seems to be the most practical method to reduce or hinder the permeation of tritium through materials. TiN+TiC+TiN multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel by ion-beam assisted deposition technology. The characteristics of films are tested by XPS ASEM and XRD, which shows that the film are compact and uniform with a thickness of about 15 μm, and have a good adherence with the substrate below 773 K. The diffraction peaks in the XRD patterns for TiC and TiN are broadened, implying that the multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel. Meanwhile, the C-H bonded CH{sub 4}-appears in the infrared spectra of multiple films, suggesting that the CH{sub 4}- is in a static state, so hydrogen atom cannot migrate from the site bonded with carbon to a neighboring site. The measured deuterium permeability in 1Cr18Ni9Ti stainless steel coated with multiple films is 2-3 orders of magnitude lower than that of pure 1Cr18Ni9Ti stainless steel substrate from 473 K to 773 K. However, this barrier is partly destroyed above 773 K.

  6. Pulsed Current Activated Synthesis and Consolidation of Nanostructured Ti-TiC Composite and Its Mechanical Properties.

    PubMed

    Kim, Dong-Ki; Park, Na-Ra; Kim, Byung-Su; Yoon, Jin-Kook; Hong, Kyung-Tae; Shon, In-Jin

    2016-02-01

    Ti and CNT powders were milled by high energy ball milling. The milled powders were then simultaneously synthesized and consolidated using pulsed current activated sintering (PCAS) within one minute under the applied pressure of 80 MPa. The advantage of this process is not only rapid densification to near theoretical density but also to prevent grain growth in nano-structured materials The milling did not induce any reaction between the constituent powders. Meanwhile, PCAS of the Ti-CNT mixture produced a Ti-TiC composite according to the reaction (Ti + 0.06CNT --> 0.94Ti+0.06TiC, Ti+0.12CNT --> 0.88Ti+0.12TiC). Highly dense nanocrystalline Ti-TiC compos- ites with a relative density of up to 99.5% were obtained within one minute. The hardness and fracture toughness of the dense Ti-6mole% TiC and Ti-12 mole% TiC produced by PCAS were also investigated.

  7. A study of TiB2/TiB gradient coating by laser cladding on titanium alloy

    NASA Astrophysics Data System (ADS)

    Lin, Yinghua; Lei, Yongping; Li, Xueqiao; Zhi, Xiaohui; Fu, Hanguang

    2016-07-01

    TiB2/TiB gradient coating has been fabricated by a laser cladding technique on the surface of a Ti-6Al-4V substrate using TiB2 powder as the cladding material. The microstructure and mechanical properties of the gradient coating were analyzed by SEM, EPMA, XRD, TEM and an instrument to measure hardness. With the increasing distance from the coating surface, the content of TiB2 particles gradually decreased, but the content of TiB short fibers gradually increased. Meanwhile, the micro-hardness and the elastic modulus of the TiB2/TiB coating showed a gradient decreasing trend, but the fracture toughness showed a gradient increasing trend. The fracture toughness of the TiB2/TiB coating between the center and the bottom was improved, primarily due to the debonding of TiB2 particles and the high fracture of TiB short fibers, and the fracture position of TiB short fiber can be moved to an adjacent position. However, the debonding of TiB2 particles was difficult to achieve at the surface of the TiB2/TiB coating.

  8. Corrosion behavior and biocompatibility of nanostructured TiO2 film on Ti6Al4V.

    PubMed

    Karpagavalli, Ramji; Zhou, Anhong; Chellamuthu, Prithiviraj; Nguyen, Kytai

    2007-12-15

    The corrosion behavior and cell adhesion property of nanostructured TiO2 films deposited electrolytically on Ti6Al4V were examined in the present in vitro study. The nanostructured TiO2 film deposition on Ti6Al4V was achieved via peroxoprecursors. SEM micrographs exhibit the formation of amorphous and crystallite TiO2 nanoparticles on Ti6Al4V before and after being annealed at 500 degrees C. Corrosion behavior of TiO2-deposited and uncoated Ti6Al4V was evaluated in freely aerated Hank's solution at 37 degrees C by the measurement and analysis of open-circuit potential variation with time, Tafel plots, and electrochemical impedance spectroscopy. The electrochemical results indicated that nano-TiO2 coated Ti6Al4V showed a better corrosion resistance in simulated biofluid than uncoated Ti6Al4V. Rat bone cells and human aortic smooth muscle cells were grown on these substrates to study the cellular responses in vitro. The SEM images revealed enhanced cell adhesion, cell spreading, and proliferation on nano-TiO2 coated Ti6Al4V compared to those grown on uncoated substrates for both cell lines. These results suggested that nanotopography produced by deposition of nanostructured TiO2 onto Ti alloy surfaces might enhance corrosion resistance, biocompatibility, and cell integration for implants made of Ti alloys.

  9. Investigation of Phase Equilibria and Some Properties of Alloys of Ti-Al-Fe and Ti-Al-V Systems,

    DTIC Science & Technology

    Some data on the structure and properties of Ti-Al-Fe alloys are presented. The phase equilibria in alloys in the system Ti-Al-V were studies...However, the data available in the literature on phase equilibria in the systems Ti-Al-Fe and Ti-Al-V require refinement, as they are insufficiently

  10. Interstitial Ti for intermediate band formation in Ti-supersaturated silicon

    NASA Astrophysics Data System (ADS)

    Pastor, D.; Olea, J.; Muñoz-Martín, A.; Climent-Font, A.; Mártil, I.; González-Díaz, G.

    2012-12-01

    We have analyzed by means of Rutherford backscattering spectrometry (RBS) the Ti lattice location and the degree of crystalline lattice recovery in heavily Ti implanted silicon layers subsequently pulsed laser melted (PLM). Theoretical studies have predicted that Ti should occupy interstitial sites in silicon for a metallic-intermediate band (IB) formation. The analysis of Ti lattice location after PLM processes is a crucial point to evaluate the IB formation that can be clarifyied by means of RBS measurements. After PLM, time-of-flight secondary ion mass spectrometry measurements show that the Ti concentration in the layers is well above the theoretical limit for IB formation. RBS measurements have shown a significant improvement of the lattice quality at the highest PLM energy density studied. The RBS channeling spectra reveals clearly that after PLM processes Ti impurities are mostly occupying interstitial lattice sites.

  11. Crystal structure of TiBi2

    PubMed Central

    Watanabe, Kei; Yamane, Hisanori

    2016-01-01

    Black granular single crystals of monotitanium dibismuth, TiBi2, were synthesized by slow cooling of a mixture of Bi and Ti from 693 K. The title compound is isostructural with CuMg2 (ortho­rhom­bic Fddd symmetry). Ti atoms are located in square anti­prisms of Bi atoms. The network of one type of Bi atom spirals along the a-axis direction while honeycomb layers of the other type of Bi atom spreading in the ab plane inter­lace one another. PMID:27920910

  12. [The electrochemical behavior of TiTa30 and TiNb30 alloys for implantology].

    PubMed

    Hildebrand, H F; Ralison, A; Traisnel, M; Breme, J

    1997-11-01

    The electrochemical behavior in artificial saliva of TiNb30 and TiTa30 alloys were compared with that of commercial pure titanium. The anodic potential, the current density, the passivation potential and the galvanic corrosion vs. Au were determined. Both alloys have a similar behavior to that of pure titanium. Crevace corrosion, which is very weak in pure Ti, is completely inhibited by the addition of Nb or Ta.

  13. Two-Phase (TiAl+TiCrAl) Coating Alloys for Titanium Aluminides

    NASA Technical Reports Server (NTRS)

    Brady, Michael P. (Inventor); Smialek, James L. (Inventor); Brindley, William J. (Inventor)

    1998-01-01

    A coating for protecting titanium aluminide alloys, including the TiAl gamma + Ti3Al (alpha(sub 2)) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C. is disclosed. This protective coating consists essentially of titanium, aluminum. and chromium in the following approximate atomic ratio: Ti(41.5-34.5)Al(49-53)Cr(9.5-12.5)

  14. LASE Ti:Sapphire Laser

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In the photo, Dr. Larry B. Petway (Science Applications International Corp.) is making final adjustments to the Ti:Sapphire Laser in preparing the Lidar Atmospheric Sensing Experiment (LASE) Instrument for intergration into a NASA/ER-2 aircraft. LASE is the first fully- engineered, autonomous differential Absorption Lidar (DIAL) System for the measurement of water vapor, aerosol and cloud in the troposphere. LASE uses a double-pulsed Ti:Sapphire laser for the transmitter with a 30 ns pulse length and 150mJ/pulse. The laser beam is seeded to operate on a selected water vapor absorption line in the 815-nm region using a laser diode and an onboard absorption reference cell. A 40 cm diameter telescope collects the backscattered signals and directs them onto two detectors. LASE collects DIAL data at 5 Hz while flying at altitudes from 16-21 km. LASE was designed to operate autonomously within the environment and physical constraints of the ER-2 aircraft and to make water vapor profile measurements across the troposphere with accuracy having less than 6% of error. No other instrument can provide the spatial coverage and accuracy of LASE.Water vapor is the most radiative active gas in the troposphere, and the lack of understanding about its distribution provides one of the largest uncertainties in modeling climate change. LASE has demonstrated the necessary potential in providing high resolution water vapor measurements that can advance the studies of tropospheric water vapor distributions. LASE has flown 19 times during the development of the instrument and the validation of the science data. A joint international field mission was completed in the summer of 1996; adding 9 more successful flights. The LASE Instument is being adapted to other aircraft platforms to support planned missions and to increase its utility.

  15. Formation of TiO2 layers on commercially pure Ti and Ti-Mo and Ti-Nb alloys by two-step thermal oxidation and their photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sado, Shota; Ueda, Takatoshi; Ueda, Kyosuke; Narushima, Takayuki

    2015-12-01

    Anatase-containing TiO2 layers were formed on commercially pure (CP) Ti and Ti-25mass%Mo (Ti-25Mo) and Ti-25mass%Nb (Ti-25Nb) alloys by two-step thermal oxidation. The first-step treatment was conducted in an Ar-1%CO atmosphere at 1073 K for 3.6 ks, and the second-step treatment was conducted in air at 673-1073 K for 10.8 ks. The second-step temperature range for anatase formation was wider in the Ti alloys than in CP Ti. Photo-induced superhydrophilicity under UV irradiation was observed for the TiO2 layers with anatase fractions ≥0.6 on CP Ti and the Ti-25Mo alloy, and with anatase fractions ≥0.18 on the Ti-25Nb alloy. The TiO2 layers on the Ti-25Nb alloy exhibited excellent photocatalytic activity in the low anatase fraction region, which is considered to be caused by the incorporation of 1-3 at% Nb into the TiO2 layers. The rate constant of methylene blue degradation showed maxima at anatase fractions of 0.6-0.9.

  16. Electron-induced Ti-rich surface segregation on SrTiO3 nanoparticles.

    PubMed

    Lin, Yuyuan; Wen, Jianguo; Hu, Linhua; McCarthy, James A; Wang, Shichao; Poeppelmeier, Kenneth R; Marks, Laurence D

    2015-01-01

    Atomic surface structures of nanoparticles are of interest in catalysis and other fields. Aberration-corrected HREM facilitates direct imaging of the surfaces of nanoparticles. A remaining concern of surface imaging arises from beam damage. It is important to identify the intrinsic surface structures and the ones created by electron beam irradiation in TEM. In this study, we performed aberration-corrected HREM and EELS to demonstrate that TiO and bcc type Ti islands form due to intense electron irradiation. The formation of Ti-rich islands is in agreement with previous high temperature annealing experiments on the surfaces of SrTiO3 single crystals.

  17. Investigations of EPR parameters for the trigonal Ti3+-Ti3+ pair in beryl crystal.

    PubMed

    Wang, Fang; Zheng, Wen-Chen

    2007-08-01

    By using the complete diagonalization of energy matrix of 3d1 ions in trigonal symmetry, the EPR parameters (g factors g( parallel), g( perpendicular) and zero-field splitting D) of the trigonal Ti3+-Ti3+ pair in beryl crystal are calculated. In the calculations, the exchange interaction in the Ti3+-Ti3+ pair is taken as the perturbation and the local trigonal distortion in the defect center is considered. The results (which are in agreement with the experimental values) are discussed.

  18. Structural properties of nanometric and micrometric TiCN/TiNbCN supperlattices

    NASA Astrophysics Data System (ADS)

    Caicedo, Julio; Yate, Luis; Ramírez, Juan; Gómez, Maria Elena; Lousa, Arturo; Esteve, Joan; Prieto, Pedro

    2010-03-01

    TiCN and TiNbCN systems have broadly been used as protective hard and anticorrosive coatings. [TiCN/TiNbCN]n multilayers were deposited on silicon substrates by two-target-r.f. magnetron sputtering with alternatively changing the sputtering plasma composition between pure Ti+C and Nb elements under a reactive mixture Ar/N2. TiCN/TiNbCN bilayer period varied from nanometric range (15 nm) to higher micrometric range (1.5 μm) values. Structural, morphological and stoichiometric of the coatings were analyzed by high-angle- and low-angle X-ray diffraction, X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and cross-sectional transmission electron microscopy (TEM). We determined multilayer period, λ, and individual layer thicknesses. We found a cube-on-cube epitaxial growth structure and with epitaxial relationship between layers inside each columnar crystallite given by (111)[110]TiCN//(111)[110]TiNbCN.

  19. Synchrotron diffraction studies of TiC/FeTi cermets obtained by SHS

    SciTech Connect

    Contreras, L.; Turrillas, X.; Mas-Guindal, M.J.; Vaughan, G.B.M.; Kvick, A.; Rodriguez, M.A. . E-mail: mar@icv.csic.es

    2005-05-15

    TiC/FeTi composites have been obtained in situ by Self-propagating High-temperature Synthesis (SHS) of an intimate mixture of compacted powders of elemental carbon, titanium and iron. The reaction has been followed in real time by X-ray diffraction at the ESRF. The mechanism of the reaction is discussed in terms of the formation of a liquid phase corresponding to the eutectic of the Fe/Ti system prior to the TiC synthesis. Temperatures of reaction have been estimated by correlating thermal expansion coefficients with diffraction peaks shifts. The microstructures obtained by this method, suitable for cutting tools and wear resistant applications, are presented.

  20. Microstructure and corrosion behavior of TiC/Ti(CN)/TiN multilayer CVD coatings on high strength steels

    NASA Astrophysics Data System (ADS)

    Zhang, Jin; Xue, Qi; Li, Songxia

    2013-09-01

    Titanium carbide/titanium carbonitride/titanium nitride (TiC/Ti(CN)/TiN) multilayer coatings are prepared on the surface of three high-strength steels (35CrMo, 42CrMo, and 40CrNiMo) by chemical vapor deposition method. The fracture morphology, elemental distribution, phase composition, micro-hardness, and adhesion of the multilayer film are analyzed. The hydrogen sulfide stress corrosion resistance of the coating is evaluated by the National Association of Corrosion Engineers saturated hydrogen sulfide solution immersion test. A test simulating the environment of the natural gas wells with high temperature and pressure in Luojiazhai in Sichuan is also performed. The results show that the multilayer coatings have dense structures, ∼11 μm thickness, 24.5 ± 2.0 GPa nano-hardness, and ∼70 N adhesion. The corrosion sample also shows no brittle failure induced by stress corrosion after treatment with the coating. Gravimetric analysis shows that the deposition of TiC/Ti(CN)/TiN multilayer coatings results in a corrosion rate reduction of at least 50 times compared with the high-strength steel substrate. A preliminary analysis on this phenomenon is conducted.

  1. Synthesis of heterostructured Pd@TiO{sub 2}/TiOF{sub 2} nanohybrids with enhanced photocatalytic performance

    SciTech Connect

    Zhao, Xixia; Wei, Guijuan; Liu, Junxue; Wang, Zhaojie; An, Changhua; Zhang, Jun

    2016-08-15

    Highlights: • TiO{sub 2}/TiOF{sub 2} nanohybrids was synthesized via a two-step solvothermal method. • TiO{sub 2}/TiOF{sub 2} exhibited superior photoactivity in comparison with TiOF{sub 2} or TiO{sub 2}. • The photocatalytic activity was further improved by loading Pd nanoparticles. • Synergistic effect between TiOF{sub 2} and TiO{sub 2} was responsible for the enhanced photocatalytic performance over TiO{sub 2}/TiOF{sub 2}. - Abstract: TiO{sub 2}/TiOF{sub 2} heterostructured nanocomposites has been synthesized through a solvothermal method and characterized by X-ray diffraction, scanning electronic microscopy, transmission electronic microscopy, nitrogen adsorption–desorption isotherms, UV–vis and photo-luminescent spectroscopy. It was found that, compared with single TiOF{sub 2} or TiO{sub 2}, the as-prepared TiO{sub 2}/TiOF{sub 2} nanocomposites exhibited superior photoactivity towards the degradation of organic pollutants, i.e. rhodamine B and solar hydrogen evolution. The results are in accordance with the prohibition of photogenerated electrons and holes recombination in these two samples under light illumination. The photocatalytic activity can be further boosted by introducing Pd nanoparticles onto the surfaces of TiO{sub 2}/TiOF{sub 2} through a simple deposition method without using any stabilizers, which is probably attributed to the enhanced visible-light absorption as well as the facilitated charge-carrier separation after the introduction of Pd nanoparticles. The synergistic effect between TiOF{sub 2} and TiO{sub 2} was discussed and was responsible for the enhancement of their activity in comparison with single counterpart.

  2. An ab initio study on atomic and electronic structures of two-dimensional Al3Ti at Al/TiB2 interface

    NASA Astrophysics Data System (ADS)

    Men, H.

    2016-09-01

    The atomic and electronic structures of a two-dimentional (2D) Al3Ti layer at Al/TiB2 interface has been investigated using first-principle calculations. The result reveals the 2D-Al3Ti adopts the structure of bulk Al3Ti. There exists a strong Ti(3d)-Al(3p) hybridization between Ti and Al atoms of the 2D-Al3Ti, as well as between surface Ti atoms of TiB2 and Al atoms of 2D-Al3Ti. It leads to a stronger covalent Ti-Al bonding at the Al/2D-Al3Ti/TiB2 interface than at the Al/TiB2 interface, which is responsible for the stability of 2D-Al3Ti.

  3. Oxidation of TiAl3 and L12 Coatings on Ti-45Al-5Nb Alloy at 1173K

    NASA Astrophysics Data System (ADS)

    Nishimoto, Takumi; Kitajima, Yuri; Hayashi, Shigenari; Narita, Toshio

    Oxidation behavior of TiAl3 and L12 coated Ti-45at%Al-5at%Nb alloys at 1173K in air was investigated using mass gain measurement, field emission scanning electron microscopy, transmission electron microscopy, electron-probe microanalysis, glow discharge optical electron spectroscopy, and glancing angle X-ray diffraction analysis. The TiAl3 formed meta-stable alumina θ-Al2O3, while the oxide scale on the L12 consisted of a duplex structure with an outer rutile TiO2 and an inner α-Al2O3. During the very initial stages of oxidation both Ti and Al in the L12 coating could be oxidized, and then the faster diffusing Ti goes out to form an outer, continuous Ti-rich oxide which covers the slow growing Al2O3. In case of the TiAl3 an outer, continuous TiO2 layer was not observed because of the smaller amount of Ti in the TiAl3. It could be concluded that the outer, Ti-rich oxide enhanced a phase transformation of Al2O3 from θ to α. To elucidate the Ti effect, Ti-vapor treated TiAl3 and Ni-50at%Al were oxidized at 1173K in air, and showed formation of an α-Al2O3, in contrast to θ-Al2O3 on their bare alloys.

  4. Electrochemical properties of core-shell TiC-TiO2 nanoparticle films immobilized at ITO electrode surfaces.

    PubMed

    Stott, Susan J; Mortimer, Roger J; Dann, Sandie E; Oyama, Munetaka; Marken, Frank

    2006-12-14

    Titanium carbide (TiC) nanoparticles are readily deposited onto tin-doped indium oxide (ITO) electrodes in the form of thin porous films. The nanoparticle deposits are electrically highly conducting and electrochemically active. In aqueous media (at pH 7) and at applied potentials positive of 0.3 V vs. SCE partial anodic surface oxidation and formation (at least in part) of novel core-shell TiC-TiO2 nanoparticles is observed. Significant thermal oxidation of TiC nanoparticles by heating in air occurs at a temperature of 250 degrees C and leads first to core-shell TiC-TiO2 nanoparticles, next at ca. 350 degrees C to TiO2 (anatase), and finally at temperatures higher than 750 degrees C to TiO2 (rutile). Electrochemically and thermally partially oxidized TiC nanoparticles still remain very active and for some redox systems electrocatalytically active. Scanning and transmission electron microscopy (SEM and TEM), temperature dependent XRD, quartz crystal microbalance, and voltammetric measurements are reported. The electrocatalytic properties of the core-shell TiC-TiO2 nanoparticulate films are surveyed for the oxidation of hydroquinone, ascorbic acid, and dopamine in aqueous buffer media. In TiC-TiO2 core-shell nanoparticle films TiO2 surface reactivity can be combined with TiC conductivity.

  5. Calculation of the Ti(C y N1- y )-Ti4C2S2-MnS-austenite equilibrium in Ti-bearing steels

    NASA Astrophysics Data System (ADS)

    Liu, W. J.; Jonas, J. J.

    1989-08-01

    A thermodynamic model is presented for the equilibria among various precipitates (Ti(C y N1- y ), Ti4C2S2, and MnS) and austenite containing six alloying elements (C, Mn, N, S, Si, and Ti). This model is applied to four microalloyed steels with Ti levels of 0.05, 0.11, 0.18, and 0.25 pct. The calculations show that the Ti in these steels cannot be completely dissolved over the austenite temperature range. However, the compositions of the undissolved Ti carbonitrides differ significantly from pure TiN, as 10 to 40 pct of the nitrogen is replaced by carbon. An expression for the Gibbs energy for the formation of Ti4C2S2 in austenite is estimated. The present predictions are compared with those of the Hudd, Jones, and Kale (HJK) model; considerable differences are observed at temperatures below 1250°C.

  6. Instability of Hydrogenated TiO2

    SciTech Connect

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.

    2015-11-06

    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  7. Porous TiO2 Assembled from Monodispersed Nanoparticles.

    PubMed

    Liu, Xu; Duan, Weijie; Chen, Yan; Jiao, Shihui; Zhao, Yue; Kang, Yutang; Li, Lu; Fang, Zhenxing; Xu, Wei; Pang, Guangsheng

    2016-12-01

    Porous TiO2 were assembled by evaporating or refluxing TiO2 colloid, which was obtained by dispersing the TiO2 nanoparticles with a crystallite size (d XRD) of 3.2 nm into water or ethanol without any additives. Porous transparent bulk TiO2 was obtained by evaporating the TiO2-C2H5OH colloid at room temperature for 2 weeks, while porous TiO2 nanospheres were assembled by refluxing the TiO2-H2O colloid at 80 °C for 36 h. Both of the porous TiO2 architectures were pore-size-adjustable depending on the further treating temperature. Porous TiO2 nanospheres exhibited enhanced photocatalysis activity compared to the nanoparticles.

  8. Cermet with Slow TiC Coarsening During Sintering

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Ming; Tsai, Che-Wei; Huang, Sheng-Min; Yang, Chih-Chao; Yeh, Jien-Wei

    2014-10-01

    New TiC/Co1.5CrFeNi1.5Ti0.5 cermet was developed by exploiting the advantages of the high-entropy alloy (HEA) binder. A much finer grain structure and thus improved hardness-toughness combination were obtained as compared with two traditional binders, Ni and Ni13Mo7. From the coarsening behavior of TiC grains, the coarsening process of TiC in these three binders is diffusion-controlled. The activation energy of TiC + 20%Co1.5CrFeNi1.5Ti0.5 is the highest and that of TiC + 20%Ni is the lowest. The high activation energy of the Co1.5CrFeNi1.5Ti0.5 binder was attributable to its high content of carbon-strong-binding elements, Cr and Ti, and cooperative diffusion and higher packing density of multiple different-sized atoms. Low diffusion coefficient, low surface energy of TiC grains, and low solubility of Ti in the HEA liquid explain the slow coarsening of TiC grains. This study demonstrates that Co1.5CrFeNi1.5Ti0.5 is an excellent HEA binder for TiC cermets.

  9. Hierarchical fabrication of heterojunctioned SrTiO3/TiO2 nanotubes on 3D microporous Ti substrate with enhanced photocatalytic activity and adhesive strength

    NASA Astrophysics Data System (ADS)

    Zhou, Jie; Yin, Lu; Zha, Kang; Li, Huirong; Liu, Zhiyuan; Wang, Jianxin; Duan, Ke; Feng, Bo

    2016-03-01

    Recently, construction of three-dimensional (3D) architecture and design of heterostructure have been proved to be two important approaches for improving photocatalytic (PC) properties of TiO2-based catalysts. In this work, a 3D microporous surface on Ti substrate (MPT) was prepared by simple acid etching. Then, heterojunctioned SrTiO3/TiO2 nanotubes with dominant {001} facets of anatase TiO2were successfully fabricated on MPT by combining anodization with hydrothermal treatment. The 3D microporous-patterned SrTiO3/TiO2 nanotubes heterojunction shows significantly enhanced photo-current density and ∼200% improved PC effect in degradation of Rhodamine B owing to its higher specific surface area, stronger light-harvesting ability and positive heterojunction effect in comparison with TiO2 nanotubes formed on flat Ti substrate. Moreover, the 3D microporous structure on Ti substrate improved the adhesive strength between the nanotubes layer and Ti substrate, which can be ascribed to the effective release of internal stress. Therefore, this present strategy is expected to expand the application of TiO2-based catalysts in many fields which require excellent PC properties and mechanical stability.

  10. Piezoelectric and Dielectric Properties of Multilayered BaTiO3/(Ba,Ca)TiO3/CaTiO3 Thin Films.

    PubMed

    Zhu, Xiao Na; Gao, Ting Ting; Xu, Xing; Liang, Wei Zheng; Lin, Yuan; Chen, Chonglin; Chen, Xiang Ming

    2016-08-31

    Highly oriented multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films were fabricated on Nb-doped (001) SrTiO3 (Nb:STO) substrates by pulsed laser deposition. The configurations of multilayered BaTiO3-(Ba,Ca)TiO3-CaTiO3 thin films are designed with the thickness ratio of 1:1:1 and 2:1:1 and total thickness ∼300 nm. Microstructural characterization by X-ray diffraction indicates that the as-deposited thin films are highly c-axis oriented and large in-plane strain is determined in BaTiO3 and CaTiO3 layers. Piezoresponse force microscopy (PFM) studies reveal an intense in-plane polarization component, whereas the out-of-plane shows inferior phase contrast. The optimized combination is found to be the BaTiO3-(Ba0.85Ca0.15)TiO3-CaTiO3 structure with combination ratio 2:1:1, which displays the largest domain switching amplitude under DC electric field, the largest room-temperature dielectric constant ∼646, a small dielectric loss of 0.03, and the largest dielectric tunability of ∼50% at 400 kV/cm. These results suggest that the enhanced dielectric and tunability performance are greatly associated with the large in-plane polarization component and domain switching.

  11. Controllable two-scale network architecture and enhanced mechanical properties of (Ti5Si3+TiBw)/Ti6Al4V composites

    PubMed Central

    Jiao, Y.; Huang, L. J.; Duan, T. B.; Wei, S. L.; Kaveendran, B.; Geng, L.

    2016-01-01

    Novel Ti6Al4V alloy matrix composites with a controllable two-scale network architecture were successfully fabricated by reaction hot pressing (RHP). TiB whiskers (TiBw) were in-situ synthesized around the Ti6Al4V matrix particles, and formed the first-scale network structure (FSNS). Ti5Si3 needles (Ti5Si3) precipitated in the β phase around the equiaxed α phase, and formed the secondary-scale network structure (SSNS). This resulted in increased deformation compatibility accompanied with enhanced mechanical properties. Apart from the reinforcement distribution and the volume fraction, the ratio between Ti5Si3 and TiBw fraction were controlled. The prepared (Ti5Si3 + TiBw)/Ti6Al4V composites showed higher tensile strength and ductility than the composites with a one-scale microstructure, and superior wear resistance over the Ti6Al4V alloy under dry sliding wear conditions at room temperature. PMID:27622992

  12. Rapid synthesis of TiO2 nanoparticles by electrochemical anodization of a Ti wire.

    PubMed

    Ali, Ghafar; Kim, Hyun Jin; Kum, Jong Min; Cho, Sung Oh

    2013-05-10

    We present a simple and novel strategy to synthesize TiO2 nanoparticles (NPs) based on electrochemical anodization of a Ti wire in an aqueous KCl electrolyte. The Ti wire is very rapidly and directly converted to TiO2 NPs by the anodization process, allowing mass production of TiO2 NPs. The size of the synthesized NPs can be readily tuned by changing the concentration of the electrolyte. We found that the field-assisted etching related to a strong electric field and the rapid etching rate caused by chloride ions play important roles for the formation of TiO2 NPs. This approach can also be applied to the mass production of other semiconducting metal oxide NPs such as tungsten-oxide NPs. TiO2 NPs showed higher photocatalytic activity compared to Degussa (P 25) under the same conditions. The higher photocatalytic activity of TiO2 NPs is attributed to the polymorphism. We believe that our approach can be used in broad areas including biomedical applications, photovoltaics, optics, and electronics.

  13. A new, energy-efficient chemical pathway for extracting Ti metal from Ti minerals.

    PubMed

    Fang, Zhigang Zak; Middlemas, Scott; Guo, Jun; Fan, Peng

    2013-12-11

    Titanium is the ninth most abundant element, fourth among common metals, in the Earth's crust. Apart from some high-value applications in, e.g., the aerospace, biomedicine, and defense industries, the use of titanium in industrial or civilian applications has been extremely limited because of its high embodied energy and high cost. However, employing titanium would significantly reduce energy consumption of mechanical systems such as civilian transportation vehicles, which would have a profound impact on the sustainability of a global economy and the society of the future. The root cause of the high cost of titanium is its very strong affinity for oxygen. Conventional methods for Ti extraction involve several energy-intensive processes, including upgrading ilmenite ore to Ti-slag and then to synthetic rutile, high-temperature carbo-chlorination to produce TiCl4, and batch reduction of TiCl4 using Mg or Na (Kroll or Hunter process). This Communication describes a novel chemical pathway for extracting titanium metal from the upgraded titanium minerals (Ti-slag) with 60% less energy consumption than conventional methods. The new method involves direct reduction of Ti-slag using magnesium hydride, forming titanium hydride, which is subsequently purified by a series of chemical leaching steps. By directly reducing Ti-slag in the first step, Ti is chemically separated from impurities without using high-temperature processes.

  14. Double-Shelled TiO2 Hollow Spheres Assembled with TiO2 Nanosheets.

    PubMed

    Zhang, Chao; Zhou, Yuming; Zhang, Yiwei; Zhao, Shuo; Fang, Jiasheng; Sheng, Xiaoli; Zhang, Tao; Zhang, Hongxing

    2017-02-08

    High-quality double-shelled TiO2 hollow spheres (DHS-Ti) assembled with TiO2 nanosheets have been synthesized for the first time through a simple hydrothermal treatment of sSiO2 @TiO2 (TiO2 -coated solid SiO2 spheres). The double-shelled structure shows a high BET surface area up to 417.6 m(2)  g(-1) . Anatase DHS-Ti of high crystallinity can be obtained without structural collapse by calcination treatment. The effects of cetyl trimethylammonium bromide (CTAB) concentration, pH, and hydrothermal reaction temperature have also been investigated with a series of contrast experiments. A formation mechanism involving the in situ growth of amorphous TiO2 nanosheets followed by the redeposition of dissolved silica species is proposed. Lastly, the DHS-Ti forming strategy can be extended as a general strategy to fabricate various morphological hollow nanostructures and double-shelled Pt nanocatalysts by rationally selecting functional sSiO2 nanoparticles as core materials. This work could open up a new strategy for controllable synthesis of complex hollow structures and other functional materials.

  15. Pure rotational spectra of TiO and TiO2 in VY Canis Majoris

    NASA Astrophysics Data System (ADS)

    Kamiński, T.; Gottlieb, C. A.; Menten, K. M.; Patel, N. A.; Young, K. H.; Brünken, S.; Müller, H. S. P.; McCarthy, M. C.; Winters, J. M.; Decin, L.

    2013-03-01

    We report the first detection of pure rotational transitions of TiO and TiO2 at (sub-)millimeter wavelengths towards the red supergiant VY CMa. A rotational temperature, Trot, of about 250 K was derived for TiO2. Although Trot was not well constrained for TiO, it is likely somewhat higher than that of TiO2. The detection of the Ti oxides confirms that they are formed in the circumstellar envelopes of cool oxygen-rich stars and may be the "seeds" of inorganic-dust formation, but alternative explanations for our observation of TiO and TiO2 in the cooler regions of the envelope cannot be ruled out at this time. The observations suggest that a significant fraction of the oxides is not converted to dust, but instead remains in the gas phase throughout the outflow. Based on observations carried out with the Submillimeter Array and IRAM Plateau de Bure Interferometer.Plateau de Bure data (FITS file) is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A113

  16. High damping NiTi/Ti3Sn in situ composite with transformation-mediated plasticity

    SciTech Connect

    Zhang, Junsong; Liu, Yinong; Huan, Yong; Hao, Shijie; Jiang, Daqiang; Ren, Yang; Shao, Yang; Ru, Yadong; Wang, Zhongqiang; Cui, Lishan

    2014-11-01

    The concept of transformation-induced plasticity effect is introduced in this work to improve the plasticity of brittle intermetallic compound Ti3Sn, which is a potent high damping material. This concept is achieved in an in situ NiTi/Ti3Sn composite. The composite is composed of primary Ti3Sn phase and (NiTi + Ti3Sn) eutectic structure formed via hypereutectic solidification. The composite exhibits a high damping capacity of 0.075 (indexed by tan δ), a high ultimate compressive strength of 1350 MPa, and a large plasticity of 27.5%. In situ synchrotron high-energy X-ray diffraction measurements revealed clear evidence of the stress-induced martensitic transformation (B2 → B19) of the NiTi component during deformation. The strength of the composite mainly stems from the Ti3Sn, whereas the NiTi component is responsible for the excellent plasticity of the composite.

  17. Mechanical and Tribological Properties of Cold-Sprayed Ti Coatings on Ti-6Al-4V Substrates

    NASA Astrophysics Data System (ADS)

    Khun, N. W.; Tan, A. W. Y.; Liu, E.

    2016-04-01

    A cold spray process was used to deposit titanium (Ti) coatings of different thicknesses on commercial Ti-6Al-4V (Ti64) substrates. The hardness of the Ti coatings was measured using a Vickers micro-indenter. It was found that the thicker Ti coatings had higher hardness probably due to the better uniformity and higher density of the coatings. The tribological results showed that the friction and wear of the Ti coatings tested against a steel ball under dry condition became lower with higher thickness probably due to the higher wear resistance of the thicker coatings associated with their higher hardness. The specific wear rates of all the Ti coatings were significantly lower than that of the Ti64 substrate as a result of the higher wear resistance of the Ti coatings associated with their cold-worked microstructures and the formation of high wear resistant oxide layers on their wear tracks during the wear testing.

  18. Preparation and characterization of sulfur-doped TiO(2)/Ti photoelectrodes and their photoelectrocatalytic performance.

    PubMed

    Sun, Haijian; Liu, Huiling; Ma, Jun; Wang, Xiangyu; Wang, Bin; Han, Lei

    2008-08-15

    Sulfur-doped TiO(2)/Ti photoelectrodes were prepared by anodization and characterized by SEM, AFM, XRD, XPS, UV-vis and SPS. The results of investigation indicated that S(4+) and S(6+) were dispersed on the surface of TiO(2) nanoparticles. The doping with an appropriate amount of sulfur expanded the response range of TiO(2)/Ti photoelectrodes to visible light, and enhanced the separation of photoinduced electrons from cavities. The photoelectrocatalytic performance test run with sulfur-doped TiO(2)/Ti photoelectrodes under Xenon light indicated that Na(2)SO(3) concentration of 750 mg/L and voltage of 160 V were the optimal conditions for preparation of sulfur-doped TiO(2)/Ti photoelectrodes.

  19. Resistive Switching Memory of TiO2 Nanowire Networks Grown on Ti Foil by a Single Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Xiao, Ming; Musselman, Kevin P.; Duley, Walter W.; Zhou, Norman Y.

    2017-04-01

    The resistive switching characteristics of TiO2 nanowire networks directly grown on Ti foil by a single-step hydrothermal technique are discussed in this paper. The Ti foil serves as the supply of Ti atoms for growth of the TiO2 nanowires, making the preparation straightforward. It also acts as a bottom electrode for the device. A top Al electrode was fabricated by e-beam evaporation process. The Al/TiO2 nanowire networks/Ti device fabricated in this way displayed a highly repeatable and electroforming-free bipolar resistive behavior with retention for more than 104 s and an OFF/ON ratio of approximately 70. The switching mechanism of this Al/TiO2 nanowire networks/Ti device is suggested to arise from the migration of oxygen vacancies under applied electric field. This provides a facile way to obtain metal oxide nanowire-based ReRAM device in the future.

  20. Surface characterization of Ti and Ti (6 percent, Al-4 percent, V) metal powders and interaction with primer solutions

    NASA Technical Reports Server (NTRS)

    Siriwardane, R. V.; Wightman, J. P.

    1983-01-01

    The interaction of Ti and Ti 6-4 powders with water and primer solutions was investigated experimentally by measuring the heats of immersion. Similar comparative studies were made on anatase and rutile TiO2 powders. The surface oxide layers of Ti and Ti 6-4 cracked on heating in vacuum between 300 and 400 C as evidenced by high heats of immersion in both water and primer solutions. Polyimide and polyphenylquinoxaline interacted preferentially, compared with the solvents with both metal powders after outgassing at room temperature. The heats of immersion of Ti 6-4 in water, solvents, and primer solutions increased significantly after pretreatment of the powder by an alkaline etch and a phosphate-fluoride process. The TiO2 powders were not satisfactory models for the surface oxide layer on either Ti or Ti 6-4 powder.

  1. A facile in-situ hydrothermal synthesis of SrTiO3/TiO2 microsphere composite

    NASA Astrophysics Data System (ADS)

    Wang, Hongxing; Zhao, Wei; Zhang, Yubo; Zhang, Shimeng; Wang, Zihao; Zhao, Dan

    2016-06-01

    TiO2 was successfully used as sacrificed template to synthesise SrTiO3/TiO2 microsphere composite via an in-situ hydrothermal process. The diameter of SrTiO3/TiO2 microsphere was about 700 nm with the same size of the template, and all of the microspheres were in good dispersity. The optimized reaction parameters for the phase and morphology of the as-synthesized samples were investigated. The results showed the SrTiO3/TiO2 microsphere can be synthesized at 170 °C when the concentration of sodium hydroxide was 0.1 M. Lower hydrothermal temperature hampered the formation of the SrTiO3/TiO2 composite, the higher alkali concentration, however, will destroy the morphology of products. The formation mechanism of SrTiO3/TiO2 microsphere composite was proposed and the photocatalytic properties of the samples were characterized using methylene blue solution as the pollutant under the UV light irradiation. The results indicated the proper OH- concentration will provide a channel for Sr2+ to react with Ti4+ located in the template and form the SrTiO3/TiO2 composite, and those with micro-scaled spherical morphology exhibited good photocatalytic activities.

  2. Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

    NASA Astrophysics Data System (ADS)

    Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

    2014-12-01

    Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

  3. Self-doped TiO2-x nanowires with enhanced photocatalytic activity: Facile synthesis and effects of the Ti3+

    NASA Astrophysics Data System (ADS)

    Wang, Junpeng; Yang, Ping; Huang, Baibiao

    2015-11-01

    Synthesis of Ti3+ self-doped TiO2 with high stability is very necessary to understand the role of Ti3+ defects in photocatalytic process. In this study, we report a simple strategy for preparing stable Ti3+ self-doped TiO2 nanowires with Ti2O3 as precursors. Raman and XPS spectrum confirmed the existence of Ti3+ and oxygen vacancies. Compared with the pure TiO2, the photocatalytic activity of the Ti3+ self-doped TiO2 enhanced under UV light irradiation, however, neither pure TiO2 nor the self-dope TiO2 samples exhibit photocatalytic activity while irradiated under visible light, though the self-doped TiO2 have an enhanced absorption in visible region. On the basis of the experimental results, the possible mechanism of Ti3+ in photocatalytic process is proposed.

  4. Laser Processed TiN Reinforced Ti6Al4V Composite Coatings

    PubMed Central

    Balla, Vamsi Krishna; Bhat, Abhimanyu; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    The purpose of this first generation investigation is to evaluate fabrication, in vitro cytotoxicity, cell-materials interactions and tribological performance of TiN particle reinforced Ti6Al4V composite coatings for potential wear resistant load bearing implant applications. The microstructural analysis of the composites was performed using scanning electron microscope and phase analysis was done with X-ray diffraction. In vitro cell-materials interactions, using human fetal osteoblast cell line, have been assessed on these composite coatings and compared with Ti6Al4V alloy control samples. The tribological performance of the coatings were evaluated, in simulated body fluids, up to 1000 m sliding distance under 10N normal load. The results show that the composite coatings contain distinct TiN particles embedded in α + β phase matrix. The average top surface hardness of Ti6Al4V alloy increased from 394 ± 8 HV to 1138 ± 61 HV with 40 wt.% TiN reinforcement. Among the composite coatings, the coatings reinforced with 40 wt. % TiN exhibited the highest wear resistance of 3.74 × 10-6 mm3/Nm, which is lower than the wear rate, 1.04 × 10-5 mm3/Nm, of laser processed CoCrMo alloy tested under identical experimental conditions. In vitro biocompatibility study showed that these composite coatings were non-toxic and provides superior cell-material interactions compared to Ti6Al4V control, as a result of their high surface energy. In summary, excellent in vitro wear resistance and biocompatibility of present laser processed TiN reinforced Ti6Al4V alloy composite coatings clearly show their potential as wear resistant contact surfaces for load bearing implant applications. PMID:22301169

  5. Healing of complement activating Ti implants compared with non-activating Ti in rat tibia.

    PubMed

    Harmankaya, N; Igawa, K; Stenlund, P; Palmquist, A; Tengvall, P

    2012-09-01

    Recent studies have revealed that ozone ultraviolet (UVO) illumination of titanium (Ti) implants improves bone-implant anchorage by altering the physico-chemical and immune activating properties of the titanium dioxide (TiO(2)) layer. In the present rat tibia model, the authors compared the early events of inflammation and bone formation around UVO-treated Ti and complement activating immunoglobin g (IgG)-coated Ti. Machined Ti and machined Ti coated with a physical vapour-deposited Ti layer were used as references. Screw-shaped test and reference implants were implanted into rat tibia and harvested after 1, 7 and 28 days. Messenger RNA expression of implant adhered cells and peri-implant tissue ~250 μm from the surface were subsequently analysed with regard to IL-1β, TNF-α, osteocalcin, cathepsin K, BMP-2 and PDGF. Separate implants were retrieved after 7 and 28 days for removal torque measurements, and histological staining and histomorphometric analysis of bone area and bone-to-implant contact. While enhanced expression of inflammatory markers, TNF-α and IL-1β, was observed on IgG-coated surfaces throughout the observation time, UVO-treated surfaces indicated a significantly lower early inflammatory response. In the early phases (1 and 7 days), the UVO-treated surfaces displayed a significantly higher expression of osteoblast markers BMP-2 and osteocalcin. In summary, complement activating Ti implants elicited a stronger inflammatory response than UVO-treated Ti, with low complement activation during the first week of healing. In spite of this, the UVO-treated Ti induced only marginally more bone growth outside the implants.

  6. Investigations on structural, elastic, thermodynamic and electronic properties of TiN, Ti2N and Ti3N2 under high pressure by first-principles

    NASA Astrophysics Data System (ADS)

    Yang, Ruike; Zhu, Chuanshuai; Wei, Qun; Du, Zheng

    2016-11-01

    The lattice parameters, cell volume, elastic constants, bulk modulus, shear modulus, Young's modulus and Poisson's ratio are calculated at zero pressure, and their values are in excellent agreement with the available data, for TiN, Ti2N and Ti3N2. By using the elastic stability criteria, it is shown that the three structures are all stable. The brittle/ductile behaviors are assessed in the pressures from 0 GPa to 50 GPa. Our calculations present that the performances for TiN, Ti2N and Ti3N2 become from brittle to ductile with pressure rise. The Debye temperature rises as pressure increase. With increasing N content, the enhancement of covalent interactions and decline of metallicity lead to the increase of the micro-hardness. Their constant volume heat capacities increase rapidly in the lower temperature, at a given pressure. At higher temperature, the heat capacities are close to the Dulong-Petit limit, and the heat capacities of TiN and Ti2N are larger than that of c-BN. The thermal expansion coefficients of titanium nitrides are slightly larger than that of c-BN. The band structure and the total Density of States (DOS) are calculated at 0 GPa and 50 GPa. The results show that TiN and Ti2N present metallic character. Ti3N2 present semiconducting character. The band structures have some discrepancies between 0 GPa and 50 GPa. The extent of energy dispersion increases slightly at 50 GPa, which means that the itinerant character of electrons becomes stronger at 50 GPa. The main bonding peaks of TiN, Ti2N and Ti3N2 locate in the range from -10 to 10 eV, which originate from the contribution of valance electron numbers of Ti s, Ti p, Ti d, N s and N p orbits. We can also find that the pressure makes that the total DOS decrease at the Fermi level for Ti2N. The bonding behavior of N-Ti compounds is a combination of covalent and ionic nature. As N content increases, valence band broadens, valence electron concentration increases, and covalent interactions become stronger

  7. 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.

  8. Effects of strong interactions between Ti and ceria on the structures of Ti/CeO2.

    PubMed

    Yao, Xiao-Dan; Zhu, Kong-Jie; Teng, Bo-Tao; Yu, Cao-Ming; Zhang, Yun-Lei; Liu, Ya; Fan, Maohong; Wen, Xiao-Dong

    2016-11-30

    The effects of strong interactions between Ti and ceria on the structures of Ti/CeO2(111) are systematically investigated by density functional theory calculation. To our best knowledge, the adsorption energy of a Ti atom at the hollow site of CeO2 is the highest value (-7.99 eV) reported in the literature compared with those of Au (-0.88--1.26 eV), Ag (-1.42 eV), Cu (-2.69 eV), Pd (-1.75 eV), Pt (-2.62 eV) and Sn (-3.68 eV). It is very interesting to find that Ti adatoms disperse at the hollow site of CeO2(111) to form surface TiOx species, instead of aggregating to form Ti metal clusters for the Ti-CeO2 interactions that are much stronger than those of Ti-Ti ones. Ti adatoms are completely oxidized to Ti(4+) ions if they are monatomically dispersed on the next near hollow sites of CeO2(111) (xTi-NN-hollow); while Ti(3+) ions are observed when they locate at the near hollow sites (xTi-N-hollow). Due to the electronic repulsive effects among Ti(3+) ions, the adsorption energies of xTi-N-hollow are slightly weaker than those of xTi-NN-hollow. Simultaneously, the existence of unstable Ti(3+) ions on xTi-N-hollow also leads to the restructuring of xTi-N-hollow by surface O atoms of ceria transferring to the top of Ti(3+) ions, or oxidation by O2 adsorption and dissociation. Both processes improve the stability of the xTi/CeO2 system by Ti(3+) oxidation. Correspondingly, surface TiO2-like species form. This work sheds light into the structures of metal/CeO2 catalysts with strong interactions between the metal and the ceria support.

  9. Microstructure and properties of Cu-Ti-Ni alloys

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Wang, Xian-hui; Guo, Ting-ting; Zou, Jun-tao; Yang, Xiao-hong

    2015-11-01

    The effects of Ni addition and aging treatments on the microstructure and properties of a Cu-3Ti alloy were investigated. The microstructure and precipitation phases were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy; the hardness, electrical conductivity, and elastic modulus of the resulting alloys were also tested. The results show that Ni addition increases the electrical conductivity and elastic modulus, but decreases the hardness of the aged Cu-3Ti alloy. Within the range of the experimentally investigated parameters, the optimal two-stage aging treatment for the Cu-3Ti-1Ni and Cu-3Ti-5Ni alloy was 300°C for 2 h and 450°C for 7 h. The hardness, electrical conductivity, and elastic modulus of the Cu-3Ti-1Ni alloy were HV 205, 18.2% IACS, and 146 GPa, respectively, whereas the hardness, electrical conductivity, and elastic modulus of the Cu-3Ti-5Ni alloy were HV 187, 31.32% IACS, and 147 GPa, respectively. Microstructural analyses revealed that β'-Ni3Ti and β'-Cu4Ti precipitate from the Cu matrix during aging of the Cu-3Ti-5Ni alloy and that some residual NiTi phase remains. The increased electrical conductivity is ascribed to the formation of NiTi, β'-Ni3Ti, and β'-Cu4Ti phases.

  10. Facile oxidative conversion of TiH2 to high-concentration Ti(3+)-self-doped rutile TiO2 with visible-light photoactivity.

    PubMed

    Grabstanowicz, Lauren R; Gao, Shanmin; Li, Tao; Rickard, Robert M; Rajh, Tijana; Liu, Di-Jia; Xu, Tao

    2013-04-01

    TiO2, in the rutile phase with a high concentration of self-doped Ti(3+), has been synthesized via a facile, all inorganic-based, and scalable method of oxidizing TiH2 in H2O2 followed by calcinations in Ar gas. The material was shown to be photoactive in the visible-region of the electromagnetic spectrum. Powdered X-ray diffraction (PXRD), transmission electron microscopy (TEM), ultraviolet-visible-near-infrared (UV-vis-NIR), diffuse reflectance spectroscopy (DRS), and Brunauer-Emmett-Teller (BET) methods were used to characterize the crystalline, structural, and optical properties and specific surface area of the as-synthesized Ti(3+)-doped rutile, respectively. The concentration of Ti(3+) was quantitatively studied by electron paramagnetic resonance (EPR) to be as high as one Ti(3+) per ~4300 Ti(4+). Furthermore, methylene blue (MB) solution and an industry wastewater sample were used to examine the photocatalytic activity of the Ti(3+)-doped TiO2 which was analyzed by UV-vis absorption, Fourier transform infrared spectroscopy (FT-IR), and electrospray ionization mass spectrometry (ESI-MS). In comparison to pristine anatase TiO2, our Ti(3+) self-doped rutile sample exhibited remarkably enhanced visible-light photocatalytic degradation on organic pollutants in water.

  11. Coatings on NiTi Alloy

    NASA Astrophysics Data System (ADS)

    Kei, C. C.; Yu, Y. S.; Racek, J.; Vokoun, D.; Šittner, P.

    2014-07-01

    Atomic layer deposition is introduced as a method suitable for preparation of Al2O3 layers on the surface of NiTi medical devices such as stents because of the excellent thickness control and conformal protective coating on complex structures. The corrosion properties of NiTi plates with Al2O3 coatings of various thicknesses in an environment similar to that occurring in the human body were studied using open circuit potential, potentiostatic electrochemical impedance spectroscopy, and cyclic polarization tests. It shows that the layer thickness plays a key role in the inhibition of corrosion. The thinner layers are more diffuse and make it easier for anodic reaction of passive NiTi with protective TiO2 underneath of Al2O3, while the thicker layers have the barrier effect with local pores initiating pitting corrosion. The results of our electrochemical experiments consistently show that corrosion properties of thick Al2O3 coatings on NiTi plate are inferior compared to the thin layers.

  12. Half-life of {sup 44}Ti

    SciTech Connect

    Ahmad, I.; Kutschera, W.; Castagnoli, G.; Paul, M.

    1995-08-01

    The measurement of the {sup 44}Ti half-life, started 3 years ago, is still continuing. The goal of this measurement is to determine the half-life of {sup 44}Ti, which is {approximately}52 y, to a precision of {approximately}5%. An accurate value of this half-life is of interest to cosmologists who need it to determine the production of heavy elements in supernova. Three sets of samples - a pure 200-nCi {sup 44}Ti sample, a pure 300-nCi {sup 60}Co source, and a mixed {sup 44}Ti-{sup 60}Co source of similar strength - were prepared and their spectra are being measured with Ge spectrometers at Argonne, Torino and Jerusalem. Each sample is counted for a period of 2 days, at approximate intervals of 4 months. The room background is also measured for the same length of time. We hope to start data analysis at the end of summer and obtain a value for the {sup 44}Ti half-life.

  13. Microstructural and chemical transformation of thin Ti/Pd and TiDy/Pd bilayer films induced by vacuum annealing.

    PubMed

    Lisowski, W; Keim, E G; Kaszkur, Z; van den Berg, A H J; Smithers, M A

    2007-11-01

    Using a combination of scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction and X-ray photoelectron spectroscopy (XPS), we made a comparative study of the high-temperature annealing impact on thin titanium deuteride (TiD(y)) films covered by an ultrathin Pd layer, and on Ti/Pd bilayer films. The bilayer films were prepared under ultrahigh vacuum conditions and were in situ annealed using the same annealing procedure. It was found that the surface and the bulk morphology of both films undergo different annealing-induced transformations, leading to an extensive intermixing between the Ti and Pd layers and the formation of a new PdTi(2) bimetallic phase. Energy-filtered TEM imaging and energy-dispersive X-ray spectrometry analysis, as well as XPS depth profiling all provided evidence of a different distribution of Pd and Ti in the annealed TiD(y)/Pd film compared with the annealed Ti/Pd film. Our results show that thermal decomposition of TiD(y), as a consequence of annealing the TiD(y)/Pd film, modifies the intermixing process, thereby promoting Ti diffusion into the Pd-rich top layer of the TiD(y) film and thus providing a more likely path for the formation of the PdTi(2) phase than in an annealed Ti/Pd film.

  14. TiC/Ti-Al composite fabricated by SHS/dynamic pseudo isostatic compaction through sand medium

    SciTech Connect

    Ohyanagi, M.; Fukushima, M.; Koizumi, M.

    1996-12-31

    TiC/Ti-Al composite was fabricated by pseudo isostatic compaction (DPIC) just after self-propagating high temperature synthesis (SHS). The pressing of 100 MPa was performed through a sand medium. The process enables to simultaneously synthesize and densify the TiC/Ti-Al composite from Ti/C/Al powders. The sample could be taken out from a reaction vessel within a couple of minutes after ignition. The adiabatic combustion temperatures were also calculated as a function of the mixing ratio of the elemental powders in the reaction system. X-ray diffraction patterns of TiC/Ti-Al produced revealed that the Ti-Al portion consisted of TiAl, Ti{sub 3}Al, TiAl{sub 3} and a slight Ti{sub 4}Al{sub 2}C{sub 2} alloys. The time delay between SHS and DPIC was affected greatly on the product density. The influence of the reactant mixing time on the phase component of the product was also studied. The density and Vickers hardness of the composite were highest in a mixing mole ratio of Ti/C/Al = 2/1/1, 4.2 g/cm{sup 3} and 13 GPa. The Young`s modulus and bending strength were approximately 300 GPa and 500 MPa, respectively.

  15. Carbon coating stabilized Ti(3+)-doped TiO2 for photocatalytic hydrogen generation under visible light irradiation.

    PubMed

    Fu, Gao; Zhou, Peng; Zhao, Meiming; Zhu, Weidong; Yan, Shicheng; Yu, Tao; Zou, Zhigang

    2015-07-28

    Self-doping by Ti(3+) is a useful method to expand the light response of TiO2 into the visible light region. However, to obtain a stable Ti(3+)-doped TiO2 seems to be a challenge due to the easy oxidation of Ti(3+) during the heterogeneous reaction. Here, we propose a simple carbon coating route to stabilize the Ti(3+)-doped TiO2, in which both the Ti(3+) and precursor of the carbon coating layer were in situ formed from the hydrothermal hydrolysis of titanium isopropoxide. The carbon coated Ti(3+)-doped TiO2 exhibited excellent stability for photocatalytic hydrogen production. Based on electron paramagnetic resonance (EPR) analysis, the proposed stabilizing mechanism is that the conductive carbon coating layer as a barrier layer prevents the H2O and O2 from diffusing into the surface of the photocatalyst, which can oxidize the surface O vacancies and Ti(3+) in TiO2. Our findings offer a simple route to prepare a highly stable TiO2-based photocatalyst with visible light response.

  16. Constant stress of XD trademark TiAl containing nitrogen

    SciTech Connect

    Robertson, E.; Martin, P.L.

    1990-01-01

    Ti-47at%Al+7vol%(TiN+TiB{sub 2}) alloys, produced by the Martin Marietta XD{trademark} process, were subjected to tensile constant stress creep deformation in the range 760--850{degree}C temperature and 138--276 MPa (20--40 ksi) stress. These alloys have a matrix of TiAl and Ti{sub 3}Al initially containing 1 to 10 {mu}m diameter equiaxed particles of TiB{sub 2} and Ti{sub 2}AlN. Microstructures were examined using optical, SEM and TEM methods in an attempt to correlate the substructures with the property data. In particular, fine coherent particles have been observed to decorate dislocations and the interior of TiAl grains. The presence of these particles is thought to explain the creep resistance of this alloy. 14 refs., 5 figs.

  17. Proton and neutron irradiation effect of Ti: Sapphires

    SciTech Connect

    Wang, G.; Zhang, J.; Yang, J.

    1999-07-01

    Various effects of proton and neutron irradiated Ti: sapphires were studied. Proton irradiation induced F, F{sup +} and V center in Ti: sapphires and 3310 cm{sup -1} infrared absorption, and made ultraviolet absorption edge shift to short wave. Neutron irradiation produced a number of F, F{sup +} and F{sub 2} centers and larger defects in Ti: sapphires, and changed Ti{sup 4+}into Ti{sup 3+} ions. Such valence state variation enhanced characteristic luminescence of Ti: sapphires, and no singular variances of intrinsic fluorescence spectra of Ti: sapphires took place with neutron flux of 1 x 10{sup 17}n/cm{sup 2}, but the fluorescence vanished with neutron flux of 1 x 10{sup 18}n/cm{sup 2} which means the threshold for the concentration of improving Ti{sup 3+} ions by neutron irradiation.

  18. Influence of Ti content on synthesis and characteristics of W-Ti ODS alloy

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Liang; Zeng, Yong

    2016-02-01

    Tungsten-titanium alloys are considered as promising materials for the future fusion devices, in particular for the divertor and other first wall components. The microstructure and the mechanical properties of the material are dependent on the amount of Ti present in the alloy. In this study, W-Ti-Y2O3 alloys with varied Ti contents between 1 wt.% and 10 wt.% fabricated by mechanical alloying were investigated. The effect of Ti on the phase formation and mechanical properties of W-Ti-Y2O3 alloys has been examined. The results suggest that the alloys containing low Ti content exhibit homogeneous microstructure with a uniform distribution of fine titanium oxide particles and tungsten carbides, leading to a significant increase in hardness and elastic modulus of alloys. In addition, high-energy ball milling can facilitate a solid-state reaction between Y2O3 particles and the tungsten-titanium matrix and the subsequent sintering processing promotes the formation of stable nano Ti2Y2O7 oxide particles, which greatly increase the mechanical properties at elevated temperature and enhance irradiation resistance.

  19. 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.

  20. Tensile deformation of NiTi wires.

    PubMed

    Gall, Ken; Tyber, Jeff; Brice, Valerie; Frick, Carl P; Maier, Hans J; Morgan, Neil

    2005-12-15

    We examine the structure and properties of cold drawn Ti-50.1 at % Ni and Ti-50.9 at % Ni shape memory alloy wires. Wires with both compositions possess a strong <111> fiber texture in the wire drawing direction, a grain size on the order of micrometers, and a high dislocation density. The more Ni rich wires contain fine second phase precipitates, while the wires with lower Ni content are relatively free of precipitates. The wire stress-strain response depends strongly on composition through operant deformation mechanisms, and cannot be explained based solely on measured differences in the transformation temperatures. We provide fundamental connections between the material structure, deformation mechanisms, and resulting stress-strain responses. The results help clarify some inconsistencies and common misconceptions in the literature. Ramifications on materials selection and design for emerging biomedical applications of NiTi shape memory alloys are discussed.

  1. Modeling wear of cast Ti alloys.

    PubMed

    Chan, Kwai S; Koike, Marie; Okabe, Toru

    2007-05-01

    The wear behavior of Ti-based alloys was analyzed by considering the elastic-plastic fracture of individual alloys in response to the relevant contact stress field. Using the contact stresses as the process driving force, wear was computed as the wear rate or volume loss as a function of hardness and tensile ductility for Ti-based cast alloys containing an alpha, alpha+beta or beta microstructure with or without the intermetallic precipitates. Model predictions indicated that wear of Ti alloys increases with increasing hardness but with decreasing fracture toughness or tensile ductility. The theoretical results are compared with experimental data to elucidate the roles of microstructure in wear and contrasted against those in grindability.

  2. Modeling wear of cast Ti alloys

    PubMed Central

    Chan, Kwai S.; Koike, Marie; Okabe, Toru

    2007-01-01

    The wear behavior of Ti-based alloys was analyzed by considering the elastic–plastic fracture of individual alloys in response to the relevant contact stress field. Using the contact stresses as the process driving force, wear was computed as the wear rate or volume loss as a function of hardness and tensile ductility for Ti-based cast alloys containing an α, α+β or β microstructure with or without the intermetallic precipitates. Model predictions indicated that wear of Ti alloys increases with increasing hardness but with decreasing fracture toughness or tensile ductility. The theoretical results are compared with experimental data to elucidate the roles of microstructure in wear and contrasted against those in grindability. PMID:17224314

  3. Morphology, deformation, and defect structures of TiCr{sub 2} in Ti-Cr alloys

    SciTech Connect

    Chen, K.C.; Allen, S.M.; Livingston, J.D.

    1992-12-31

    The morphologies and defect structures of TiCr{sub 2} in several Ti-Cr alloys have been examined by optical metallography, x-ray diffraction, and transmission electron microscopy (TEM), in order to explore the room-temperature deformability of the Laves phase TiCr{sub 2}. The morphology of the Laves phase was found to be dependent upon alloy composition and annealing temperature. Samples deformed by compression have also been studied using TEM. Comparisons of microstructures before and after deformation suggest an increase in twin, stacking fault, and dislocation density within the Laves phase, indicating some but not extensive room-temperature deformability.

  4. Facile method to enhance the adhesion of TiO₂ nanotube arrays to Ti substrate.

    PubMed

    Yu, Dongliang; Zhu, Xufei; Xu, Zhen; Zhong, Xiaomin; Gui, Qunfang; Song, Ye; Zhang, Shaoyu; Chen, Xiaoyuan; Li, Dongdong

    2014-06-11

    The weak adhesion of anodic TiO2 nanotube arrays (TNTAs) to the underlying Ti substrate compromises many promising applications. In this work, a compact oxide layer between TNTAs and Ti substrate is introduced by employing an additional anodization in a fluoride-free electrolyte. The additional anodization results in an about 200 nm thick compact layer near the nanotube bottoms. Scratch test demonstrates that the critical load of TNTAs with the compact oxide layer is a more than threefold increase in comparison with those without the compact layer. Moreover, this facile method can also improve the photoactivity and supercapacitor performances of TNTAs markedly.

  5. Enhancement of NiTi superelastic endodontic instruments by TiO2 coating.

    PubMed

    Aun, Diego Pinheiro; Peixoto, Isabella Faria da Cunha; Houmard, Manuel; Buono, Vicente Tadeu Lopes

    2016-11-01

    Rotary nickel-titanium (NiTi) endodontic instruments were coated with a nanometric flexible TiO2 layer through dip-coating sol-gel. Control groups and coated samples of superelastic NiTi instruments model RaCe 25/0.06 (0.25mm tip-diameter, 6% conicity) were comparatively investigated with respect to the cutting efficiency, fatigue life, and corrosion resistance. Results showed an improvement in cutting efficiency for the coated samples and a high resistance to corrosion in NaClO. The coated instruments showed a better performance in fatigue life after corrosion.

  6. Synthesis of Ti-based electrodes using Ti-salt flocculated sludge and their application in lithium-ion batteries

    SciTech Connect

    Kang, Jungwon; Rai, Alok Kumar; Kim, Sungjin; Choi, Eunseok; Yoo, Insun; Kim, Jongho; Kim, Jaekook

    2012-10-15

    We report a simple strategy to synthesize the nanostructured TiO{sub 2} samples by a solid state reaction using Ti-salt flocculated sludge. The structure and morphology of the Ti-salt flocculated sludge, nanostructured TiO{sub 2} samples and pure commercial Aldrich TiO{sub 2} powder were characterized by powder X-ray diffraction and field emission scanning electron microscopy (FE-SEM). The electrochemical performances were evaluated in coin type cells. Nanostructured TiO{sub 2} samples, obtained by Ti-salt flocculated sludge shows a higher capacity and better cycling performances than pure commercial Aldrich TiO{sub 2} powder at the cutoff of 1.0–2.5 V especially at high current rate. The enhanced cycling performance can be attributed to the facts that their high crystallinity and uniform nano-sized distribution.

  7. TiO2 coating of high surface area silica gel by chemical vapor deposition of TiCl4 in a fluidized-bed reactor.

    PubMed

    Xia, Wei; Mei, Bastian; Sánchez, Miguel D; Strunk, Jennifer; Muhler, Martin

    2011-09-01

    TiO2 was deposited on high surface area porous silica gel (400 m2g(-1)) in a fluidized bed reactor. Chemical vapor deposition was employed for the coating under vacuum conditions with TiCl4 as precursor. Nitrogen physisorption, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis spectroscopy were applied to characterize the obtained TiO2-SiO2 composites with different Ti loadings up to 5 wt%. Only a slight decrease in the specific surface area was detected at low Ti loadings. At a Ti loading of 2 wt%, TiO2 was found to be highly dispersed on the SiO2 surface likely in form of a thin film. At higher Ti loadings, two weak reflections corresponding to anatase TiO2 were observed in the diffraction patterns indicating the presence of crystalline bulk TiO2. High resolution XPS clearly distinguished two types of Ti species, i.e., Ti-O-Si at the interface and Ti-O-Ti in bulk TiO2. The presence of polymeric TiOx species at low Ti loadings was confirmed by a blue shift in the UV-vis spectra as compared to bulk TiO2. All these results point to a strong interaction between the TiO2 deposit and the porous SiO2 substrate especially at low Ti loadings.

  8. Carrier-Controlled Ferromagnetism in SrTiO3

    DOE PAGES

    Moetakef, Pouya; Williams, James R.; Ouellette, Daniel G.; ...

    2012-06-27

    Magnetotransport and superconducting properties are investigated for uniformly La-doped SrTiO3 films and GdTiO3/SrTiO3 heterostructures, respectively. GdTiO3/SrTiO3 interfaces exhibit a high-density 2D electron gas on the SrTiO3 side of the interface, while, for the SrTiO3 films, carriers are provided by the dopant atoms. Both types of samples exhibit ferromagnetism at low temperatures, as evidenced by a hysteresis in the magnetoresistance. For the uniformly doped SrTiO3 films, the Curie temperature is found to increase with doping and to coexist with superconductivity for carrier concentrations on the high-density side of the superconducting dome. The Curie temperature of the GdTiO3/SrTiO3 heterostructures scales with themore » thickness of the SrTiO3 quantum well. The results are used to construct a stability diagram for the ferromagnetic and superconducting phases of SrTiO3.« less

  9. Photocatalytic activity of polyaniline-TiO2 nanocomposites

    NASA Astrophysics Data System (ADS)

    Sarmah, S.; Kumar, A.

    2011-05-01

    The characteristics of the UV illumination-assisted degradation of Malachite green (MG) on highly active nanostructured-anatase TiO2, bulk Polyaniline (PAni), PAni nanoparticles and PAni-TiO2 nanocomposites have been studied. Dodecylbenzene sulphonic acid doped PAni-TiO2 nanocomposites were synthesized by a water-assisted self-assembly method. Samples were characterized using transmission electron microscopy, X-ray diffraction studies, Fourier Transform Infra red spectroscopy and photoluminescence studies. Photoluminescence intensity of TiO2 nanoparticles was found to decrease with the increase of PAni in the nanocomposite which can be attributed to the reduction of electron-hole pair recombination at the interface of PAni and TiO2 due to electron transfer from TiO2 to PAni. Exposure to UV light brought about the photocatalytic oxidation of MG in contact with bulk PAni, PAni and TiO2 nanoparticles, and PAni-TiO2 nanocomposites. The decrease in absorbance was measured, and its kinetics was analyzed using the Langmuir-Hinshelwood kinetic model. PAni-TiO2 nanocomposites exhibit higher photocatalytic activity than pure TiO2 nanoparticles, bulk PAni and PAni nanoparticles under the same degradation condition for MG. The enhanced photocatalytic activity of nanocomposites is attributed to the electron transfer from TiO2 to PAni resulting in enhancing the oxidative property of the TiO2 nanoparticles.

  10. TiB 2/TiSi 2 bilayer fabrication by various techniques: Structure and contact properties

    NASA Astrophysics Data System (ADS)

    Pelleg, Joshua; Sade, G.

    2006-01-01

    TiB 2/TiSi 2 films were produced by several techniques in an attempt to evaluate the most appropriate method to fabricate this system. Analysis by X-ray diffraction, Auger electron spectroscopy, transmission and high-resolution transmission electron microscopy indicate that the best method to obtain the above system is by sequential cosputtering of the layers without exposure to air between the two cosputtering sequences. Post-deposition annealing was performed to obtain a low resistive bilayer. Schottky diodes fabricated by this method provided an average barrier height of ∼0.68 V with an ideality factor in the range of 1.0-1.04 (excluding the as-deposited specimen). In specimens fabricated by silicidation of TiB 2/Ti films formation of TiSi 2 was Ti thickness dependent [G. Sade, Ph.D. Thesis, Ben Gurion University of the Negev, Beer Sheva, Israel, 1999]. Small amounts of Ti 5Si 3 were observed at 1123 K. The attempts to obtain a TiB 2/TiSi 2 bilayer from (Ti+B) enriched with Ti at 1073 K resulted in the formation of small amounts of Ti 5Si 3, and some crystallization of the amorphous TiB 2 also occurred. Diodes fabricated by this technique showed Ohmic rather than rectifying character. The shift from rectifying to Ohmic behavior is the result of B out-diffusion to the Si and the consequent change of the substrate from an n- to a p-type Si. The results place the Fermi level of TiB 2 about 0.9 eV below the silicon conduction band. A remedy to this problem could result in a challenging method of fabricating a TiB 2/TiSi 2 bilayer structure in a one-step process.

  11. Study on improved tribological properties by alloying copper to CP-Ti and Ti-6Al-4V alloy.

    PubMed

    Wang, Song; Ma, Zheng; Liao, Zhenhua; Song, Jian; Yang, Ke; Liu, Weiqiang

    2015-12-01

    Copper alloying to titanium and its alloys is believed to show an antibacterial performance. However, the tribological properties of Cu alloyed titanium alloys were seldom studied. Ti-5Cu and Ti-6Al-4V-5Cu alloys were fabricated in the present study in order to further study the friction and wear properties of titanium alloys with Cu additive. The microstructure, composition and hardness were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and hardness tester. The tribological behaviors were tested with ZrO2 counterface in 25% bovine serum using a ball-on-disc tribo-tester. The results revealed that precipitations of Ti2Cu intermetallic compounds appeared in both Ti-5Cu and Ti-6Al-4V-5Cu alloys. The tribological results showed an improvement in friction and wear resistance for both Ti-5Cu and Ti-6Al-4V-5Cu alloys due to the precipitation of Ti2Cu. The results also indicated that both CP-Ti and Ti-5Cu behaved better wear resistance than Ti-6Al-4V and Ti-6Al-4V-5Cu due to different wear mechanisms when articulated with hard zirconia. Both CP-Ti and Ti-5Cu revealed dominant adhesive wear with secondary abrasive wear mechanism while both Ti-6Al-4V and Ti-6Al-4V-5Cu showed severe abrasive wear and cracks with secondary adhesive wear mechanism due to different surface hardness integrated by their microstructures and material types.

  12. Electronic properties of ultrathin GdTiO3 thin films and GdTiO3/SrTiO3 interfaces

    NASA Astrophysics Data System (ADS)

    Moetakef, Pouya; Jalan, Bharat; Zhang, Jack; Allen, S. James; Stemmer, Susanne

    2011-03-01

    Interfaces between Mott insulators, such as the rare earth titanates, and band insulators, such as SrTiO3, have recently attracted much attention. We report on the transport properties of epitaxial rare earth titanate thin films, GdTiO3, grown by molecular beam epitaxy (MBE) and those of heterostructures with SrTiO3 and GdTiO3. Growth of GdTiO3 was performed by shuttered growth of alternating titanium tetra isopropoxide (TTIP) and Gd fluxes, in the absence of any additional oxygen. We show that to stabilize the GdTiO3 perovskite phase, SrTiO3 buffer layers are needed for growth on perovskite substrates, such as LSAT ((LaAlO3)0.3(Sr2AlTaO6)0.7). The contribution of n-type SrTiO3 buffer layers and that of the SrTiO3/GdTiO3 interfaces to the transport properties are determined by measurements of the electrical resistance and Hall coefficient as a function of temperature and magnetic field.

  13. Enhanced photocatalytic degradation of dyes over graphene/Pd/TiO2 nanocomposites: TiO2 nanowires versus TiO2 nanoparticles.

    PubMed

    Safajou, Hamed; Khojasteh, Hossein; Salavati-Niasari, Masoud; Mortazavi-Derazkola, Sobhan

    2017-07-15

    In this study, at first, TiO2 nanowire was prepared by an alkaline hydrothermal process. In the following, Gr/Pd/TiO2-NPs and Gr/Pd/TiO2-NWs were synthesized by a combination of hydrothermal and photodeposition methods. The properties of as prepared products were characterized using XRD, FT-IR, SEM, DRS, TEM, ICP-OES, EDS and TGA analysis. SEM results confirmed nanodimension structure for all samples. Also the band gap values obtained using DRS technique suggests that all the samples have semiconductor behavior. Using TGA analysis, the amount of graphene loaded onto the powders was confirmed. Photocatalytic degradation of rhodamine B by TiO2-NWs, Gr/Pd/TiO2-NPs and Gr/Pd/TiO2-NWs nanocomposites was compared under ultraviolet light irradiation. Results confirmed that the Gr/Pd/TiO2-NWs composite show the highest photocatalytic activity due to much higher available surface area of TiO2 substrate in nanowire structure. It is expected that the synthesis of the high surface area TiO2 nanowires, facile photodeposition of palladium into its texture, and simple conversion of GO to graphene during hydrothermal process without using strong reducing agents, could be a suitable rote for preparing different types of carbon based TiO2 nanocomposite photocatalysts.

  14. Linear combination of XANES for quantitative analysis of Ti-Si binary oxides.

    PubMed

    Lee, J S; Kim, W B; Choi, S H

    2001-03-01

    A new method is demonstrated for the quantification of Ti-O-Si and Ti-O-Ti bonds in Ti-Si binary oxides. It is based on the linear combination of two reference X-ray absorption near-edge structure (XANES) spectra at the Ti K edge. The proper selection of a Ti-O-Si reference material is most important for the successful application of this method. Three Ti-Si binary oxide systems have been analysed by the new method: Ti-Si mixed oxides, titania supported on silica and Ti-substituted MCM-41 (crystalline mesoporous molecular sieve material invented by Mobil) with various Ti contents.

  15. In situ synthesized TiB-TiN reinforced Ti6Al4V alloy composite coatings: microstructure, tribological and in-vitro biocompatibility.

    PubMed

    Das, Mitun; Bhattacharya, Kaushik; Dittrick, Stanley A; Mandal, Chitra; Balla, Vamsi Krishna; Sampath Kumar, T S; Bandyopadhyay, Amit; Manna, Indranil

    2014-01-01

    Wear resistant TiB-TiN reinforced Ti6Al4V alloy composite coatings were deposited on Ti substrate using laser based additive manufacturing technology. Ti6Al4V alloy powder premixed with 5wt% and 15wt% of boron nitride (BN) powder was used to synthesize TiB-TiN reinforcements in situ during laser deposition. Influences of laser power, scanning speed and concentration of BN on the microstructure, mechanical, in vitro tribological and biological properties of the coatings were investigated. Microstructural analysis of the composite coatings showed that the high temperature generated due to laser interaction with Ti6Al4V alloy and BN results in situ formation of TiB and TiN phases. With increasing BN concentration, from 5wt% to 15wt%, the Young's modulus of the composite coatings, measured by nanoindentation, increased from 170±5GPa to 204±14GPa. In vitro tribological tests showed significant increase in the wear resistance with increasing BN concentration. Under identical test conditions TiB-TiN composite coatings with 15wt% BN exhibited an order of magnitude less wear rate than CoCrMo alloy-a common material for articulating surfaces of orthopedic implants. Average top surface hardness of the composite coatings increased from 543±21HV to 877±75HV with increase in the BN concentration. In vitro biocompatibility and flow cytometry study showed that these composite coatings were non-toxic, exhibit similar cell-materials interactions and biocompatibility as that of commercially pure titanium (CP-Ti) samples. In summary, excellent in vitro wear resistance, high stiffness and suitable biocompatibility make these composite coatings as a potential material for load-bearing articulating surfaces towards orthopaedic implants.

  16. Design, Fabrication, and Testing of a TiN/Ti/TiN Trilayer KID Array for 3 mm CMB Observations

    NASA Astrophysics Data System (ADS)

    Lowitz, A. E.; Brown, A. D.; Mikula, V.; Stevenson, T. R.; Timbie, P. T.; Wollack, E. J.

    2016-08-01

    Kinetic inductance detectors (KIDs) are a promising technology for astronomical observations over a wide range of wavelengths in the mm and sub-mm regime. Simple fabrication, in as little as one lithographic layer, and passive frequency-domain multiplexing, with readout of up to ˜ 1000 pixels on a single line with a single cold amplifier, make KIDs an attractive solution for high-pixel-count detector arrays. We are developing an array that optimizes KIDs for optical frequencies near 100 GHz to expand their usefulness in mm-wave applications, with a particular focus on CMB B-mode measurement efforts in association with the QUBIC telescope. We have designed, fabricated, and tested a 20-pixel prototype array using a simple quasi-lumped microstrip design and pulsed DC reactive magnetron-sputtered TiN/Ti/TiN trilayer resonators, optimized for detecting 100 GHz (3 mm) signals. Here we present a discussion of design considerations for the array, as well as preliminary detector characterization measurements and results from a study of TiN trilayer properties.

  17. Influence of Au and TiO2 structures on hydrogen dissociation over TiO2/Au(100)

    NASA Astrophysics Data System (ADS)

    Nakamura, I.; Mantoku, H.; Furukawa, T.; Takahashi, A.; Fujitani, T.

    2012-11-01

    We performed H2-D2 exchange reactions over TiOx/Au(100) and compared the observed reaction kinetics with those reported for TiOx/Au(111) in order to clarify the influence of the Au and TiO2 structures on dissociation of H2 molecules. Low energy electron diffraction observations showed that the TiO2 produced on Au(100) was disordered, in contrast to the comparatively ordered TiO2 structure formed on Au(111). The activation energies and the turnover frequencies for HD formation over TiO2/Au(100) agreed well with those for TiO2/Au(111), clearly indicating that the hydrogen dissociation sites created over TiO2/Au(100) were the perimeter interface between stoichiometric TiO2 and Au, as was previously concluded for TiO2/Au(111). We concluded that the creation of active sites for hydrogen dissociation was independent of the Au and TiO2 structures consisting perimeter interface, and that local bonds that formed between Au and O atoms of stoichiometric TiO2 were essential for the creation of active sites.

  18. 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.

  19. Mechanical properties and microstructures of dental cast Ti-Ag and Ti-Cu alloys.

    PubMed

    Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo; Okuno, Osamu

    2002-09-01

    In this study, experimental Ti-Ag alloys (5, 10, and 20 mass% Ag) and Ti-Cu alloys (2, 5, and 10 mass% Cu) were made in an argon-arc melting furnace. The alloys were cast into magnesia molds using an argon gas-pressure dental casting machine, and the mechanical properties and microstructures of the castings were investigated. As the concentration of silver or copper in the alloys increased, the tensile strength, yield strength, and hardness of the alloys became higher than those of CP Ti, and the elongation of the alloys became lower than that of CP Ti. Changes in the mechanical properties by alloying were considered to be caused by solid-solution strengthening of the a-phases and by precipitation of intermetallic compounds.

  20. Pulsed Nd-YAG laser deposition of TiN and TiAlN coating

    NASA Astrophysics Data System (ADS)

    Kathuria, Y. P.; Uchida, Yoshiyuki

    This paper demonstrates the feasibility of generating a thin clad coating of TiN and TiAlN on SS304 base material by using the pulsed Nd-YAG laser. In the experiment TiN based coating was created with and without the addition of Al-powder. In the post processing, a precision grinder was employed to smoothen the top surface. SEM, XRD and EDS analysis were employed to study the surface topography etc. Microhardness mapping was performed at various points across the surface. The results show the average microhardness of the coating deposited with TiN is lower (1035 HV) than that of using Al-mixed powder (1264 HV).

  1. Giant persistent photoconductivity in BaTiO3/TiO2 heterostructures

    NASA Astrophysics Data System (ADS)

    Plodinec, Milivoj; Šantić, Ana; Zavašnik, Janez; Čeh, Miran; Gajović, Andreja

    2014-10-01

    The persistent photoconductivity (PPC) effect in nanotube arrays of barium titanate and TiO2 (BTO/TiO2NT) was studied at room temperature under daylight illumination. The BTO/TiO2NT heterostructures exhibited a giant PPC effect that was six orders of magnitude higher than the dark conductivity, followed by a slow relaxation for 3 h. The PPC in this material was explained by the existence of defects at the surfaces and the interfaces of the investigated heterostructures. The sample was prepared using a two-step synthesis: the anodization of a Ti-foil and a subsequent hydrothermal synthesis. The structural and electrical characteristics were studied by micro-Raman spectroscopy, field-emission-gun scanning electron microscopy, and impedance spectroscopy.

  2. Diffusion barrier properties of Ti/TiN investigated by transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Mändl, M.; Hoffmann, H.; Kücher, P.

    1990-09-01

    Detailed analytical transmission electron microscopy investigations were performed on a well-known diffusion barrier system for very-large-scale integration metallization. It will be demonstrated that interfacial reactions are of great importance for the barrier mechanism. Both Ti and TiN act as diffusion barrier for the semiconductor and the metallization, respectively. For an aluminum-based metallization, TiN has a ``spongelike'' function due to its ability to absorb several amounts of aluminum at elevated temperatures and therefore inhibits diffusion towards the substrate. Ti acts for silicon as a compound forming barrier according to Nicolet's classification [in Tungsten and Other Refractory Metals for Very Large Scale Integration Applications II, edited by E. K. Broadbent (Materials Research Society, Pittsburgh, 1987); pp. 19-26].

  3. Formation of Ti3+ in sapphire by co-implantation of Ti and O ions

    NASA Astrophysics Data System (ADS)

    Morpeth, L. D.; McCallum, J. C.

    2000-01-01

    We have demonstrated that co-implantation of Ti and O ions into c-axis oriented α-Al2O3 substrates followed by thermal annealing can substantially increase the fraction of Ti ions present in the optically active 3+ oxidation state. Evidence for the presence of Ti3+ is given by the observation of strong luminescence over the wavelength range ˜600-900 nm under Ar laser excitation and by the presence of the characteristic absorption band at ˜450-550 nm. We have studied the luminescence intensity as a function of implantation and annealing parameters and have found that there is a strong dependence on the ratio of implanted Ti and O and on the annealing temperature.

  4. Synthesis of ultrathin TiO2/Ti films with tunable structural color.

    PubMed

    Wang, Yanlu; Han, Rushuai; Qi, Liqian; Liu, Lihu; Sun, Huiyuan

    2016-12-10

    A series of ultrathin TiO2/Ti films with iridescent structural colors were fabricated on high-purity titanium sheets via a one-step anodization procedure. Tunable color in the films can be obtained by adjusting the anodization time and can be adjusted across the entire visible range. It was found that all the films displayed highly saturated colors. Trichromatic coordinates of color x, y were delineated, and the color was identified by positioning the x and y values in the Commission International de I'Eclairage chromaticity diagram. Theoretical and experimental results of the changes in the structural color according to the principle of complementary colors are consistent with the experimental results. The TiO2/Ti films may have potential in color displays, decoration, and anticounterfeiting technology.

  5. Electronic structure study of TiB{sub 2} and Ti{sub 2}B

    SciTech Connect

    Vashistha, M. Vyas, V.; Kabra, K.; Sharma, G.

    2015-06-24

    In this paper, the electronic properties of TiB{sub 2} and Ti{sub 2}B are computed within the framework of Density Functional Theory (DFT) based on Linear Combination of Atomic Orbitals (LCAO) method. In the present calculations, the generalized gradient approximation (GGA) proposed by Perdew-Burke-Erenzerhof (PBE) and Becke’s scheme are considered to treat the correlation and exchange effects respectively. TiB{sub 2} crystallizes in the hexagonal AlB{sub 2} type structure which is designated as C32 with the space group P6/mmm. While the crystal structure of Ti{sub 2}B described in this paper is isomorphous to the body centered tetragonal (Al{sub 2}Cu - type) structure with space group I4/mcm.

  6. Wear and corrosion of metal-matrix (stainless steel or NiTi)-TiC coatings

    NASA Astrophysics Data System (ADS)

    Fernandez, Javier; Isalgue, Antonio; Cinca, Nuria; Dosta, Sergi; Ventayol, Judith

    Different spraying technologies (plasma and High Velocity Oxi-Fuel) have been use to obtain TiC - stainless steel or NiTi matrix coatings. The starting feedstock powders have been obtained by SHS technology. After crushing and sieving, the fraction of particles between 20 and 63 μ m, have been selected for thermal spray. The obtained coatings have been characterized by XRD and SEM-EDS to observe the surface and cross section. The coatings adhesion, wear (ball-on-disk and rubber wheel tests) and electrochemical corrosion test have been carried out. Results show that the plasma sprayed coatings with NiTi have better adhesion than the stainless steel matrix coatings. However, the opposite happens for HVOF coatings. NiTi matrix coatings exhibit higher wear resistance both for plasma and HVOF spraying processes.

  7. Giant persistent photoconductivity in BaTiO{sub 3}/TiO{sub 2} heterostructures

    SciTech Connect

    Plodinec, Milivoj; Šantić, Ana; Gajović, Andreja; Zavašnik, Janez; Čeh, Miran

    2014-10-13

    The persistent photoconductivity (PPC) effect in nanotube arrays of barium titanate and TiO{sub 2} (BTO/TiO{sub 2}NT) was studied at room temperature under daylight illumination. The BTO/TiO{sub 2}NT heterostructures exhibited a giant PPC effect that was six orders of magnitude higher than the dark conductivity, followed by a slow relaxation for 3 h. The PPC in this material was explained by the existence of defects at the surfaces and the interfaces of the investigated heterostructures. The sample was prepared using a two-step synthesis: the anodization of a Ti-foil and a subsequent hydrothermal synthesis. The structural and electrical characteristics were studied by micro-Raman spectroscopy, field-emission-gun scanning electron microscopy, and impedance spectroscopy.

  8. Effects of boron on the mechanical properties of the TiAl-Ti3Al alloy: A first-principles investigation

    NASA Astrophysics Data System (ADS)

    Li, Zhong-Zhu; Wei, Ye; Zhou, Hong-Bo; Lu, Guang-Hong

    2017-01-01

    Employing a first-principles method in combination with the empirical criterions, we have investigated the site preference of boron (B) and its effect on the mechanical properties of the binary-phase TiAl-Ti3Al alloy. It is found that B energetically prefers to occupy the Ti-rich octahedral interstitial site, because B is more favorable to bond with Ti in comparison with Al. The occupancy tendency of B in the TiAl-Ti3Al alloy is the TiAl/Ti3Al interface > Ti3Al > TiAl, thus B tends to segregate into the binary-phase interface in the TiAl-Ti3Al alloy. The charge density difference shows that B at the TiAl-Ti3Al interface will form strong B-Ti bonds and weak B-Al bonds, leading to the significant increasing of the cleavage energy (γcl) and the unstable stacking fault energy (γus). This indicates that the presence of B will strengthen the TiAl/Ti3Al interface, but block its mobility. Further, the ratio of γcl/γus of the B-doped system is 4.63%, 8.19% lower than that of the clean system. Based on the empirical criterions, B will have a negative effect on the ductility of the TiAl-Ti3Al alloy.

  9. Thin NiTi Films Deposited on Graphene Substrates

    NASA Astrophysics Data System (ADS)

    Hahn, S.; Schulze, A.; Böhme, M.; Hahn, T.; Wagner, M. F.-X.

    2017-03-01

    We present experimental results on the deposition of Nickel Titanium (NiTi) films on graphene substrates using a PVD magnetron sputter process. Characterization of the 2-4 micron thick NiTi films by electron microscopy, electron backscatter diffraction, and transmission electron microscopy shows that grain size and orientation of the thin NiTi films strongly depend on the type of combination of graphene and copper layers below. Our experimental findings are supported by density functional theory calculations: a theoretical estimation of the binding energies of different NiTi-graphene interfaces is in line with the experimentally determined microstructural features of the functional NiTi top layer.

  10. Thin NiTi Films Deposited on Graphene Substrates

    NASA Astrophysics Data System (ADS)

    Hahn, S.; Schulze, A.; Böhme, M.; Hahn, T.; Wagner, M. F.-X.

    2016-12-01

    We present experimental results on the deposition of Nickel Titanium (NiTi) films on graphene substrates using a PVD magnetron sputter process. Characterization of the 2-4 micron thick NiTi films by electron microscopy, electron backscatter diffraction, and transmission electron microscopy shows that grain size and orientation of the thin NiTi films strongly depend on the type of combination of graphene and copper layers below. Our experimental findings are supported by density functional theory calculations: a theoretical estimation of the binding energies of different NiTi-graphene interfaces is in line with the experimentally determined microstructural features of the functional NiTi top layer.

  11. Diffusion Research in BCC Ti-Al-Mo Ternary Alloys

    NASA Astrophysics Data System (ADS)

    Chen, Yi; Tang, Bin; Xu, Guanglong; Wang, Chuanyun; Kou, Hongchao; Li, Jinshan; Cui, Yuwen

    2014-04-01

    Interdiffusion in Ti-Al-Mo β solid solution was investigated at 1523 K (1250 °C) by analyzing diffusion couples. From the concentration profiles analytically represented by error function expansion (ERFEX), the ternary interdiffusion coefficients and impurity diffusivity were extracted by the Whittle-Green and generalized Hall methods. A comparison of the diffusion in five Ti-Al-X (Co, Cr, Fe, Mo, and V) ternaries reveals Ti-Al-Mo is comparably like Ti-Al-(Cr, V) while Ti-Al-(Co, Fe) are predominantly of interstitial nature.

  12. First Ti-XANES analyses of refractory inclusions from Murchison

    SciTech Connect

    Simon, S.B.; Sutton, S.R.; Grossman, L.

    2009-03-23

    Ti valence in refractory phases is an important recorder of redox conditions in the early solar nebula. We report the valence of Ti in pyroxene, spinel and hibonite in spinel-hibonite and spinel-pyroxene inclusions and in a coarse hibonite grain. A system of solar composition is so reducing that Ti{sup 3+} and Ti{sup 4+} can coexist, making the valence of Ti a valuable indicator of f{sub O2} conditions during formation of nebular materials. The Ti{sup 3+}/Ti{sup 4+} ratios observed in the Ti-rich phases fassaite and rhoenite in coarse-grained refractory inclusions from CV3 chondrites have been shown to be quantitatively consistent with formation in a gas of solar composition (log f{sub O2} = IW-6.8), but these are the only objects in chondrites for which this is the case. Here, we report the valence of Ti in various phases in refractory inclusions from the Murchison CM2 chondrite. The second-highest temperature, major-element-bearing phase predicted to condense from a gas of solar composition, hibonite (ideally CaAl{sub 12}O{sub 19}), can contain significant amounts of Ti, but the hibonite structure can have oxygen vacancies, so calculation of Ti valence from stoichiometry of electron probe analyses is not recommended for hibonite. To date, the only reported measurement of Ti valence in meteoritic hibonite was done by electron spin resonance, on coarse crystals from a Murchison hibonite-perovskite-melilite inclusion. Spinel and most of the pyroxene in CM inclusions contain too little Ti for derivation of Ti{sup 3+}/Ti{sup 4+} ratios from electron probe analyses. X-ray absorption near edge spectroscopy (XANES), however, allows determination of Ti valence in relatively Ti-poor phases. In the present work, we apply synchrotron microXANES to a large hibonite grain from Murchison and to spinel-hibonite (sp-hib) and spinel-pyroxene (sp-pyx) inclusions from Murchison, refractory materials whose Ti{sup 3+}/Ti{sup 4+} ratios have not been previously measured. Analysis of

  13. Spin current transport in ceramic: TiN thin film

    NASA Astrophysics Data System (ADS)

    An, Hongyu; Kanno, Yusuke; Tashiro, Takaharu; Nakamura, Yoshio; Shi, Ji; Ando, Kazuya

    2016-03-01

    The spin current transport property in a ceramic material TiN has been investigated at room temperature. By attaching TiN thin films on Ni20Fe80 with different thicknesses of TiN, the spin pumping experiment has been conducted, and the spin diffusion length in TiN was measured to be around 43 nm. Spin-torque ferromagnetic resonance has also been taken to investigate the spin Hall angle of TiN, which was estimated to be around 0.0052. This study on ceramic material provides a potential selection in emerging materials for spintronics application.

  14. Superhydrophobic surface of TiO2 hierarchical nanostructures fabricated by Ti anodization.

    PubMed

    Dong, Junye; Ouyang, Xin; Han, Jie; Qiu, Wei; Gao, Wei

    2014-04-15

    A hierarchical structure of TiO2 with disordered nanowires on top of regular nanotubes was fabricated. With organic monolayers, it showed stronger superhydrophobic properties than regular nanotubes. The surface roughness was further enhanced by removing the dense nanowires layer, resulting in 172° water contact angle. The potential application for aquatic devices was explored by the treated Ti mesh which showed striking floating stability.

  15. High-Quality TiS2 For Li/TiS2 Cells

    NASA Technical Reports Server (NTRS)

    Huang, Chen-Kuo; Surampudi, Subbarao; Shen, David H.; Delgiannis, Fotios; Halpert, Gerald

    1992-01-01

    Modified process for synthesis of battery-grade titanium sulfide (TiS2) yields substantially improved material for Li/TiS2 electrochemical cells. Includes all-vapor-phase reaction between sulfur and titanium. Product less dense and more homogeneous, consists of smaller particles of higher crystalline quality, and purer. Cells have high cathode utilization and long cycle life performance. Expected to find applications in rechargeable lithium batteries for spacecraft, military equipment, telecommunication systems, automobiles, and consumer products.

  16. TiC growth in C fiber/Ti alloy composites during liquid infiltration

    NASA Technical Reports Server (NTRS)

    Warrier, S. G.; Lin, R. Y.

    1993-01-01

    A cylindrical model is developed for predicting the reaction zone thickness of carbon fiber-reinforced Ti-matrix composites, and good agreement is obtained between its predicted values and experimental results. The reaction-rate constant for TiC formation is estimated to be 1.5 x 10 exp -9 sq cm/sec. The model is extended to evaluate the relationship between C-coating thicknesses on SiC fibers and processing times.

  17. Reduction of hydrogen content in pure Ti

    NASA Astrophysics Data System (ADS)

    Ogiwara, N.; Suganuma, K.; Hikichi, Y.; Kamiya, J.; Kinsho, M.; Sukenobu, S.

    2008-03-01

    Pure Ti is adopted as a material for ducts and bellows at the proton accelerator 3 GeV-RCS in J-PARC project, because of its small residual radioactivity. In the particle accelerator, the H2 outgassing due to ion impact is often the dominant source of gas release. As the reduction of hydrogen content will probably suppress ion induced desorption, we attempted to reduce the hydrogen content in the Ti by in-situ vacuum baking. First, thermal desorption behavior and the change in hydrogen content after the heat treatment were investigated. Vacuum firing at temperatures higher than 550°C was effective in reducing the hydrogen content in the Ti. At the same time, the mechanical properties were monitored because grain growth leads to decrease in mechanical strength. Even after treatment at 750°C for 12 hr, the decreases in tensile and yield strength were so small (~10%) that we have no anxiety about the reduction of mechanical strength. Based upon the results of this study, vacuum firing has been applied to reduce the hydrogen content in the Ti bellows and ducts of the RCS machine.

  18. Photoreduction of CO2 on TiO2/SrTiO3 Heterojunction Network Film

    NASA Astrophysics Data System (ADS)

    Bi, Yongsheng; Zong, Lanlan; Li, Chen; Li, Qiuye; Yang, Jianjun

    2015-08-01

    Nanotube titanic acid (NTA) network film has a porous structure and large BET surface area, which lead them to possessing high utilization of the incident light and strong adsorption ability. We used NTA as the precursor to fabricate a TiO2/ SrTiO3 heterojunction film by the hydrothermal method. In the process of the reaction, part of NTA reacted with SrCl2 to form SrTiO3 nanocubes, and the remainder dehydrated to transform to the rutile TiO2. The ratio of TiO2 and SrTiO3 varied with the hydrothermal reaction time. SEM and TEM images indicated that SrTiO3 nanocubes dispersed uniformly on TiO2 film, and the particle size and crystallinity of SrTiO3 nanocubes increased with the reaction time prolonging. The TiO2/SrTiO3 heterojunction obtained by 1 h showed the best activity for CO2 photoreduction, where the mole ratio of TiO2 and SrTiO3 was 4:1. And the photo-conversion efficiency of CO2 to CH4 improved remarkably after the foreign electron traps of Pt and Pd nanoparticles were loaded. The highest photocatalytic production rate of CH4 reached 20.83 ppm/h cm2. In addition, the selectivity of photoreduction product of CO2 was also increased apparently when Pd acted as the cocatalyst on TiO2/SrTiO3 heterojunction film.

  19. Heteroepitaxial structures of SrTiO3/TiN on Si(100) by in situ pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Vispute, R. D.; Narayan, J.; Dovidenko, K.; Jagannadham, K.; Parikh, N.; Suvkhanov, A.; Budai, J. D.

    1996-12-01

    High-quality ceramics based heteroepitaxial structures of oxide-nitride-semiconductors, i.e., SrTiO3/TiN/Si(100) have been fabricated by in situ pulsed laser deposition. The dependence of substrate temperature and oxygen partial pressure on the crystalline quality of the SrTiO3 films on Si with epitaxial TiN template has been examined. We found that epitaxial growth occurs on TiN/Si(100) above 500 °C, initially at a reduced O2 pressure (10-6 Torr), and followed by a deposition in the range of 5-10×10-4 Torr. X-ray diffraction (Θ, ω, and Φ scans) and transmission electron microscope (TEM) results revealed an excellent alignment of SrTiO3 and TiN films on Si(100) with a cube-on-cube epitaxy. Rutherford backscattering and ion channeling results show a channeling minimum yield (χmin) of ˜13% for the SrTiO3 films. High-resolution TEM results on the SrTiO3/TiN interface show that the epitaxial SrTiO3 film is separated from the TiN by an uniform 80-90 Å crystalline interposing layer presumably of TiNxO1-x (oxy-nitride). The SrTiO3 film fabricated at 700 °C showed a high relative dielectric constant of 312 at the frequency of 1 MHz. The electrical resistivity and the breakdown field of the SrTiO3 films were more than 5×1012 Ω cm and 6×105 V cm-1, respectively. An estimated leakage current density measured at an electric field of 5×105 V/cm-1 was less than 10-7 A/cm2.

  20. Improvement of the Electrochemical Behavior of Steel Surfaces Using a [Ti-Al/Ti-Al-N] n Multilayer System

    NASA Astrophysics Data System (ADS)

    Ipaz, L.; Aperador, W.; Caicedo, J. C.; Esteve, J.; Zambrano, G.

    2013-05-01

    The aim of this work is to improve the corrosion resistance of AISI D3 steel surfaces using a [Ti-Al/Ti-Al-N] n multilayer system deposited with different periods (Λ) and bilayer numbers ( n), via magnetron co-sputtering pulsed d.c. procedure, from a metallic (Ti-Al) binary target. The multilayer coatings were characterized by cross-sectional scanning electron microscopy that showed the modulation and microstructure of the [Ti-Al/Ti-Al-N] n multilayer system. The composition of the single Ti-Al and Ti-Al-N layer films was studied via x-ray photoelectron spectroscopy, where typical signals for Ti2p1/2, Ti2p, N1s, and Al2p3/2 were detected. The electrochemical properties were evaluated by electrochemical impedance spectroscopy and Tafel polarization curves. The optimal electrochemical behavior was obtained for the [Ti-Al/Ti-Al-N] n multilayered period of Λ = 25 nm (100 bilayers). At these conditions, the maximum polarization resistance (1719.32 kΩ cm2) and corrosion rate (0.7 μmy) were 300 and 35 times higher than that of uncoated AISI D3 steel substrate (5.61 kΩ cm2 and 25 μmy, respectively). Finally, scanning electron microscopy was used to analyze the [Ti-Al/Ti-Al-N] n multilayered surface after the corrosive attack. The improvement effects in the electrochemical behavior of the AISI D3 coated with the [Ti-Al/Ti-Al-N] n multilayered coatings could be attributed to the number of interfaces that act as obstacles for the inward and outward diffusions of Cl- ions, generating an increment in the energy or potential required for translating the corrosive ions across the coating/substrate interface.

  1. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires

    PubMed Central

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-01-01

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19′ martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19′ martensitic transformation, and (V) plastic deformation of the specimen. PMID:27049025

  2. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires.

    PubMed

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-04-06

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19' martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19' martensitic transformation, and (V) plastic deformation of the specimen.

  3. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    NASA Astrophysics Data System (ADS)

    Ghalamboran, Milad; Saedi, Yasin

    2016-03-01

    The fabrication method and characterization results of a TiO2-TiO2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO2 crystallites embedded in a matrix of nanometric TiO2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant.

  4. Multilayer (TiN, TiAlN) ceramic coatings for nuclear fuel cladding

    NASA Astrophysics Data System (ADS)

    Alat, Ece; Motta, Arthur T.; Comstock, Robert J.; Partezana, Jonna M.; Wolfe, Douglas E.

    2016-09-01

    In an attempt to develop an accident-tolerant fuel (ATF) that can delay the deleterious consequences of loss-of-coolant-accidents (LOCA), multilayer coatings were deposited onto ZIRLO® coupon substrates by cathodic arc physical vapor deposition (CA-PVD). Coatings were composed of alternating TiN (top) and Ti1-xAlxN (2-layer, 4-layer, 8-layer and 16-layer) layers. The minimum TiN top coating thickness and coating architecture were optimized for good corrosion and oxidation resistance. Corrosion tests were performed in static pure water at 360 °C and 18.7 MPa for up to 90 days. The optimized coatings showed no spallation/delamination and had a maximum of 6 mg/dm2 weight gain, which is 6 times smaller than that of a control sample of uncoated ZIRLO® which showed a weight gain of 40.2 mg/dm2. The optimized architecture features a ∼1 μm TiN top layer to prevent boehmite phase formation during corrosion and a TiN/TiAlN 8-layer architecture which provides the best corrosion performance.

  5. Redistribution of Ti and Al in deuterium charged TiAl

    NASA Technical Reports Server (NTRS)

    Legzdina, D.; Robertson, I. M.; Birnbaum, H. K.

    1992-01-01

    The redistribution of titanium and aluminum in a single-phase TiAl alloy that has been exposed to a high pressure of deuterium gas at high temperature is studied. The microstructure in the as-received, uncharged condition consisted of single-phase gamma TiAl grains and a random distribution of precipitates. Precipitates were distributed throughout the matrix and along the grain boundaries. The chemistry of the precipitates varied considerably; some were rich in Al, while other were mostly Ti with some Si and Al. The dislocation density in most grains was low, although in a few grains a high dislocation density was observed. FCC deuterides with a lattice parameter of 0.45 nm form in a Ti-52.1Al-2.1Ta (at. pct) alloy after exposure to 1.38 MPa of deuterium gas at 650 C for 213 hr. The structure and lattice parameter are consistent with the formation of Ti(l)D2. The deuterides that form in this alloy are enriched in Ti and deficient in Al and Ta compared to the deuteride-free matrix. Regions of the matrix contiguous with the deuterides have a correspondingly enhanced aluminum and tantalum concentration.

  6. Effect of Ti concentration on the structure and texture of SiTiOC glasses

    SciTech Connect

    Tellez, L.; Rubio, J.; Valenzuela, M.A.; Rubio, F.; Oteo, J.L.

    2009-06-15

    Five different silicon-titanium organic-inorganic hybrid materials were prepared by the reaction of tetraethoxysilane, titanium tetrabutoxide and silanol-terminated polydimethylsiloxane. Si-Ti oxycarbide glasses were prepared by pyrolysis of the hybrid materials in nitrogen atmosphere in the range of 400 to 1500 deg. C. The obtained Si-Ti oxycarbide materials were characterized by Fourier Transform-Infra Red spectroscopy, X-ray-diffraction, mercury porosimetry and SEM. The study indicated that the reactivity towards water increases up to 1000 deg. C, at higher temperatures it decreases for all samples. During the pyrolysis, Ti atoms were incorporated into the silicate network leading to the formation of Si-Ti oxycarbide glasses, except with sample containing 7% of Ti which presented also the formation of {beta}-SiC and TiC crystalline phases. The porosity was increased up to 600 deg. C and then decreased tending to disappear at 1500 deg. C. When the titanium concentration increased from 1 to 3% in the oxycarbide glass, the porosity decreased; for higher concentration, an increase in the porosity was observed.

  7. Damping capacity of TiNi-based shape memory alloys

    NASA Astrophysics Data System (ADS)

    Rong, L. J.; Jiang, H. C.; Liu, S. W.; Zhao, X. Q.

    2007-07-01

    Damping capacity is another primary characteristic of shape memory alloys (SMA) besides shape memory effect and superelasticity. Damping behavior of Ti-riched TiNi SMA, porous TiNi SMA and a novel TiNi/AlSi composite have been investigated using dynamic mechanical analyzer (DMA) in this investigation. All these alloys are in martensitic state at room temperature and thus possess the high potential application value. Ti 50.2Ni 49.8 SMA has better damping capacity in pure martensitic state and phase transformation region due to the motion of martensite twin interface. As a kind of promising material for effective dampers and shock absorbing devices, porous TiNi SMA can exhibit higher damping capacity than the dense one due to the existence of the three-dimensioned connecting pore structure. It is found that the internal friction of porous TiNi SMA mainly originates from microplastic deformation and mobility of martensite interface and increases with the increase of the porosity. A novel TiNi/AlSi composite has been developed successfully by infiltrating AlSi alloy into the open pores of porous TiNi alloy with 60% porosity through compression casting. It shows the same phase transformation characteristics as the porous TiNi alloy. The damping capacity of the composite has been increased and the compressive strength has been also promoted remarkably. Suggestions for developing higher damping alloys based on TiNi shape memory alloy are proposed in this paper.

  8. Control of interface reactions in SIC/TI composites

    NASA Technical Reports Server (NTRS)

    Houska, C. R.; Rao, V.

    1982-01-01

    The reaction between a 0.5 to 1.0 Al film and a thick Ti substrate to form TiAl3 occurs very rapidly on heating to 635 C and causes the Al to be confined to the surface region. After heating to 900 C Ti3Al is formed with little release of Al into alpha Ti. Further annealing at 900 C eventually causes the Ti3Al phase to decompose and a substantial amount of Al is released into alpha Ti. The interdiffusion coefficient for Al in alpha Ti at 900 C increases by less than one order of magnitude as Al is varied from 0 to 20 at %. These data were obtained from the (101) X-ray diffraction intensity band using polycrystalline samples. Improvements in the analysis of X-ray diffraction data for the determination of composition profiles are discussed.

  9. Corrosion resistance tests on NiTi shape memory alloy.

    PubMed

    Rondelli, G

    1996-10-01

    The corrosion performances of NiTi shape memory alloys (SMA) in human body simulating fluids were evaluated in comparison with other implant materials. As for the passivity current in potentiostatic conditions, taken as an index of ion release, the values are about three times higher for NiTi than for Ti6Al4V and austenitic stainless steels. Regarding the localized corrosion, while plain potentiodynamic scans indicated for NiTi alloy good resistance to pitting attack similar to Ti6Al4V, tests in which the passive film is abruptly damaged (i.e. potentiostatic scratch test and modified ASTM F746) pointed out that the characteristics of the passive film formed on NiTi alloy (whose strength can be related to the alloy's biocompatibility) are not as good as those on Ti6Al4V but are comparable or inferior to those on austenitic stainless steels.

  10. The corrosivity and passivity of sputtered Mg-Ti alloys

    DOE PAGES

    Song, Guang -Ling; Unocic, Kinga A.; Meyer, III, Harry M.; ...

    2015-11-30

    Our study explored the possibility of forming a “stainless” Mg–Ti alloy. The electrochemical behavior of magnetron-sputtered Mg–Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg–Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. Moreover, the surface film that formed on sputtered Mg–Ti based alloys in NaCl solution was thick, discontinuous and non-protective, whereas a thin, continuous and protective Mg and Ti oxide filmmore » was formed on a sputtered Ti–Mg based alloy.« less

  11. The corrosivity and passivity of sputtered Mg-Ti alloys

    SciTech Connect

    Song, Guang -Ling; Unocic, Kinga A.; Meyer, III, Harry M.; Cakmak, Ercan; Brady, Michael P.; Gannon, Paul E.; Himmer, Phil; Andrews, Quinn

    2015-11-30

    Our study explored the possibility of forming a “stainless” Mg–Ti alloy. The electrochemical behavior of magnetron-sputtered Mg–Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg–Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. Moreover, the surface film that formed on sputtered Mg–Ti based alloys in NaCl solution was thick, discontinuous and non-protective, whereas a thin, continuous and protective Mg and Ti oxide film was formed on a sputtered Ti–Mg based alloy.

  12. 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.

  13. Procurement of V-Cr-Ti alloys to study minor variations on V-4Cr-4Ti

    SciTech Connect

    Grossbeck, M.L.

    1998-03-01

    The alloys V-6Cr-3Ti, V-4Cr-4Ti-Si, V-6Cr-6Ti, and V-3Cr-3Ti, were prepared by Teledyne Wah Chang Albany Corp. in 1994. Plate and sheet ranging from 0.76 mm to 6.25 mm with residual material being left in 12--20 mm thick bar were fabricated. Although the heats were prepared on a pilot plant scale using different equipment, an effort was made to keep the processing as close to Wah Chang Heat 832665, the reference fusion heat of V-4Cr-4Ti, as possible.

  14. TiCl4 as a source of TiO2 particles for laser anemometry measurements in hot gas

    NASA Technical Reports Server (NTRS)

    Weikle, Donald H.; Seasholtz, Richard G.; Oberle, Lawrence G.

    1990-01-01

    A method of reacting TiCl4 with water saturated gaseous nitrogen (GN2) at the entrance into a high temperature gas flow is described. The TiO2 particles formed are then entrained in the gas flow and used as seed particles for making laser anemometry (LA) measurements of the flow velocity distribution in the hot gas. Scanning electron microscope photographs of the TiO2 particles are shown. Data rate of the LA processor was measured to determine the amount of TiO2 formed. The TiCl4 and mixing gas flow diagram is shown. This work was performed in an open jet burner.

  15. The influence of Ti doping and annealing on Ce2Ti2O7 flash memory devices

    NASA Astrophysics Data System (ADS)

    Kao, Chyuan Haur; Chen, Su Zhien; Luo, Yang; Chiu, Wang Ting; Chiu, Shih Wei; Chen, I. Chien; Lin, Chan-Yu; Chen, Hsiang

    2017-02-01

    In this research, a CeO2 film with Ti doping was used as a trapping layer in metal oxide high-K-oxide-Si (MOHOS)-type memory devices. Since incorporation of Ti atoms into the film could fix dangling bonds and defects, the Ce2Ti2O7 trapping layer with annealing treatment could have a larger memory window and a faster programming/erasing speed. To confirm the origin, multiple material analyses indicate that annealing at an appropriate temperature and Ti doping could enhance crystallization. The Ce2Ti2O7-based memory device is promising for future industrial flash memory applications.

  16. 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.

  17. Charge Transport at Ti-Doped Hematite (001)/Aqueous Interfaces

    SciTech Connect

    Chatman, Shawn ME; Pearce, Carolyn I.; Rosso, Kevin M.

    2015-03-10

    Solid-state transport and electrochemical properties of Ti-doped hematite (001) epitaxial thin films (6.0, 8.3, and 16.6 at% Ti) were probed to achieve a better understanding of doped hematite for photoelectrochemical (PEC) applications. Room temperature resistivity measurements predict a resistivity minimum near 10 at% Ti doping, which can be rationalized as maximizing charge compensating Fe2+ concentration and Fe3+ electron accepting percolation pathways simultaneously. Temperature dependent resistivity data are consistent with small polaron hopping, revealing an activation energy that is Ti concentration dependent and commensurate with previously reported values (≈ 0.11 eV). In contact with inert electrolyte, linear Mott-Schottky data at various pH values indicate that there is predominantly a single donor for Ti-doped hematite at 6.0 at% Ti and 16.6 at% Ti concentrations. Two slope Mott-Schottky data at pH extremes indicate the presence of a second donor or surface state in the 8.3 at% Ti-doped film, with an energy level ≈ 0.7 eV below the Fermi level. Mott-Schottky plots indicate pH and Ti concentration dependent flatband potentials of -0.4 to -1.1 V vs. Ag/AgCl, commensurate with previously reported data. Flatband potentials exhibited super-Nernstian pH dependence ranging from -69.1 to -101.0 mV/pH. Carrier concentration data indicate that the Fermi energy of the Ti-doped system is Ti concentration dependent, with a minimum of 0.15 eV near 10 at% Ti. These energy level data allow us to construct an energy band diagram for Ti-doped hematite electrode/electrolyte interfaces, and to determine a Ti-doping concentration t

  18. SiH/TiO2 and GeH/TiO2 heterojunctions: promising TiO2-based photocatalysts under visible light.

    PubMed

    Niu, Mang; Cheng, Daojian; Cao, Dapeng

    2014-05-02

    We use hybrid density functional calculations to find that the monolayer silicane (SiH) and the anatase TiO2(101) composite (i.e. the SiH/TiO2 heterojunction) is a promising TiO2-based photocatalyst under visible light. The band gap of the SiH/TiO2(101) heterojunction is 2.082 eV, which is an ideal material for the visible-light photoexcitation of electron-hole pairs. Furthermore, the SiH/TiO2(101) heterojunction has a favorable type-II band alignment and thus the photoexcited electron can be injected to the conduction band of anatase TiO2 from that of silicane. Finally, the proper interface charge distribution facilitates the carrier separation in the SiH/TiO2(101) interface region. The electron injection and carrier separation can prevent the recombination of electron-hole pairs. Our calculation results suggest that such electronic structure of SiH/TiO2(101) heterojunction has significant advantages over these of doped TiO2 systems for visible-light photocatalysis.

  19. Au-free ohmic Ti/Al/TiN contacts to UID n-GaN fabricated by sputter deposition

    NASA Astrophysics Data System (ADS)

    Garbe, V.; Weise, J.; Motylenko, M.; Münchgesang, W.; Schmid, A.; Rafaja, D.; Abendroth, B.; Meyer, D. C.

    2017-02-01

    The fabrication and characterization of an Au-free Ti/Al/TiN (20/100/100 nm) contact stack to unintentionally doped n-GaN with TiN serving as the diffusion barrier is presented. Sputter deposition and lift-off in combination with post deposition annealing at 850 °C are used for contact formation. After annealing, contact shows ohmic behavior to n-GaN and a specific contact resistivity of 1.60 × 10-3 Ω cm2. To understand the contact formation on the microscopic scale, the contact was characterized by current-voltage measurements, linear transmission line method, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results show the formation of Ti-N bonds at the GaN/Ti interface in the as-deposited stack. Annealing leads to diffusion of Ti, Al, Ga, and N, and the remaining metallic Ti is fully consumed by the formation of the intermetallic tetragonal Al3Ti phase. Native oxide from the GaN surface is trapped during annealing and accumulated in the Al interlayer. The TiN capping layer, however, was chemically stable during annealing. It prevented oxidation of the Ti/Al contact bilayer successfully and thus proved to be a well suitable diffusion barrier with ideal compatibility to the Ti/Al contact metallization.

  20. Microstructure and properties of TiB2-TiB reinforced titanium matrix composite coating by laser cladding

    NASA Astrophysics Data System (ADS)

    Lin, Yinghua; Yao, Jianhua; Lei, Yongping; Fu, Hanguang; Wang, Liang

    2016-11-01

    TiB2 particle and TiB short fiber reinforced titanium matrix composite coatings were prepared utilizing in situ synthesized technique by laser cladding on the surface of Ti6Al4V alloy. Through the experiment, it was found that the surface of the single-track coatings appeared in the depression, but it can be improved by laser track overlapping. With the increase of laser power density, the amount of TiB short fiber was increased, and the distribution of TiB2 and TiB became more uniform from the top to bottom. The micro-hardness of TiB2/TiB coating showed a gradient decreasing trend, and the average micro-hardness of the coatings was two-fold higher than that of the substrate. Due to the strengthening effect of TiB2 particle and TiB short fiber, the wear volume loss of the center of the coating was approximately 30% less than that of the Ti-6Al-4V substrate, and the wear mechanism of the coating was mild fatigue particle detachment.

  1. Fabrication of the Ti5Si3/Ti composite inoculants and its refining mechanism on pure titanium

    NASA Astrophysics Data System (ADS)

    Li, Nuo; Cui, Chunxiang; Liu, Shaungjin; Zhao, Long; Liu, Shuiqing

    2017-03-01

    The in situ Ti5Si3/Ti inoculants were successfully prepared by vacuum arc-melting and melt-spinning method. An efficient route by adding a small quantity of Ti5Si3/Ti inoculants to Ti melt has been first proposed to modify the coarse grains of as cast microstructure of pure titanium in this paper. It was found that the microstructure of ribbon inoculants was cellular structure that composed of Ti5Si3 and α-Ti phases. The grain refining effect of the inoculants was significantly improved with the adding ratio range from 0.2% to 0.5% in weight. With the increase of addition amount of inoculants on Ti melt, the tensile strength, yield strength and microhardness of pure titanium are significantly improved except elongation. The excellent grain refining effect can be attributed to the heterogeneous nucleation of the titanium grain on the precipitated Ti5Si3 phases in the Si-rich regions and the constitutional supercooling of Si in the Si-poverty regions. It is suggested that the in situ Ti5Si3/Ti inoculants is a promising inoculants for titanium alloys.

  2. Efficient photodegradation of methyl violet dye using TiO2/Pt and TiO2/Pd photocatalysts

    NASA Astrophysics Data System (ADS)

    Saeed, Khalid; Khan, Idrees; Gul, Tamanna; Sadiq, Mohammad

    2017-02-01

    Titanium oxide supported palladium (TiO2/Pd) and titanium oxide supported platinum (TiO2/Pt) nanoparticles were prepared from their precursors through the incipient wetness method. The TiO2/Pd and TiO2/Pt nanoparticles were characterized by scanning electron microscopy (SEM), and energy dispersive X-rays (EDX), while the photodegradation study of methyl violet was performed by UV/VIS spectrophotometry. The morphological study shows that the Pd and Pt were well deposited on the surface of TiO2, which was confirmed by EDX. Both TiO2/Pd and TiO2/Pt nanoparticles were used as photocatalysts for the photodegradation of methyl violet in aqueous media under UV-light irradiation. The photodegradation study revealed that the TiO2/Pd and TiO2/Pt nanoparticles degraded about 95 and 78% of dye within 20 min, respectively. The effect of various parameters such as catalyst dosage, concentration of dye, and medium on the photocatalytic degradation was examined. The activity of recovered TiO2/Pd and TiO2/Pt nanoparticles was studied.

  3. Effect of Al on the Wetting Behavior Between TiC x and Molten Ti-Al Alloys

    NASA Astrophysics Data System (ADS)

    Liu, Xuyang; Lv, Xuewei; Dong, Hongbiao; Li, Chunxin; Bai, Chenguang

    2015-10-01

    The wetting behavior and the interfacial reactions between TiC x substrate and molten Ti-Al alloys with different Al contents were studied using the Sessile Drop method at 1758 K (1485 °C) in argon atmosphere. It is found that the wettability and interface reaction products depend on Al content in the molten alloy. The initial contact angles between the molten Ti-Al alloy and TiC0.78 surface reduces from 110 to 80 deg when Al content in the alloy changes from 40 to 80 wt pct. The reduction in the initial contact angle is due to the decrease of surface tension of the molten Ti-Al alloys with increasing Al contents. The segregation of Al atoms to the surface occurred at all bulk concentrations of Ti-Al alloys. Al with lower surface tension tends to segregate on the surface of liquid Ti-Al alloy. In the spreading stage, the interfacial reaction led to the decrease in the contact angle. The adhesion in Ti-Al/TiC x system can be interpreted in terms of strong chemical interactions, which is greatly affected by the diffusion of C. The equilibrium contact angle was measured less than 10 deg. Finally, the reaction sequence at the Ti-Al melt and TiC x substrate interface is proposed.

  4. Osteoconductivity and Hydrophilicity of TiO(2) Coatings on Ti Substrates Prepared by Different Oxidizing Processes.

    PubMed

    Yamamoto, Dai; Kawai, Ikki; Kuroda, Kensuke; Ichino, Ryoichi; Okido, Masazumi; Seki, Azusa

    2012-01-01

    Various techniques for forming TiO(2) coatings on Ti have been investigated for the improvement of the osteoconductivity of Ti implants. However, it is not clear how the oxidizing process affects this osteoconductivity. In this study, TiO(2) coatings were prepared using the following three processes: anodizing in 0.1 M H(3)PO(4) or 0.1 M NaOH aqueous solution; thermal oxidation at 673 K for 2 h in air; and a two-step process of anodizing followed by thermal oxidation. The oxide coatings were evaluated using SEM, XRD, and XPS. The water contact angle on the TiO(2) coatings was measured as a surface property. The osteoconductivity of these samples was evaluated by measuring the contact ratio of formed hard tissue on the implanted samples (defined as the R(B-I) value) after 14 d implantation in rats' tibias. Anatase was formed by anodizing and rutile by thermal oxidation, but the difference in the TiO(2) crystal structure did not influence the osteoconductivity. Anodized TiO(2) coatings were hydrophilic, but thermally oxidized TiO(2) coatings were less hydrophilic than anodized TiO(2) coatings because they lacked in surface OH groups. The TiO(2) coating process using anodizing without thermal oxidation gave effective improvement of the osteoconductivity of Ti samples.

  5. Osteoconductivity and Hydrophilicity of TiO2 Coatings on Ti Substrates Prepared by Different Oxidizing Processes

    PubMed Central

    Yamamoto, Dai; Kawai, Ikki; Kuroda, Kensuke; Ichino, Ryoichi; Okido, Masazumi; Seki, Azusa

    2012-01-01

    Various techniques for forming TiO2 coatings on Ti have been investigated for the improvement of the osteoconductivity of Ti implants. However, it is not clear how the oxidizing process affects this osteoconductivity. In this study, TiO2 coatings were prepared using the following three processes: anodizing in 0.1 M H3PO4 or 0.1 M NaOH aqueous solution; thermal oxidation at 673 K for 2 h in air; and a two-step process of anodizing followed by thermal oxidation. The oxide coatings were evaluated using SEM, XRD, and XPS. The water contact angle on the TiO2 coatings was measured as a surface property. The osteoconductivity of these samples was evaluated by measuring the contact ratio of formed hard tissue on the implanted samples (defined as the RB-I value) after 14 d implantation in rats' tibias. Anatase was formed by anodizing and rutile by thermal oxidation, but the difference in the TiO2 crystal structure did not influence the osteoconductivity. Anodized TiO2 coatings were hydrophilic, but thermally oxidized TiO2 coatings were less hydrophilic than anodized TiO2 coatings because they lacked in surface OH groups. The TiO2 coating process using anodizing without thermal oxidation gave effective improvement of the osteoconductivity of Ti samples. PMID:23316128

  6. [Study of blood compatibility on TiO2 coated biomedical Ni-Ti shape memory alloy].

    PubMed

    Gao, Shuchun; Zhai, Yuchun; Hu, Jinling

    2011-10-01

    We coated a thin TiO2 film on the surface of Ni-Ti shape memory alloy by activated sputter method in the present work. The blood platelet adherence and antithrombogenicity of the TiO2-coated Ni-Ti alloy were evaluated. The results showed that the platelets on the TiO2-coated Ni-Ti alloy were fewer than those on 316L stainless steel, and no agglomeration or distortion for the platelets on the coated alloy was found, which means less probability of blood coagulation for the alloy. The coagulation time on the coated Ni-Ti shape memory alloy was longer than that on the 316L. Compared with that on the 316L stainless steel, the TiO2 coated Ni-Ti shape memory alloy showed better blood compatibility, indicating that the Ni-Ti alloy with TiO2 coating is a kind of ideal biomedical materials with high clinical value.

  7. In situ synthesis of Fe-based alloy clad coatings containing TiB2-TiN-(h-BN)

    NASA Astrophysics Data System (ADS)

    Jiang, Shao-qun; Wang, Gang; Ren, Qing-wen; Yang, Chuan-duo; Wang, Ze-hua; Zhou, Ze-hua

    2015-06-01

    Fe-based alloy coatings containing TiB2-TiN-(h-BN) were synthesized in situ on Q235 steel substrates by a plasma cladding process using the powders of Fe901 alloy, Ti, and h-BN as raw materials. The effects of Ti/h-BN mass ratio on interfacial bonds between the coating and substrate along with the microstructures and microhardnesses of the coatings were investigated. The results show that the Ti/h-BN mass ratio is a vital factor in the formation of the coatings. Free h-BN can be introduced into the coatings by adding an excess amount of h-BN into the precursor. Decreases in the Ti/h-BN mass ratio improve the microstructural uniformity and compactness and enhance the interfacial bonds of the coatings. At a Ti/h-BN mass ratio of 10/20, the coating is free of cracks and micropores, and mainly consists of Fe-Cr, Fe3B, TiB2, TiN, Ti2N, TiB, FeN, FeB, Fe2B, and h-BN phases. Its average microhardness in the zone between 0.1-2.8 mm from the coating surface is about Hv0.2 551.5.

  8. Thermal stability study of TiN/TiSi2 diffusion barrier between Cu and n + Si

    NASA Astrophysics Data System (ADS)

    Chang, Tzong-Sheng; Wang, Wen-Chun; Wang, Lih-Ping; Hwang, Jenn-Chang; Huang, Fon-Shan

    1994-06-01

    The failure mechanism of the TiN/TiSi2 bilayers as diffusion barriers between Cu and n+Si was investigated. The TiN/TiSi2 bilayers were formed by either annealing Ti (50 nm)/n+Si via various rapid thermal processes or reactively sputtering TiN (50 nm) on TiSi2. The degradation study of the Cu/TiN/TiSi2/n+Si contact system was undertaken by scanning electron microscopy, cross-section transmission electron microscopy (XTEM), secondary-ion-mass spectrometry (SIMS), and diode leakage current and contact resistance measurements. Leakage current measurements indicated no deterioration of n+-p diode junctions up to 475 °C for 30 min in a N2 ambient. For the sintering temperature at 500 °C, the leakage current increased abruptly and SIMS profiles revealed a large amount of Cu atoms diffusing into the junctions of n+-p diodes. XTEM showed that the small pyramidal-shaped Cu3Si crystallite (with a size 0.25 μm) precipitated in the n+Si substrate. The formation of Cu3Si increased the occupied volume, then generated the gap between TiSi2 and n+Si, and gradually increased the specific contact resistance. The diffusion resistance, depending on the thickness of TiN film, was also observed.

  9. Fabrication of High Efficiency Dye-Sensitized Solar Cells Based on TiO2 Nanoparticles Embedded in Ti Substrate.

    PubMed

    Kim, Kang-Pil; Lee, Sang-Ju; Hwang, Dae-Kue; Kim, Dae-Hwan; Heo, Young-Woo

    2015-01-01

    We have embedded a TiO2 nanoparticle (NP) photoelectrode in a Ti substrate to improve the cell efficiency of conventional TiO2 NP based dye-sensitized solar cells (DSSCs) using Ti substrate. Compared to the conventional standing-type (TiO2 NPs on Ti substrate) DSSCs, the embedded-type (TiO2 NPs embedded in Ti substrate) DSSCs have shown an approximately 35% improvement in power conversion efficiency due to the improvement of J(sc). The embedded-type DSSCs have more charge transport paths than do standing-type DSSCs due to the increase of contact area between the TiO2 NP sidewall and the Ti substrate. This increased contact area decreases the electrical resistance and increases the charge collection efficiency, which leads to the improvement of J(sc). The embedded-type NP-DSSCs are very effective DSSC structures for enhancing the power conversion efficiency of Ti substrate based DSSCs.

  10. Effect of TiO2 nano fillers on the electrical conductivity of PSAN/TiO2 polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Ningaraju, S.; Munirathnamma, L. M.; Kumar, K. V. Aneesh; Ravikumar, H. B.

    2016-05-01

    The microstructural characterization of Polystyrene co-acrylonitrile and Titanium dioxide (PSAN/TiO2) nanocomposites has been performed by Positron Annihilation Lifetime Spectroscopy. The decrease of positron lifetime parameters viz. o-Ps lifetime (τ3) and free volume size (Vf) up to 0.6 wt% of TiO2 is attributed to the filling of free volume holes by TiO2 nanoparticles. The increased free volume size (Vf) after 0.6 wt% of TiO2 indicates the formation of interface due to TiO2 nanoclusters. The variation of electrical conductivity at the lower and higher concentration of TiO2 in (PSAN/TiO2) nanocomposites is attributed to the blocking effect and space charge effect respectively.

  11. Selective conditions for the fabrication of a flexible dye-sensitized solar cell with Ti/TiO 2 photoanode

    NASA Astrophysics Data System (ADS)

    Lin, Lu-Yin; Lee, Chuan-Pei; Vittal, R.; Ho, Kuo-Chuan

    The effects of four factors, i.e., (i) sputter-deposition time of platinum (Pt) film, (ii) sintering temperature of TiO 2-coated Ti foil (Ti/TiO 2), (iii) thickness of Ti foil, and (iv) concentration of iodine are reported for the photovoltaic performance of a back-illuminated flexible dye-sensitized solar cell (DSSC) with Ti foil substrate for the TiO 2 layer. Optimization of these four factors yields a solar-to-electricity conversion efficiency (η) of 5.95%. Transmittance spectra, cyclic voltammetry (CV), electrochemical impedance spectra (EIS), X-ray diffraction (XRD), scanning electron micrographs (SEM), and laser-induced photovoltage transient technique are used to substantiate the explanations.

  12. EFFECTS OF TiOx INTERLAYER ON RESISTANCE SWITCHING OF Pt/TiOx/ZnO/n+-Si STRUCTURES

    NASA Astrophysics Data System (ADS)

    Li, Hongxia; Lv, Xiaojun; Xi, Junhua; Wu, Xin; Mao, Qinan; Liu, Qingmin; Ji, Zhenguo

    2014-08-01

    In this paper, we fabricated Pt/TiOx/ZnO/n+-Si structures by inserting TiOx interlayer between Pt top electrode (TE) and ZnO thin film for non-volatile resistive random access memory (ReRAM) applications. Effects of TiOx interlayer with different thickness on the resistance switching of Pt/TiOx/ZnO/n+-Si structures were investigated. Conduction behaviors in high and low resistance state (HRS and LRS) fit well with the trap-controlled space-charge-limited conduction (SCLC) and Ohmic behavior, respectively. Variations of set and reset voltages and HRS and LRS resistances of Pt/TiOx/ZnO/n+-Si structures were investigated as a function of TiOx thickness. Switching cycling tests were attempted to evaluate the endurance reliability of Pt/TiOx/ZnO/n+-Si structures. Additionally, the switching mechanism was analyzed by the filament model.

  13. Formation of Equiaxed Alpha and Titanium Nitride Precipitates in Spark Plasma Sintered TiB/Ti-6Al-4V Composites (Preprint)

    DTIC Science & Technology

    2012-08-01

    AFRL-RX-WP-TP-2012-0372 FORMATION OF EQUIAXED ALPHA AND TITANIUM NITRIDE PRECIPITATES IN SPARK PLASMA SINTERED TiB/Ti-6Al-4V COMPOSITES...ALPHA AND TITANIUM NITRIDE PRECIPITATES IN SPARK PLASMA SINTERED TiB/Ti-6Al-4V COMPOSITES (PREPRINT) 5a. CONTRACT NUMBER FA8650-08-C-5226 5b...distribution of TiN precipitates, as revealed by TEM studies. 15. SUBJECT TERMS Ti-6Al-4V; TiB; TiN; Spark Plasma Sintering ; Composite; α/β phase

  14. The underlying biological mechanisms of biocompatibility differences between bare and TiN-coated NiTi alloys.

    PubMed

    Lifeng, Zhao; Yan, Hong; Dayun, Yang; Xiaoying, Lü; Tingfei, Xi; Deyuan, Zhang; Ying, Hong; Jinfeng, Yuan

    2011-04-01

    TiN coating has been demonstrated to improve the biocompatibility of bare NiTi alloys; however, essential biocompatibility differences between NiTi alloys before and after TiN coating are not known so far. In this study, to explore the underlying biological mechanisms of biocompatibility differences between them, the changes of bare and TiN-coated NiTi alloys in surface chemical composition, morphology, hydrophilicity, Ni ions release, cytotoxicity, apoptosis, and gene expression profiles were compared using energy-dispersive spectroscopy, scanning electron microscopy, contact angle, surface energy, Ni ions release analysis, the methylthiazoltetrazolium (MTT) method, flow cytometry and microarray methods, respectively. Pathways binding to networks and real-time polymerase chain reaction (PCR) were employed to analyze and validate the microarray data, respectively. It was found that, compared with the bare NiTi alloys, TiN coating significantly decreased Ni ions content on the surfaces of the NiTi alloys and reduced the release of Ni ions from the alloys, attenuated the inhibition of Ni ions to the expression of genes associated with anti-inflammatory, and also suppressed the promotion of Ni ions to the expression of apoptosis-related genes. Moreover, TiN coating distinctly improved the hydrophilicity and uniformity of the surfaces of the NiTi alloys, and contributed to the expression of genes participating in cell adhesion and other physiological activities. These results indicate that the TiN-coated NiTi alloys will help overcome the shortcomings of NiTi alloys used in clinical application currently, and can be expected to be a replacement of biomaterials for a medical device field.

  15. Effect of neutron irradiation on defect evolution in Ti3SiC2 and Ti2AlC

    DOE PAGES

    Tallman, Darin J.; He, Lingfeng; Garcia-Diaz, Brenda L.; ...

    2015-10-23

    Here, we report on the characterization of defects formed in polycrystalline Ti3SiC2 and Ti2AlC samples exposed to neutron irradiation – up to 0.1 displacements per atom (dpa) at 350 ± 40 °C or 695 ± 25 °C, and up to 0.4 dpa at 350 ± 40 °C. Black spots are observed in both Ti3SiC2 and Ti2AlC after irradiation to both 0.1 and 0.4 dpa at 350 °C. After irradiation to 0.1 dpa at 695 °C, small basal dislocation loops, with a Burgers vector of b = 1/2 [0001] are observed in both materials. At 9 ± 3 and 10 ±more » 5 nm, the loop diameters in the Ti3SiC2 and Ti2AlC samples, respectively, were comparable. At 1 × 1023 loops/m3, the dislocation loop density in Ti2AlC was ≈1.5 orders of magnitude greater than in Ti3SiC2, at 3 x 1021 loops/m3. After irradiation at 350 °C, extensive microcracking was observed in Ti2AlC, but not in Ti3SiC2. The room temperature electrical resistivities increased as a function of neutron dose for all samples tested, and appear to saturate in the case of Ti3SiC2. The MAX phases are unequivocally more neutron radiation tolerant than the impurity phases TiC and Al2O3. Based on these results, Ti3SiC2 appears to be a more promising MAX phase candidate for high temperature nuclear applications than Ti2AlC.« less

  16. The Ti environment in natural hibonite: XANES spectroscopy and computer modelling

    NASA Astrophysics Data System (ADS)

    Kravtsova, Antonina N.; Soldatov, Alexander V.; Walker, Andrew M.; Berry, Andrew J.

    2016-05-01

    The local atomic structure around Ti in Ti-bearing hibonite (CaAl12O19) was studied using X-ray absorption near-edge structure (XANES) spectroscopy and computer modelling. Structural models of the direct substitution of Al by Ti3+, Al by Ti4+ charge balanced by the coupled substitution of Mg2+ for Al, and small Ti clusters were considered. The Ti K-XANES spectra of natural hibonite with different Ti concentration were recorded. Theoretical Ti K- XANES spectra for structural models of hibonite were calculated. It was shown that the theoretical Ti K-XANES spectra for a model with Ti at the five-coordinated M2 site are in agreement with the experimental XANES spectra of hibonite with low concentrations of Ti, while the theoretical spectra for a structural model of clustered Ti are in agreement with the experimental spectra of hibonite with higher Ti contents.

  17. Gas nitriding and subsequent oxidation of Ti-6Al-4V alloys

    PubMed Central

    2012-01-01

    Ti-6Al-4V alloys consisting of α-Ti grains and intergranular β-Ti islands were nitrided at 850°C for 1 to 12 h under a nitrogen pressure of 1 Pa. With increasing nitriding time, the Ti-N compound layer became thicker, and the α-Ti diffusion zone containing dissolved nitrogen became wider. In the Ti-N compound layer, the initially formed Ti2N became TiN as the nitriding progressed. The nitride layers were oxidized to rutile-TiO2 after oxidation at 700°C for 10 h in air. PMID:22221679

  18. Mechanical properties and biocompatibility of the sputtered Ti doped hydroxyapatite.

    PubMed

    Vladescu, A; Padmanabhan, S C; Ak Azem, F; Braic, M; Titorencu, I; Birlik, I; Morris, M A; Braic, V

    2016-10-01

    The hydroxyapatite enriched with Ti were prepared as possible candidates for biomedical applications especially for implantable devices that are in direct contact to the bone. The hydroxyapatites with different Ti content were prepared by RF magnetron sputtering on Ti-6Al-4V alloy using pure hydroxyapatite and TiO2 targets. The content of Ti was modified by changing the RF power fed on TiO2 target. The XPS and FTIR analyses revealed the presence of hydroxyapatite structure. The hardness and elastic modulus of the hydroxyapatite were increased by Ti addition. After 5 days of culture, the cell viability of the Ti-6Al-4V was enhanced by depositing with undoped or doped hydroxyapatite. The Ti additions led to an increase in cell viability of hydroxyapatite, after 5 days of culture. The electron microscopy showed the presence of more cells on the surface of Ti-enriched hydroxyapatite than those observed on the surface of the uncoated alloys or undoped hydroxyapatite.

  19. Preparation of directionally solidified BaTi2O5-Ba6Ti17O40 eutectic by the floating zone method

    NASA Astrophysics Data System (ADS)

    Shiga, K.; Katsui, H.; Goto, T.

    2017-02-01

    The BaTi2O5-Ba6Ti17O40 eutectic (BaO-68.7 mol% TiO2) was directionally solidified by the floating zone (FZ) method and crystalline phases, microstructures and orientation were investigated. Ba6Ti17O40 with faceted rod-like shape was dispersed in the BaTi2O5 matrix. The growth directions of BaTi2O5 and Ba6Ti17O40 were parallel to the b and a axis, respectively, and the orientation relations were BaTi2O5 (010)//Ba6Ti17O40(60 2 ̅) and BaTi2O5 (001)//Ba6Ti17O40 (001).

  20. Direct Extraction of Ti and Ti Alloy from Ti-Bearing Dust Slag in Molten CaCl2

    NASA Astrophysics Data System (ADS)

    Chen, Chaoyi; Zhao, Chong; Li, Junqi; Yang, Shufeng

    2016-06-01

    Using process of solid oxygen-ion conducting membrane (SOM), titanium metal and its alloy can be prepared directly from Ti-bearing dust slag by immersing it in the molten CaCl2 at 1,100℃, which has been proposed by constant voltage of 3.5 V for 2-6 h. The dust slag was ball-milled and pressed into pellets, then employed as the cathode, while the liquid copper, which was saturated with graphite powder and encased in yttria-stabilized zirconia (YSZ) tube, acted as the anode. The effect of forming pressure and electrolytic time on products was analyzed. The results show that the content of titanium increased with electrolytic time and the characteristic morphology presents as granule. Ti-Fe alloy can be obtained from Ti-Fe residue by 6 h electrolysis. For titanium-rich residue, when the forming pressure of pellets decreased from 6 to 3 MPa, only electrolysis for more than 4 h can completely remove the oxygen, and pure titanium is obtained by 6 h electrolysis. Besides, there is an unprecedented finding that the porous cathode is conducive to the removal of impurity elements.

  1. Wear Behavior of Low-Cost, Lightweight TiC/Ti-6Al-4V Composite Under Fretting: Effectiveness of Solid-Film Lubricant Counterparts

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Street, Kenneth W., Jr.; Sanders, Jeffrey H.; Hager, Carl H., Jr.; Zabinski, Jeffrey S.; VanderWal, Randall L.; Andrews, Rodney; Lerch, Bradley A.

    2007-01-01

    The wear behavior of low-cost, lightweight 10-wt% TiC-particulate-reinforced Ti-6Al-4V matrix composite (TiC/Ti- 6Al-4V) was examined under fretting at 296, 423, and 523 K in air. Bare 10-wt% TiC/Ti-6Al-4V hemispherical pins were used in contact with dispersed multiwalled carbon nanotubes (MWNTs), magnetron-sputtered diamondlike carbon/chromium (DLC/Cr), magnetron-sputtered graphite-like carbon/chromium (GLC/Cr), and magnetron-sputtered molybdenum disulphide/titanium (MoS2/Ti) deposited on Ti-6Al-4V, Ti-48Al-2Cr-2Nb, and nickel-based superalloy 718. When TiC/Ti-6Al-4V was brought into contact with bare Ti-6Al-4V, bare Ti-48Al-2Cr-2Nb, and bare nickel-based superalloy 718, strong adhesion, severe galling, and severe wear occurred. However, when TiC/Ti-6Al-4V was brought into contact with MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings, no galling occurred in the contact, and relatively minor wear was observed regardless of the coating. All the solid-film lubricants were effective from 296 to 523 K, but the effectiveness of the MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings decreased as temperature increased.

  2. 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.

  3. Fracture analysis of cast pure Ti and Ti-6Al-4V alloy for dental use.

    PubMed

    Kim, K H; Choi, M Y; Kishi, T

    1997-01-01

    The fracture behavior of cast two types of pure Ti and Ti-6Al-4V alloy was understood by acoustic emission (AE) analysis during a fracture toughness test. Specimens for test were cast by the lost wax method using a specially designed Ti casting machine of pressure-different method for dental use. A fatigue crack was inserted from the machined notch tip into the body of a specimen in the range of 0.45-0.55 a/W. Acoustic emission signals released during the fracture toughness test were detected by two sensors attached to both ends of the specimen. Then the signals were recorded and analysed by the PAC 3000/3104 system. From the early stage of the fracture toughness test, AE signals started to be released in all types of specimens tested. A reaction layer with the investment materials of about 50-100 microns was thought to be the result of the AE release from an early stage of the fracture toughness test. A microfracture behavior of the cast pure Ti and Ti alloys was proposed based on the results obtained from the AE releasing pattern and fracture surface findings.

  4. TiSi2/TiN-A Stable Multilayered Contact Structure for Shallow Implanted Junctions in VLSI Technology

    NASA Astrophysics Data System (ADS)

    Norström, H.; Donchev, T.; Östling, M.; Petersson, C. S.

    1983-12-01

    A low resistive, electrically and mechanically stable three level metallization scheme has been developed TiSi2 was adopted as a low contact resistance material to silicon, and TiN was selected as a diffusion barrier between the silicide and the A1 interconnect layer. The Ti/TiN bilayer was deposited by magnetron sputtering. It is shown, using RBS and X-ray diffraction that the deposited Ti reacts to form TiSi2, and the upper titanium nitride layer transforms to a stoichiometric compound TiN. Furthermore, it is demonstrated that TiN acts as a diffusion barrier between TiSi2 and aluminium up to 550°C and that the onset for interdiffusion occurs at 600°C. Finally, the interposition of a third sacrificial Ti layer between the nitride film and the aluminium top layer is shown to prevent intermixing between the A1 layer and Si even after a prolonged heat treatment at 600°C.

  5. Minimum ignition energy of nano and micro Ti powder in the presence of inert nano TiO₂ powder.

    PubMed

    Chunmiao, Yuan; Amyotte, Paul R; Hossain, Md Nur; Li, Chang

    2014-06-15

    The inerting effect of nano-sized TiO2 powder on ignition sensitivity of nano and micro Ti powders was investigated with a Mike 3 apparatus. "A little is not good enough" is also suitable for micro Ti powders mixed with nano-sized solid inertants. MIE of the mixtures did not significantly increase until the TiO2 percentage exceeded 50%. Nano-sized TiO2 powders were ineffective as an inertant when mixed with nano Ti powders, especially at higher dust loadings. Even with 90% nano TiO2 powder, mixtures still showed high ignition sensitivity because the statistic energy was as low as 2.1 mJ. Layer fires induced by ignited but unburned metal particles may occur for micro Ti powders mixed with nano TiO2 powders following a low level dust explosion. Such layer fires could lead to a violent dust explosion after a second dispersion. Thus, additional attention is needed to prevent metallic layer fires even where electric spark potential is low. In the case of nano Ti powder, no layer fires were observed because of less flammable material involved in the mixtures investigated, and faster flame propagation in nanoparticle clouds.

  6. Adhesion and Corrosion Behavior of Al-Zn and TiN/Ti/TiN Coatings on a DU-0.75 WT% Ti Alloy,

    DTIC Science & Technology

    1992-08-01

    LAViLAJTINIOU X z JAM ILC IN LAI a LAS LAS F,, NOWL LORA0 F, , Norma Lo#AN (a) (hI Fig 2. AE signal inensit%. frictional ICorcc /-, and friction coeflicient I...reported that the DU-0.75Ti behaved as the .4STY Spe(.. Publ. 640. 1978, p. 134 ( ASTM Philadelphia. PA). anode during the initial immersion for 72 h but

  7. Structure and ductility of TiAl

    SciTech Connect

    Imayev, R.; Salishchev, G.; Imayev, V.; Shagiev, M.; Kuznetzov, A.

    1995-12-31

    The effect of structural factors (grain size and grain boundary structure) and strain rate on the deformation mechanism and ductility of TiAl in the temperature range of brittle-to-ductile transition and at room temperature was systematically investigated. It has been established that it is possible to substantially affect the deformation mechanism and ductility of this intermetallic by controlling structural factors, particularly the grain size, and varying the strain rate.

  8. Deposition of a thin film of TiOx from a titanium metal target as novel blocking layers at conducting glass/TiO2 interfaces in ionic liquid mesoscopic TiO2 dye-sensitized solar cells.

    PubMed

    Xia, Jiangbin; Masaki, Naruhiko; Jiang, Kejian; Yanagida, Shozo

    2006-12-21

    In dye-sensitized TiO2 solar cells, charge recombination processes at interfaces between fluorine-doped tin oxide (FTO), TiO2, dye, and electrolyte play an important role in limiting the photon-to-electron conversion efficiency. From this point of view, a high work function material such as titanium deposited by sputtering on FTO has been investigated as an effective blocking layer for preventing electron leakage from FTO without influencing electron injection. X-ray photoelectron spectroscopy analysis indicates that different species of Ti (Ti4+, Ti3+, Ti2+, and a small amount of Ti0) exist on FTO. Electrochemical and photoelectrochemical measurements reveal that thin films of titanium species, expressed as TiOx, work as a compact blocking layer between FTO and TiO2 nanocrystaline film, improving Voc and the fill factor, finally giving a better conversion efficiency for dye-sensitized TiO2 solar cells with ionic liquid electrolytes.

  9. Atomistic Modeling of Pd Site Preference in NiTi

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    An analysis of the site subsitution behavior of Pd in NiTi was performed using the BFS method for alloys. Through a combination of Monte Carlo simulations and detailed atom-by-atom energetic analyses of various computational cells, representing compositions of NiTi with up to 10 at% Pd, a detailed understanding of site occupancy of Pd in NiTi was revealed. Pd subsituted at the expense of Ni in a NiTi alloy will prefer the Ni-sites. Pd subsituted at the expense of Ti shows a very weak preference for Ti-sites that diminishes as the amount of Pd in the alloy increases and as the temperature increases.

  10. Cost-Effective TiAl based Materials

    NASA Technical Reports Server (NTRS)

    Moxson, V. S.; Sun, Fusheng; Draper, Susan L.; Froes, F. H.; Duz, V.

    2003-01-01

    Because of their inherent low ductility, TiAl-based materials are difficult to fabricate, especially thin gage titanium gamma aluminide (TiAl) sheet and foil. In this paper, an innovative powder metallurgy approach for producing cost-effective thin gage TiAl sheets (with 356 mm long and 235 mm wide, and a thickness of 0.74, 1.09, 1.55, and 2.34 mm, respectively) is presented. The microstructures and tensile properties at room and elevated temperatures of the thin gage TiAl are studied. Results show that these TiAl sheets have a relatively homogenous chemistry, uniform microstructure, and acceptable mechanical properties. This work demonstrates a cost-effective method for producing both flat products (sheet/foil) and complex chunky parts of TiAl for various advanced applications including aerospace and automotive industries.

  11. Metallic biomaterials TiN-coated: corrosion analysis and biocompatibility.

    PubMed

    Paschoal, André Luís; Vanâncio, Everaldo Carlos; Canale, Lauralice de Campos Franceschini; da Silva, Orivaldo Lopes; Huerta-Vilca, Domingos; Motheo, Artur de Jesus

    2003-05-01

    Corrosion processes due to contact with the physiological environment should be avoided or minimized in orthopedic implants. Four metallic substrates frequently used as biomaterials: pure Ti, Ti-6Al-4V alloy, ASTM F138 stainless steel, and Co-Cr-Mo alloy, were coated with TiN using the physical vapor deposition (PVD) technique. These coatings have been screened by polarization curves in physiological solutions. TiN prepared by PVD is efficient as coating for stainless steel. On titanium and alloy there are no benefits concerning the corrosion resistance compared to the bare Ti-materials. TiN coatings have been screened according to ISO 10993 standard tests for biocompatibility and exhibited no cytotoxicity, dermal irritation, or acute systemic toxicity response.

  12. 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.

  13. Mechanical properties and grindability of experimental Ti-Au alloys.

    PubMed

    Takahashi, Masatoshi; Kikuchi, Masafumi; Okuno, Osamu

    2004-06-01

    Experimental Ti-Au alloys (5, 10, 20 and 40 mass% Au) were made. Mechanical properties and grindability of the castings of the Ti-Au alloys were examined. As the concentration of gold increased to 20%, the yield strength and the tensile strength of the Ti-Au alloys became higher without markedly deteriorating their ductility. This higher strength can be explained by the solid-solution strengthening of the a titanium. The Ti-40%Au alloy became brittle because the intermetallic compound Ti3Au precipitated intensively near the grain boundaries. There was no significant difference in the grinding rate and grinding ratio among all the Ti-Au alloys and the pure titanium at any speed.

  14. Giant resonances in {sup 46,48}Ti

    SciTech Connect

    Tokimoto, Y.; Lui, Y.-W.; Clark, H. L.; John, B.; Chen, X.; Youngblood, D. H.

    2006-10-15

    The giant resonance region from 9 MeV Ti and {sup 48}Ti has been studied with inelastic scattering of 240 MeV {alpha} particles at small angles including 0 deg. Isoscalar monopole strength in {sup 46}Ti ({sup 48}Ti) was found corresponding to have 71+15/-12% (96+14/-12%) of the E0 energy weighted sum rule (EWSR) with a centroid of 18.66+0.65/-0.25% MeV (18.80+0.45/-0.18% MeV), respectively. In {sup 46}Ti ({sup 48}Ti), 46{+-}12% (56{+-}12%) of the E1, and 60{+-}11% (87{+-}11%) of the E2 EWSR were identified.

  15. Electron Impact Excitation Of Ti XIX

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, F. P.

    2012-05-01

    Emission lines of Ti XIX are important for the modeling and diagnostics of lasing, fusion and astrophysical plasmas, for which atomic data are required for a variety of parameters, such as energy levels, radiative rates (A- values), and excitation rates or equivalently the effective collision strengths (Υ), which are obtained from the electron impact collision strengths (Ω). Experimentally, energy levels are available for Ti XIX on the NIST website, but there is paucity for accurate collisional atomic data. Therefore, here we report a complete set of results (namely energy levels, radiative rates, and effective collision strengths) for all transitions among the lowest 98 levels of Ti XIX. These levels belong to the (1s2) 2s2, 2s2p, 2p2, 2s3l, 2p3l, 2s4l, and 2p4l configurations. Finally, we also report the A- values for four types of transitions, namely electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2), because these are also required for plasma modeling. For our calculations of wavefunctions, we have adopted the fully relativistic GRASP code, and for the calculations of Ω, the Dirac atomic R-matrix code (DARC) of PH Norrington and IP Grant. Additionally, parallel calculations have also been performed with the Flexible Atomic Code (FAC) of Gu, so that all atomic parameters can be rigorously assessed for accuracy.

  16. NiTi superelasticity via atomistic simulations

    NASA Astrophysics Data System (ADS)

    Chowdhury, Piyas; Ren, Guowu; Sehitoglu, Huseyin

    2015-12-01

    The NiTi shape memory alloys (SMAs) are promising candidates for the next-generation multifunctional materials. These materials are superelastic i.e. they can fully recover their original shape even after fairly large inelastic deformations once the mechanical forces are removed. The superelasticity reportedly stems from atomic scale crystal transformations. However, very few computer simulations have emerged, elucidating the transformation mechanisms at the discrete lattice level, which underlie the extraordinary strain recoverability. Here, we conduct breakthrough molecular dynamics modelling on the superelastic behaviour of the NiTi single crystals, and unravel the atomistic genesis thereof. The deformation recovery is clearly traced to the reversible transformation between austenite and martensite crystals through simulations. We examine the mechanistic origin of the tension-compression asymmetries and the effects of pressure/temperature/strain rate variation isolatedly. Hence, this work essentially brings a new dimension to probing the NiTi performance based on the mesoscale physics under more complicated thermo-mechanical loading scenarios.

  17. Evaluation of the Comparative Corrosion Resistance Between AKOT Ti Alloy and Ti Gr 7 Alloy

    SciTech Connect

    Lian, T

    2005-08-01

    In its current design, the drip shields for the high-level nuclear waste containers for the Yucca Mountain repository will be mainly made using Ti Gr 7 (R52400). Ti Gr 7 is a highly corrosion resistant alloy, especially because it contains 0.15% palladium (Pd). The goal of this study was to determine whether an AKOT low-Pd (0.01%) titanium alloy would have a similar corrosion resistance than the more expensive Ti Gr 7 in environments that could be related to the performance of the drip shield. The focus of this testing program was on the susceptibility of the alloys to localized corrosion. Therefore, only artificially creviced specimens were used.

  18. Spray Forming of NiTi and NiTiPd Shape-Memory Alloys

    NASA Technical Reports Server (NTRS)

    Mabe, James; Ruggeri, Robert; Noebe, Ronald

    2008-01-01

    In the work to be presented, vacuum plasma spray forming has been used as a process to deposit and consolidate prealloyed NiTi and NiTiPd powders into near net shape actuators. Testing showed that excellent shape memory behavior could be developed in the deposited materials and the investigation proved that VPS forming could be a means to directly form a wide range of shape memory alloy components. The results of DSC characterization and actual actuation test results will be presented demonstrating the behavior of a Nitinol 55 alloy and a higher transition temperature NiTiPd alloy in the form of torque tube actuators that could be used in aircraft and aerospace controls.

  19. Effects of TiCl4 Purity on the Sinterability of Armstrong-Processed Ti Powder

    SciTech Connect

    Weil, K. Scott; Hovanski, Yuri; Lavender, Curt A.

    2009-04-03

    A series of high purity and low purity powders were synthesized from TiCl4 by the Armstrong process. While both powders displayed swelling when consolidated and sintered, the lower purity powder exhibited this phenomenon in significantly lower degree. The improvement is attributed to the increase in the onset of sintering temperature, which mitigates the entrapment of volatile impurities that would otherwise lead to pore formation and growth. The net effect is that the use of a lower purity TiCl4 may beneficial in two ways: (1) it is a potentially lower cost precursor to Ti powder production and (2) the trace impurities allow higher density components to be fabricated via a typical low-cost press and sinter approach.

  20. A Review Corrosion of TI Grade 7 and Other TI Alloys in Nuclear Waste Repository Environments

    SciTech Connect

    F. Hua; K. Mon; P. Pasupathi; G. Gordon

    2004-05-11

    Titanium alloy degradation modes are reviewed in relation to their performance in repository environments. General corrosion, localized corrosion, stress corrosion cracking, hydrogen induced cracking, microbially influenced corrosion, and radiation-assisted corrosion of Ti alloys are considered. With respect to the Ti Grade 7 drip shields selected for emplacement in the repository at Yucca Mountain, general corrosion, hydrogen induced cracking, and radiation-assisted corrosion will not lead to failure within the 10,000 year regulatory period; stress corrosion cracking (in the absence of disruptive events) is of no consequence to barrier performance; and localized corrosion and microbially influenced corrosion are not expected to occur. To facilitate the discussion, Ti Grades 2, 5, 7, 9, 11, 12, 16, 17, 18, and 24 are included in this review.

  1. (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.

  2. Electrical resistivity of V-Cr-Ti alloys

    SciTech Connect

    Zinkle, S.J.; Gubbi, A.N.; Eatherly, W.S.

    1997-04-01

    Room temperature electrical resistivity measurements have been performed on vanadium alloys containing 3-6%Cr and 3-6%Ti in order to evaluate the microstructural stability of these alloys. A nonlinear dependence on Cr and Ti concentration was observed, which suggests that either short range ordering or solute precipitation (perhaps in concert with interstitial solute clustering) has occurred in V-6Cr-6Ti.

  3. Communication: Uncovering molecule-TiO₂ interactions with nonlinear spectroscopy

    SciTech Connect

    Miller, Stephen A.; West, Brantley A.; Curtis, Anna C.; Papanikolas, John M.; Moran, Andrew M.

    2011-08-28

    Femtosecond transient grating tests are used to investigate electronic structures and transport mediums in dye-sensitized nanocrystalline TiO₂ films. This experiment examines two molecular sensitizers bridging the weak (a phosphonated Ruthenium complex) and strong (catechol) molecule TiO₂ joining systems. It is shown that strong molecule-TiO₂ exchanges give rise to light-induced pulsation coherences at the boundaries between species.

  4. Ab initio Study of He Stability in hcp-Ti

    SciTech Connect

    Dai, Yunya; Yang, Li; Peng, SM; Long, XG; Gao, Fei; Zu, Xiaotao T.

    2010-12-20

    The stability of He in hcp-Ti was studied using ab initio method based on density functional theory. The results indicate that a single He atom prefers to occupy the tetrahedral site rather than the octahedral site. The interaction of He defects with Ti atoms has been used to explain the relative stabilities of He point defects in hcp-Ti. The relative stability of He defects in hcp-Ti is useful for He clustering and bubble nucleation in metal tritides, which provides the basis for development of improved atomistic models.

  5. Photoinduced underwater superoleophobicity of TiO2 thin films.

    PubMed

    Sawai, Yusuke; Nishimoto, Shunsuke; Kameshima, Yoshikazu; Fujii, Eiji; Miyake, Michihiro

    2013-06-11

    The photoinduced wettabilities of water, n-hexadecane, dodecane, and n-heptane on a flat TiO2 surface prepared by a sol-gel method-based coating were investigated. An amphiphilic surface produced by UV irradiation exhibited underwater superoleophobicity with an extremely high static oil contact angle (CA) of over 160°. The TiO2 surface almost completely repelled the oil droplet in water. A robust TiO2 surface with no fragile nanomicrostructure was fabricated on a Ti mesh with a pore size of approximately 150 μm. The fabricated mesh was found to be applicable as an oil/water separation filter.

  6. Antibacterial activity and cytocompatibility of Cu-Ti-O nanotubes.

    PubMed

    Hang, Ruiqiang; Gao, Ang; Huang, Xiaobo; Wang, Xiaoguang; Zhang, Xiangyu; Qin, Lin; Tang, Bin

    2014-06-01

    TiO2 nanotubes (NTs) have favorable biological properties, but the poor antibacterial activity limits their application especially in orthopedics fields. In this article, Cu-Ti-O nanotubes with different Cu contents are fabricated on sputtered TiCu films. Scanning electron microscopy reveals the NTs can be formed on sputtered TiCu films when the Cu content is less than 14.6 at %. X-ray photoelectron spectroscopy results indicate the NTs are consist of CuO mixed with TiO2 and the Cu content in NTs decreases dramatically compared with that in TiCu films. Biological experiments show that although these NTs have poor release antibacterial activity, their contact antibacterial activity has proven to be excellent, indicating the NT surface can effectively inhibit biomaterial-associated infections. The cytocompatibility of the NTs is closely related to the Cu content and when its content is relatively low (1.01 at %), there is no appreciable cytotoxicity. So Cu-Ti-O NTs with 1 at % Cu may be suitable to achieve proper antibacterial activity and desired cytocompatibility. The Cu-Ti-O NTs integrate the favorable antibacterial activity of Cu and excellent biological properties of TiO2 NTs therefore have potential applications in orthopedics, dentistry, and other biomedical fields.

  7. Ab Initio Study of Phase Equilibria in TiCx

    NASA Astrophysics Data System (ADS)

    Korzhavyi, P. A.; Pourovskii, L. V.; Hugosson, H. W.; Ruban, A. V.; Johansson, B.

    2002-01-01

    The phase diagram for the vacancy-ordered structures in the substoichiometric TiCx ( x = 0.5-1.0) has been established from Monte Carlo simulations with the long-range pair and multisite effective interactions obtained from ab initio calculations. Three ordered superstructures of vacancies ( Ti2C, Ti3C2, and Ti6C5) are found to be ground state configurations. Their stability has been verified by full-potential total energy calculations of the fully relaxed structures.

  8. Nanostructured diamond-TiC composites with high fracture toughness

    NASA Astrophysics Data System (ADS)

    Wang, Haikuo; He, Duanwei; Xu, Chao; Tang, Mingjun; Li, Yu; Dong, Haini; Meng, Chuanmin; Wang, Zhigang; Zhu, Wenjun

    2013-01-01

    We report the preparation of nanostructured diamond-TiC composites with high fracture toughness and high hardness starting from a ball-milled mixture of nano-sized Ti3SiC2 and submicron-sized diamond by simultaneously tuning the pressure-temperature conditions. The phase segregation of Ti3SiC2 at pressure of 5.5 GPa were investigated by X-ray diffraction and high resolution transmission electron microscopy, we found that the Ti3SiC2 could decompose into nanosized TiC and amorphous Ti-Si at 600-700 °C. The subsequent reaction between diamond and Ti-Si led to an amorphous Ti-Si-C matrix in which diamond and TiC crystals are embedded. With a loading force of 98 N, the measured fracture toughness KIC and Vicker's hardness HV of the synthesized composites reach up to 14 MPa m1/2 and 45.5 GPa, respectively. Our results demonstrate that the nanocrystalline/amorphous bonding matrix could largely enhance the toughness of the brittle composites.

  9. Dual laser deposition of Ti:DLC composite for implants

    NASA Astrophysics Data System (ADS)

    Jelínek, Miroslav; Zemek, Josef; Kocourek, Tomáš; Remsa, Jan; Mikšovský, Jan; Písařík, Petr; Jurek, Karel; Tolde, Zdeněk; Trávníčková, Martina; Vandrovcová, Marta; Filová, Elena

    2016-10-01

    Ti-doped hydrogen free diamond-like carbon (DLC) layers of dopation up to ~25 at.% were prepared by dual beam pulsed laser deposition (PLD) using two excimer lasers. The arrangement allows continuous fine tuning of dopant concentration on a large scale and deposition flexibility. The layers were prepared on Si(1 0 0) and Ti6Al4V substrates at room temperature. The surface morphology, mechanical properties, bonds, composition, morphology of human osteoblast-like Saos-2 cells, their metabolic activity and production of osteocalcin, a marker of osteogenic cells’ differentiation were tested. The films’ composition changed after x-ray photoelectron spectroscopy (XPS) surface cleaning by argon clusters. Adhesion moved with Ti dopation from 4 N (DLC film) to 11 N (25 at.% of Ti in DLC). Creation of TiC was observed for higher Ti dopation. The contact angle and surface free energy stayed unchanged for higher Ti dopation. Saos-2 cells had the highest metabolic activity/viability on DLC with 10 at.% of Ti and on control polystyrene dishes on days 1 and 3. The Ti dopation improved the formation of vinculin-containing focal adhesion plaques in Saos-2 cells. Immunofluorescence staining revealed similar production of osteocalcin in cells on all tested samples.

  10. High Precision Ti stable Isotope Measurement of Terrestrial Rocks

    NASA Astrophysics Data System (ADS)

    Millet, M. A.; Dauphas, N.; Williams, H. M.; Burton, K. W.; Nowell, G. M.

    2014-12-01

    Advances in multi-collection plasma source mass spectrometry have allowed the determination of stable isotope composition of transition metals to address questions relevant to both high and low temperature geochemistry. However, titanium has received only very limited attention. Here we present a new technique allowing the determination of the stable isotope composition of titanium in geological samples (d49Ti or deviation of the 49Ti/47Ti ratio from the OL-Ti in-house standard of reference) using double-spike methodology and high-resolution MC-ICP-MS. We have carried out a range analytical tests for a wide spectrum of samples matrices to demonstrate a external reproducibility of ±0.02‰ on the d49Ti while using as little as 150ng of natural Ti for a single analysis. We have analysed a comprehensive selection of mantle-derived samples covering a range of geodynamic contexts (MORB, IAB, OIB, adakites, eclogites, serpentines) and geographical distribution (MORB: Mid-Atlantic Ridge, Southwest Indian Ridge and Eastern Pacific Ridge; IAB: New Britain reference suite and Marianas Arc). The samples show a very limited range from -0.06‰ to +0.04‰ with a main mode at +0.004‰ relative to the OL-Ti standard. Average values for MORB, IAB and eclogites are similar within uncertainty and thus argue for limited mobility of Ti during subduction zone processes and homogeneity of the Ti stable isotope composition of the upper mantle. However, preliminary data for more evolved igneous rocks suggest that they display heavier Ti stable isotope compositions, which may reflect the removal of isotopically light Ti as a function of Fe-Ti oxide crystallisation. This is in good agreement with Ti being present in 5-fold and 6-fold coordination in basaltic melts and preferential uptake of 6-folded Ti by Ti-bearing oxides [1]. This dataset will be complemented by analysis of abyssal peridotites to confirm the homogeneity of the mantle as well as data for a range of ferromanganese crusts

  11. Preparation of Ti-coated diamond particles by microwave heating

    NASA Astrophysics Data System (ADS)

    Gu, Quanchao; Peng, Jinghui; Xu, Lei; Srinivasakannan, C.; Zhang, Libo; Xia, Yi; Wu, Qingtian; Xia, Hongying

    2016-12-01

    Depositing strong carbide-forming elements on diamond surface can dramatically improve the interfacial bonding strength between diamond grits and metal matrix. In the present work, investigation on the preparation of Ti-coated diamond particles by microwave heating has been conducted. The morphology, microstructure, and the chemical composition of Ti-coated diamond particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive x-ray spectrometer (EDX). The thickness of Ti coating was measured and the interfacial binding strength between Ti coating and diamond was analyzed. The results show that the surface of the diamond particles could be successfully coated with Ti, forming a uniform and continuous Ti-coated layer. The TiC was found to form between the surface of diamond particles and Ti-coated layer. The amount of TiC as well as the thickness of coating increased with increasing coating temperature, furthermore, the grain size of the coating also grew gradually. The interfacial bonding strength between coating and diamond was found to be best at the temperature of 760 °C.

  12. thermodynamics of nitrogen in BaO-TiOx melts

    NASA Astrophysics Data System (ADS)

    Tomioka, Katsutomo; Suito, Hideaki

    1993-02-01

    Using a gas-slag-metal equilibration technique, nitrogen contents in BaO-TiO^ slags and nitrogen and titanium contents in liquid Cu were measured at 1823, 1873, and 1923 K under controlled partial pressures of oxygen (@#@ PO 2 = 10-11.5 ≈ 10-13.7 atm) and nitrogen (@#@ PN 2 = 0.9 atm). The nitride capacity, C(N) [=(mass pct N) · PO2/3/4, (mass pct Ti3+)/(mass pct Ti4+) ratio, and solubility of TiN in BaO-TiO2-TiO1.5 slags were obtained as a function of slag com-position (@#@ XBaO = 0.20 = 0.43) and temperature. Activity coefficients of TiN were estimated, using the values for activity coefficients of Ti in liquid Cu which were calculated from the results of a TiN saturation experiment. Free energy of dissolution of nitrogen into liquid Cu was derived as °GGN o = 32,400 + 46.17 ± 1400 (J/g · atom).

  13. Effect of TiCl4 Post-Treatment on the Embedded-Type TiO2 Nanotubes Dye-Sensitized Solar Cells.

    PubMed

    Kim, Kang-Pil; Kim, Jeong-Hwa; Hwang, Dae-Kue; Sung, Shi-Joon; Heo, Young-Woo

    2015-10-01

    We have studied the effect of TiCl4 post-treatment on the embedded-type TiO2 nanotubes (NT)-dye-sensitized solar cells (DSSCs). The TiO2 nanoparticles layer formed on TiO2 NTs surface by TiCl4 post-treatment showed different morphologies depending on TiCl4 treatment temperature. These different morphologies influenced the cell efficiency of TiO2 NT-DSSCs. The TiO2 NT treated with TiCl4 at 50 °C exhibited a rougher surface than that treated at 70 °C. The rough surface of the TiO2 NT improved the charge exchange between the dye and electrolyte. The TiO2 NT treated with TiCl4 at 50 °C showed better fill factor and cell efficiency than that treated at 70 °C. The TiCl4 post-treatment of TiO2 NT was effective at conditions of low temperature and long times. The TiO2 NT-DSSCs with TiCl4 post-treatment at 50 °C for 1.5 h showed an efficiency of 6.52%.

  14. Electrochemical Corrosion Behavior of TiN-Coated Biomedical Ti-Cu Alloy Foam in Fluoride Containing Artificial Saliva

    NASA Astrophysics Data System (ADS)

    Mutlu, Ilven

    2014-07-01

    Highly porous Ti-Cu alloy foams were produced by powder metallurgy method for implant applications. Ti-Cu alloys were prepared with 3, 5, 7, and 10 wt pct Cu contents in order to determine optimum Cu addition. Cu addition enhances sinterability, and the Ti-Cu compacts were sintered at lower temperatures and times than pure Ti. Specimens were coated with a TiN film to enhance wear and corrosion resistance. Sintered specimens were precipitation hardened (aged) in order to increase mechanical properties. Corrosion properties of foams were examined by electrochemical techniques, such as potentiodynamic polarization, cyclic polarization, Tafel extrapolation, linear polarization resistance, and open-circuit potential measurement. Effect of Cu content, TiN coating, pH, and fluoride content of artificial saliva on electrochemical corrosion behavior of specimens was investigated.

  15. Local resilience of the 1 T -TiSe2 charge density wave to Ti self-doping

    NASA Astrophysics Data System (ADS)

    Hildebrand, B.; Jaouen, T.; Didiot, C.; Razzoli, E.; Monney, G.; Mottas, M.-L.; Vanini, F.; Barreteau, C.; Ubaldini, A.; Giannini, E.; Berger, H.; Bowler, D. R.; Aebi, P.

    2017-02-01

    In Ti-intercalated self-doped 1 T -TiSe2 crystals, the charge density wave (CDW) superstructure induces two nonequivalent sites for Ti dopants. Recently, it has been shown that increasing Ti doping dramatically influences the CDW by breaking it into phase-shifted domains. Here, we report scanning tunneling microscopy and spectroscopy experiments that reveal a dopant-site dependence of the CDW gap. Supported by density functional theory, we demonstrate that the loss of the long-range phase coherence introduces an imbalance in the intercalated-Ti site distribution and restrains the CDW gap closure. This local resilient behavior of the 1 T -TiSe2 CDW reveals an entangled mechanism between CDW, periodic lattice distortion, and induced nonequivalent defects.

  16. Correlation between dispersion properties of TiO2 colloidal sols and photoelectric characteristics of TiO2 films.

    PubMed

    Jung, Hyun Suk; Lee, Sang-Wook; Kim, Jin Young; Hong, Kug Sun; Lee, Young Cheol; Ko, Kyung Hyun

    2004-11-15

    TiO2 film for use as dye-sensitized solar cell was prepared using the TiO2 colloidal sols (unpeptized sol and peptized sol). The optical properties and photocurrent-voltage characteristics of the resultant films were investigated. The optical transmittance of TiO2 thin film prepared from the peptized colloidal sol was over 90%, while that of TiO2 film from the unpeptized sol was under 80%. The TiO2 photoelectrode prepared from the peptized colloidal sol showed low photoelectric conversion efficiency (eta), 1.30%, whereas the efficiency of photoelectrode from the unpeptized sol was 2.21%. The high optical transmittance and low conversion efficiency of TiO2 film from the peptized sol are discussed in terms of dense microstructure due to the drying nature of well-dispersed colloidal sol.

  17. Cathodic cage plasma deposition of TiN and TiO{sub 2} thin films on silicon substrates

    SciTech Connect

    Sousa, Romulo R. M. de; Sato, Patricia S.; Nascente, Pedro A. P.; Viana, Bartolomeu C.; Alves, Clodomiro; Nishimoto, Akio

    2015-07-15

    Cathodic cage plasma deposition (CCPD) was used for growing titanium nitride (TiN) and titanium dioxide (TiO{sub 2}) thin films on silicon substrates. The main advantages of the CCPD technique are the uniformity, tridimensionality, and high rate of the film deposition that occurs at higher pressures, lower temperatures, and lower treatment times than those used in conventional nitriding treatments. In this work, the influence of the temperature and gas atmosphere upon the characteristics of the deposited films was investigated. The TiN and TiO{sub 2} thin films were characterized by x-ray diffraction, scanning electron microscopy, and Raman spectroscopy to analyze their chemical, structural, and morphological characteristics, and the combination of these results indicates that the low-cost CCPD technique can be used to produce even and highly crystalline TiN and TiO{sub 2} films.

  18. Dye-sensitized solar cells with modified TiO2 surface chemical states: The role of Ti3+

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Wu, Kunjie; Wang, Deliang

    2011-11-01

    Dye-sensitized solar cells (DSSCs) with TiO2 electrodes, which were modified to have different surface chemical states, were fabricated. The DSSCs had an ultra-flat TiO2 electrode, on which only a mono-layer dye was attached. The cell I-V measurement showed that Ti3+ ion had a dramatic effect on cell performance. The efficiency of a DSSC was shown to have a strong correlation with the concentration of the Ti3+ surface state, it decreased almost linearly with increased Ti3+ concentration. The oxygen vacancy-Ti3+ defect served as electron recombination center and decreased both the open-circuit voltage and the fill factor.

  19. Microstructure and Creep Properties of TiAl-Ti3Al In-Situ Composites

    SciTech Connect

    Hodge, A M; Hsiung, L L

    2004-02-18

    Objectives: {lg_bullet} Exploit thermomechanical-processing techniques to fabricate TiAl/Ti3Al in-situ laminate composites with the size of lamella width down to submicron or nanometer length-scales. {lg_bullet} Characterize microstructure and elevated-temperature creep resistance of the in-situ composites. {lg_bullet} Investigate the fundamental interrelationships among microstructures, alloying additions, and mechanical properties of the in-situ composites so as to achieve the desired properties of the in-situ composites for high-temperature structural applications.

  20. CermeTi® discontinuously reinforced Ti-matrix composites: Manufacturing, properties, and applications

    NASA Astrophysics Data System (ADS)

    Abkowitz, Stanley; Abkowitz, Susan M.; Fisher, Harvey; Schwartz, Patricia J.

    2004-05-01

    Advanced powder-metallurgy technology has led to the development of the CermeTi® family of titanium metalmatrix composites. Reinforcing the titanium alloy matrix with titanium carbide or titanium boride particles results in superior properties. These discontinuously reinforced titanium composites have excellent room- and elevated-temperature properties and are exceptionally wear resistant. High quality, near-net shape CermeTi composite components are being produced commercially and are being evaluated for potential applications in military vehicles, commercial automotive engines, sporting goods, industrial tooling, and biomedical devices.

  1. Thermoelastic Analysis of a Vibrating TiB/Ti Cantilever Beam Using Differential Thermography

    SciTech Connect

    Byrd, Larry; Wyen, Travis; Byrd, Alex

    2008-02-15

    Differential thermography has been used to detect the fluctuating temperatures due the thermoelastic effect for a number of years. This paper examines functionally graded TiB/Ti cantilever beams excited on an electromechanical shaker in fully reversed bending. Finite difference analysis of specimens was used to look at the effect of heat conduction, convection and the fundamental frequency on the surface temperature distribution and compared to experimental data. The thermoelastic effect was also used to detect cracking and the stress field at the tip of the fixture during fatigue.

  2. Localized Excitation of Ti(3+) Ions in the Photoabsorption and Photocatalytic Activity of Reduced Rutile TiO2.

    PubMed

    Wang, Zhiqiang; Wen, Bo; Hao, Qunqing; Liu, Li-Min; Zhou, Chuanyao; Mao, Xinchun; Lang, Xiufeng; Yin, Wen-Jin; Dai, Dongxu; Selloni, Annabella; Yang, Xueming

    2015-07-22

    In reduced TiO2, electronic transitions originating from the Ti(3+)-induced states in the band gap are known to contribute to the photoabsorption, being in fact responsible for the material's blue color, but the excited states accessed by these transitions have not been characterized in detail. In this work we investigate the excited state electronic structure of the prototypical rutile TiO2(110) surface using two-photon photoemission spectroscopy (2PPE) and density functional theory (DFT) calculations. Using 2PPE, an excited resonant state derived from Ti(3+) species is identified at 2.5 ± 0.2 eV above the Fermi level (EF) on both the reduced and hydroxylated surfaces. DFT calculations reveal that this excited state is closely related to the gap state at ∼1.0 eV below EF, as they both result from the Jahn-Teller induced splitting of the 3d orbitals of Ti(3+) ions in reduced TiO2. Localized excitation of Ti(3+) ions via 3d → 3d transitions from the gap state to this empty resonant state significantly increases the TiO2 photoabsorption and extends the absorbance to the visible region, consistent with the observed enhancement of the visible light induced photocatalytic activity of TiO2 through Ti(3+) self-doping. Our work reveals the physical origin of the Ti(3+) related photoabsorption and visible light photocatalytic activity in prototypical TiO2 and also paves the way for the investigation of the electronic structure and photoabsorption of other metal oxides.

  3. Cu-TiO2/Ti dual rotating disk photocatalytic (PC) reactor: dual electrode degradation facilitated by spontaneous electron transfer.

    PubMed

    Xu, Yunlan; He, Yi; Jia, Jinping; Zhong, Dengjie; Wang, Yalin

    2009-08-15

    A Cu-TiO2/Ti dual rotating disk photocatalytic (PC) reactor has been developed based on our single rotating disk photoelectrocatalytic (PEC) reactor (Y. Xu, et al, Environ. Sci. Technol. 2008, 42, 2612-2617), and successfully applied to the treatment of laboratory and industrial dye wastewater. Round TiO2/Ti and Cu disks of the same size are connected by a Cu wire and fixed parallel on an axis continually rotating at 90 rpm. High treatment efficiency is obtained due to direct photooxidation on the TiO2/Ti photoanode as well as additional degradation on the Cu cathode, which is speculated via indirect hydrogen peroxide (H2O2) oxidation and direct electro-reduction of dye on cathode. The mechanism of the Cu-TiO2/Ti dual rotating disk PC reactor was investigated. In a 20 mg L(-1) Rhodamine B (RB) solution, approximately 100 mV of potential and 10 microA of current were measured between the Cu and TiO2/Ti electrode during PC treatment. Such phenomenon was explained by spontaneous electron transfer based on the same principle of establishing a Schottky barrier. On the Cu electrode surface, the photoelectrons either reduced dye molecules directly or reacted with dissolved oxygen (DO) to form H2O2. Rotation of electrodes out of the solution enhanced the mass transfer of target compound and kept the aqueous film fresh. The Cu-TiO2/ Ti dual rotating disk PC reactor is a simple and effective device for the treatment of RB dye wastewater.

  4. Characterization of microstructure and mechanical behavior of sputter deposited Ti-containing amorphous carbon coatings.

    SciTech Connect

    Feng, B.; Cao, D. M.; Meng, W. J.; Xu, J.; Tittsworth, R. C.; Rehn, L. E.; Baldo, P. M.; Doll, G. L.; Materials Science Division; Louisiana State Univ.; The Timken Company

    2001-12-03

    We report on the characterization of microstructure and mechanical properties of sputter deposited Ti-containing amorphous carbon (Ti-aC) coatings as a function of Ti composition. Ti-aC coatings have been deposited by unbalanced magnetron sputter deposition, in an industrial-scale four-target coating deposition system. The composition and microstructure of the Ti-aC coatings have been characterized in detail by combining the techniques of Rutherford backscattering spectrometry (RBS) and hydrogen elastic recoil detection (ERD), transmission electron microscopy (TEM), X-ray absorption near edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. At Ti compositions <4at.%, Ti atoms dissolve in an amorphous carbon (a-C) matrix. The dissolution limit of Ti atoms in an a-C matrix is determined to be between 4 and 8 at.%. At Ti compositions >8 at.%, XANES and EXAFS data indicate that the average Ti atomic bonding environment in Ti-aC coatings resembles that in cubic B1-TiC, consistent with TEM observation of precipitation of TiC nanocrystallites in the a-C matrix. Beyond the Ti dissolution limit, the Ti-aC coatings are nanocomposites with nanocrystalline TiC clusters embedded in an a-C matrix. A large scale, quasi one-dimensional composition modulation in the Ti-aC coatings was observed due to the particular coating deposition geometry. Elastic stiffness and hardness of the Ti-aC coatings were measured by instrumented nanoindentation and found to vary systematically as a function of Ti composition. Unlubricated friction coefficient of Ti-aC coatings against WC-Co balls was found to increase as the Ti composition increases. As Ti composition increases, the overall mechanical behavior of the Ti-aC coatings becomes more TiC-like.

  5. Synthesis of CdSe -- TiO2 Nanocomposites and Their Applications to TiO2 Sensitized Solar Cells

    SciTech Connect

    Kim, J. Y.; Choi, S. B.; Noh, J. H.; HunYoon, S.; Lee, S.; Noh, T. H.; Frank, A. J.; Hong, K. S.

    2009-01-01

    CdSe-TiO{sub 2} nanocomposites were synthesized via aminolysis of Ti-oleate complexes in the presence of CdSe nanocrystals, and their application as sensitizers for TiO{sub 2} solar cells was investigated. The formation of CdSe-TiO{sub 2} nanocomposites was confirmed using transmission electron microscopy and Raman spectroscopy. The emission spectrum of CdSe-TiO{sub 2} nanocomposites revealed photoinduced charge separation at the CdSe-TiO{sub 2} interface of the composite. The photocurrent-voltage properties of CdSe-TiO{sub 2}-sensitized TiO{sub 2} particle films compared favorably with those of CdSe-sensitized TiO{sub 2} films. Evidence was also found indicating that the TiO{sub 2} component of the composite protects CdSe against degradation during film annealing.

  6. Thin carbon layer coated Ti3+-TiO2 nanocrystallites for visible-light driven photocatalysis

    NASA Astrophysics Data System (ADS)

    Jiang, Baojiang; Tang, Yunqi; Qu, Yang; Wang, Jian-Qiang; Xie, Ying; Tian, Chungui; Zhou, Wei; Fu, Honggang

    2015-03-01

    Black TiO2 containing Ti3+ attracts enormous attention due to its excellent visible-light driven photocatalytic activity. Herein, an in situ thermal decomposition approach to synthesize uniform thin carbon coated Ti3+-TiO2 nanocrystals is presented. During the oleic acid-assisted solvothermal process, the crystal size and morphology of TiO2 were controlled through oleic acid with carboxylic acid groups. Then the residual small quantities of oleic acid anchored on TiO2 were used as a carbon source, which could be in situ pyrolyzed into a carbon layer on TiO2 at high temperature and under an inert atmosphere. Meanwhile, Ti4+ species were partly reduced into Ti3+ states/oxygen vacancies on the surface of TiO2 due to the carbothermal reduction reaction for the carbon-encapsulated Ti3+-TiO2 structure. A series of characterizations indicated that the 20-25 nm TiO2 nanocrystals obtained were wrapped evenly by 1-2 nm carbon layers, which had an important effect on the energy band structure change of TiO2. The presence of the carbon layer also improves the Ti3+ stability and the conduction behavior of the composites. The Ti3+ states/oxygen vacancies created on the surface of TiO2 were responsible for the remarkable photogenerated charge separation and extended visible-light absorption range. Furthermore, Ti3+ states/oxygen vacancies and the carbon layer together could enhance the adsorption ability of O2 so as to promote the photogenerated electrons captured by the adsorbed O2, leading to a great increase in the charge separation. As a result, the composites exhibit high photocatalytic performance for organic pollutants under visible light irradiation. This simple and new method may pave the way to practical applications for efficient photocatalytic degradation under visible light.Black TiO2 containing Ti3+ attracts enormous attention due to its excellent visible-light driven photocatalytic activity. Herein, an in situ thermal decomposition approach to synthesize uniform

  7. Stopping cross sections of protons in Ti, TiO2 and Si using medium energy ion scattering

    NASA Astrophysics Data System (ADS)

    Brocklebank, Mitchell; Dedyulin, Sergey N.; Goncharova, Lyudmila V.

    2016-11-01

    Stopping cross sections of protons in Ti, Si, and TiO2 films in the energy range 50-170 keV were determined from medium energy ion scattering (MEIS) spectra by an iterative procedure. The energy loss of protons was investigated for pure Ti and Si films, deposited by molecular beam epitaxy (MBE) onto n-Si(100) and diamond-like carbon (DLC) substrates respectively. Consecutive annealing of Ti at 200 °C in O2 resulted in stoichiometric TiO2 thin-films. Thickness and composition of the films and the interfacial properties were determined using Rutherford backscattering spectroscopy (RBS), MEIS, and X-ray photoelectron spectroscopy (XPS). Calculated stopping cross sections of Ti, Si, and TiO2 in the range of energies were compared with the commonly used SRIM2003 values. For Ti and Si, SRIM2003 values appear to be overestimated over the entire energy range. The new stopping cross sections explain deviations from previously reported values for SrTiO3. We note that the stopping cross sections of O in a gaseous phase, used in Bragg's rule calculations, cannot be applied for accurate quantitative ion beam analysis in solid compounds in the medium ion energy range.

  8. Growth of YBCO Thin Films on TiN(001) and CeO2-Coated TiN Surfaces

    DTIC Science & Technology

    2012-02-01

    substrates. Thin CeO2 (~200 nm thick) and YBCO (~300 nm thick) layers were grown on TiN-coated MgO substrates, using pulsed laser deposition. While YBCO ...and YBCO (300 nm thick) layers were grown on TiN-coated MgO substrates, using pulsed laser deposition. While YBCO grown directly on TiN was of poor...grown on the TiN-coated MgO and then an 300 nm thick YBCO layers was subsequently depos- ited. For other samples, YBCO deposition directly on the

  9. Phase stability of U-Mo-Ti alloys and interdiffusion behaviors of U-Mo-Ti/Al-Si

    SciTech Connect

    Park, Jong Man; Ryu, Ho Jin; Park, Jae Soon; Oh, Seok Jin; Kim, Chang Kyu; Kim, Yeon Soo; Hofman, Gerard L.

    2008-07-15

    As a remedy for reducing reaction between U-Mo and Al in U-Mo/Al dispersion fuel, adding an alloying element such as Zr and Ti in U-Mo has been proposed at ANL. Although ANL's work showed the potential effectiveness of these elements based on thermodynamic and metallurgical analyses, the effect of a Ti addition in U-Mo remains unproven. The out-of-pile tests of U-Mo-Ti alloys, which focused on phase stability and interdiffusion behavior against Al, are meaningful to predict their efficacy during an irradiation. At the 2006 RERTR conference, we presented our work on the interdiffusion behaviors of U-Mo-Zr/Al-Si. In this paper, we will present the results for substituting U-Mo-Zr with U-Mo-Ti. Unlike U-Mo-Zr alloys, the gamma-heat-treated U-7Mo-xTi (x=1{approx}3 wt%) exhibited a metastable {gamma}-U phase, regardless of the Ti content. In these samples, however, a small amount of second-phase precipitates with a high Ti concentration was observed. The gamma phase stability of the U-Mo-Ti alloys at 500 deg C was similar to that of the U-Mo-Zr alloys. Interdiffusion test results between U-Mo-Ti alloys and Al-Si alloys will also be presented and a comparison with the previous results with U- Mo-Zr/Al-Si will also be included. (author)

  10. Energy dependence on formation of TiO{sub 2} nanofilms by Ti ion implantation and annealing

    SciTech Connect

    Liu, Yichao; Ren, Feng Cai, Guangxu; Zhou, Xiaodong; Hong, Mengqing; Li, Wenqing; Xiao, Xiangheng; Wu, Wei; Jiang, Changzhong

    2014-03-01

    Graphical abstract: - Highlights: • Fabrication of TiO{sub 2} films by ion implantation and annealing strongly depends on ion energy. • Best photocatalytic activity is achieved in the TiO{sub 2} nanofilm annealed at 1000 °C. • Phase transformation of TiO{sub 2} appears under annealing temperature of 900 °C. - Abstract: TiO{sub 2} nanofilms were fabricated by a solid-phase-growth progress. The silica glass slides were implanted with Ti ions to the fluence of 1.84 × 10{sup 17} ions/cm{sup 2} at accelerate voltages of 20, 50, and 80 kV, respectively. The samples were annealed in oxygen atmosphere at 700, 800, 900, and 1000 °C for 4 h, respectively. The influence of the ion energy and the annealing temperature on the formation and phase transformation of the TiO{sub 2} films was studied. It was found that anatase TiO{sub 2} nanofilms instead of embedded rutile TiO{sub 2} nanoparticles on the substrate surfaces when the energy of implanted Ti atoms was 20 kV.

  11. Identification of Ti clusters during nucleation and growth of sol-gel-derived TiO2 nanoparticles.

    PubMed

    Simonsen, Morten Enggrob; Søgaard, Erik Gydesen

    2013-01-01

    In the present work, electrospray ionization mass spectrometry (ESI-MS) was used to investigate the titanium clusters present during nucleation and growth of sol-gel derived TiO2 nanoparticles. Depending on the alkoxide precursor used, Ti clusters of different sizes were identified [titanium isopropoxide (TTIP)-11-12 Ti atoms, titanium butoxide (TTB)-10-11 Ti atoms and titanium tetraethoxide (TTE)-5-7 Ti atoms]. The Ti-O-Ti backbone/core of the titanium clusters were found to be quite stable after formation and do not easily break up into smaller clusters. The results of this investigation suggest that these clusters are used as building blocks in the growth during the induction period. The h-ratio (n H2O/n alcoxide) and the pH were not found to influence the identity of the Ti clusters present during nucleation of the growth of sol-gel derived TiO2 nano-particles, although the induction period was greatly influenced. The reactivity of the alkoxy group are OEt > OPri > OBu. The difference in reactivity of the alkoxides is generally believed to be due to the increasing size of the alkoxy group which causes sterical hindrance during the nucleophilic substitution reaction.

  12. Novel stable hard transparent conductors in TiO2-TiC system: Design materials from scratch

    PubMed Central

    Meng, Xiangying; Liu, Dongyan; Dai, Xuefeng; Pan, Haijun; Wen, Xiaohong; Zuo, Liang; Qin, Gaowu

    2014-01-01

    Two new ternary compounds in the TiO2-TiC system, Ti5C2O6 and Ti3C2O2, are reported for the first time based on ab initio evolutionary algorithm. Ti5C2O6 has a tube-structure in which sp1 hybridized carbon chains run through the lattice along the b-axis; while in the Ti3C2O2 lattice, double TiO6 polyhedral are separated by the non-coplanar sp2 hybridized hexagon graphite layers along the c-axis, forming a sandwich-like structure. At ambient conditions, the two compounds are found to be mechanically and dynamically stable and intrinsic transparent conductors with high hardness (about twice harder than the conventional transparent conducting oxides). These mechanical, electronic, and optical properties make Ti5C2O6 and Ti3C2O2 ternary compounds be promising robust, hard, transparent, and conductive materials. PMID:25511583

  13. The development of Ti alloys for dental implant with high corrosion resistance and mechanical strength.

    PubMed

    Yamazoe, Junichi; Nakagawa, Masaharu; Matono, Yoshinari; Takeuchi, Akari; Ishikawa, Kunio

    2007-03-01

    The corrosion behaviors of Ti and Ti-6Al-4V, Ti-6Al-7Nb, Ti-0.5Pt, Ti-6Al-4V-0.5Pt, and Ti-6Al-7Nb-0.5Pt alloys were examined using an electrochemical analyzer in artificial saliva containing 0.1 and 0.2% NaF at a pH of 4.0. The SEM observations revealed that the surfaces of the alloys containing 0.5 wt% Pt were not affected in fluoride-containing environments, whereas the surfaces of Ti, Ti-6A1-4V, and Ti-6Al-7Nb alloys were markedly rough. In artificial saliva containing 0.1% NaF at a pH of 4.0, the amounts of Ti dissolved from the Ti, Ti-6Al-4V, and Ti-6Al-7Nb alloys were about 50 times larger than those of the alloys containing 0.5 wt% Pt. The tensile strengths of the alloys containing 0.5 wt% Pt were equal to or higher than those of pure Ti or the alloys without Pt. The Ti-0.5Pt, Ti-6Al-4V-0.5Pt, and Ti-6Al-7Nb-0.5 alloys are expected to be useful in clinical dentistry as new Ti alloys with high corrosion resistance and mechanical strength.

  14. Characteristics of Ti(C, N)/TiB composite layer on Ti-6Al-4V alloy produced by laser surface melting

    NASA Astrophysics Data System (ADS)

    Zeng, Xian; Yamaguchi, Tomiko; Nishio, Kazumasa

    2016-06-01

    A Ti(C, N)/TiB reinforced titanium matrix composite layer was successfully in-situ synthesized by laser melting on Ti-6Al-4V alloy surface with Ti-BN-C mixed powder, aiming at improving the wear resistance. The microstructure, chemical composition, hardness and wear behavior were analyzed. The results showed that, the cross sectional microstructure can be clearly divided into three parts, which were the laser melted layer, heat affected zone and non-affected zone. The reinforcements in laser melted layer consisted of dendritic TiC0.3N0.7 phases and fine-structure TiB phases. The matrix in laser melted layer was in a two-phase structure, being composed of platelet α titanium and intergranular β titanium. The hardness was increased from 320 HV in the substrate to 450-550 HV in the modified layer. The wear resistance was improved that, the wear volume loss of the laser treated sample was approximately half of the as received Ti-6Al-4V alloy after 8 h wear test.

  15. Electron channeling in TiO2 coated Cu layers

    NASA Astrophysics Data System (ADS)

    Zheng, Pengyuan; Zhou, Tianji; Gall, Daniel

    2016-05-01

    Electron transport in metal conductors with ˜5-30 nm width is dominated by surface scattering. In situ transport measurements as a function of surface chemistry demonstrate that the primary parameter determining the surface scattering specularity is the localized surface density of states at the Fermi level N(E f ). In particular, the measured sheet resistance of epitaxial Cu(001) layers with thickness d Cu = 9-25 nm increases when coated with d Ti = 0.1-4.0 monolayers (MLs) of Ti, but decreases again during exposure to 37 Pa of O2. These resistivity changes are a function of d Cu and d Ti and are due to a transition from partially specular electron scattering at the Cu surface to completely diffuse scattering at the Cu-Ti interface, and the recovery of surface specularity as the Ti is oxidized. X-ray reflectivity and photoelectron spectroscopy indicate the formation of a 0.47 ± 0.03 nm thick Cu2O surface layer on top of the TiO2-Cu2O during air exposure, while density functional calculations of TiO x cap layers as a function of x = 0-2 and d Ti = 0.25-1.0 ML show a reduction of N(E f ) by up to a factor of four. This reduction is proposed to be the key cause for the recovery of surface specularity and results in electron confinement and channeling in the Cu layer upon Ti oxidation. Transport measurements at 293 and 77 K confirm the channeling and demonstrate the potential for high-conductivity metal nanowires by quantifying the surface specularity parameter p = 0.67 ± 0.05, 0.00 ± 0.05, and 0.35 ± 0.05 at the Cu-vacuum, Cu-Ti, and Cu-TiO2 interfaces.

  16. The Formation Time of Ti-O(•) and Ti-O(•)-Ti Radicals at the n-SrTiO3/Aqueous Interface during Photocatalytic Water Oxidation.

    PubMed

    Chen, Xihan; Choing, Stephanie N; Aschaffenburg, Daniel J; Pemmaraju, C D; Prendergast, David; Cuk, Tanja

    2017-02-08

    The initial step of photocatalytic water oxidation reaction at the metal oxide/aqueous interface involves intermediates formed by trapping photogenerated, valence band holes on different reactive sites of the oxide surface. In SrTiO3, these one-electron intermediates are radicals located in Ti-O(•) (oxyl) and Ti-O(•)-Ti (bridge) groups arranged perpendicular and parallel to the surface respectively, and form electronic states in the band gap of SrTiO3. Using an ultrafast sub band gap probe of 400 nm and white light, we excited transitions between these radical states and the conduction band. By measuring the time evolution of surface reflectivity following the pump pulse of 266 nm light, we determined an initial radical formation time of 1.3 ± 0.2 ps, which is identical to the time to populate the surface with titanium oxyl (Ti-O(•)) radicals. The oxyl was separately observed by a subsurface vibration near 800 cm(-1) from Ti-O located in the plane right below Ti-O(•). Second, a polarized transition optical dipole allows us to assign the 1.3 ps time constant to the production of both O-site radicals. After a 4.5 ps delay, another distinct surface species forms with a time constant of 36 ± 10 ps with a yet undetermined structure. As would be expected, the radicals' decay, specifically probed by the oxyl's subsurface vibration, parallels that of the photocurrent. Our results led us to propose a nonadiabatic kinetic mechanism for generating radicals of the type Ti-O(•) and Ti-O(•)-Ti from valence band holes based on their solvation at aqueous interfaces.

  17. Ternary Phases (Heusler) in the System Ti-Co-Sn

    NASA Astrophysics Data System (ADS)

    Kosinskiy, Andrey; Karlsen, Ole Bjørn; Sørby, Magnus H.; Prytz, Øystein

    2016-12-01

    Some of the Heusler-phases ( XY 2 Z and XYZ) are known to have large homogeneity ranges which can be useful for tuning material properties. In this work, we have revised the isothermal section of the Ti-Co-Sn system at 973 K (700 °C). A total of 29 ternary compositions, mostly in the regions TiCo2- x Sn for 0 ≤ x ≤ 1 and Ti1+ y Co2Sn1- y for 0 ≤ y ≤ 1, were prepared by arc-melting, then ball-milled and annealed. The resulting annealed powder samples were studied by applying the Rietveld method to X-ray and neutron powder diffraction data. Half-Heusler TiCoSn was not observed. The Heusler phase observed in TiCo2- x Sn has compositions ranging from TiCo1.52Sn to TiCo2Sn and has the half-Heusler structure where the excess of Co is located on the semi-filled tetrahedral site 4 d (¾, ¾, ¾) in the space group F-43 m. At 1273 K (1000 °C), this solid solubility is expanded from TiCo2Sn to TiCo with full solid solubility where Ti is gradually replacing Sn (Ti1+ y Co2Sn1- y for 0 ≤ y ≤ 1), while at 973 K (700 °C) there is a small solubility gap for 0.0 ≤ y ≤ 0.2.

  18. Photocatalytic TiO2 nanoparticles enhanced polymer antimicrobial coating

    NASA Astrophysics Data System (ADS)

    Wei, Xiaojin; Yang, Zhendi; Tay, See Leng; Gao, Wei

    2014-01-01

    Copper (Cu) containing coatings can provide sustainable protection against microbial contamination. However, metallic Cu coatings have not been widely used due to the relatively high cost, poor corrosion resistance, and low compatibility with non-metal substrates. Titanium dioxide (TiO2) possesses antibacterial functions by its photocatalytic properties which can destroy bacteria or suppress their reproduction. TiO2 also has the function of improving the mechanical properties through particle dispersion strengthening. We have recently developed an innovative polymer based coating system containing fine particles of Cu and TiO2 nanoparticles. These polymer based coatings simultaneously display excellent antimicrobial and good mechanical properties. The results showed that the addition of TiO2 has improved the antimicrobial property under sunlight, which provides extended applications in outdoor environment. The elimination of 106 bacterial by contacting the coatings without TiO2 needs 5 h, while contacting with the Cu/TiO2- 1 wt.% TiO2 took only 2 h to kill the same amount of bacteria. The coatings also presented enhanced hardness and wear resistance after adding TiO2. The width of wear track decreased from 270 μm of the Cu-polymer coating to 206 μm of Cu/TiO2-polymer coatings with 10 wt.% TiO2. Synchrotron Infrared Microscopy was used to in-situ and in-vivo study the bacteria killing process at the molecular level. The real-time chemical images of bacterial activities showed that the bacterial cell membranes were damaged by the Cu and TiO2 containing coatings

  19. Mechanical Property Enhancement of Ti-6Al-4V by Multilayer Thin Solid Film Ti/TiO2 Nanotubular Array Coating for Biomedical Application

    NASA Astrophysics Data System (ADS)

    Zalnezhad, Erfan; Baradaran, Saeid; Bushroa, A. R.; Sarhan, Ahmed A. D.

    2014-02-01

    With the intention of improving the mechanical properties of Ti-6Al-4V, samples were first coated with pure titanium using the physical vapor deposition (PVD) magnetron sputtering technique. The Taguchi optimization method was used to attain a higher coating on substrate adhesion. Second, pure titanium-coated samples with higher adhesion were anodized to generate TiO2 nanotubes. Next, the TiO2-coated specimens were heat treated at annealing temperatures of 753.15 K and 923.15 K (480 °C and 650 °C). The XRD results indicate that the varying heat treatment temperatures produced different phases, namely, anatase [753.15 K (480 °C)] and rutile [923.15 K (650 °C)]. Finally, the coated samples' mechanical properties (surface hardness, adhesion, and fretting fatigue life) were investigated. The fretting fatigue lives of TiO2-coated specimens at 753.15 K and 923.15 K (480 °C and 650 °C) annealing temperatures were significantly enhanced compared to uncoated samples at low and high cyclic fatigue. The results also indicate that TiO2-coated samples heat treated at an annealing temperature of 753.15 K (480 °C) (anatase phase) are more suitable for increasing fretting fatigue life at high cyclic fatigue (HCF), while at low cyclic fatigue, the annealing temperature of 923.15 K (650 °C) seemed to be more appropriate. The fretting fatigue life enhancement of thin-film TiO2 nanotubular array-coated Ti-6Al-4V is due to the ceramic nature of TiO2 which produces a hard surface as well as a lower coefficient of friction of the TiO2 nanotube surface that decreases the fretting between contacting components, namely, the sample and friction pad surfaces.

  20. Metal-insulator transitions in LaTiO3 / CaTiO3 superlattices

    NASA Astrophysics Data System (ADS)

    Seo, Sung Seok A.; Lee, Ho Nyung

    2010-03-01

    Strongly correlated electrons at an interface of complex oxide heterostructures often show interesting behaviors that require an introduction of new physical concepts. For example, the metallic transport behavior found in the superlattices of a Mott insulator LaTiO3 and a band insulator SrTiO3 (STO) has established the concept of interfacial electronic reconstruction. In this work, we have studied the transport property of a new type of Mott/band insulator LaTiO3/CaTiO3 (LTO/CTO) superlattices grown by pulsed laser deposition (PLD). In order to rule out concerns about the PLD plume-triggered oxygen vacancies generated in STO substrates, which might influence transport measurement, and to investigate the effect of epitaxial strain, we have used insulating NdGaO3 substrates. While both LTO and CTO single films are highly insulating, we have observed intriguing metal-insulator transitions (MIT) in the LTO/CTO superlattices depending on the global LTO/CTO thickness ratio and temperature. (Note that LTO/STO superlattices are metallic at all temperatures (2-300 K)). In this talk, we will discuss the origin of the MIT in the scheme of self compensation mechanism of d-electrons at the hetero-interface between LTO and CTO.

  1. 1020 steel coated with Ti/TiN by Cathodic Arc and Ion Implantation

    NASA Astrophysics Data System (ADS)

    Bermeo, F.; Quintana, J. P.; Kleiman, A.; Sequeda, F.; Márquez, A.

    2017-01-01

    TiN coatings have been widely studied in order to improve mechanical properties of steels. In this work, thin Ti/TiN films were prepared by plasma based immersion ion implantation and deposition (PBII&D) with a cathodic arc on AISI 1020 steel substrates. Substrates were exposed to the discharge during 1 min in vacuum for the deposition of a Tiunderlayer with the aim of improving the adhesion to the substrate. Then, a TiN layer was deposited during 6 min in a nitrogen environment at a pressure of 3xl0-4 mbar. Samples were obtained at room temperature and at 300 °C, and with or without ion implantation in order to analyze differences between the effects of each treatment on the tribological properties. The mechanical and tribological properties of the films were characterized. The coatings deposited by PBII&D at 300 °C presented the highest hardness and young modulus, the best wear resistance and corrosion performance.

  2. Fabrication of TiN/AlN/TiN tunnel junctions

    NASA Astrophysics Data System (ADS)

    Nakayama, Takeru; Naruse, Masato; Myoren, Hiroaki; Taino, Tohru

    2016-11-01

    We have fabricated TiN/AlN/TiN tunnel junctions with an epitaxial layer. The critical temperature of TiN can be changed in the range from 0.5 to 5.0 K. Therefore, it is easy to set 5.0 K as the target critical temperature. When a Superconducting Tunnel Junction (STJ) is operated as a photon detector, it is necessary to cool it to within 0.1 K of the critical temperature in consideration of the noise of the thermally stimulated currents. Because 0.3 K was desirable, as for the manufacture of general purpose photon detectors, the critical temperature 5.0 K. TiN and AlN films were deposited by dc and rf magnetron sputtering in a load-lock sputtering system at ambient substrate temperatures. The junctions have a gap voltage of Vg = 1.1 mV, and critical current density of Jc = 0.24 A/cm2, and Rsg/Rn of 7.2, and low subgap leakage current (Isub@ 500 μV = 180 nA). We report our experiment system, the manufacture method and the junction properties in this paper.

  3. Ti-Based Metal Matrix Composites Reinforced with TiB Particles

    DTIC Science & Technology

    2006-05-16

    Activity number and title 3. Determination of the thermomechanical processing and heat treatment conditions required to control and produce...additional to arc, high frequency induction source of heating which provides also STCU PROJECT Р-132 - QUARTERLY PROGRESS REPORT Q03...microstructure of Ti-64-B alloys. Activity number and title 3.Determination of the thermomechanical processing and heat treatment conditions required to

  4. Quantum Oscillations at LaTiO3/SrTiO3 Interfaces

    NASA Astrophysics Data System (ADS)

    Veit, Michael; Suzuki, Yuri

    Emergent metallic behavior at the interface of the Mott insulator LaTiO3 and the band insulator SrTiO3 was observed for the first time more than a decade ago. Since then the metallicity has been explained in terms of charge redistribution at the interface combined with lattice relaxation. However to date, Shubnikov de Haas oscillations have not been reported in this two dimensional metallic system. For ultrathin (3-4 unit cells) LaTiO3 thin films on SrTiO3, we report the observation of Shubnikov-de Haas oscillations whose frequency corresponds to a small Fermi pocket. Surprisingly the oscillation are only observed between 1 and 4 T. Above this range, the quantum limit is reached for this pocket so no more oscillations are observed. A Berry's phase of π is also detected in these oscillations. Additionally a strong in-plane anisotropic magnetoresistance was measured in the heterostructures which, along with the Berry's phase, is attributed to a giant Rashba coupling at the interface. This work is funded by a National Security Science Engineering Faculty Fellowship of the Department of Defense under N00014-15-1-0045.

  5. Equation of State Model Quality Study for Ti and Ti64.

    SciTech Connect

    Wills, Ann Elisabet; Sanchez, Jason James

    2015-02-01

    Titanium and the titanium alloy Ti64 (6% aluminum, 4% vanadium and the balance ti- tanium) are materials used in many technologically important applications. To be able to computationally investigate and design these applications, accurate Equations of State (EOS) are needed and in many cases also additional constitutive relations. This report describes what data is available for constructing EOS for these two materials, and also describes some references giving data for stress-strain constitutive models. We also give some suggestions for projects to achieve improved EOS and constitutive models. In an appendix, we present a study of the 'cloud formation' issue observed in the ALEGRA code. This issue was one of the motivating factors for this literature search of available data for constructing improved EOS for Ti and Ti64. However, the study shows that the cloud formation issue is only marginally connected to the quality of the EOS, and, in fact, is a physical behavior of the system in question. We give some suggestions for settings in, and improvements of, the ALEGRA code to address this computational di culty.

  6. Ab initio calculation of Ti NMR shieldings for titanium oxides and halides

    NASA Astrophysics Data System (ADS)

    Tossell, J. A.

    Titanium NMR shielding constants have been calculated using ab initio coupled Hartree-Fock perturbation theory and polarized double-zeta basis sets for TiF 4, TiF 62-, TiCI 4, Ti(OH) 4, Ti(OH 2) 64+, Ti(OH) 4O, and Ti(OH) 3O -. In all cases the calculations were performed at Hartree-Fuck energy-optimized geometries. For Ti(OH) 4 a S4-symmetry geometry with nonlinear ∠ TiOH was employed. Relative shieldings are in reasonable agreement with experiment for TiF 62-, TiCI 4, and Ti(OR) 4, where R = H or alkyl. Ti(OH 2) 64+ is predicted to be more highly shielded than Ti(OH) 4 by about 340 ppm. The five-coordinate complex Ti(OH) 4O, whose calculated structure matches well that measured by extended X-ray absorption fine structure in K 2O · TiO 2 · SiO 2 glass, is actually deshielded compared to Ti(OH) 4 by about 40 ppm. X-ray absorption-near-edge spectral energies have also been calculated for TiF 4, TiCI 4, Ti(OH) 4, and Ti(OH) 4O using an equivalent ionic core virtual-orbital method and the observed reduction in term energy for the five-coordinate species compared to Ti(OH) 4 has been reproduced. Replacement of the H atoms in Ti(OH) 4 by point charges has only a slight effect upon σTi, suggesting a possible means of incorporating second-neighbor effects in NMR calculations for condensed phases.

  7. Minimum ignition temperature of nano and micro Ti powder clouds in the presence of inert nano TiO2 powder.

    PubMed

    Yuan, Chunmiao; Amyotte, Paul R; Hossain, Md Nur; Li, Chang

    2014-06-30

    Minimum ignition temperature (MIT) of micro Ti powder increased gradually with increases in nano-sized TiO2 employed as an inertant. Solid TiO2 inertant significantly reduced ignition hazard of micro Ti powder in contact with hot surfaces. The MIT of nano Ti powder remained low (583 K), however, even with 90% TiO2. The MIT of micro Ti powder, when mixed with nano Ti powder at concentrations as low as 10%, decreased so dramatically that its application as a solid fuel may be possible. A simple MIT model was proposed for aggregate particle size estimation and better understanding of the inerting effect of nano TiO2 on MIT. Estimated particle size was 1.46-1.51 μm larger than that in the 20-L sphere due to poor dispersion in the BAM oven. Calculated MITs were lower than corresponding empirically determined values for micro Ti powder because nano-sized TiO2 coated the micro Ti powder, thereby decreasing its reaction kinetics. In the case of nano Ti powder, nano-sized TiO2 facilitated dispersion of nano Ti powder which resulted in a calculated MIT that was greater than the experimentally determined value.

  8. The influence of FeTi and NiTi intermetallide additions on high-temperature oxidation of permalloy alloy

    SciTech Connect

    Klimenko, V.N.; Lavrenko, V.A.; Panasyuk, O.A.; Blasova, O.V.; Protsenko, T.G.

    1995-11-01

    As a rule powder metallurgy Permalloy alloys are used in production of parts for electronic instruments. For the purpose of controlling the magnetic and electrical properties and also the wear (in the case of production of magnetic heads) and corrosion resistance appropriate additions of metals or such compounds as carbides and oxides are added to the alloy. In this work use of FeTi and NiTi intermetallides produced by reaction sintering of powders of pure metals in a protective atmosphere as alloying additions to Permalloy is recommended. The size of the original powders is less than 100 {mu}m. For reaction sintering at temperature 50{degrees}C above the eutectic temperature in the Ti-TiFe and TiNi-Ni systems was selected. The contents of titanium, iron, and oxygen in the FeTi alloy is 51.9, 45.7, and 2.4 wt.%, respectively, and of titanium, nickel, and oxygen in the NiTi alloy 59.6, 31.9, and 4.6 wt.%. High-temperature oxidation in air up to 1300{degrees}C with a rate of change in temperature of 15{degrees}C of type 78N Permalloy with additions of FeTi and NiTi alloys was investigated with use of methods of differential thermal and differential thermogravimetric analyses on an OD-103 derivatograph under nonisothermal conditions. The reaction products were studied by x-ray diffraction phase analysis on a DRON-3 instrument in CoK{sub {alpha}}-radiation. Pure 78N alloy powder with a composition of 78.1% Ni + 19.3% Fe (specimen 1) and also with additions of 1% FeTi (specimen 2) and 1% NiTi (specimen 3) were subjected to oxidation.

  9. Novel preparation of carbon-TiO2 composites.

    PubMed

    Elizalde-González, María P; García-Díaz, Esmeralda; Sabinas-Hernández, Sergio A

    2013-12-15

    Carbon-TiO2 sulfated composites were obtained from TiOSO4 · xH2O and glycerol as the TiO2 and carbon sources, respectively. The precursor xerogels were prepared in a one-step ultrasonic-assisted sol-gel reaction, followed by thermal treatment at 400°C under a nitrogen atmosphere to produce carbon-TiO2 sulfated composites. XRD, micro-Raman, SEM, and TEM studies showed that the composites consisted of nanocrystalline clusters of TiO2 and carbon. Ultrasonication in glycerol promoted the crystallinity of the xerogel precursors prior to thermal treatment. X-ray powder diffraction and Raman spectroscopy studies confirmed that glycerol also facilitated the formation of small crystallites. The band gaps of carbon-TiO2 composites with two different carbon loadings were found to be 3.06 eV and 2.69 eV. By contrast, the band gap of TiO2 prepared by our method was 3.53 eV. Calcination of the precursors led to an unusual increase in the specific surface and porosity of the composites compared to TiO2. The photocatalytic activities of the prepared composites were tested in a decomposition assay of Acid Orange 7. The reaction was monitored by UV-vis spectrophotometry and by LC-ESI-(Qq)-TOF-MS-DAD. Some intermediate species were identified by LC-ESI-QTOF-MS.

  10. Energetics of point defects in {gamma}-TiAl

    SciTech Connect

    Raju, S.; Mohandas, E.; Raghunathan, V.S.

    1996-02-15

    {gamma}TiAl has been receiving a great deal of attention in recent times owing to its industrial importance. This structural intermetallic is a candidate material for high temperature aerospace applications. Therefore, a study of point defect properties is useful in elucidating its physical metallurgy. In this brief communication, the authors discuss the vacancy and antisite defect properties of {gamma}-TiAl.

  11. Biocompatilibity-related surface characteristics of oxidized NiTi.

    PubMed

    Danilov, Anatoli; Tuukkanen, Tuomas; Tuukkanen, Juha; Jämsä, Timo

    2007-09-15

    In the present study, we examined the effect of NiTi oxidation on material surface characteristics related to biocompatibility. Correspondence between electron work function (EWF) and adhesive force predicted by electron theory of adsorption as well as the effect of surface mechanical stress on the adhesive force were studied on the nonoxidized and oxidized at 350, 450, and 600 degrees C NiTi alloy for medical application. The adhesive force generated by the material surface towards the drops of alpha-minimal essential medium (alpha-MEM) was used as a characteristic of NiTi adsorption properties. The study showed that variations in EWF and mechanical stress caused by surface treatment were accompanied by variations in adhesive force. NiTi oxidation at all temperatures used gave rise to decrease in adhesive force and surface stress values in comparison to the nonoxidized state. In contrary, the EWF value revealed increase under the same condition. Variations in surface oxide layer thickness and its phase composition were also followed. The important role of oxide crystallite size in EWF values within the range of crystallite dimensions typical for NiTi surface oxide as an instrument for the fine regulation of NiTi adsorption properties was demonstrated. The comparative oxidation of pure titanium and NiTi showed that the effect of Ni on the EWF value of NiTi surface oxide is negligible.

  12. Dielectrical properties of PANI/TiO2 nanocomposites

    NASA Astrophysics Data System (ADS)

    Chaturmukha, V. S.; Naveen, C. S.; Rajeeva, M. P.; Avinash, B. S.; Jayanna, H. S.; Lamani, Ashok R.

    2016-05-01

    Conducting polyaniline/titanium dioxide (PANI/TiO2) composites have been succesfully synthesized by insitu polymerization technique. The PANI/TiO2 nanocomposites of different compositions were prepared by varying weight percentage of TiO2 nanoparticles such as 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% into the fixed amount of the aniline monomer. The prepared powder samples were characterized by X-ray diffractometer (XRD) and Scanning electron microscope (SEM). The intensity of diffraction peaks for PANI/TiO2 composites is lower than that for TiO2. SEM pictures show that the nanocomposite were prepared in the form of long PANi chains decorated with TiO2 nanoparticles. The dielectric properties and AC conductivity were studied in the frequency range1K Hz-10M Hz. At higher frequencies, the composites exhibit almost zero dielectric loss and maximum value of σac is found for a concentration of 20 wt% TiO2 in polyaniline. The interface between polyaniline and TiO2 plays an important role in yielding a large dielectric constant in nanocomposites.

  13. Experimental Micromechanics Study of Lamellar TiA1

    DTIC Science & Technology

    2007-02-15

    of the 2005 SEM Annual Conference & Exposition, Portland, OR USA, June 7-9, 2005 "Brazilian Tests in Lamellar TiAr ", F.P. Chiang, Y. Ding, A.Ho, A.H...Experimental Mechanics, July 1-6, Alexandroupolis, Greece, 2007 "Experimental Micromechanics Study of Lamellar TiAr ", Fu-pen Chiang, Gunes Uzer, Andrew H

  14. Corrosion of NiTi Wires with Cracked Oxide Layer

    NASA Astrophysics Data System (ADS)

    Racek, Jan; Šittner, Petr; Heller, Luděk; Pilch, Jan; Petrenec, Martin; Sedlák, Petr

    2014-07-01

    Corrosion behavior of superelastic NiTi shape memory alloy wires with cracked TiO2 surface oxide layers was investigated by electrochemical corrosion tests (Electrochemical Impedance Spectroscopy, Open Circuit Potential, and Potentiodynamic Polarization) on wires bent into U-shapes of various bending radii. Cracks within the oxide on the surface of the bent wires were observed by FIB-SEM and TEM methods. The density and width of the surface oxide cracks dramatically increase with decreasing bending radius. The results of electrochemical experiments consistently show that corrosion properties of NiTi wires with cracked oxide layers (static load keeps the cracks opened) are inferior compared to the corrosion properties of the straight NiTi wires covered by virgin uncracked oxides. Out of the three methods employed, the Electrochemical Impedance Spectroscopy seems to be the most appropriate test for the electrochemical characterization of the cracked oxide layers, since the impedance curves (Nyquist plot) of differently bent NiTi wires can be associated with increasing state of the surface cracking and since the NiTi wires are exposed to similar conditions as the surfaces of NiTi implants in human body. On the other hand, the potentiodynamic polarization test accelerates the corrosion processes and provides clear evidence that the corrosion resistance of bent superelastic NiTi wires degrades with oxide cracking.

  15. On the low-lying states of TiN

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.

    1983-01-01

    A series of CAS SCF and multi-reference CI calculations are used to describe the lowest states of TiN. The bonding in all states is described as a triple bond involving the Ti 3d orbitals. The system has some ionic character as seen from both population analysis and dipole moment. The origins of the excited states are discussed.

  16. Oxidation studies on small atom doped TI*5*SI*3*

    SciTech Connect

    Thom, Andrew

    1995-09-26

    This report described the oxidation and oxidation resistance of Ti5Si3, along with a discussion on general material properties. Single crystal studies of Ti5Si3Zx are included.

  17. Mg/Ti multilayers: Structural and hydrogen absorption properties

    NASA Astrophysics Data System (ADS)

    Baldi, A.; Pálsson, G. K.; Gonzalez-Silveira, M.; Schreuders, H.; Slaman, M.; Rector, J. H.; Krishnan, G.; Kooi, B. J.; Walker, G. S.; Fay, M. W.; Hjörvarsson, B.; Wijngaarden, R. J.; Dam, B.; Griessen, R.

    2010-06-01

    Mg-Ti alloys have uncommon optical and hydrogen absorbing properties, originating from a “spinodal-like” microstructure with a small degree of chemical short-range order in the atomic distribution. In the present study we artificially engineer short-range order by depositing Pd-capped Mg/Ti multilayers with different periodicities. Notwithstanding the large lattice mismatch between Mg and Ti, the as-deposited metallic multilayers show good structural coherence. On exposure to H2 gas a two-step hydrogenation process occurs with the Ti layers forming the hydride before Mg. From in situ measurements of the bilayer thickness Λ at different hydrogen pressures, we observe large out-of-plane expansions of Mg and Ti layers on hydrogenation, indicating strong plastic deformations in the films and a consequent shortening of the coherence length. On unloading at room temperature in air, hydrogen atoms remain trapped in the Ti layers due to kinetic constraints. Such loading/unloading sequence can be explained in terms of the different thermodynamic properties of hydrogen in Mg and Ti, as shown by diffusion calculations on a model multilayered systems. Absorption isotherms measured by hydrogenography can be interpreted as a result of the elastic clamping arising from strongly bonded Mg/Pd and broken Mg/Ti interfaces.

  18. Precipitation evolution in a Ti-free and Ti-containing stainless maraging steel.

    PubMed

    Schober, M; Schnitzer, R; Leitner, H

    2009-04-01

    Stainless maraging steels have a Cr content higher than 12wt% and show a excellent combination of high strength and ductility, which make them attractive for use in machinery fields and aircraft applications. The massive increase of strength during ageing treatment of maraging steels is related to a precipitation sequence of various nm-scaled intermetallic phases. The peak hardness especially in Ti-containing maraging steels can be reached after short-time ageing at temperatures around 500 degrees C. However, precipitation reactions in different stainless maraging steels are not fully understood, especially the evolution from clustering over growing to coarsening. In the present work a commercial maraging steel and a Ti-containing model alloy are investigated and compared to each other. The steels were isothermally heat treated at 525 degrees C for a range of times. Special emphasis was laid on the correlation of hardness to the formation and presence of different kinds of precipitates. The isothermal aged samples were investigated by using two advanced three-dimensional energy compensated atom probes (LEAP and 3DAP) both in voltage mode and in laser mode. The atom probe data were correlated to standard hardness measurements. The results show that the partial substitution of Al by Ti results in a different precipitation behaviour. While the Ti-free maraging steel exhibit only one type of precipitate, the Ti-containing grade shows a change in the type of precipitates during ageing. However, this change leads to an accelerated coarsening and thus to a faster drop in hardness.

  19. -Ti-Based Homogeneous and Bi-layered Composites

    NASA Astrophysics Data System (ADS)

    Gupta, Neha; Parameswaran, Venkitanarayanan; Basu, Bikramjit

    2014-09-01

    The growing threats due to increased use of small-caliber armor piercing projectiles demand the development of new light-weight body armor materials. In this context, TiB2 appears to be a promising ceramic material. However, poor sinterability and low fracture toughness remain two major issues for TiB2. In order to address these issues together, Ti as a sinter-aid is used to develop TiB2-( x wt pct Ti), ( x = 10, 20) homogeneous composites and a bi-layered composite (BLC) with each layer having Ti content of 10 and 20 wt pct. The present study uniquely demonstrates the efficacy of two-stage spark plasma sintering route to develop dense TiB2-Ti composites with an excellent combination of nanoscale hardness (~36 GPa) and indentation fracture toughness (~12 MPa m1/2). In case of BLC, these properties are not compromised w.r.t. homogeneous composites, suggesting the retention of baseline material properties even in the bi-layer design due to optimal relief of residual stresses. The better indentation toughness of TiB2-(10 wt pct Ti) and TiB2-(20 wt pct Ti) composites can be attributed to the observed crack deflection/arrest, indicating better damage tolerance. Transmission electron microscope investigation reveals the presence of dense dislocation networks and deformation twins in α-Ti at the grain boundaries and triple pockets, surrounded by TiB2 grains. The dynamic strength of around 4 GPa has been measured using Split Hopkinson Pressure Bar tests in a reproducible manner at strain rates of the order of 600 s-1. The damage progression under high strain rate has been investigated by acquiring real time images for the entire test duration using ultra-high speed imaging. An attempt has been made to establish microstructure-property correlation and a simple analysis based on Mohr-Coulomb theory is used to rationalize the measured strength properties.

  20. Atomic-scale investigation of a new phase transformation process in TiO2 nanofibers.

    PubMed

    Lei, Yimin; Li, Jian; Wang, Zhan; Sun, Jun; Chen, Fuyi; Liu, Hongwei; Ma, Xiaohua; Liu, Zongwen

    2017-03-21

    Crystallography of phase transformation combining transmission electron microscopy (TEM) with in situ heating techniques and X-ray diffraction (XRD) can provide critical information regarding solid-state phase transitions and the transition-induced interfaces in TiO2 nanomaterials theoretically and experimentally. Two types of reduced titanium oxides (Ti3O5, Ti6O11) are found during ex situ and in situ heating of TiO2 (B) nanofibers with a specific morphology of the {100} single form (SF) in air and vacuum. The results indicate that the phase transformation process from TiO2 (B) follows the TiO2 (B) → Ti3O5 → Ti6O11 → anatase sequence for the nanofibers with the {100} SF. The occurrence of such a phase transition is selective to the morphology of TiO2 (B) nanofibers. The corresponding orientation relationships (COR) between the four phases are revealed according to the TEM characterization. Four types of coherent interfaces, following the CORs are also found. They are TiO2 (B)/Ti3O5, TiO2 (B)/Ti6O11, Ti6O11/anatase and TiO2 (B)/anatase respectively. The habit plane for the TiO2 (B) to Ti3O5 transition is calculated as the {100}TB by using the invariant line model. The detailed atomic transformation mechanism is elucidated based on the crystallographic features of the four phases.

  1. Constructing bulk defective perovskite SrTiO3 nanocubes for high performance photocatalysts.

    PubMed

    Zhang, Guoqiang; Jiang, Wenshuai; Hua, Shixin; Zhao, Haifeng; Zhang, Ligong; Sun, Zaicheng

    2016-09-29

    Defects (Ti(3+) or oxygen vacancies) have been demonstrated to promote the charge separation process in TiO2 based photocatalysts. Particularly, the bulk defects within a certain concentration can give a great enhancement for both light absorption and charge separation efficiency. In this report, we explored a one-step molten salts route to synthesize SrTiO3 nanocubes with bulk defects (Ti(3+) doped) by using SrCO3 as a Sr source, and TiO2 and Ti powder as Ti sources. The amount of defects can be tuned by changing the molar ratio of Ti/TiO2. The corresponding bandgap of SrTiO3 can be changed from 3.29 to 2.73 eV with the increase of defects. X-ray diffraction and electron microscopy disclose that SrTiO3 is highly crystalline and has a cubic morphology. X-ray photoelectron spectroscopy and electron paramagnetic resonance indicate that the as-prepared SrTiO3 is close to the Ti(3+) doped SrTiO3. Surface photovoltage spectroscopy (SPS) and field-induced SPS confirm that Ti(3+) doping in the SrTiO3 turns it from an n-type semiconductor to p-type. The SrTiO3 with an optimal amount of defects exhibits highly enhanced photocatalytic performance. An excess amount of defects results in a weak SPS response and photocatalytic performance.

  2. Structural and magnetic properties of Ti12M clusters (M=Sc to Zn)

    NASA Astrophysics Data System (ADS)

    Sun, Houqian; Xu, Ning

    2016-12-01

    The geometries, electronic, and magnetic properties of the 3d atom doped icosahedron (ICO) Ti12M (M=Sc to Zn), where a dopant atom replaces either the centra l(Ti12Mc) or surface (Ti12Ms) Ti atom in ICO Ti13 cluster, have been systematically investigated by using the density functional theory. The structures of all the optimized Ti12Mc and Ti12Ms clusters are distorted ICO. Sc, Ni, Cu, and Zn atoms prefer to displace surface Ti atom, V, Cr, Mn, and Fe atoms prefer to displace central Ti atom. The position of impurity atom depends on the strength of the interaction between the central atom and the surface atoms. As compared to the pure Ti13 cluster, Ti12Mc and Ti12Ms (M=V, Fe, Co, and Ni) clusters are more stable, Ti12Mc and Ti12Ms (M=Sc, Cr, Mn, Cu, and Zn) are less stable. Both Ti12Nis and Ti12Nic are magic clusters, which originate from their electronic as well as geometric closed shells. Because the exchange interaction prevails over the crystal field in Ti12M clusters, the valence electrons fill molecular orbitals in terms of Hund's rule of maximum spin.

  3. Ti/Al Design/Cost Trade-Off Analysis

    DTIC Science & Technology

    1978-10-01

    4099 5705 41 6388 9304 (44/Rev) 46 8258 9761 Speed - 13, 533 rpm (100% N) 31 10,000 2T I42/Rev Material Clamped atI a goo - Rene ’ 80 DovetailI 0TiAl...as the F1O1 Stage 4 Blade Materiel. 41 9. Maximum Blade and Dovetail Stresses for Ti-36-5Nb F1O0 Fourth-Stage Compressor Blade. 42 10. Strain Range of...Tensile Properties. 92 A-4. Ti-36A1-5Nb rreep and Stress Rupture Results. 93 A-5. Ti-36AI-5Nb Strain Control LCF Results. 93 A-6. HCF Results on Ti

  4. Structure of Al-Ti-C master alloys

    NASA Astrophysics Data System (ADS)

    Popova, E. A.; Brodova, I. G.; Yablonskikh, T. I.; Shirinkina, I. G.; Barbin, N. M.; Bodrova, L. E.; Dolmatov, A. V.; Pastukhov, E. A.; Vatolin, N. A.; Chebykin, V. V.; Chernov, Ya. B.

    2011-06-01

    A binary Al-Ti master alloy of hyperperitectic composition, whose structural characteristics ensure high modifying efficiency, has been prepared by the aluminothermy method. The treatment of the alloy by low-frequency vibrations (LFVs) and its interaction with the carbon emitter of LFVs in the process of crystallization lead to the formation of a ternary Al-Ti-C alloy containing titanium aluminide Al3Ti and titanium carbide TiC. The presence of these phases creates favorable conditions for the formation of solidification nuclei in the aluminum melt when using a ternary master alloy as a modifier. A comparison of the efficiency of the structure refinement when using experimental master alloys and the standard Al-Ti master alloy poured into a metallic chill mold has been performed.

  5. Ellipsoidal TiO2 hierarchitectures with enhanced photovoltaic performance.

    PubMed

    Peng, Wenqin; Yanagida, Masatoshi; Chen, Han; Han, Liyuan

    2012-04-23

    Hierarchical TiO(2) ellipsoids 250-500 nm in size have been synthesized on a large scale by a template-free hydrothermal route. The submicrometer-sized hierarchitectures are assembled from highly crystallized anatase nanorods about 17 nm in diameter with macroporous cavities on the outer shells. Based on the time-dependent morphological evolution under hydrothermal conditions, an oriented attachment process is proposed to explain formation of the hierarchical structures. Such hierarchical TiO(2) not only adsorbs large amounts of dye molecules due to high surface area, but also shows good light scattering caused by the submicrometer size. The TiO(2) hierarchitectures were deposited on top of a transparent TiO(2) nanocrystalline main layer to construct a double-layered photoanode for dye-sensitized solar cell (DSC) application, exhibiting enhanced light harvesting and power-conversion efficiency compared to a commercial TiO(2)-based electrode.

  6. Ubiquitous isotopic anomalies in Ti from normal Allende inclusions

    NASA Technical Reports Server (NTRS)

    Niemeyer, S.; Lugmair, G. W.

    1981-01-01

    A novel technique for the high-precision isotopic analysis of titanium was applied to three terrestrial rocks and coarse- and fine-grained Allende inclusions. Repeated analyses of the three terrestrial rocks gave excellent agreement with a Ti metal standard. All seven Allende inclusions were previously determined to contain isotopically normal Nd and/or Sm, indicating that none belongs to a small group of peculiar intrusions. The discovery of widespread Ti isotopic anomalies in normal Allende inclusions establishes Ti as the first non-noble gas element studied since oxygen to show such isotopic heterogeneity. A survey of nucleosynthetic origins of Ti isotopes suggests that the dominant Ti-50 excesses in these inclusions are due to the relative enrichment of isotopes synthesized during hydrostatic burning in, or near, the core of a massive star.

  7. Crystallography of Martensite in TiAu Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Inamura, T.; Hosoda, H.

    2011-01-01

    The twin structure, habit plane orientation, and morphology of B19 martensite in TiAu, which is a candidate shape memory alloy (SMA) for high-temperature and biomedical applications, were investigated by conventional transmission electron microscopy. Almost all internal twins were {111} type I twins as lattice-invariant deformation (LID). The <211> type II twin was scarcely observed in TiAu, unlike in TiPd and TiPt SMAs. The habit plane roughly corresponded to the twinning plane ( K 1 plane) of the <211> type II twin because of the superb lattice parameter ratio of TiAu. As a result, an energy-minimizing microstructure referred to as "twins within twins" appears as the major microstructure. The selection rules for the twinning of LID are also discussed considering the results of extensive studies on LID in SMAs.

  8. Design of Heusler Precipitation Strengthened NiTi- and PdTi-Base SMAs for Cyclic Performance

    NASA Astrophysics Data System (ADS)

    Frankel, Dana J.; Olson, Gregory B.

    2015-06-01

    For a wide range of actuation applications, the performance of NiTi-based shape memory alloys is limited by cyclic instability associated with accommodation slip. For medical applications, low-Ni compositions are also desirable. Increasing yield strength via precipitation of a coherent nanoscale Ni2TiAl-type Heusler phase from a supersaturated B2 matrix is an effective approach for eliminating slip in order to improve the stability of the functional response and increase the structural fatigue life. Quaternary additions that partition into the L21 Heusler phase, such as Zr or Pd, are favorable for reducing interphase misfit and maintaining coherency during aging. Phase relations and precipitation kinetics in quaternary Ni(TiZrAl), low-Ni (PdNi)(TiAl), and Ni-free (PdFe)(TiAl) systems are summarized from TEM and atom probe tomography data in the literature. Strengthening behavior during isothermal aging is compared in the NiTiZrAl and PdNiTiAl systems, and recent work characterizing a high-strength, low-Ni "Hybrid" (PdNi)(TiZrAl) alloy is presented. A systems design approach is taken in which an optimal microstructure for peak strengthening is identified while other property objectives such as transformation temperature, misfit, radiopacity, and biocompatibility are satisfied.

  9. Fabrication of TiO{sub 2} Thick Film for Photocatalyst from Commercial TiO{sub 2} Powder

    SciTech Connect

    Asteti, S. Fuji; Syarif, D. Gustaman

    2008-03-17

    Photocatalytic activity of TiO{sub 2} thick film ceramics made of commercial TiO{sub 2} powder has been studied. The TiO{sub 2} powder was nano sized one that was derived from dried TiO{sub 2} suspension. The TiO{sub 2} suspension was made by pouring some blended commercial TiO{sub 2} powder into some amount of water. The paste of TiO{sub 2} was made by mixing the nano sized TiO{sub 2} powder with organic vehicle and glass frit. The paste was spread on a glass substrate. The paste was dried at 100 deg. C and heated at different temperatures (400 deg. C and 500 deg. C) for 60 minutes to produce thick film ceramics. The photocatalytic activity of these films was evaluated by measuring the concentration of a solution of methylene blue where the thick films were inside after being illuminated by UV light at various periods of times. The initial concentration of the methylene blue solution was 5 ppm. Structural analyses were carried out by X-ray diffraction (XRD). The XRD analyses showed that the produced thick film ceramic had mainly crystal structure of anatase. According to the photocatalytical data, it was known that the produced thick film ceramics were photocatalyst which were capable of decomposing an organic compound such as the methylene blue.

  10. Effective nitrogen doping into TiO2 (N-TiO2) for visible light response photocatalysis.

    PubMed

    Yoshida, Tomoko; Niimi, Satoshi; Yamamoto, Muneaki; Nomoto, Toyokazu; Yagi, Shinya

    2015-06-01

    The thickness-controlled TiO2 thin films are fabricated by the pulsed laser deposition (PLD) method. These samples function as photocatalysts under UV light irradiation and the reaction rate depends on the TiO2 thickness, i.e., with an increase of thickness, it increases to the maximum, followed by decreasing to be constant. Such variation of the reaction rate is fundamentally explained by the competitive production and annihilation processes of photogenerated electrons and holes in TiO2 films, and the optimum TiO2 thickness is estimated to be ca. 10nm. We also tried to dope nitrogen into the effective depth region (ca. 10nm) of TiO2 by an ion implantation technique. The nitrogen doped TiO2 enhanced photocatalytic activity under visible-light irradiation. XANES and XPS analyses indicated two types of chemical state of nitrogen, one photo-catalytically active N substituting the O sites and the other inactive NOx (1⩽x⩽2) species. In the valence band XPS spectrum of the high active sample, the additional electronic states were observed just above the valence band edge of a TiO2. The electronic state would be originated from the substituting nitrogen and be responsible for the band gap narrowing, i.e., visible light response of TiO2 photocatalysts.

  11. 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.

  12. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V.

    PubMed

    Mahdipoor, M S; Kirols, H S; Kevorkov, D; Jedrzejowski, P; Medraj, M

    2015-09-22

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER ~ V(n), where the speed exponent is 7-9 for Ti6Al4V and 11-13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603 μm. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl.

  13. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Mahdipoor, M. S.; Kirols, H. S.; Kevorkov, D.; Jedrzejowski, P.; Medraj, M.

    2015-09-01

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER ~ Vn, where the speed exponent is 7-9 for Ti6Al4V and 11-13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603 μm. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl.

  14. Photoelectrocatalytic properties of nitrogen doped TiO2/Ti photoelectrode prepared by plasma based ion implantation under visible light.

    PubMed

    Han, Lei; Xin, Yanjun; Liu, Huiling; Ma, Xinxin; Tang, Guangze

    2010-03-15

    Nitrogen doped TiO(2)/Ti photoelectrodes were prepared by a sequence of anodization and plasma based ion implantation (PBII). The properties of this photoelectrode were characterized by scanning electronic microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), Ultra violet/visible light diffuse reflectance spectra (UV/vis/DRS), surface photovoltage (SPV), etc. Photoelectrocatalytic (PEC) performance of N-doped TiO(2)/Ti photoelectrode was tested under visible light irradiation. Their photocatalytic activity was evaluated by degradation of Rhodamine B (Rh.B). The results of XPS showed that nitrogen element was in form of three species, i.e. beta-N, molecular gamma-N and O-Ti-N, which existed in the lattices of TiO(2) and gaps between molecules. The results of UV/vis/DRS spectra and SPV revealed that proper doping of nitrogen could expand the response of photoelectrodes towards visible light and diminish the recombination of photo-generated holes and electrons, respectively. The photoelectrocatalytic activity of N-doped TiO(2)/Ti photoelectrodes was superior to those of undoped one under visible light region irradiation.

  15. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V

    PubMed Central

    Mahdipoor, M.S.; Kirols, H.S.; Kevorkov, D.; Jedrzejowski, P.; Medraj, M.

    2015-01-01

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER ~ Vn, where the speed exponent is 7–9 for Ti6Al4V and 11–13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603 μm. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl. PMID:26391370

  16. Hyaluronic acid immobilization on the poly-allylamine coated nano-network TiO2 surface.

    PubMed

    Shim, Jae-Won; Lee, Kang; Jeong, Moon-Jin; Jung, Sang-Chul; Kim, Byung-Hoon

    2011-08-01

    Recently, biocompatibility report revealed that the TiO2 nano-network (TiO2 NT) structure has much higher cells colonization than the native TiO2 on Ti surface. In this study, we prepared the hyaluronic acid (HA) immobilized TiO2 NT layer by plasma surface modification and then evaluated biological behavior of MC3T3-E1 on the Ti, TiO2 NT and TiO2 NT/NH2/HA surface. The cell viability tests revealed slightly enhanced viability on the TiO2 NT/NH2/HA surfaces than on the untreated Ti surfaces.

  17. XANES and micro-Raman spectroscopy study of the barium titanosilicates BaTiSi2O7 and BaTiSi4O11

    NASA Astrophysics Data System (ADS)

    Viani, A.; Pollastri, S.; Macova, P.; Palermo, A.; Peréz-Estébanez, M.; Gualtieri, A. F.

    2016-04-01

    The coordination environment around Ti4+ in the photoluminescent compound BaTiSi2O7 and in BaTiSi4O11 was investigated with X-ray absorption near-edge structure spectroscopy and micro-Raman spectroscopy. The presence of VTi in TiO5 pyramidal units with one short Ti-O bond involving the apical oxygen was detected in both compounds. Interpretation of the vibrational signal from the silicate framework suggested that BaTiSi4O11 is a metasilicate containing building units of SiO4 tetrahedra, which are larger than in other barium titanosilicates. These results confirmed the same structural environment of Ti4+ as recently disclosed by structure refinement of BaTiSi2O7 and provided new insights into the unknown structure of BaTiSi4O11 in the light of the study of its physical properties as potential functional material.

  18. Dual phase Li4Ti5O12-TiO2 hierarchical hollow microspheres as anode materials for high rate lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Kunxu; Hu, Guoxin

    2017-01-01

    Dual phase Li4Ti5O12-TiO2 hierarchical hollow microspheres composed of nanosheets are successfully fabricated by the calcination of hydrothermal product obtained from lithium peroxotitanate complex solution. Low-cost industrial H2TiO3 particles are chosen as titanium sources, which is significant for the inexpensive and large-scale production of Li4Ti5O12-TiO2 composite material. The Li4Ti5O12-TiO2 electrode yields excellent rate capability (151, 139 and 134 mA h g-1 at 10, 20 and 25 C, respectively) and good cycling stability (96% capacity retention after 500 cycles at 10 C). The mesoporous hierarchical morphology and high grain boundary density are likely the contributing factors to the excellent electrochemical performance of Li4Ti5O12-TiO2 composite.

  19. Synthesis of TiN-BaTiO3 core-shell structured ceramics: A new approach to ferroelectric thin-film formation

    NASA Astrophysics Data System (ADS)

    Fujimoto, Masayuki; Cheng, Ikung; Kao, Yuju; Kuwabara, Satoshi; Sano, Tatsuo; Matsumoto, Hiroaki

    2015-01-01

    This is the first report of the topotaxial growth of perovskite BaTiO3 on TiN by a solid-state reaction between BaCO3 and TiN. The sintering of the BaTiO3 powder in a conventional controlled-atmosphere continuous furnace is also quite unique in the sense that it mainly involves the mass transfer of BaTiO3 shell layers by diffusion. Consequently, the TiN core does not actually contribute to the sintering process, as its diffusion activity is very low. Thus, the obtained core-shell structured TiN-BaTiO3 ceramic is rather unique in having a retained TiN core that can act as a noncontact metallic electrode.

  20. Crystalline structure of TiC ultrathin layers formed on highly oriented pyrolytic graphite by chemical reaction from Ti/graphite system

    NASA Astrophysics Data System (ADS)

    Nakatsuka, Osamu; Hisada, Kenji; Oida, Satoshi; Sakai, Akira; Zaima, Shigeaki

    2016-06-01

    We have investigated the atomic-scale reaction between a Ti thin layer and highly oriented pyrolytic graphite (HOPG) mainly by scanning tunneling microscopy. A deposited Ti layer shows an epitaxial orientation structure on a HOPG substrate even in room-temperature deposition, while the bonding between Ti and HOPG is very weak. The chemical reaction between Ti and HOPG takes place, and epitaxial TiC domains on HOPG are formed for annealing at above 600 °C. The TiC domains shows a smooth surface corresponding to the TiC(111) plane after annealing at 700 °C. The formation of TiC(001) facets and significant surface roughening of not only TiC but also HOPG substrates are observed for annealing at as high as 900 °C.

  1. WO x , SiO2, TiO2/Ti composites, fabricated by means of plasma electrolytic oxidation, as catalysts of ethanol dehydration into ethylene

    NASA Astrophysics Data System (ADS)

    Vasilyeva, M. S.; Rudnev, V. S.; Tulush, A. I.; Nedozorov, P. M.; Ustinov, A. Yu.

    2015-06-01

    WO3, SiO2, TiO2/Ti composites are fabricated and studied by means of X-ray diffraction analysis and X-ray photoelectron and IR spectroscopy. It is established that the surface of an oxide coating contains up to 2% of tungsten in the composition of WO3, SiO2, and TiO2, along with carbon compounds. Data on the catalytic activity of SiO2, TiO2/Ti and WO3, SiO2, TiO2/Ti composites in ethanol dehydration are obtained. In the case of WO3, SiO2, TiO2/Ti composites, the degree of conversion and the selectivity of ethanol transformation into ethylene at 480°C reaches 97%.

  2. Improved performance of dye-sensitized solar cell based on TiO2 photoanode with FTO glass and film both treated by TiCl4

    NASA Astrophysics Data System (ADS)

    Li, Jinlun; Zhang, Haiyan; Wang, Wenguang; Qian, Yannan; Li, Zhenghui

    2016-11-01

    The dye-sensitized solar cell (DSSC) based on TiO2 photoanode with FTO glass and TiO2 film co-treated by TiCl4 were fabricated. The effects of TiCl4 treatment on the photovoltaic performance of the DSSCs were investigated. TiCl4 treatment of the FTO glass resulted in the formation of a compact TiO2 thin layer on its surface, which could increase the electron collection efficiency. Meanwhile, TiCl4 treatment of the TiO2 film could fill gaps between nanoparticles in the TiO2 film, leading to better electron transfer. These advantages make the DSSC exhibit a highest conversion efficiency of 3.34% under a simulated solar irradiation with an intensity of 100 mW/cm2 (1 sun), increased by 38% compared with that of the untreated DSSC.

  3. Role of interfacial layer on complementary resistive switching in the TiN/HfO{sub x}/TiN resistive memory device

    SciTech Connect

    Zhang, H. Z.; Ang, D. S. Gu, C. J.; Yew, K. S.; Wang, X. P.; Lo, G. Q.

    2014-12-01

    The role of the bottom interfacial layer (IL) in enabling stable complementary resistive switching (CRS) in the TiN/HfO{sub x}/IL/TiN resistive memory device is revealed. Stable CRS is obtained for the TiN/HfO{sub x}/IL/TiN device, where a bottom IL comprising Hf and Ti sub-oxides resulted from the oxidation of TiN during the initial stages of atomic-layer deposition of HfO{sub x} layer. In the TiN/HfO{sub x}/Pt device, where formation of the bottom IL is suppressed by the inert Pt metal, no CRS is observed. Oxygen-ion exchange between IL and the conductive path in HfO{sub x} layer is proposed to have caused the complementary bipolar switching behavior observed in the TiN/HfO{sub x}/IL/TiN device.

  4. Commercially pure titanium (cp-Ti) versus titanium alloy (Ti6Al4V) materials as bone anchored implants - Is one truly better than the other?

    PubMed

    Shah, Furqan A; Trobos, Margarita; Thomsen, Peter; Palmquist, Anders

    2016-05-01

    Commercially pure titanium (cp-Ti) and titanium alloys (typically Ti6Al4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally, influenced material selection for different clinical applications: predominantly Ti6Al4V in orthopaedics while cp-Ti in dentistry. This paper attempts to address three important questions: (i) To what extent do the surface properties differ when cp-Ti and Ti6Al4V materials are manufactured with the same processing technique?, (ii) Does bone tissue respond differently to the two materials, and (iii) Do bacteria responsible for causing biomaterial-associated infections respond differently to the two materials? It is concluded that: (i) Machined cp-Ti and Ti6Al4V exhibit similar surface morphology, topography, phase composition and chemistry, (ii) Under experimental conditions, cp-Ti and Ti6Al4V demonstrate similar osseointegration and biomechanical anchorage, and (iii) Experiments in vitro fail to disclose differences between cp-Ti and Ti6Al4V to harbour Staphylococcus epidermidis growth. No clinical comparative studies exist which could determine if long-term, clinical differences exist between the two types of bulk materials. It is debatable whether cp-Ti or Ti6Al4V exhibit superiority over the other, and further comparative studies, particularly in a clinical setting, are required.

  5. Degradation of TiB2/TiC Composites in Liquid Nd and Molten NdF3-LiF-Nd2O3 System

    NASA Astrophysics Data System (ADS)

    Wang, Huihua; Su, Lijuan; Wang, Deyong; Qu, Tianpeng; Tu, Ganfeng

    2016-11-01

    The degradation of titanium diboride (TiB2)/titanium carbide (TiC) composites in the liquid Nd and molten NdF3-Nd2O3-LiF salts is investigated at 1,060 °C, respectively. The penetration of TiB2/TiC composites by liquid Nd mainly depended on the grain boundaries and residual pores, even if the coherent interface is formed between TiB2 and TiC. The oxidation of TiB2 led to further interfacial chemistry reactions, which speeded up the degradation of TiB2/TiC composites at the initial stage in NdF3 -LiF-Nd2O3 system. After that, the degradation was slowed because of the formation of diffusion boundary layer, and then chemical penetration was replaced gradually by the physical penetration. The dissolved Ti in liquid Nd and NdF3-LiF-Nd2O3 melts are used to evaluate the corrosion rate of TiB2/TiC composites, and the calculated values were about 0.56 and 7.8 mm/year, respectively. After the penetration by liquid Nd and NdF3-LiF-Nd2O3 melts, the bending strengths of TiB2/TiC composites decreased and the fracture mode changed from transgranular to intergranular due to the decreased grain boundary force.

  6. Growth mechanism of atomic-layer-deposited TiAlC metal gate based on TiCl4 and TMA precursors

    NASA Astrophysics Data System (ADS)

    Jinjuan, Xiang; Yuqiang, Ding; Liyong, Du; Junfeng, Li; Wenwu, Wang; Chao, Zhao

    2016-03-01

    TiAlC metal gate for the metal-oxide-semiconductor field-effect-transistor (MOSFET) is grown by the atomic layer deposition method using TiCl4 and Al(CH3)3(TMA) as precursors. It is found that the major product of the TiCl4 and TMA reaction is TiAlC, and the components of C and Al are found to increase with higher growth temperature. The reaction mechanism is investigated by using x-ray photoemission spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The reaction mechanism is as follows. Ti is generated through the reduction of TiCl4 by TMA. The reductive behavior of TMA involves the formation of ethane. The Ti from the reduction of TiCl4 by TMA reacts with ethane easily forming heterogenetic TiCH2, TiCH=CH2 and TiC fragments. In addition, TMA thermally decomposes, driving Al into the TiC film and leading to TiAlC formation. With the growth temperature increasing, TMA decomposes more severely, resulting in more C and Al in the TiAlC film. Thus, the film composition can be controlled by the growth temperature to a certain extent. Project supported by the Key Technology Study for 16/14 nm Program of the Ministry of Science and Technology of China (Grant No. 2013ZX02303).

  7. Photocatalysis effect of nanometer TiO2 and TiO2-coated ceramic plate on Hepatitis B virus.

    PubMed

    Zan, Ling; Fa, Wenjun; Peng, Tianyou; Gong, Zhen-Kui

    2007-02-01

    The photocatalysis effect of nanometer TiO2 particles and TiO2-coated ceramic plate on Hepatitis B virus surface antigen (HBsAg) was investigated. The ELISA (enzyme-linked immunosorbent assay) standard method was used to assess the efficiency of TiO2 material to destroy the HBsAg. The research has shown that the suspension of TiO2 (0.5g/L) can destroy most of the HBsAg under the irradiation of mercury lamp, with the light intensity of 0.6mW/cm(2) at 365nm wavelength, or under the sunlight irradiation for a few hours. TiO2-coated ceramic plates can also destroy the HBsAg under the irradiation of mercury lamp, with the light intensity of 0.05mW/cm(2) at 365nm wavelength or under the room daylight for a few hours.

  8. Effect of TiO2 blocking layer on TiO2 nanorod arrays based dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Sivakumar, R.; Paulraj, M.

    2016-05-01

    Highly ordered rutile titanium dioxide nanorod (TNR) arrays (1.2 to 6.2 μm thickness) were grown on TiO2 blocking layer chemically deposited on fluorine doped tin oxide (FTO) substrate and were used as photo-electrodes to fabricate dye sensitized solar cells (DSSC's). Homogeneous layer of TiO2 on FTO was achieved by using aqueous peroxo- titanium complex (PTC) solutions via chemical bath deposition. Structural and morphological properties of the prepared samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) measurements. TNR arrays (6.2 μm) with TiO2 blocking layer showed higher energy conversion efficiency (1.46%) than that without TiO2 blocking layer. The reason can be ascertained to the suppression of electron-hole recombination at the semiconductor/electrolyte interface by the effect of TiO2 blocking layer.

  9. Microstructure and high-temperature oxidation resistance of TiN/Ti3Al intermetallic matrix composite coatings on Ti6Al4V alloy surface by laser cladding

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaowei; Liu, Hongxi; Wang, Chuanqi; Zeng, Weihua; Jiang, Yehua

    2010-11-01

    A high-temperature oxidation resistant TiN embedded in Ti3Al intermetallic matrix composite coating was fabricated on titanium alloy Ti6Al4V surface by 6kW transverse-flow CO2 laser apparatus. The composition, morphology and microstructure of the laser clad TiN/Ti3Al intermetallic matrix composite coating were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). In order to evaluate the high-temperature oxidation resistance of the composite coatings and the titanium alloy substrate, isothermal oxidation test was performed in a conventional high-temperature resistance furnace at 600°C and 800°C respectively. The result shows that the laser clad intermetallic composite coating has a rapidly solidified fine microstructure consisting of TiN primary phase (granular-like, flake-like, and dendrites), and uniformly distributed in the Ti3Al matrix. It indicates that a physical and chemical reaction between the Ti powder and AlN powder occurred completely under the laser irradiation. In addition, the microhardness of the TiN/Ti3Al intermetallic matrix composite coating is 844HV0.2, 3.4 times higher than that of the titanium alloy substrate. The high-temperature oxidation resistance test reveals that TiN/Ti3Al intermetallic matrix composite coating results in the better modification of high-temperature oxidation behavior than the titanium substrate. The excellent high-temperature oxidation resistance of the laser cladding layer is attributed to the formation of the reinforced phase TiN and Al2O3, TiO2 hybrid oxide. Therefore, the laser cladding TiN/Ti3Al intermetallic matrix composite coating is anticipated to be a promising oxidation resistance surface modification technique for Ti6Al4V alloy.

  10. Antifungal activity of Ag:hydroxyapatite thin films synthesized by pulsed laser deposition on Ti and Ti modified by TiO2 nanotubes substrates

    NASA Astrophysics Data System (ADS)

    Eraković, S.; Janković, A.; Ristoscu, C.; Duta, L.; Serban, N.; Visan, A.; Mihailescu, I. N.; Stan, G. E.; Socol, M.; Iordache, O.; Dumitrescu, I.; Luculescu, C. R.; Janaćković, Dj.; Miškovic-Stanković, V.

    2014-02-01

    Hydroxyapatite (HA) is a widely used biomaterial for implant thin films, largely recognized for its excellent capability to chemically bond to hard tissue inducing the osteogenesis without immune response from human tissues. Nowadays, intense research efforts are focused on development of antimicrobial HA doped thin films. In particular, HA doped with Ag (Ag:HA) is expected to inhibit the attachment of microbes and contamination of metallic implant surface. We herewith report on nano-sized HA and Ag:HA thin films synthesized by pulsed laser deposition on pure Ti and Ti modified with 100 nm diameter TiO2 nanotubes (fabricated by anodization of Ti plates) substrates. The HA-based thin films were characterized by SEM, AFM, EDS, FTIR, and XRD. The cytotoxic activity was tested with HEp2 cells against controls. The antifungal efficiency of the deposited layers was tested against the Candida albicans and Aspergillus niger strains. The Ti substrates modified with TiO2 nanotubes covered with Ag:HA thin films showed the highest antifungal activity.

  11. Thermodynamic Destabilization of Ti-O Solid Solution by H2 and Deoxygenation of Ti Using Mg.

    PubMed

    Zhang, Ying; Fang, Zhigang Zak; Sun, Pei; Zhang, Tuoyang; Xia, Yang; Zhou, Chengshang; Huang, Zhe

    2016-06-08

    Reactive metals including Ti, Zr, Hf, and V, among others, have a strong chemical affinity to oxygen, which makes them difficult to produce and costly to use. It is especially challenging to produce pure or metal alloy powders of these elements when extremely low oxygen content is required, because they have high solubility for oxygen, and the solid solution of these metals with oxygen is often more stable thermodynamically than their oxides. We report a novel thermochemical approach to destabilize Ti(O) solid solutions using hydrogen, thus enabling deoxygenation of Ti powder using Mg, which has not been possible before because of the thermodynamic stability of Ti(O) solid solutions relative to MgO. The work on Ti serves as an example for other reactive metals. Both analytical modeling and experimental results show that hydrogen can indeed increase the oxygen potential of Ti-O solid solution alloys; in other words, the stability of Ti-O solid solutions is effectively decreased, thus increasing the thermodynamic driving force for Mg to react with oxygen in Ti. Because hydrogen can be easily removed from Ti by a simple heat treatment, it is used only as a temporary alloying element to destabilize the Ti-O systems. The thermodynamic approach described here is a breakthrough and is applicable to a range of different materials. This work is expected to provide an enabling solution to overcome one of the key scientific and technological hurdles to the additive manufacturing of metals, which is emerging rapidly as the future of the manufacturing industry.

  12. Structural Transformation of Hexagonal (0001)BaTiO3 Ceramics to Tetragonal (111)BaTiO3 Ceramics

    NASA Astrophysics Data System (ADS)

    Watanabe, Takayuki; Shimada, Mikio; Aiba, Toshiaki; Yabuta, Hisato; Miura, Kaoru; Oka, Kengo; Azuma, Masaki; Wada, Satoshi; Kumada, Nobuhiro

    2011-09-01

    A ceramic slurry that contains a 6H-type Ba(Ti0.95Mn0.05)O3 powder was casted into a plaster mold under 10 T magnetic field to form a green compact of (0001)-oriented Ba(Ti0.95Mn0.05)O3. After sintering the green compact at 1300 °C in air, it was confirmed that the (0001)-oriented 6H-type perovskite structure transformed to a (111)-oriented 3C-type perovskite structure. The structural transformation was again examined using hexagonal BaTiO3 prepared by reducing pseudo-cubic BaTiO3 powder in H2 atmosphere. In this case, the preferred (0001) orientation was not confirmed for the green compacts. After sintering the green compacts at 1300 °C in air, mixed crystal orientations of (100)/(001) and (111) were observed for the resultant tetragonal BaTiO3 ceramics. This (100)/(001) orientation was suppressed by annealing the hexagonal BaTiO3 powder at 1000 °C before slip-casting, leading to highly (111)-oriented ceramics. It was found that the green compacts of (0001)-oriented hexagonal BaTiO3 can transform into (111)-oriented tetragonal BaTiO3 ceramics, maintaining the macroscopic crystal orientations due to a similar atomic stacking along [0001] of 6H-type BaTiO3 and [111] of 3C-type BaTiO3.

  13. 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.

  14. Synthesis and Isolation of the Titanium–Scandium Endohedral Fullerenes—Sc2TiC@Ih-C80, Sc2TiC@D5h-C80 and Sc2TiC2@Ih-C80 : Metal Size Tuning of the TiIV/TiIII Redox Potentials

    PubMed Central

    Junghans, Katrin; Ghiassi, Kamran B.; Samoylova, Nataliya A.; Deng, Qingming; Rosenkranz, Marco; Olmstead, Marilyn M.; Balch, Alan L.; Popov, Alexey A.

    2016-01-01

    The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed-metal Sc–Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH4 and Ti/CH4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH4 system are Sc4C2@C80 (the most abundant EMF from this synthesis), Sc3C2@C80, isomers of Sc2C2@C82, and the family Sc2C2n (2n=74, 76, 82, 86, 90, etc.), as well as Sc3CH@C80. The Sc–Ti/CH4 system produces the mixed-metal Sc2TiC@C2n (2n=68, 78, 80) and Sc2TiC2@C2n (2n=80) clusterfullerene families. The molecular structures of the new, transition-metal-containing endohedral fullerenes, Sc2TiC@Ih-C80, Sc2TiC@D5h-C80, and Sc2TiC2@Ih-C80, were characterized by NMR spectroscopy. The structure of Sc2TiC@Ih-C80 was also determined by single-crystal X-ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc2TiC- and Sc2TiC2-containing clusterfullerenes have Ti-localized LUMOs. Encapsulation of the redox-active Ti ion inside the fullerene cage enables analysis of the cluster–cage strain in the endohedral fullerenes through electrochemical measurements. PMID:27459520

  15. Synthesis and Isolation of the Titanium-Scandium Endohedral Fullerenes-Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 and Sc2 TiC2 @Ih -C80 : Metal Size Tuning of the Ti(IV) /Ti(III) Redox Potentials.

    PubMed

    Junghans, Katrin; Ghiassi, Kamran B; Samoylova, Nataliya A; Deng, Qingming; Rosenkranz, Marco; Olmstead, Marilyn M; Balch, Alan L; Popov, Alexey A

    2016-09-05

    The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed-metal Sc-Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH4 and Ti/CH4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH4 system are Sc4 C2 @C80 (the most abundant EMF from this synthesis), Sc3 C2 @C80 , isomers of Sc2 C2 @C82 , and the family Sc2 C2 n (2 n=74, 76, 82, 86, 90, etc.), as well as Sc3 CH@C80 . The Sc-Ti/CH4 system produces the mixed-metal Sc2 TiC@C2 n (2 n=68, 78, 80) and Sc2 TiC2 @C2 n (2 n=80) clusterfullerene families. The molecular structures of the new, transition-metal-containing endohedral fullerenes, Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 , and Sc2 TiC2 @Ih -C80 , were characterized by NMR spectroscopy. The structure of Sc2 TiC@Ih -C80 was also determined by single-crystal X-ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc2 TiC- and Sc2 TiC2 -containing clusterfullerenes have Ti-localized LUMOs. Encapsulation of the redox-active Ti ion inside the fullerene cage enables analysis of the cluster-cage strain in the endohedral fullerenes through electrochemical measurements.

  16. Mixed Ti-O-Si oxide films formation by oxidation of titanium-silicon interfaces

    NASA Astrophysics Data System (ADS)

    Benito, N.; Palacio, C.

    2014-05-01

    The reaction of oxygen with titanium deposited on Si (1 0 0) surfaces has been studied at room temperature and low oxygen pressures, using XPS and ARXPS. The experimental results for Ti growth on Si can be explained using a model involving a two stage mechanism. The first stage is characterized by the formation of a uniform TiSix layer ˜4 ML thick and the second one by the formation of metallic titanium that grows following a Stranki-Krastanov mechanism, that is, the formation of a Ti monolayer followed by the growth of Ti islands (7 ML thick) over the TiSix layer previously formed. The oxidation of Ti/Si interfaces strongly depends on the interface that is oxidized. For an interface corresponding to the first stage of deposition a Ti-O-Si mixed oxide layer is formed on the near surface. This layer is on top of a multilayer structure which is composed of TiO2 (Ti4+), titanium suboxides along with TiSi (TiSi + Ti1+ + Ti2+ + Ti3+), and substrate when going from the outer surface to the substrate whereas for an interface corresponding to the second stage no Ti-O-Si mixed oxide is detected and a Ti0 rich layer is observed between the titanium suboxides and the Si substrate.

  17. Phase equilibria, formation, crystal and electronic structure of ternary compounds in Ti-Ni-Sn and Ti-Ni-Sb ternary systems

    SciTech Connect

    Romaka, V.V.; Rogl, P.; Romaka, L.; Stadnyk, Yu.; Melnychenko, N.; Grytsiv, A.; Falmbigl, M.; Skryabina, N.

    2013-01-15

    The phase equilibria of the Ti-Ni-Sn and Ti-Ni-Sb ternary systems have been studied in the whole concentration range by means of X-ray and EPM analyses at 1073 K and 873 K, respectively. Four ternary intermetallic compounds TiNiSn (MgAgAs-type), TiNi{sub 2-x}Sn (MnCu{sub 2}Al-type), Ti{sub 2}Ni{sub 2}Sn (U{sub 2}Pt{sub 2}Sn-type), and Ti{sub 5}NiSn{sub 3} (Hf{sub 5}CuSn{sub 3}-type) are formed in Ti-Ni-Sn system at 1073 K. The TiNi{sub 2}Sn stannide is characterized by homogeneity in the range of 50-47 at% of Ni. The Ti-Ni-Sb ternary system at 873 K is characterized by formation of three ternary intermetallic compounds, Ti{sub 0.8}NiSb (MgAgAs-type), Ti{sub 5}Ni{sub 0.45}Sb{sub 2.55} (W{sub 5}Si{sub 3}-type), and Ti{sub 5}NiSb{sub 3} (Hf{sub 5}CuSn{sub 3}-type). The solubility of Ni in Ti{sub 0.8}NiSb decreases number of vacancies in Ti site up to Ti{sub 0.91}Ni{sub 1.1}Sb composition. - Graphical abstract: Isothermal section of the Ti-Ni-Sn phase diagram and DOS distribution in hypothetical TiNi{sub 1+x}Sn solid solution. Highlights: Black-Right-Pointing-Pointer Ti-Ni-Sn phase diagram was constructed at 1073 K. Black-Right-Pointing-Pointer Four ternary compounds are formed: TiNiSn, TiNi{sub 2-x}Sn, Ti{sub 2}Ni{sub 2}Sn, and Ti{sub 5}NiSn{sub 3}. Black-Right-Pointing-Pointer Three ternary compounds exist in Ti-Ni-Sb system at 873 K. Black-Right-Pointing-Pointer The TiNi{sub 2}Sb compound is absent.

  18. Dye-sensitized TiO2 nanotube solar cells: rational structural and surface engineering on TiO2 nanotubes.

    PubMed

    Wang, Jun; Lin, Zhiqun

    2012-12-01

    Owing to well-defined structural parameters and enhanced electronic properties, highly ordered TiO(2) nanotube arrays have been employed to substitute TiO(2) nanoparticles for use in dye-sensitized solar cells. To further improve the performance of dye-sensitized TiO(2) nanotube solar cells, efforts have been directed toward the optimization of TiO(2) photoanodes, dyes, electrolytes, and counter electrodes. Herein, we highlight recent progress in rational structural and surface engineering on anodic TiO(2) nanotube arrays and their effects on improving the power conversion efficiency of dye-sensitized TiO(2) nanotube solar cells.

  19. Conversion of Nanocellulose Aerogel into TiO2 and TiO2@C Nano-thorns by Direct Anhydrous Mineralization with TiCl4. Evaluation of Electrochemical Properties in Li Batteries.

    PubMed

    Henry, Aurélien; Plumejeau, Sandrine; Heux, Laurent; Louvain, Nicolas; Monconduit, Laure; Stievano, Lorenzo; Boury, Bruno

    2015-07-15

    Nanostructured TiO2 and TiO2@C nanocomposites were prepared by an original process combining biotemplating and mineralization of aerogels of nanofibrillated cellulose (NFC). A direct one step treatment of NFC with TiCl4 in strictly anhydrous conditions allows TiO2 formation at the outermost part of the nanofibrils while preserving their shape and size. Such TiO2@cellulose composites can be transformed into TiO2 nanotubes (TiO2-NT) by calcination in air at 600 and 900 °C, or into TiO2@C nanocomposites by pyrolysis in argon at 600 and 900 °C. Detailed characterization of these materials is reported here, along with an assessment of their performance as negative electrode materials for Li-ion batteries.

  20. Centerless grinding of TiAl using conventional grinding wheels

    SciTech Connect

    Jones, P.E.; Smits, D.; Eylon, D.; Smits, C.

    1995-12-31

    Ordered gamma titanium aluminide (TiAl) based alloys are now under consideration for automotive valves because of their light weight and high strength at temperatures up to 850 C. Finishing comprises as much as 70% of the cost of an automotive valve, therefore the grindability of TiAl valves will influence their commercial viability. This study compared the grindability of the TiAl alloy Ti-47Al-2Nb-1.75Cr (at%) to standard valve steels, nickel base superalloys, and conventional titanium alloys using the centerless grinding process. Three grinding conditions simulating stem grinding were selected. The power requirements, grinding time, and grinding wheel consumption were used to estimate the cost to grind TiAl on conventional centerless grinding equipment using vitrified bonded silicon carbide wheels. The metallurgical effects of rough and finish stem grinding cycles on the surface were determined. The grindability factor of TiAl, a measure of grinding cost, was slightly inferior to conventional valve steels, but much better than conventional titanium alloys. The high work hardening rate of the TiAl resulted in much better surface finish at high metal removal rates than that achieved in steels. No grinding cracks were observed, even under the rough grinding conditions. Microhardness profiles indicated significant work hardening of the surface under all three grinding conditions.

  1. Electronic band structure of TiN/MgO nanostructures

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kazuaki; Takaki, Hirokazu; Shimono, Masato; Kobayashi, Nobuhiko; Hirose, Kenji

    2017-04-01

    Various nanostructured TiN(001)/MgO(001) superlattices based on a repeated slab model with a vacuum region have been investigated by the total energy pseudopotential method. They are rectangular and rectangular parallelepiped TiN(001) dot structures on MgO(001)-2×2 and 3×3 substrates. A rectangular TiN(001) structure on a MgO(001)-2×1 substrate has also been calculated. Their detailed electronic and internal lattice properties were investigated systematically. The internal atomic coordinates in a unit cell were fully relaxed. The rectangular TiN(001) structure on the MgO(001)-2×1 superlattice, which is not a dot owing to its periodicity, corresponds to metallicity. The electronic states of relaxed rectangular TiN(001) dot/MgO(001)-2×2 and MgO(001)-3×3 superlattices are semiconducting. All relaxed rectangular parallelepiped TiN(001) dot/MgO(001)-2×2 and MgO(001)-3×3 superlattices correspond to metallicity. The electronic properties depend on the shape of the TiN dot and the size of the MgO substrate.

  2. Diffusion between Nb and Ti related to superconductor wire processing

    NASA Astrophysics Data System (ADS)

    Bormio-Nunes, Cristina; Nunes, Carlos A.; Porto, Fernando S. A.; de Souza, Vanessa S.; Tirelli, Marcelo A.; Edwards, Elilton R.

    2003-04-01

    Quantitative data on the diffusion between Nb and Ti are important for the processing of Nb-Ti superconductor wires through the 'artificial pinning centre-diffusion process'. In the literature, most of the Nb-Ti diffusion studies are focused on the 1173-1973 K temperature range which is inappropriate for this application. The objective of this study was to evaluate the diffusion between Nb and Ti at 1023 K and 1073 K, from a Nb-Ti cylindrical composite that has been mechanically deformed by swaging. It has been found that at both temperatures most of the diffusion layer is formed through the diffusion of Nb into Ti. A plot of diffusion layer thickness versus t1/2 (t is the time) showed a linear behaviour for both temperatures with angular coefficients of 0.0867 mum s-1/2 (1023 K) and 0.253 mum s-1/2 (1073 K). Longer heat treatment and higher temperature leads to a Ti-rich diffusion layer, which is not interesting in terms of superconducting properties. After heat treatment at 1023 K for 150 h, the monofilament wire (0.610 mm) presented a critical temperature of 10 K and an upper critical field close to 6 T.

  3. Porous NiTi surfaces for biomedical applications

    NASA Astrophysics Data System (ADS)

    Huan, Z.; Fratila-Apachitei, L. E.; Apachitei, I.; Duszczyk, J.

    2012-04-01

    In this study, the NiTi shape memory alloy was surface modified by plasma electrolytic oxidation (PEO) in Na3PO4 with the aim to produce porous NiTi surfaces for biomedical applications. The oxidation was performed potentiostatically and the characteristics of the resultant surfaces were compared with those obtained in NaAlO2/NaPO2H2 under similar conditions. Surfaces with sub-micron sized pores could be produced in Na3PO4 electrolyte at 300 V. The process was accompanied by intense gas evolution and enhanced thermal effects relative to the NaAlO2/NaPO2H2 electrolyte. The EDS analyses revealed the presence of O, Ti, P, Ni, and a Ni/Ti atomic ratio of 0.4 suggesting preferential oxidation of titanium during the process and depletion of Ni from the surface. No crystalline oxide phases were detected by X-ray diffraction (XRD). By comparison, the layers formed in NaAlO2/NaPO2H2 consisted of crystalline Al2O3 and the Ni/Ti atomic ratio was 0.74. Following oxidation, the wettability and surface free energy of NiTi increased significantly. The findings of this study indicate that the PEO process shows potential for expanding the biofunctionality of NiTi.

  4. Valence state of Ti in conductive nanowires in sapphire

    SciTech Connect

    Mizoguchi, Teruyasu; Nakamura, Atsutomo; Matsunaga, Katsuyuki; Ikuhara, Yuichi; Sakurai, Masaki; Tanaka, Isao; Yamamoto, Takahisa

    2004-10-15

    In order to reveal the valence state of Ti in conductive nanowires in sapphire, near-edge x-ray-absorption fine structures (NEXAFS) were observed. From experimental and theoretical studies on NEXAFS of reference compounds including rutile, anatase, and Ti{sub 2}O{sub 3}, it was found that the valence state of Ti can be identified by regarding the positions of the spectral onset and the shoulder in the main peak of Ti-K NEXAFS. The valence states of Ti doped Al{sub 2}O{sub 3} polycrystalline specimens which were annealed at oxidized and reduced atmospheres were determined to be +4 and +3, respectively. The solubility limit of Ti in Al{sub 2}O{sub 3} polycrystal was found to be between 1000 ppm to 1.0% at the both atmospheres. The spectrum from Ti nanowires in sapphire has a lot of similarities to the reduced specimen, the valence state was therefore concluded to be +3.

  5. Isotope Shifts in the TiO B- X (1-0) Band

    NASA Astrophysics Data System (ADS)

    Amiot, C.; Luc, P.; Vetter, R.

    2002-08-01

    The absorption spectrum of the B3Π- X3Δ (1-0) band of the TiO molecule has been studied at sub-Doppler resolution by crossing an effusive beam of TiO with a cw tunable laser beam and by collecting the induced fluorescence light. The five bands involving the 46Ti, 47Ti, 48Ti, 49Ti, and 50Ti isotopic species have been observed and interpreted. A simultaneous analysis of the five isotopic data leads to accurate molecular constants and energy levels for the B3Π electronic state.

  6. Microstructure of TiC-Based Coatings on Cemented Carbide Derived by Sol-Gel Routes

    NASA Astrophysics Data System (ADS)

    Yang, Mei; Guo, Zhixing; Qi, Kaifeng; Huang, Kun; Deng, Jianxiong; Liu, Jia

    2017-02-01

    TiC-based coating is prepared by depositing TiO2 sol on cemented carbide compact and liquid phase sintering. TiC forms due to carbothermal reduction reaction of TiO2 and then reacts with WC and transforms to TiC-based solid solution. Ti content changes the WC growth mechanism and results in the multi-stepped morphology. When sintered cemented carbide is used as substrate, WC keeps the equilibrium truncated triangle prism morphology due to the relatively weak diffusion among Ti, WC, and Co.

  7. Grindability of dental cast Ti-Ag and Ti-Cu alloys.

    PubMed

    Kikuchi, Masafumi; Takahashi, Masatoshi; Okabe, Toru; Okuno, Osamu

    2003-06-01

    Experimental Ti-Ag alloys (5, 10, and 20 mass% Ag) and Ti-Cu alloys (2, 5, and 10 mass% Cu) were cast into magnesia molds using a dental casting machine, and their grindability was investigated. At the lowest grinding speed (500 m min(-1)), there were no statistical differences among the grindability values of the titanium and titanium alloys. The grindability of the alloys increased as the grinding speed increased. At the highest grinding speed (1500 m x min(-1)), the grindability of the 20% Ag, 5% Cu, and 10% Cu alloys was significantly higher than that of titanium. It was found that alloying with silver or copper improved the grindability of titanium, particularly at a high speed. It appeared that the decrease in elongation caused by the precipitation of small amounts of intermetallic compounds primarily contributed to the favorable grindability of the experimental alloys.

  8. Characterization and Modeling of Nonfilamentary Ta/TaOx/TiO2/Ti Analog Synaptic Device

    PubMed Central

    Wang, Yu-Fen; Lin, Yen-Chuan; Wang, I-Ting; Lin, Tzu-Ping; Hou, Tuo-Hung

    2015-01-01

    A two-terminal analog synaptic device that precisely emulates biological synaptic features is expected to be a critical component for future hardware-based neuromorphic computing. Typical synaptic devices based on filamentary resistive switching face severe limitations on the implementation of concurrent inhibitory and excitatory synapses with low conductance and state fluctuation. For overcoming these limitations, we propose a Ta/TaOx/TiO2/Ti device with superior analog synaptic features. A physical simulation based on the homogeneous (nonfilamentary) barrier modulation induced by oxygen ion migration accurately reproduces various DC and AC evolutions of synaptic states, including the spike-timing-dependent plasticity and paired-pulse facilitation. Furthermore, a physics-based compact model for facilitating circuit-level design is proposed on the basis of the general definition of memristor devices. This comprehensive experimental and theoretical study of the promising electronic synapse can facilitate realizing large-scale neuromorphic systems. PMID:25955658

  9. Solute partitioning in TiAl/Ti{sub 3}Al alloys

    SciTech Connect

    Munroe, P.R.; Baker, I.

    1999-11-19

    Over the last few years there have been intense research and development efforts on two-phase alloys based on ({gamma}) TiAl + ({alpha}{sub 2}) Ti{sub 3}Al; the goal being to develop alloys for aerospace and, possibly, automotive applications. Two-phase alloys have been studied which contain numerous elemental additions, the more common ones of which are W, Mo, Nb, Cr, W, V, Si, Mn, Ta, C and B. These have been studied both for their phase stability and to determine their monotonic and cycling loading response both at low and high temperature. Although the mechanical properties and physical behavior of these alloys have been studied in detail, there is surprisingly little published information on the distribution of these alloying additions between the two phases. Here the authors report a short study on two recently developed alloys concerning how some of these elemental additions partition between the two phases.

  10. Cold Sprayability of Mixed Commercial Purity Ti Plus Ti6Al4V Metal Powders

    NASA Astrophysics Data System (ADS)

    Aydin, Huseyin; Alomair, Mashael; Wong, Wilson; Vo, Phuong; Yue, Stephen

    2017-02-01

    In the present work, metallic composite coatings of commercial purity Ti plus Ti6Al4V were produced by cold spraying to explore the effect of mixing on porosity and mechanical properties of the coatings. The coatings were deposited using N2 gas at 800 °C and 4 MPa pressure on 1020 steel substrate. Coating characteristics were studied by examining porosity percentages and Vickers's hardness. The microstructure was examined using optical and electron microscopy techniques. It was observed that mixing metal powders can lead to improvements in cold sprayability, specifically decreases in the porosity of the `matrix' powder. It is shown that a critical addition can significantly influence porosity, but above this critical level, there is a little change in porosity. Hardness differences between the two powders are considered to be the first-order influence, but differences in particle sizes and morphology may also be contributing factors.

  11. Photocatalytic performance of TiO2-zeolite templated carbon composites in organic contaminant degradation.

    PubMed

    Donphai, Waleeporn; Kamegawa, Takashi; Chareonpanich, Metta; Nueangnoraj, Khanin; Nishihara, Hirotomo; Kyotani, Takashi; Yamashita, Hiromi

    2014-12-07

    TiO2 composites with zeolite templated carbon (TiO2-ZTC) and activated carbon (TiO2-AC) were prepared and used as the photocatalysts for comparative studies with pure TiO2. TiO2-ZTC exhibited the highest rate of methylene blue degradation with a rate approximately 4 and 400 times higher than those of TiO2-AC and pure TiO2, respectively. Moreover, the highest catalytic performance of TiO2-ZTC in gas-phase degradation of acetone was approximately 1.1 and 12.9 times higher than TiO2-AC and pure TiO2, respectively. These outstanding performances could be attributed to high surface area, pore volume, and hydrophobic surface properties, leading to improvement in the adsorption properties of organic molecules.

  12. Microstructures and Properties of Ti-Coated SiCp Reinforced Al-Si Alloy Composites

    NASA Astrophysics Data System (ADS)

    Feng, Yan; Ren, Junpeng; Dong, Cuige; Wang, Richu

    2016-12-01

    A double-layer structure of Ti coating was plated on the surface of SiC particles using a diffusion method in a vacuum reactor, which is a new method to fabricate a Ti-coating layer on the SiC particles. The phase structure of Ti coating on the surface of SiC particles was composed inside of Ti5Si3 and outside of TiC investigated by x-ray diffraction. The Ti5Si3 and TiC double-layer structure realizes the tight chemical bonding between SiC particles and the Ti coating, and significantly promotes the wettability between the aluminum matrix and the Ti-coated SiC particles. The Ti-coated SiCp-reinforced Al-Si composites are prepared by a powder metallurgy method, and express excellent relative densities, desirable mechanical properties and frictional wear resistance.

  13. Highly active nanocrystalline TiO(2) photoelectrodes.

    PubMed

    Paronyan, Tereza M; Kechiantz, A M; Lin, M C

    2008-03-19

    A simple method for the fabrication of highly photoactive nanocrystalline two-layer TiO(2) electrodes for solar cell applications is presented. Diluted titanium acetylacetonate has been used as a precursor for covering SnO(2):F (FTO) films with dense packed TiO(2) nanocrystallites. The nanoporous thick TiO(2) film follows the dense packed thin TiO(2) film as a second layer. For the latter, amorphous TiO(2) nanoparticles have been successfully synthesized by a sol-gel technique in an acidic environment with pH<1 and hydrothermal growth at a temperature of 200 °C. The acidic nanoparticle gel was neutralized by basic ammonia and a TiO(2) gel of pH 5 was obtained; this pH value is higher than the recently reported value of 3.1 (Park et al 2005 Adv. Mater. 17 2349-53). Highly interconnected, nanoporous, transparent and active TiO(2) films have been fabricated from the pH 5 gel. SEM, AFM and XRD analyses have been carried out for investigation of the crystal structure and the size of nanoparticles as well as the surface morphology of the films. Investigation of the photocurrent-voltage characteristics has shown improvement in cell performance along with the modification of the surface morphology, depending on pH of the TiO(2) gel. Increasing the pH of the gel from 2.1 to 5 enhanced the overall conversion efficiency of the dye-sensitized solar cells by approximately 30%. An energy conversion efficiency of 8.83% has been achieved for the cell (AM1.5, 100  mWcm(-2) simulated sunlight) compared to 6.61% efficiency in the absence of ammonia in the TiO(2) gel.

  14. TiO₂ beads and TiO₂-chitosan beads for urease immobilization.

    PubMed

    Ispirli Doğaç, Yasemin; Deveci, Ilyas; Teke, Mustafa; Mercimek, Bedrettin

    2014-09-01

    The aim of the present study is to synthesize TiO2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO2 beads. In the first method (A), urease enzyme was immobilized onto TiO2 beads by adsorption and then crosslinking. In the second method (B), TiO2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5mg/ml for A and 1.0mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60°C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4-70°C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30°C (A), 40°C (B) and 35°C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65°C. However, at this temperature free urease protected only 15% activity.

  15. Migration of Ti from nano-TiO₂-polyethylene composite packaging into food simulants.

    PubMed

    Lin, Qin-Bao; Li, He; Zhong, Huai-Ning; Zhao, Quan; Xiao, Da-Hui; Wang, Zhi-Wei

    2014-01-01

    An analytical method based on ICP-MS was developed for the determination of Ti in food simulants (3% (w/v) aqueous acetic acid and 50% (v/v) aqueous ethanol). The method was used to determine the migration of Ti from nano-TiO₂-PE films used for food packaging into food simulants under different temperature and migration time conditions. The maximum migration amounts into 3% (w/v) aqueous acetic acid were 1.4 ± 0.02, 6.3 ± 0.5 and 12.1 ± 0.2 μg kg(-1) at 25, 70 and 100°C, respectively, while into 50% (v/v) aqueous ethanol, the maximum migration amounts were 0.5 ± 0.1, 0.6 ± 0.03 and 2.1 ± 0.1 μg kg(-1) at 25, 70 and 100°C, respectively. Increasing the additive content in the film promoted migration of nanoparticles. The results indicated that the migration of nanoparticles might occur via dissolution from the surface and cut edges of the solid phase (film) into the liquid phase (food simulant).

  16. Improvement of dye-sensitized solar cell performance through infiltration of TiO{sub 2} nanoparticles between mesoporous TiO{sub 2} particles

    SciTech Connect

    Park, Su-Bin; Chung, Il Jun; Woo, Ji Won; Kim, Tae Hun; Li, Zhenghua; Jin, Mingshi; Lee, Duk Jae; Kim, Ji Man

    2014-10-15

    Highlights: • Spherical mesoporous TiO{sub 2} materials were obtained by a simple sol–gel method. • Physical mixture of TiO{sub 2} nanoparticle and mesoporous TiO{sub 2} was utilized for solar cell electrode. • Mixed electrode system exhibited higher DSSC performance. - Abstract: There are two factors on the efficiency of dye-sensitized solar cell (DSSC): one is the amount of dye adsorbed, and the other is contact resistance. In this study, TiO{sub 2} nanoparticles (nano-TiO{sub 2}, about 20 nm particle size) were infiltrated between mesoporous TiO{sub 2} (meso-TiO{sub 2}) particles with about 300 nm particle sizes, in order to reduce the contact resistance of TiO{sub 2} electrodes. The infiltrated nano-TiO{sub 2} can facilitate electron transfer between meso-TiO{sub 2} particles by filling the empty volume of DSSC electrodes. As a result, the TiO{sub 2} electrode containing 65 wt% of meso-TiO{sub 2} and 35 wt% of nano-TiO{sub 2} exhibited the highest performance of DSSC.

  17. SiO2/TiO2/n-Si/Ag(Cr)/TiO2 thin films with superhydrophilicity and low-emissivity

    NASA Astrophysics Data System (ADS)

    Loka, Chadrasekhar; Ryeol Park, Kyoung; Lee, Kee-Sun

    2016-01-01

    In this study, SiO2/TiO2/n-Si/Ag(Cr)/TiO2 multilayer structures have been designed and deposited by the RF and DC magnetron sputtering at room temperature. The as-deposited TiO2/glass films which are initially amorphous in nature were subjected to post annealing at 673 K for anatase phase TiO2. The anatase TiO2 films showed an optical bandgap ˜3.32 eV. The Ag(Cr)/TiO2 showed very low-emissivity (low-e) value ˜0.081 which is evaluated by using the sheet resistance (6.51 Ω/□) of the films. All the deposited films showed high visible transmittance (˜81%) and high infrared reflectance (72%) which are recorded by using the UV-vis-NIR spectrophotometer. In addition, experimentally obtained optical properties were in good agreement with the simulation data. The TiO2/n-Si heterojunction concept has been employed to enhance the superhydrophilicity of the deposited multilayer stack, TiO2/n-Si/Ag(Cr)/TiO2 films exhibited best superhydrophilicity with water contact angle ˜2°. The deposited multilayer structures SiO2/TiO2/n-Si/Ag(Cr)/TiO2 and TiO2/n-Si/Ag(Cr)/TiO2 achieved significant low-e and superhydrophilicity.

  18. Mechanical Response of Titanium Aluminide (TiAl3)

    DTIC Science & Technology

    2010-06-01

    Mechanical Response of Titanium Aluminide (TiAl3) by Ajmer Dwivedi and Jermaine Bradley ARL-CR-0669 June 2010 prepared by...Mechanical Response Of Titanium Aluminide (TiAl3) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER...SUPPLEMENTARY NOTES 14. ABSTRACT Compression tests have been performed on TiAl3 at strain rates from 0.00003?500/s. All tests were done at room temperature

  19. Growth of TiO2 nanoparticles under heat treatment

    NASA Astrophysics Data System (ADS)

    Bahadur, J.; Sen, D.; Mazumder, S.; Sastry, P. U.; Paul, B.

    2013-02-01

    The effect of heat treatment, on growth of NiO doped TiO2, have been investigated. The nanoparticle size has been estimated by small-angle x-ray scattering. The average particle size increases with increasing temperature. The growth of crystallite size has been probed by X-ray diffraction. A polymorphic phase transition of TiO2 is observed beyond 600°C due to growth of TiO2 nanoparticles beyond 14 nm of size.

  20. 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.

  1. Photocatalytic activity of hydrogenated TiO2.

    PubMed

    Leshuk, Tim; Parviz, Roozbeh; Everett, Perry; Krishnakumar, Harish; Varin, Robert A; Gu, Frank

    2013-03-01

    Photocatalysis is a promising advanced water treatment technology, and recently the possibility of using hydrogenation to improve the photocatalytic efficiency of titanium dioxide has generated much research interest. Herein we report that the use of high-temperature hydrogenation to prepare black TiO2 primarily results in the formation of bulk defects in the material without affecting its electronic band structure. The hydrogenated TiO2 exhibited significantly worse photocatalytic activity under simulated sunlight compared to the unhydrogenated control, and thus we propose that high-temperature hydrogenation can be counterproductive to improving the photocatalytic activity of TiO2, because of its propensity to form bulk vacancy defects.

  2. Optical and photocatalytic properties of TiO2 nanoplumes

    PubMed Central

    Scuderi, Viviana; Miritello, Maria; Nicotra, Giuseppe; Impellizzeri, Giuliana; Privitera, Vittorio

    2017-01-01

    Here we report the photocatalytic efficiency of hydrogenated TiO2 nanoplumes studied by measuring dye degradation in water. Nanoplumes were synthesized by peroxide etching of Ti films with different thicknesses. Structural characterization was carried out by scanning electron microscopy and transmission electron microscopy. We investigated in detail the optical properties of the synthesized material and related them to the efficiency of UV photodegradation of methylene blue dye. The obtained results show that TiO2 nanoplumes act as an effective antireflective layer increasing the UV photocatalytic yield of the film. PMID:28243556

  3. Nondestructive Evaluation of Ni-Ti Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Meir, S.; Gordon, S.; Karsh, M.; Wiezman, A.; Ayers, R.; Olson, D. L.

    2011-06-01

    The nondestructive evaluation of nickel titanium (Ni-Ti) alloys for applications such as heat treatment for biomaterials applications (dental) and welding was investigated. Ni-Ti alloys and its ternary alloys are valued for mechanical properties in addition to the shape memory effect. Two analytical approaches were perused in this work. Assessment of the microstructure of the alloy that determines the martensitic start temperature (Ms) of Ni-Ti alloy as a function of heat treatment, and secondly, an attempt to evaluate a Friction Stir Welding, which involves thermo-mechanical processing of the alloy.

  4. Nondestructive evaluation of Ni-Ti shape memory alloy

    SciTech Connect

    Meir, S.; Gordon, S.; Karsh, M.; Ayers, R.; Olson, D. L.; Wiezman, A.

    2011-06-23

    The nondestructive evaluation of nickel titanium (Ni-Ti) alloys for applications such as heat treatment for biomaterials applications (dental) and welding was investigated. Ni-Ti alloys and its ternary alloys are valued for mechanical properties in addition to the shape memory effect. Two analytical approaches were perused in this work. Assessment of the microstructure of the alloy that determines the martensitic start temperature (Ms) of Ni-Ti alloy as a function of heat treatment, and secondly, an attempt to evaluate a Friction Stir Welding, which involves thermo-mechanical processing of the alloy.

  5. Enhanced low-temperature impact toughness of nanostructured Ti

    SciTech Connect

    Stolyarov, V.V.; Valiev, R.Z.; Zhu, Y.T.

    2006-01-23

    Impact toughness is one of the major mechanical properties for structural materials. It is generally observed that in coarse-grained materials the impact toughness decreases with decreasing testing temperature. Here, we report that the impact toughness of nanostructured Ti processed by severe plastic deformation is enhanced at low temperatures of -70 deg. C and -196 deg. C, a unique phenomenon that contradicts the observations in coarse-grained materials. The enhanced impact toughness is attributed to the increased strength and ductility of nanostructured Ti as well as smaller fracture dimples at lower temperatures. This result demonstrates the advantage of using nanostructured Ti in low-temperature applications.

  6. Influence of Ti nanocrystallization on microstructure, interface bonding, surface energy and blood compatibility of surface TiO 2 films

    NASA Astrophysics Data System (ADS)

    Shao, Honghong; Yu, Chunhang; Xu, Xiaojing; Wang, Ji; Zhai, Rui; Wang, Xiaojing

    2010-12-01

    Recent progress in ultrafine-grained/nano-grained (UFG/NG) titanium permits a consideration for TiO 2 films deposited on nano-grained titanium for antithrombogenic application such as artificial valves and stents. For this paper, the microstructure, interface bonding, surface energy, and blood compatibility features of TiO 2 films deposited by direct current magnetron reactive sputtering technology on NG titanium and coarse-grained (CG) titanium were investigated. The results show that the nanocrystallization of titanium substrate has a significant influence on TiO 2 films. At the same deposition parameters, the content of rutile phase of TiO 2 film was increased from 47% (on the CG titanium substrate) to 72% (on the NG titanium substrate); the adhesion of TiO 2 film was improved from 5.8 N to 17 N; the surface energy was reduced from 6.37 dyn/cm to 3.01 dyn/cm; the clotting time was improved from 18 min to 28 min; the platelets accumulation and pseudopodium of adherent platelets on TiO 2 film on NG titanium were considerably reduced compared to that on CG titanium. The present results demonstrate the possibility of improving the blood compatibility of TiO 2 film through the approach of substrate nanocrystallization. Also it may provide an attractive idea to prepare stents with biological coatings of more outstanding blood compatibility and interface bonding.

  7. Comparison of the Electrochemical Behavior of Ti and Nanostructured Ti-Coated AISI 304 Stainless Steel in Strongly Acidic Solutions

    NASA Astrophysics Data System (ADS)

    Attarzadeh, Farid Reza; Elmkhah, Hassan; Fattah-Alhosseini, Arash

    2017-02-01

    In this study, the electrochemical behaviors of pure titanium (Ti) and nanostructured (NS) Ti-coated AISI 304 stainless steel (SS) in strongly acidic solutions of H2SO4 were investigated and compared. A type of physical vapor deposition method, cathodic arc evaporation, was applied to deposit NS Ti on 304 SS. Scanning electron microscope and X-ray diffraction were used to characterize surface coating morphology. Potentiodynamic polarization, electrochemical impedance spectroscopy, and Mott-Schottky (M-S) analysis were used to evaluate the passive behavior of the samples. Electrochemical measurements revealed that the passive behavior of NS Ti coating was better than that of pure Ti in 0.1 and 0.01 M H2SO4 solutions. M-S analysis indicated that the passive films behaved as n-type semiconductors in H2SO4 solutions and the deposition method did not affect the semiconducting type of passive films formed on the coated samples. In addition, this analysis showed that the NS Ti coating had lower donor densities. Finally, all electrochemical tests showed that the passive behavior of the Ti-coated samples was superior, mainly due to the formation of thicker, yet less defective passive films.

  8. Ti TiO2 Al normal metal insulator superconductor tunnel junctions fabricated in direct-write technology

    NASA Astrophysics Data System (ADS)

    Otto, Ernst; Tarasov, Mikhail; Kuzmin, Leonid

    2007-08-01

    We present a novel Ti-based direct-write technology for fabricating Ti TiO2 Al tunnel junctions for bolometer and thermometry applications. The goal of our research is to develop simple and efficient technology for fabricating SIS tunnel junctions between Ti and Al with TiO2 as an insulating barrier. The key point of this technology is the deposition of a Ti film as a base electrode and deposition of an Al electrode after oxidation of the Ti. This approach allows one to realize any geometry of the tunnel junctions and of the absorber with no limitation related to the area of the junctions or the thickness of the absorber. In particular, a very thin and completely flat absorber can be created with no bending parts, which is not possible using the shadow evaporation technique or standard trilayer technology. Besides, the proposed new approach does not require one-cycle evaporation for deposition of tunnel junctions which gives us more freedom in the geometry of the counter-electrodes. The junctions are to be used for bolometer applications, such as the fabrication of microwave receivers for sensitive measurements in new generation telescopes, e.g. CLOVER and BOOMERANG projects including polarization cosmic microwave background radiation measurements, and the OLIMPO balloon telescope project which is dedicated to measuring the Sunyaev Zeldovich effect in clusters of galaxies. As the first step, SIN tunnel junctions have been fabricated and characterized.

  9. Synthesis of TiB2-TiC/Fe nano-composite coating by laser surface engineering

    NASA Astrophysics Data System (ADS)

    Du, Baoshuai; Paital, Sameer R.; Dahotre, Narendra B.

    2013-02-01

    The study explores the synthesis of TiB2 and TiC reinforced Fe-based nano-composite coating by laser surface engineering using Ti, B4C and Fe powder mixture as precursor. The effect of laser scanning speed on the size, morphology, and amount of nano-sized ceramic reinforcements were studied at laser fluence of 1111 J/cm2, 1667 J/cm2 and 3333 J/cm2 respectively. A bimodal microstructure with TiC and TiB2 particles dispersed in fine α-Fe matrix was evolved in the laser processed coatings. Besides, the nature of formation of nano-sized ceramic phase was examined. The laser synthesized nano-composite coating yielded 3-5 times increase in microhardness. It appears that the presence of nano-sized TiB2 and TiC particles coupled with the highly refined α-Fe matrix improves the hardness significantly. This coating offers the potential to increase the hardness and toughness simultaneously for developing wear-resistance coatings.

  10. Wear behavior of the plasma and thermal oxidized Ti-15Mo and Ti-6Al-4V alloys

    NASA Astrophysics Data System (ADS)

    Hacisalioglu, I.; Yildiz, F.; Alsaran, A.; Purcek, G.

    2017-02-01

    Titanium and its alloys widely used in load bearing applications. Titanium alloys are capable of providing lower elastic modulus and better corrosion resistance with alloying processes. In spite of the modified mechanical properties, the surface degradation is still the main critical defect. Ti-15Mo alloy is one of the alpa+beta titanium alloys with acceptable mechanical and chemical superiority. Recent researches in literature show that the wear performance of base Ti-15Mo is relatively low as compared to Ti-6Al-4V, using in high performance applications. Plasma oxidized surfaces increase the tribological and chemical performance of titanium alloys. In this study the Ti-15Mo alloy and Ti-6Al-4V alloys were compared in terms of wear performance. To obtain alloys with similar microstructure they were solution treated at 800°C 1H and then air-cooled. The plasma and thermal oxidations were applied at 650°C for 1 hour. Wear performance of oxidized surfaces investigated in dry conditions. Oxidized surface characterized with XRD, SEM, 3D profilometer and hardness measurements. Wear volume calculated with 3D profilometer. Results show that oxidizing increased the surface roughness and improved the wear performance of Ti15Mo alloy. The plasma and thermal oxidized Ti-15Mo showed a remarkable increase in wear resistance.

  11. Characteristics and Machining Performance of TiN and TiAlN Coatings on a Milling Cutter

    NASA Astrophysics Data System (ADS)

    Sarwar, Mohammed; Haider, Julfikar

    2011-01-01

    Titanium Nitride (TiN) coating deposited by Physical Vapour Deposition (PVD) or Chemical Vapour Deposition (CVD) techniques on cutting tools (single point or multipoint) has contributed towards the improvement of tool life, productivity and product quality [1]. Addition of Al in TiN coating (e.g., TiAlN or AlTiN) has further improved the coating properties required for machining applications [2, 3]. This work presents a comparative investigation on TiN and TiAlN coatings deposited on to a Powder Metallurgy High Speed Steel (PM HSS) milling cutter used for machining bimetal (M42+D6A) steel strips. PVD (Arc evaporation) technique was used to deposit the coatings after carefully preparing the cutting edges of the milling cutter. Microstructure, chemical composition, hardness and adhesion of the coatings have been characterised using different techniques. The incorporation of Al into TiN coating results in an improvement in hardness, wear resistance and cutting performance. Examination of the worn flank in the coated cutting edges revealed that abrasive and adhesive wear are the predominant failure mechanisms. Tool designers, coating suppliers and manufacturing engineers could benefit from the information provided.

  12. Lithium insertion in nanostructured TiO(2)(B) architectures.

    PubMed

    Dylla, Anthony G; Henkelman, Graeme; Stevenson, Keith J

    2013-05-21

    Electric vehicles and grid storage devices have potentialto become feasible alternatives to current technology, but only if scientists can develop energy storage materials that offer high capacity and high rate capabilities. Chemists have studied anatase, rutile, brookite and TiO2(B) (bronze) in both bulk and nanostructured forms as potential Li-ion battery anodes. In most cases, the specific capacity and rate of lithiation and delithiation increases as the materials are nanostructured. Scientists have explained these enhancements in terms of higher surface areas, shorter Li(+) diffusion paths and different surface energies for nanostructured materials allowing for more facile lithiation and delithiation. Of the most studied polymorphs, nanostructured TiO2(B) has the highest capacity with promising high rate capabilities. TiO2(B) is able to accommodate 1 Li(+) per Ti, giving a capacity of 335 mAh/g for nanotubular and nanoparticulate TiO2(B). The TiO2(B) polymorph, discovered in 1980 by Marchand and co-workers, has been the focus of many recent studies regarding high power and high capacity anode materials with potential applications for electric vehicles and grid storage. This is due to the material's stability over multiple cycles, safer lithiation potential relative to graphite, reasonable capacity, high rate capability, nontoxicity, and low cost (Bruce, P. G.; Scrosati, B.; Tarascon, J.-M. Nanomaterials for Rechargeable Lithium Batteries. Angew. Chem., Int. Ed.2008, 47, 2930-2946). One of the most interesting properties of TiO2(B) is that both bulk and nanostructured forms lithiate and delithiate through a surface redox or pseudocapacitive charging mechanism, giving rise to stable high rate charge/discharge capabilities in the case of nanostructured TiO2(B). When other polymorphs of TiO2 are nanostructured, they still mainly intercalate lithium through a bulk diffusion-controlled mechanism. TiO2(B) has a unique open crystal structure and low energy Li

  13. Phase stability in binary Ti-Al

    NASA Technical Reports Server (NTRS)

    Anderson, C. D.; Hofmeister, W. H.; Bayuzick, R. J.

    1991-01-01

    Binary Ti-Al samples containing from 46 to 54 at. pct Al were solidified while undercooled by various amounts using electromagnetic levitation techniques. A detailed thermal history of these samples was obtained with sampling rates as high as 500 KHz during recalescence. This very high sampling rate was essential to resolve the thermal events. Primary alpha solidification was observed in samples containing from 51 to 54 at. pct Al that were undercooled less than about 100 K at solidification. Primary beta solidification was found for all undercoolings tested in samples containing less than 51 at. pct Al and for undercoolings greater than about 100 K in samples containing 51 to 54 at. pct Al.

  14. Ni/TiO2 Ultraviolet Detector

    NASA Astrophysics Data System (ADS)

    Mohamadzade Lajvardi, Mehdi; Jahangiri, Mojtaba

    2016-03-01

    The fabrication technology of solid-state photon detectors based on semiconductors other than silicon is yet to mature, but their recent progress opens new possibilities. Such devices are especially attractive for ultraviolet radiation level measurements because semiconductor materials with band gaps larger than 3.0 eV can be used as “visible-blind” detectors, the operation of which do not require using visible light filters. Here, fabrication and characterization of a UV detector based on nickel/titanium dioxide Schottky junction is reported. The operation of the device is described based on the photoelectric mechanism taking place in the carrier- depleted oxide adjacent to the Ni layer. Simplicity of fabrication, cost-effectiveness and fast response are the positive features of the device. These features of the device are compared with those of the previously reported Ag/TiO2 UV detectors.

  15. The Effect of Deposition Conditions on Adhesion Strength of Ti and Ti6Al4V Cold Spray Splats

    NASA Astrophysics Data System (ADS)

    Goldbaum, Dina; Shockley, J. Michael; Chromik, Richard R.; Rezaeian, Ahmad; Yue, Stephen; Legoux, Jean-Gabriel; Irissou, Eric

    2012-03-01

    Cold spray is a complex process where many parameters have to be considered in order to achieve optimized material deposition and properties. In the cold spray process, deposition velocity influences the degree of material deformation and material adhesion. While most materials can be easily deposited at relatively low deposition velocity (<700 m/s), this is not the case for high yield strength materials like Ti and its alloys. In the present study, we evaluate the effects of deposition velocity, powder size, particle position in the gas jet, gas temperature, and substrate temperature on the adhesion strength of cold spayed Ti and Ti6Al4V splats. A micromechanical test technique was used to shear individual splats of Ti or Ti6Al4V and measure their adhesion strength. The splats were deposited onto Ti or Ti6Al4V substrates over a range of deposition conditions with either nitrogen or helium as the propelling gas. The splat adhesion testing coupled with microstructural characterization was used to define the strength, the type and the continuity of the bonded interface between splat and substrate material. The results demonstrated that optimization of spray conditions makes it possible to obtain splats with continuous bonding along the splat/substrate interface and measured adhesion strengths approaching the shear strength of bulk material. The parameters shown to improve the splat adhesion included the increase of the splat deposition velocity well above the critical deposition velocity of the tested material, increase in the temperature of both powder and the substrate material, decrease in the powder size, and optimization of the flow dynamics for the cold spray gun nozzle. Through comparisons to the literature, the adhesion strength of Ti splats measured with the splat adhesion technique correlated well with the cohesion strength of Ti coatings deposited under similar conditions and measured with tubular coating tensile (TCT) test.

  16. A comparative first-principles study of martensitic phase transformations in TiPd2 and TiPd

    SciTech Connect

    Krcmar, Maja; Morris, James R

    2014-01-01

    Martensitic phase transformations in TiPd2 and TiPd alloys are studied employing density-functional, first-principles calculations. We examine the transformation of tetragonal C11b TiPd2 to the low-temperature orthorhombic phase (C11b oI6), and the transformation of cubic B2 TiPd under orthorhombic (B2 B19) and subsequent monoclinic transformations (B19 B19 ) as the system is cooled. To evaluate the transition temperature for TiPd2 we employ a theoretical approach based on a phenomenological Landau theory of the structural phase transition and a mean-field approximation for the free energy, utilizing first-principles calculations to obtain the deformation energy as a function of strains and to deduce parameters for constructing the free energy. The predicted transition temperature for the TiPd2 C11b oI6 transition temperature is in good agreement with reported experimental results. To investigate the TiPd B2 B19 transformation, we employ both the Cauchy-Born rule and a soft-mode- based approach, and elucidate on the importance of coupling of lattice distortion and atomic displacements (i.e., shuffling) in the formation of the final structure. The estimated B2 B19 transition temperature for TiPd system agrees well with the experimental results. We also find that there exists a very small but finite (0.0005 eV/atom) energy barrier of B19 TiPd under monoclinic deformation for B19 B19 structural phase transformation.

  17. Characterization of Failed Surface of Ti and Imidex (PI) Film for Different Inter-layer Thicknesses of Ti Film

    NASA Astrophysics Data System (ADS)

    Lubna, Nusrat; Chaudhury, Zariff; Newaz, Golam

    2012-09-01

    For miniaturized biomedical devices, laser joining of dissimilar materials offers excellent potential to make precise joints. An important system for consideration is titanium (Ti) coated glass joined with biocompatible imidex polyimide (PI). Metallic Ti with various thicknesses was deposited on top of pyrex 7740 borosilicate glass by using DC-magnetron sputtering deposition method. Effect of bond strength between Ti coated glass and imidex polyimide (PI), due to thickness variation of sputtered Ti coating was studied. Three different Ti inter-layer thicknesses were considered, 50, 200, and 400 nm. Tests results indicated that the thinner film produced lower shear strength and higher thickness produced higher shear strength. It has been observed that thicker film (200 and 400 nm) enhanced considerably the bond strength with enhancing the film roughness as well. Higher roughness resulted in more contact area at the interface, results higher number of chemical bonds and increased mechanical interlocking; which in turn increase the laser joint strength. For stronger bond with higher thickness, mixed mode failure was observed which included cohesive failure of polymer, interface failure of Ti/glass and failure on the glass itself. On the other hand, for weak bond with thinner film, mostly interface failure was observed for this system of Ti coated glass/imidex. For thicker film, chemical bond of Ti-C and Ti-O were observed. The role of both surface characteristics and chemical bonding for laser joints were investigated by using advanced techniques such as X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy.

  18. Indentation creep in nanocrystalline Fe-TiN and Ni-TiN alloys prepared by mechanical alloying

    SciTech Connect

    Ogino, Yoshikiyo; Yamasaki, Tohru; Shen, B.L.

    1997-04-01

    Mechanical properties of nanocrystalline Fe-TiN and Ni-TiN alloys with various TiN contents between 17 and 64 vol pct, which are prepared by dynamically consolidating mechanically alloyed powders, have been investigated by means of hardness measurements and indentation creep tests at intermediate temperatures. The hardness increases with decreasing grain size to about 10 nm. The indentation creep curves conform well to an equation derived from a transient creep rate equation. The analysis of creep curves indicates that the deformation occurs by a dislocation mechanism controlled by grain boundary diffusion.

  19. The molecular mechanism for effects of TiN coating on NiTi alloy on endothelial cell function.

    PubMed

    Yang, Dayun; Lü, Xiaoying; Hong, Ying; Xi, Tingfei; Zhang, Deyuan

    2014-08-01

    The aim of this study is to systematically investigate the molecular mechanism of different effects of nickel titanium (NiTi) alloy surface and titanium nitride (TiN) coating on endothelial cell function. Release of nickel (Ni) ion from bare and TiN-coated NiTi alloys and proliferation of endothelial cells on the two materials were evaluated, and then influence of the two materials on cellular protein expression profiles was investigated by proteomic technology. Subsequently, proteomic data were analyzed with bioinformatics analyses and further validated using a series of biological experiments. Results showed that although the two materials did not affect cell proliferation, the Ni ions released from bare NiTi alloy generated inhibition on pathways associated with actin cytoskeleton, focal adhesion, energy metabolism, inflammation, and amino acid metabolism. In comparison, TiN coating not only effectively prevented release of Ni ions from NiTi alloy, but also promoted actin cytoskeleton and focal adhesion formation, increased energy metabolism, enhanced regulation of inflammation, and promoted amino acid metabolism. Furthermore, the two processes, "the initial mediation of adsorbed serum protein layer to endothelial cell adhesion and growth on the two materials" from our previous study, and "the following action of the two materials on cellular protein expression profile", were linked up and comprehensively analyzed. It was found that in stage of cell adhesion (within 4 h), release of Ni ions from bare NiTi alloy was very low, and the activation of adsorbed proteins to cell adhesion and growth related biological pathways (such as regulation of actin cytoskeleton, and focal adhesion pathways) was almost as same as TiN-coated NiTi alloy. This indicated that the released Ni ions did not affect the mediation of adsorbed proteins to endothelial cell adhesion. However, in stage of cell growth and proliferation, the release of Ni ions from bare NiTi alloy increased with

  20. The 44Ti(alpha,p) reaction and its implication on the 44Ti yield in supernovae

    PubMed

    Sonzogni; Rehm; Ahmad; Borasi; Bowers; Brumwell; Caggiano; Davids; Greene; Harss; Heinz; Henderson; Janssens; Jiang; McMichael; Nolen; Pardo; Paul; Schiffer; Segel; Seweryniak; Siemssen; Truran; Uusitalo; Wiedenhover; Zabransky

    2000-02-21

    Cross sections for the 44Ti(alpha,p)47V reaction which significantly affects the yield of 44Ti in supernovae were measured in the energy range 5.7 MeVTi. The cross sections and the deduced astrophysical reaction rates are larger than the results from theoretical calculations by about a factor of 2. The implications of this increase in the reaction rate for the search of supernovae using space-based gamma detectors are discussed.

  1. The Reductive Activation of CO2 Across a Ti=Ti Double Bond: Synthetic, Structural, and Mechanistic Studies.

    PubMed

    Kilpatrick, Alexander F R; Green, Jennifer C; Cloke, F Geoffrey N

    2015-10-26

    The reactivity of the bis(pentalene)dititanium double-sandwich compound Ti2Pn(†)2 (1) (Pn(†) = 1,4-{Si(i)Pr3}2C8H4) with CO2 is investigated in detail using spectroscopic, X-ray crystallographic, and computational studies. When the CO2 reaction is performed at -78 °C, the 1:1 adduct 4 is formed, and low-temperature spectroscopic measurements are consistent with a CO2 molecule bound symmetrically to the two Ti centers in a μ:η(2),η(2) binding mode, a structure also indicated by theory. Upon warming to room temperature the coordinated CO2 is quantitatively reduced over a period of minutes to give the bis(oxo)-bridged dimer 2 and the dicarbonyl complex 3. In situ NMR studies indicated that this decomposition proceeds in a stepwise process via monooxo (5) and monocarbonyl (7) double-sandwich complexes, which have been independently synthesized and structurally characterized. 5 is thermally unstable with respect to a μ-O dimer in which the Ti-Ti bond has been cleaved and one pentalene ligand binds in an η(8) fashion to each of the formally Ti(III) centers. The molecular structure of 7 shows a "side-on" bound carbonyl ligand. Bonding of the double-sandwich species Ti2Pn2 (Pn = C8H6) to other fragments has been investigated by density functional theory calculations and fragment analysis, providing insight into the CO2 reaction pathway consistent with the experimentally observed intermediates. A key step in the proposed mechanism is disproportionation of a mono(oxo) di-Ti(III) species to yield di-Ti(II) and di-Ti(IV) products. 1 forms a structurally characterized, thermally stable CS2 adduct 8 that shows symmetrical binding to the Ti2 unit and supports the formulation of 4. The reaction of 1 with COS forms a thermally unstable complex 9 that undergoes scission to give mono(μ-S) mono(CO) species 10. Ph3PS is an effective sulfur transfer agent for 1, enabling the synthesis of mono(μ-S) complex 11 with a double-sandwich structure and bis(μ-S) dimer 12 in which

  2. Catalytic formal [2+2+1] synthesis of pyrroles from alkynes and diazenes via Ti(II)/Ti(IV) redox catalysis.

    PubMed

    Gilbert, Zachary W; Hue, Ryan J; Tonks, Ian A

    2016-01-01

    Pyrroles are structurally important heterocycles. However, the synthesis of polysubstituted pyrroles is often challenging. Here, we report a multicomponent, Ti-catalysed formal [2+2+1] reaction of alkynes and diazenes for the oxidative synthesis of penta- and trisubstituted pyrroles: a nitrenoid analogue to classical Pauson-Khand-type syntheses of cyclopentenones. Given the scarcity of early transition-metal redox catalysis, preliminary mechanistic studies are presented. Initial stoichiometric and kinetic studies indicate that the mechanism of this reaction proceeds through a formally Ti(II)/Ti(IV) redox catalytic cycle, in which an azatitanacyclobutene intermediate, resulting from [2+2] alkyne + Ti imido coupling, undergoes a second alkyne insertion followed by reductive elimination to yield pyrrole and a Ti(II) species. The key component for catalytic turnover is the reoxidation of the Ti(II) species to a Ti(IV) imido via the disproportionation of an η(2)-diazene-Ti(II) complex.

  3. Anodization of Ti thin film deposited on ITO.

    PubMed

    Sadek, Abu Z; Zheng, Haidong; Latham, Kay; Wlodarski, Wojtek; Kalantar-Zadeh, Kourosh

    2009-01-06

    We have investigated several key aspects for the self-organization of nanotubes in RF sputtered titanium (Ti) thin films formed by the anodization process in fluoride-ion-containing neutral electrolytes. Ti films were deposited on indium tin oxide (ITO) glass substrates at room temperature and 300 degrees C, and then anodized. The films were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis spectrometry before and after anodization. It was observed that anodization of high temperature deposited films resulted in nanotube type structures with diameters in the range of 10-45 nm for an applied voltage of 5-20 V. In addition, the anatase form of TiO(2) is formed during the anodization process which is also confirmed using photocurrent measurements. However, the anodization of room temperature deposited Ti films resulted in irregular pores or holes.

  4. Wear of Cast Chromium Steels With TiC Reinforcement

    SciTech Connect

    Dogan,O.N.; Hawk, J.A.; Tylczak, J.H.

    2001-10-01

    Wear resistance of a series of new titanium carbide reinforced cast chromium steels was investigated under various wear conditions. The steels which were melted in a vacuum induction furnace contained 12 Cr, 3-5 Ti, 1-2 C in weight percent. Microstructure of these materials was characterized using scanning electron microscopy, light optical microscopy, and X-ray diffraction. Microstructure of steels consisted of TiC phase dispersed in a martensitic matrix. High-stress and low-stress abrasion tests, and an erosion test, were utilized to understand the wear behavior of these materials under different environments. The steels were tested in as-cast and heat treated conditions. Wear rates of the cast Cr/TiC steels were compared to those of an AISI type 440C steel and P/M composites reinforced with TiC.

  5. Photocatalytic metamaterials: TiO2 inverse opals.

    PubMed

    Sordello, Fabrizio; Duca, Clara; Maurino, Valter; Minero, Claudio

    2011-06-07

    The study of the photocatalytic activity of TiO(2) inverse opals showed that these structures behave as metamaterials: their properties arise principally from the 3D periodic structure of the material and marginally from porosity, reflectivity and scattering.

  6. Thermophysical Properties of Liquid AlTi-Based Alloys

    NASA Astrophysics Data System (ADS)

    Egry, I.; Holland-Moritz, D.; Novakovic, R.; Ricci, E.; Wunderlich, R.; Sobczak, N.

    2010-05-01

    The surface tension and density of three liquid AlTi-based alloys (AlTiV, AlTiNb, and AlTiTa) have been measured using electromagnetic levitation as a tool for containerless processing. Surface tension has been determined by the oscillating-drop method, while the density was measured using a shadowgraph technique. Both quantities were determined over a wide temperature range, including the undercooled regime. In addition, sessile-drop and pendant-drop experiments to determine the surface tension were performed in a recently built high-temperature furnace. The measured data were compared to thermodynamic calculations using phenomenological models and the Butler equation. Generally, good agreement was found.

  7. TI--CR--AL--O thin film resistors

    DOEpatents

    Jankowski, Alan F.; Schmid, Anthony P.

    2000-01-01

    Thin films of Ti--Cr--Al--O are used as a resistor material. The films are rf sputter deposited from ceramic targets using a reactive working gas mixture of Ar and O.sub.2. Resistivity values from 10.sup.4 to 10.sup.10 Ohm-cm have been measured for Ti--Cr--Al--O film <1 .mu.m thick. The film resistivity can be discretely selected through control of the target composition and the deposition parameters. The application of Ti--Cr--Al--O as a thin film resistor has been found to be thermodynamically stable, unlike other metal-oxide films. The Ti--Cr--Al--O film can be used as a vertical or lateral resistor, for example, as a layer beneath a field emission cathode in a flat panel display; or used to control surface emissivity, for example, as a coating on an insulating material such as vertical wall supports in flat panel displays.

  8. Atomistic Simulations of Ti Additions to NiAl

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Garg, Anita; Ferrante, John; Amador, Carlos

    1997-01-01

    The development of more efficient engines and power plants for future supersonic transports depends on the advancement of new high-temperature materials with temperature capabilities exceeding those of Ni-based superalloys. Having theoretical modelling techniques to aid in the design of these alloys would greatly facilitate this development. The present paper discusses a successful attempt to correlate theoretical predictions of alloy properties with experimental confirmation for ternary NiAl-Ti alloys. The B.F.S. (Bozzolo-Ferrante-Smith) method for alloys is used to predict the solubility limit and site preference energies for Ti additions of 1 to 25 at.% to NiAl. The results show the solubility limit to be around 5% Ti, above which the formation of Heusler precipitates is favored. These results were confirmed by transmission electron microscopy performed on a series of NiAl-Ti alloys.

  9. Damage testing of sapphire and Ti: sapphire laser materials

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Diffusion bonded sapphire and Ti (Titanium). Sapphire laser materials that will be damage tested to determine if there is an increase in damage threshold. Photographed in building 1145, photographic studio.

  10. Predicting the Orbits of Satellites with a TI-85 Calculator.

    ERIC Educational Resources Information Center

    Papay, Kate; And Others

    1996-01-01

    Describes a project that predicts the orbits of satellites using a TI-85 calculator. Enables students to achieve a richer understanding of longitude, latitude, time zones, orbital mechanics of satellites, and the terms associated with satellite tracking. (JRH)

  11. Hydrogen induced stabilization of meta-stable Mg-Ti

    NASA Astrophysics Data System (ADS)

    Jensen, I. J. T.; Diplas, S.; Løvvik, O. M.

    2012-03-01

    The hydrogenation of Mg0.8125Ti0.1875 was investigated by density functional calculations, using a model where Ti was segregated into nano-clusters. Introducing small amounts of hydrogen resulted in significant stabilization, with the mixing enthalpy (cohesive energy relative to standard state elements) becoming negative for hydrogen contents exceeding 0.07 H per metal. H prefers sites on the interface between Mg and Ti, with hydrogenation energies down to -115 kJ/(mol H2). Trapping of H on these very stable sites is proposed as an alternative explanation to why the reversibility of Mg-Ti thin films, which are initially meta-stable, can be preserved over many cycles of hydrogenation.

  12. Effect of laser power on the microstructure and mechanical properties of TiN/Ti3Al composite coatings on Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Liu, Zhengdao; Zhang, Xiancheng; Xuan, Fuzhen; Wang, Zhengdong; Tu, Shandong

    2013-07-01

    Laser nitriding is one of the effective techniques to improve the surface properties of titanium alloys and has potential application in the life extension of last-stage steam turbine blades. However, cracking of surface coating is a common problem due to heat concentration in laser nitriding process. Conventionally, the cracks can be avoided through heat treatment, which may have an important influence on the mechanical properties of coating. Crack-free TiN/Ti3Al IMC coatings on Ti6Al4V are prepared by plasma spraying and laser nitriding. The microstructures, phase constitutes and compositions of the coating are observed and analyzed with scanning electron microscopy(SEM), X-ray diffraction(XRD) and X-ray energy-dispersive spectroscopy(EDS). Microhardness, elastic modulus, fracture toughness of the coating are measured. The results show that the crack- and pore-free IMC coatings can be made through the proposed method; with increasing laser power, the amount and density of TiN phase in the coating first increased and then decreased, leading to the similar trend of microhardness and elastic modulus and the reverse trend of fracture toughness of the coating. Both the average microhardness and elastic modulus of the coating increase three times higher than those of the substrate. The volume fraction of the TiN reinforced phase in composite can be controlled by varying the laser power and the cracking problem in laser nitriding process is successfully solved.

  13. Potential Fluctuations at Low Temperatures in Mesoscopic-Scale SmTiO3/SrTiO3/SmTiO3 Quantum Well Structures.

    PubMed

    Hardy, Will J; Isaac, Brandon; Marshall, Patrick; Mikheev, Evgeny; Zhou, Panpan; Stemmer, Susanne; Natelson, Douglas

    2017-03-28

    Heterointerfaces of SrTiO3 with other transition metal oxides make up an intriguing family of systems with a bounty of coexisting and competing physical orders. Some examples, such as LaAlO3/SrTiO3, support a high carrier density electron gas at the interface whose electronic properties are determined by a combination of lattice distortions, spin-orbit coupling, defects, and various regimes of magnetic and charge ordering. Here, we study electronic transport in mesoscale devices made with heterostructures of SrTiO3 sandwiched between layers of SmTiO3, in which the transport properties can be tuned from a regime of Fermi-liquid like resistivity (ρ ∝ T(2)) to a non-Fermi liquid (ρ ∝ T(5/3)) by controlling the SrTiO3 thickness. In mesoscale devices at low temperatures, we find unexpected voltage fluctuations that grow in magnitude as T is decreased below 20 K, are suppressed with increasing contact electrode size, and are independent of the drive current and contact spacing distance. Magnetoresistance fluctuations are also observed, which are reminiscent of universal conductance fluctuations but not entirely consistent with their conventional properties. Candidate explanations are considered, and a mechanism is suggested based on mesoscopic temporal fluctuations of the Seebeck coefficient. An improved understanding of charge transport in these model systems, especially their quantum coherent properties, may lead to insights into the nature of transport in strongly correlated materials that deviate from Fermi liquid theory.

  14. Hydrothermal synthesis and photocatalytic activities of Bi{sub 4}Ti{sub 3}O{sub 12}/SrTiO{sub 3} composite micro-platelets

    SciTech Connect

    Zhao, Wei Wang, Hongxing; Feng, Xiangning; Jiang, Wangyang; Zhao, Dan; Li, Jiyuan

    2015-10-15

    Highlights: • Bi{sub 4}Ti{sub 3}O{sub 12}/SrTiO{sub 3} composite was fabricated by combining hydrothermal reaction and molten salt method. • Bi{sub 4}Ti{sub 3}O{sub 12}/SrTiO{sub 3} exhibits higher photocatalytic activity than pure Bi{sub 4}Ti{sub 3}O{sub 12}. • The absorption light of Bi{sub 4}Ti{sub 3}O{sub 12}/SrTiO{sub 3} has been broadened to visible light. - Abstract: In this study, Bi{sub 4}Ti{sub 3}O{sub 12}/SrTiO{sub 3} micro-platelets were successfully synthesized by using hydrothermal and molten salt methods, and the morphology and photocatalytic degradation performance of Bi{sub 4}Ti{sub 3}O{sub 12}/SrTiO{sub 3} was characterized. The results indicated a much higher degradation rate of methylene blue and methylene orange, reaching more than 90% and 65%, respectively, within 3 h under visible-light irradiation. Compared with pure Bi{sub 4}Ti{sub 3}O{sub 12}, the photocatalytic activity of Bi{sub 4}Ti{sub 3}O{sub 12}/SrTiO{sub 3} was significantly better, due to the micron–submicron heterojunction with SrTiO{sub 3} reducing the band gap of Bi{sub 4}Ti{sub 3}O{sub 12}. In addition, the perovskite structure layer facilitates the mobility of the photogenerated carriers and hampers their recombination, which were affected the photocatalytic properties.

  15. Ultraviolet and Visible Photochemistry of Methanol at 3D Mesoporous Networks: TiO2 and Au-TiO2

    DTIC Science & Technology

    2013-05-23

    Y. Titania Aerogels as a Superior Mesoporous Structure for Photoanodes of Dye-Sensitized Solar Cells . Int. J. Electrochem. Sci. 2012, 7, 6910−6919...methanol photochemistry at three-dimensionally (3D) networked aerogels of TiO2 or Au– TiO2 reveals that incorporated Au nanoparticles strongly sensitize...the oxide nanoarchitecture to visible light. Methanol dissociatively adsorbs at the surfaces of TiO2 and Au– TiO2 aerogels under dark, high-vacuum

  16. Photocatalytic degradation of organic reactive dyes over MnTiO3/TiO2 heterojunction composites under UV-visible irradiation.

    PubMed

    Sivakumar, Santhanam; Selvaraj, Ayyasamy; Ramasamy, Anaipalayam Kandasamy

    2013-01-01

    In this study, the photocatalytic degradation of organic reactive dyes have been investigated using MnTiO3/TiO2 heterojunction composites in the presence of electron acceptors under UV-Visible light irradiation. This MnTiO3/TiO2 heterojunction composites were prepared by annealing different mass ratios of pyrophanite MnTiO3 (3-11 wt%) and TiO2 at 300°C. All the MnTiO3/TiO2 heterojunction composites were characterized by spectral techniques like X-ray diffraction (XRD), scanning electron microscope (SEM) and diffused reflectance UV-visible spectroscopic analysis (DRS). Among them, 9 wt% MnTiO3/TiO2 heterojunction composites exhibited higher photocatalytic activity for the degradation of Reactive Blue 4 (RB 4). The photocatalytic efficiency of 9 wt% MnTiO3/TiO2 heterojunction composites was further enhanced by the addition of substantial amount of electron acceptors like hydrogen peroxide (H2O2) and ammonium peroxydisulfate ([NH4]2S2O8). The presence of oxidants (electron acceptors) facilitates the fast degradation of dye solution even in higher concentration upto 200 mg/L. The photocatalytic activity of MnTiO3/TiO2 heterojunction composites was also studied for the degradation of other four different structured reactive dyes. The extent of mineralization of these organic reactive dyes during photocatalytic degradation was estimated from COD analysis. MnTiO3/TiO2 heterojunction composites was also found to have good photostability in the presence of oxidants.

  17. In vitro and in vivo performance of bioactive Ti6Al4V/TiC/HA implants fabricated by a rapid microwave sintering technique.

    PubMed

    Choy, Man Tik; Tang, Chak Yin; Chen, Ling; Wong, Chi Tak; Tsui, Chi Pong

    2014-09-01

    Failure of the bone-implant interface in a joint prosthesis is a main cause of implant loosening. The introduction of a bioactive substance, hydroxyapatite (HA), to a metallic bone-implant may enhance its fixation on human bone by encouraging direct bone bonding. Ti6Al4V/TiC/HA composites with a reproducible porous structure (porosity of 27% and pore size of 6-89 μm) were successfully fabricated by a rapid microwave sintering technique. This method allows the biocomposites to be fabricated in a short period of time under ambient conditions. Ti6Al4V/TiC/HA composites exhibited a compressive strength of 93 MPa, compressive modulus of 2.9 GPa and microhardness of 556 HV which are close to those of the human cortical bone. The in vitro preosteoblast MC3T3-E1 cells cultured on the Ti6Al4V/TiC/HA composite showed that the composite surface could provide a biocompatible environment for cell adhesion, proliferation and differentiation without any cytotoxic effects. This is among the first attempts to study the in vivo performance of load-bearing Ti6Al4V/TiC and Ti6Al4V/TiC/HA composites in a live rabbit. The results indicated that the Ti6Al4V/TiC/HA composite had a better bone-implant interface compared with the Ti6Al4V/TiC implant. Based on the microstructural features, the mechanical properties, and the in vitro and in vivo test results from this study, the Ti6Al4V/TiC/HA composites have the potential to be employed in load-bearing orthopedic applications.

  18. High-rate performance of Ti3+ self-doped TiO2 prepared by imidazole reduction for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Seok, Dong-il; Wu, Mihye; Shim, Kwang Bo; Kang, Yongku; Jung, Ha-Kyun

    2016-10-01

    Ti3+ self-doped TiO2 nanoparticles were prepared via a simple imidazole reduction process and developed as an anode material for Li-ion batteries. Introducing the Ti3+-state on TiO2 nanoparticles resulted in superior rate performances that the capacity retention of 88% at 50 C. The enhanced electrochemical performances were attributed to the resulting lower internal resistance and improved electronic conductivity, based on galvanostatic intermittent titration technique and electrochemical impedance spectroscopy analyses.

  19. Self-doped Ti(3+)-TiO2 as a photocatalyst for the reduction of CO2 into a hydrocarbon fuel under visible light irradiation.

    PubMed

    Sasan, Koroush; Zuo, Fan; Wang, Yuan; Feng, Pingyun

    2015-08-28

    Self-doped TiO2 shows visible light photocatalytic activity, while commercial TiO2 (P25) is only UV responsive. The incorporation of Ti(3+) into TiO2 structures narrows the band gap (2.90 eV), leading to significantly increased photocatalytic activity for the reduction of CO2 into a renewable hydrocarbon fuel (CH4) in the presence of water vapour under visible light irradiation.

  20. Shape memory effect of laser welded NiTi plates

    NASA Astrophysics Data System (ADS)

    Oliveira, J. P.; Fernandes, F. M. Braz; Schell, N.; Miranda, R. M.

    2015-07-01

    Laser welding is a suitable joining technique for shape memory alloys (SMAs). This paper reports the existence of shape memory effect (SME) on laser welded NiTi joints, subjected to bending tests, and correlates this effect with the microstructural analysis performed with X-ray diffraction (XRD). All welded samples were able to recover their initial shape after bending to 180°, which is a remarkable result for industrial applications of NiTi involving laser welding.

  1. NiTi-Polyimide Composites Prepared Using Thermal Imidization Process

    NASA Astrophysics Data System (ADS)

    Vokoun, D.; Sysel, P.; Heller, L.; Kadeřávek, L.; Svatuška, M.; Goryczka, T.; Kafka, V.; Šittner, P.

    2016-05-01

    We manufactured NiTi plate-polyimide composite samples and analyzed their thermomechanical behavior. The residual stresses formed in the composite result from the shift of transformation temperatures and shape changes during thermal cycling. We demonstrate the use of finite element analysis for modeling the shape changes. The shape changes result from the difference in coefficients of thermal expansion and from the changes of Young's modulus and of the coefficient of thermal expansion in the NiTi shape memory alloy.

  2. Ti:sapphire - A theoretical assessment for its spectroscopy

    NASA Astrophysics Data System (ADS)

    Da Silva, A.; Boschetto, D.; Rax, J. M.; Chériaux, G.

    2017-03-01

    This article tries to theoretically compute the stimulated emission cross-sections when we know the oscillator strength of a broad material class (dielectric crystals hosting metal-transition impurity atoms). We apply the present approach to Ti:sapphire and check it by computing some emission cross-section curves for both π and σ polarizations. We also set a relationship between oscillator strength and radiative lifetime. Such an approach will allow future parametric studies for Ti:sapphire spectroscopic properties.

  3. Dynamic recrystallization and superplasticity in TiAl

    SciTech Connect

    Salishchev, G.; Imayev, R.; Imayev, V.; Shagiev, M.

    1995-12-31

    The effect of structural factors (grain size, grain boundary structure and fraction of the second phase) on dynamic recrystallization and superplasticity in the TiAl intermetallic alloy was studied. The possibilities of the formation of submicrocrystalline structure and the abrupt decrease of the superplastic temperature were shown. It was established that the occurrence of dynamic recrystallization and superplastic flow led to the formation of homogeneous microstructure and the improvement of low-temperature ductility in TiAl.

  4. The new polynuclear titanium(IV) complex [(Cp*TiCl)(mu-O)2(Cp*Ti)2(mu-O)(mu-O)2]2Ti (Cp* is eta5-C5Me5).

    PubMed

    Chen, Jie; Hu, Ning-Hai; Zhan, Jie; Li, Yue-Sheng

    2005-07-01

    A new polynuclear titanium(IV) complex, dichlorodeca-mu2-oxo-hexakis(pentamethylcyclopentadienyl)hexatitanium(IV), [Ti6(C10H15)6Cl2O10], has been synthesized by hydrolysis of a titanium complex bearing an N-(2-hydroxy-3,5-dimethylbenzyl)diethanolamine Mannich ligand. The molecule has two O-bridged Ti3O3 rings linked to two similar rings through a tetrahedrally O-coordinated Ti atom. All Ti atoms except the central one are coordinated to pentamethylcyclopentadienyl (Cp*) ligands. The Cp* ligands are arranged with approximate symmetry with respect to the Ti/O/Cl core.

  5. Influences of TiO2 phase structures on the structures and photocatalytic hydrogen production of CuOx/TiO2 photocatalysts

    NASA Astrophysics Data System (ADS)

    Liu, Yuanxu; Wang, Zhonglei; Huang, Weixin

    2016-12-01

    CuOx/TiO2 photocatalysts employing TiO2 with different phase structures as well as P25 as supports were prepared, and their structures and activity for photocatalytic H2 production in methanol/water solution under simulated solar light were comparatively studied. Structural characterization results demonstrated that the TiO2 phase structure strongly affects the CuOx-TiO2 interaction and copper species in various CuOx/TiO2 photocatalysts. The Cu2O-rutile TiO2 interaction is much stronger than the Cu2O-anatase TiO2 interaction, facilitates the interfacial charge transfer process within the Cu2O-rutile TiO2 heterojunction but disables supported Cu2O to catalyze the hole-participated methanol oxidation. The Cu2O-anatase TiO2 heterojunction with the appropriate Cu2O-anatase TiO2 interaction and thus the balancing efficiencies between the interfacial charge transfer process and hole-participated methanol oxidation is most photocatalytic active, and CuOx/P25 with the largest population of Cu2O-anatase TiO2 heterojunction exhibits the highest photocatalytic H2 production. These results provide novel insights in the applied surface science of CuOx/TiO2 photocatalysts.

  6. Bimodal TiO2 Contents of Mare Basalts at Apollo and Luna Sites and Implications for TiO2 Derived from Clementine Spectral Reflectance

    NASA Technical Reports Server (NTRS)

    Gillis, J. J.; Jolliff, B. L.

    2001-01-01

    A revised algorithm to estimate Ti contents of mare regions centered on Apollo and Luna sites shows a bimodal distribution, consistent with mare-basalt sample data. A global TiO2 map shows abundant intermediate TiO2 basalts in western Procellarum. Additional information is contained in the original extended abstract.

  7. Weldability and toughness assessment of Ti-microalloyed offshore steel

    SciTech Connect

    Rak, I.; Gliha, V.; Kocak, M.

    1997-01-01

    The present study has been carried out to investigate the coarse-grained heat-affected zone (CGHAZ) microstructure and crack tip opening displacement (CTOD) toughness of grade StE 355 Ti-microalloyed offshore steels. Three parent plates (40-mm thick) were studied, two of which had Ti microalloying with either Nb + V or Nb also present. As a third steel, conventional StE 355 steel without Ti addition was welded for comparison purposes. Multipass tandem submerged arc weld (SAW) and manual metal arc weld (SMAW) welds were produced. Different heat-affected zone (HAZ) microstructures were simulated to ascertain the detrimental effect of welding on toughness. All HAZ microstructures were examined using optical and electron microscopy. It can be concluded that Ti addition with appropriate steel processing, which disperses fine TiN precipitates uniformly, with a fine balance of other microalloying elements and with a Ti/N weight ratio of about 2.2, is beneficial for HAZ properties of StE 355 grade steel.

  8. Wear resistance of TiAlSiN thin coatings.

    PubMed

    Silva, F J G; Martinho, R P; Alexandre, R J D; Baptista, A P M

    2012-12-01

    In the last decades TiAIN coatings deposited by PVD techniques have been extensively investigated but, nowadays, their potential development for tribological applications is relatively low. However, new coatings are emerging based on them, trying to improve wear behavior. TiAlSiN thin coatings are now investigated, analyzing if Si introduction increases the wear resistance of PVD films. Attending to the application, several wear test configurations has been recently used by some researchers. In this work, TiAISiN thin coatings were produced by PVD Unbalanced Magnetron Sputtering technique and they were conveniently characterized using Scanning Electron Microscopy (SEM) provided with Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), Electron Probe Micro-Analyzer (EPMA), Micro Hardness (MH) and Scratch Test Analysis. Properties as morphology, thickness, roughness, chemical composition and structure, hardness and film adhesion to the substrate were investigated. Concerning to wear characterization, two very different ways were chosen: micro-abrasion with ball-on-flat configuration and industrial non-standardized tests based on samples inserted in a feed channel of a selected plastic injection mould working with 30% (wt.) glass fiber reinforced polypropylene. TiAISiN coatings with a small amount of about 5% (wt.) Si showed a similar wear behavior when compared with TiAIN reported performances, denoting that Si addition does not improve the wear performance of the TiAIN coatings in these wear test conditions.

  9. Tailoring of electron diffusion through TiO2 nanowires

    NASA Astrophysics Data System (ADS)

    Jose, R.; Yusoff, M. M.

    2012-11-01

    Charge transport through a random network of onedimensional TiO2 nanostructures such as nanorods, nanowires, and nanofibers developed by electrospinning technique has been studied in the presence of an electrolyte by electrochemical impedance spectroscopy and transient photocurrent measurements. The results have been compared with the charge transport parameters of random TiO2 nanoparticle (25 nm) network. The charge transport was discussed under the framework of hopping transport. Continuous nanofibers had longer charge collecting times and short nanorods have enhanced scattering losses. The TiO2 films containing random network of nanowires of aspect ratio 10:1 can have an order of magnitude higher diffusion coefficient than other morphologies. Furthermore, charge transport through Nb-doped anatase TiO2 nanofibers was studied. It was observed that the Fermi level of TiO2 rise close to its conduction band and result in a band-edge type diffusion mechanism even at low bias voltages when 2 wt% Nb atoms replaces the Ti atoms in the anatase lattice. The Nb-doped anatase electrospun nanofibers showed high chemical capacitance, high effective diffusion coefficient, and lower transport resistance compared to the undoped samples and conventional nanoparticles.

  10. Hydrogen Impurity Defects in Rutile TiO2

    PubMed Central

    Mo, Li-Bin; Wang, Yu; Bai, Yang; Xiang, Qing-Yun; Li, Qun; Yao, Wen-Qing; Wang, Jia-Ou; Ibrahim, Kurash; Wang, Huan-Hua; Wan, Cai-Hua; Cao, Jiang-Li

    2015-01-01

    Hydrogen-related defects play crucial roles in determining physical properties of their host oxides. In this work, we report our systematic experimental and theoretical (based on density functional theory) studies of the defect states formed in hydrogenated-rutile TiO2 in gaseous H2 and atomic H. In gas-hydrogenated TiO2, the incorporated hydrogen tends to occupy the oxygen vacancy site and negatively charged. The incorporated hydrogen takes the interstitial position in atom-hydrogenated TiO2, forming a weak O-H bond with the closest oxygen ion, and becomes positive. Both states of hydrogen affect the electronic structure of TiO2 mainly through changes of Ti 3d and O 2p states instead of the direct contributions of hydrogen. The resulted electronic structures of the hydrogenated TiO2 are manifested in modifications of the electrical and optical properties that will be useful for the design of new materials capable for green energy economy. PMID:26627134

  11. Fretting Wear of Ti-48Al-2Cr-2Nb

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Lerch, Bradley A.; Draper, Susan L.

    2001-01-01

    An investigation was conducted to examine the wear behavior of gamma titanium aluminide (Ti-48Al-2Cr-2Nb in atomic percent) in contact with a typical nickel-base superalloy under repeated microscopic vibratory motion in air at temperatures from 296-823 K. The surface damage observed on the interacting surfaces of both Ti-48Al-2Cr-2Nb and superalloy consisted of fracture pits, oxides, metallic debris, scratches, craters, plastic deformation, and cracks. The Ti-48Al-2Cr-2Nb transferred to the superalloy at all fretting conditions and caused scuffing or galling. The increasing rate of oxidation at elevated temperatures led to a drop in Ti-48Al-2Cr-2Nb wear at 473 K. Mild oxidative wear was observed at 473 K. However, fretting wear increased as the temperature was increased from 473-823 K. At 723 and 823 K, oxide disruption generated cracks, loose wear debris, and pits on the Ti-48Al-2Cr-2Nb wear surface. Ti-48Al-2Cr-2Nb wear generally decreased with increasing fretting frequency. Both increasing slip amplitude and increasing load tended to produce more metallic wear debris, causing severe abrasive wear in the contacting metals. Keywords

  12. Prediction of Indentation Behavior of Superelastic TiNi

    NASA Astrophysics Data System (ADS)

    Neupane, Rabin; Farhat, Zoheir

    2014-09-01

    Superelastic TiNi shape memory alloys have been extensively used in various applications. The great interest in TiNi alloys is due to its unique shape memory and superelastic effects, along with its superior wear and dent resistance. Assessment of mechanical properties and dent resistance of superelastic TiNi is commonly performed using indentation techniques. However, the coupling of deformation and reversible martensitic transformation of TiNi under indentation conditions makes the interpretation of results challenging. An attempt is made to enhance current interpretation of indentation data. A load-depth curve is predicted that takes into consideration the reversible martensitic transformation. The predicted curve is in good agreement with experimental results. It is found in this study that the elastic modulus is a function of indentation depth. At shallow depths, the elastic modulus is high due to austenite dominance, while at high depths, the elastic modulus drops as the depth increases due to austenite to martensite transition, i.e., martensite dominance. It is also found that TiNi exhibits superior dent resistance compared to AISI 304 steel. There is two orders of magnitude improvement in dent resistance of TiNi in comparison to AISI 304 steel.

  13. Thermochromic characteristics of Ti-doped VO2 thin film

    NASA Astrophysics Data System (ADS)

    Lee, Hwasoo; Ko, Kyung Hyun; Choi, Jun Oh

    2014-03-01

    Utilizing metal-to-insulator transition (MIT) properties of V-oxide film, stable VO2 phase is necessary. In sputtering deposition of VO2, simple target preparation and high deposition rate are recommendable. For this, VO2 film was deposited on quartz substrate by RF magnetron sputter system under low working pressure using V2O5 target. Due to the lower sputtering yield of oxygen compared to vanadium, oxygen ion contents is usually deficient from that of target. So, the reduction of V ions was a result of charge compensation with the oxygen ions. Under lower working pressure, deposition rate become higher so that this deficiency is getting larger to cause further reduction to destabilize VO2. Preventing this, titanium oxide co-deposition was suggested to enrich oxygen source. When TiO2 was used, Ti ion has stable +4 charge state so that extra oxygen sputtered prevents V ion reduction below +4 state. But, in case of TiO, Ti ions were oxidized from +2 to +3 and +4 state and V ions with less oxidation potential should be reduced to +3 or so. Pure VO2 film had MIT at 66°C and large resistivity ratio of 4 orders of magnitude from 30°C to 90°C. Under low working pressure, (V2O5 + TiO2) system yield fairly good films, while films with poor or absence of MIT were produced with TiO case.

  14. Porous NiTi for bone implants: A review

    PubMed Central

    Bansiddhi, A.; Sargeant, T.D.; Stupp, S.I.; Dunand, D.C.

    2011-01-01

    NiTi foams are unique among biocompatible porous metals because of their high recovery strain (due to the shape-memory or superelastic effects) and their low stiffness facilitating integration with bone structures. To optimize NiTi foams for bone implant applications, two key areas are under active study: synthesis of foams with optimal architectures, microstructure and mechanical properties; and tailoring of biological interactions through modifications of pore surfaces. This article reviews recent research on NiTi foams for bone replacement, focusing on three specific topics: (i) surface modifications designed to create bio-inert porous NiTi surfaces with low Ni release and corrosion, as well as bioactive surfaces to enhance and accelerate biological activity; (ii) In vitro and in vivo biocompatibility studies to confirm the long-term safety of porous NiTi implants; and (iii) biological evaluations for specific applications, such as in intervertebral fusion devices and bone tissue scaffolds. Possible future directions for bio-performance and processing studies are discussed that could lead to optimized porous NiTi implants. PMID:18348912

  15. Oxygen adsorption at noble metal/TiO2 junctions

    NASA Astrophysics Data System (ADS)

    Hossein-Babaei, F.; Alaei-Sheini, Navid; Lajvardi, Mehdi M.

    2016-03-01

    Electric conduction in titanium dioxide is known to be oxygen sensitive and the conductivity of a TiO2 ceramic body is determined mainly by the concentration of its naturally occurring oxygen vacancy. Recently, fabrications and electronic features of a number of noble metal/TiO2-based electronic devices, such as solar cells, UV detectors, gas sensors and memristive devices have been demonstrated. Here, we investigate the effect of oxygen adsorption at the noble metal/TiO2 junction in such devices, and show the potentials of these junctions in chemical sensor fabrication. The polycrystalline, poly-phase TiO2 layers are grown by the selective and controlled oxidation of titanium thin films vacuum deposited on silica substrates. Noble metal thin films are deposited on the oxide layers by physical vapor deposition. Current-voltage (I-V) diagrams of the fabricated devices are studied for Ag/, Au/, and Pt/TiO2 samples. The raw samples show no junction energy barrier. After a thermal annealing in air at 250° C, I-V diagrams change drastically. The annealed samples demonstrate highly non-linear I-V indicating the formation of high Schottky energy barriers at the noble metal/TiO2 junctions. The phenomenon is described based on the effect of the oxygen atoms adsorbed at the junction.

  16. 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.

  17. 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.

  18. Mesostructured perovskite solar cells based on highly ordered TiO2 network scaffold via anodization of Ti thin film.

    PubMed

    Huang, Aibin; Zhu, Jingting; Zheng, Jianyun; Yu, Yu; Liu, Yan; Yang, Songwang; Bao, Shanhu; Lei, Lei; Jin, Ping

    2017-02-03

    An anodized TiO2 interconnected network was fabricated and utilized as a mesoporous scaffold and electron transporter in perovskite solar cells. By modifying the synthesis parameters, the morphological features of the interconnected TiO2 nanostructures can be widely tuned and precisely controlled. The functional properties of the anodized TiO2 network are found to be severely influenced by morphology as well as the extent of oxidation. The device with the optimized TiO2 network exhibits superior electron extraction and transferability, resulting in conspicuous enhancement of the photocurrent and power conversion efficiency (PCE). This work proposes a promising and facile method for improving the performance of perovskite solar cells.

  19. TiO2-ITO and TiO2-ZnO nanocomposites: application on water treatment

    NASA Astrophysics Data System (ADS)

    Chorfi, H.; Saadoun, M.; Bousselmi, L.; Bessais, B.

    2012-06-01

    One of the most promising ideas to enhance the photocatalytic efficiency of the TiO2 is to couple this photocatalyst with other semiconductors. In this work, we report on the development of photo-catalytic properties of two types of composites based on TiO2 - ITO (Indium Tin Oxide) and TiO2 - ZnO deposited on conventional ceramic substrates. The samples were characterized by X-ray diffraction (XRD) and transmission Electron Microscopy (TEM). The photo-catalytic test was carried out under UV light in order to reduce/oxidize a typical textile dye (Cibacron Yellow). The experiment was carried out in a bench scale reactor using a solution having a known initial dye concentration. After optimization, we found that both nanocomposites exhibit better photocatalytic activity compared to the standard photocatalyst P25 TiO2.

  20. Characterization of optical and microstructural properties of semitransparent TiO2/Ti/glass interference decorative coatings

    NASA Astrophysics Data System (ADS)

    Skowronski, L.; Wachowiak, A. A.; Grabowski, A.

    2016-12-01

    This paper presents a study of the optical properties and the microstructure of semitransparent interference TiO2/Ti/glass systems obtained by gas injection magnetron sputtering (GIMS). The samples are examined by means of spectroscopic ellipsometry, spectrophotometry and atomic force microscopy. The investigation is complemented by colorimetric measurements. Optical constants of titanium and titanium dioxide layers are determined and carefully studied. An influence of the deposition time on the thickness of metallic and dielectric films has been found. The thickness of Ti films ranges from 12 nm to 73 nm, while that of TiO2 films varies from 11 nm to 43 nm. This thickness directly determines the color of a sample from gold to blue, respectively.

  1. Development of Ultra-Fine Grained Ti and Ti-6Al-4V Alloy by Equal Channel Angular Extrusion

    DTIC Science & Technology

    2007-11-02

    are presented and discussed. Ti alloys are a mixture of hexagonal-close-packed and body - centered - cubic crystal structures. Plastic deformation is accommodated by a mixture of dislocation motion and twinning.

  2. Ti : sapphire laser synchronised with femtosecond Yb pump laser via nonlinear pulse coupling in Ti : sapphire active medium

    NASA Astrophysics Data System (ADS)

    Didenko, N. V.; Konyashchenko, A. V.; Konyashchenko, D. A.; Kostryukov, P. V.; Kuritsyn, I. I.; Lutsenko, A. P.; Mavritskiy, A. O.

    2017-02-01

    A laser system utilising the method of synchronous pumping of a Ti : sapphire laser by a high-power femtosecond Yb3+-doped laser is described. The pulse repetition rate of the Ti : sapphire laser is successfully locked to the repetition rate of the Yb laser for more than 6 hours without the use of any additional electronics. The measured timing jitter is shown to be less than 1 fs. A simple qualitative model addressing the synchronisation mechanism utilising the cross-phase modulation of oscillation and pump pulses within a Ti : sapphire active medium is proposed. Output parameters of the Ti : sapphire laser as functions of its cavity length are discussed in terms of this model.

  3. Mesostructured perovskite solar cells based on highly ordered TiO2 network scaffold via anodization of Ti thin film

    NASA Astrophysics Data System (ADS)

    Huang, Aibin; Zhu, Jingting; Zheng, Jianyun; Yu, Yu; Liu, Yan; Yang, Songwang; Bao, Shanhu; Lei, Lei; Jin, Ping

    2017-02-01

    An anodized TiO2 interconnected network was fabricated and utilized as a mesoporous scaffold and electron transporter in perovskite solar cells. By modifying the synthesis parameters, the morphological features of the interconnected TiO2 nanostructures can be widely tuned and precisely controlled. The functional properties of the anodized TiO2 network are found to be severely influenced by morphology as well as the extent of oxidation. The device with the optimized TiO2 network exhibits superior electron extraction and transferability, resulting in conspicuous enhancement of the photocurrent and power conversion efficiency (PCE). This work proposes a promising and facile method for improving the performance of perovskite solar cells.

  4. Memristive behaviors in Pt/BaTiO{sub 3}/Nb:SrTiO{sub 3} ferroelectric tunnel junctions

    SciTech Connect

    Wen, Zheng; Wu, Di Li, Aidong

    2014-08-04

    We demonstrate memristive behaviors in Pt/BaTiO{sub 3}/Nb:SrTiO{sub 3} metal/ferroelectric/semiconductor ferroelectric tunnel junctions, in which the semiconductor electrode can be switched between the accumulated and the depleted states by polarization reversal in the BaTiO{sub 3} barrier via the ferroelectric field effect. An extra barrier, against electron tunneling, forms in the depleted region of the Nb:SrTiO{sub 3} electrode surface, which together with the ferroelectric barrier itself modulate the tunneling resistance with the change of effective polarization. Continuous resistance modulation over four orders of magnitude is hence achieved by application of programmed voltage pulses with different polarity, amplitude, and repetition numbers, as a result of the development of the extra barrier.

  5. Development of Ti-6Al-4V and Ti-1Al-8V-5Fe Alloys Using Low-Cost TiH2 Powder Feedstock

    SciTech Connect

    Joshi, Vineet V.; Lavender, Curt; Moxon, Vladimir; Duz, Vlad; Nyberg, Eric; Weil, K. Scott

    2012-09-25

    Thermo-mechanical processing was performed on two titanium alloy billets, a beta-titanium alloy (Ti1Al8V5Fe) and an alpha-beta titanium alloy (Ti6Al4V), which had been produced using a novel low-cost powder metallurgy process that relies on the use of TiH2 powder as a feedstock material. The thermomechanical processing was performed in the beta region of the respective alloys to form 16-mm diameter bars. The hot working followed by the heat treatment processes not only eliminated the porosity within the materials but also developed the preferred microstructures. Tensile testing and rotating beam fatigue tests were conducted on the as-rolled and heat-treated materials to evaluate their mechanical properties. The mechanical properties of these alloys matched well with those produced by the conventional ingot processing route.

  6. Effect of ion irradiation on the interdiffusion growth of aluminide phases in Ti Al diffusion couple

    NASA Astrophysics Data System (ADS)

    Romankov, S. E.; Mamaeva, A.; Vdovichenko, E.; Ermakov, E.

    2005-08-01

    During annealing on the Ti surface coated by the Al film, different aluminide phases were formed as the result of reactions between Ti and Al. Preliminary irradiation of the Al film with the thickness of 7 μm by Ti + ions had a strong effect on the interdiffusion growth of aluminide phases on the Ti substrate. Preliminary ion irradiation resulted in the development of more homogeneous and fine-grain microstructure during subsequent annealing. During ion irradiation of the two-phase (TiAl + Ti 3Al) overlayer the decomposition of the TiAl compound and the formation of Ti 3Al happened. In the processing of subsequent annealing, diffusion cementation of the overlayer occurred faster on the surface of the irradiated samples. After irradiation by different ions (Ti + and Al +), and during subsequent annealing the kinetics of structural formation developed in a different way.

  7. Conductive Cu-TiO2 thin films obtained via MOCVD

    NASA Astrophysics Data System (ADS)

    Alvarez Y Quintavalle, F.; Battiston, G. A.; Casellato, U.; Fregona, D.; Gerbasi, R.; Loro, F.

    2002-06-01

    Growths of nanophased Cu, CuO, Cu-TiO2 and Cu2O-TiO2 thin films were performed by using titanium tetraisopropoxide Ti(OiPr)4, and copper(II)acetylacetonatehydrate Cu(acac)2.H2O in the temperature range 275- 370 °C. The composite Cu-TiO2 with very low percent of titanium dioxide (TiO2<5%) can be an alternative procedure to obtain well adherent, smooth and well connected Cu films. Cu2O-TiO2 were obtained by annealing of Cu-TiO2 thin films. Cu2O in a TiO2 matrix remains unaltered after repeated thermal treatments when the Cu:Ti metal ratio is equal or less than 15:1. The films exhibited semiconductor characteristics with a moderate transparency, 40-60% in the visible region.

  8. TiO2 anode materials for lithium-ion batteries with different morphology and additives

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Ng, Yip Hang; Leung, Yu Hang; Liu, Fangzhou; Djurišic, Aleksandra B.; Xie, Mao Hai; Chan, Wai Kin

    2014-03-01

    Electrochemical performances of different TiO2 nanostructures, TiO2/CNT composite and TiO2 with titanium isopropoxide (TTIP) treatment anode were investigated. For different TiO2 nanostructures, we investigated vertically aligned TiO2 nanotubes on Ti foil and TiO2 nanotube-powders fabricated by rapid breakdown anodization technique. The morphology of the prepared samples was characterized by scanning probe microscopy (SEM). The electrochemical lithium storage abilities were studied by galvanostatic method. In addition, carbon nanotubes (CNT) additives and solution treatment process of TiO2 anode were investigated, and the results show that the additives and treatment could enhance the cycling performance of the TiO2 anode on lithium ion batteries.

  9. Preliminary study on rotary ultrasonic machining of CFRP/Ti stacks.

    PubMed

    Cong, W L; Pei, Z J; Treadwell, C

    2014-08-01

    Reported drilling methods for CFRP/Ti stacks include twist drilling, end milling, core grinding, and their derived methods. The literature does not have any report on drilling of CFRP/Ti stacks using rotary ultrasonic machining (RUM). This paper, for the first time, reports a study on drilling of CFRP/Ti stacks using RUM. It also compares results on drilling of CFRP/Ti stacks using RUM with reported results on drilling of CFRP/Ti stacks using other methods. When drilling CFRP/Ti stacks using RUM, cutting force, torque, and CFRP surface roughness were lower, hole size variation was smaller, CFRP groove depth was smaller, tool life was longer, and there was no obvious Ti exit burr and CFRP entrance delamination. Ti surface roughness when drilling of CFRP/Ti stacks using RUM was about the same as those when using other methods.

  10. Structure and Formation Mechanism of Black TiO2 Nanoparticles.

    PubMed

    Tian, Mengkun; Mahjouri-Samani, Masoud; Eres, Gyula; Sachan, Ritesh; Yoon, Mina; Chisholm, Matthew F; Wang, Kai; Puretzky, Alexander A; Rouleau, Christopher M; Geohegan, David B; Duscher, Gerd

    2015-10-27

    The remarkable properties of black TiO2 are due to its disordered surface shell surrounding a crystalline core. However, the chemical composition and the atomic and electronic structure of the disordered shell and its relationship to the core remain poorly understood. Using advanced transmission electron microscopy methods, we show that the outermost layer of black TiO2 nanoparticles consists of a disordered Ti2O3 shell. The measurements show a transition region that connects the disordered Ti2O3 shell to the perfect rutile core consisting first of four to five monolayers of defective rutile, containing clearly visible Ti interstitial atoms, followed by an ordered reconstruction layer of Ti interstitial atoms. Our data suggest that this reconstructed layer presents a template on which the disordered Ti2O3 layers form by interstitial diffusion of Ti ions. In contrast to recent reports that attribute TiO2 band-gap narrowing to the synergistic action of oxygen vacancies and surface disorder of nonspecific origin, our results point to Ti2O3, which is a narrow-band-gap semiconductor. As a stoichiometric compound of the lower oxidation state Ti(3+) it is expected to be a more robust atomic structure than oxygen-deficient TiO2 for preserving and stabilizing Ti(3+) surface species that are the key to the enhanced photocatalytic activity of black TiO2.

  11. Effect of nano-hydroxyapatite reinforcement in mechanically alloyed NiTi composites for biomedical implant.

    PubMed

    Akmal, Muhammad; Raza, Ahmad; Khan, Muhammad Mudasser; Khan, M Imran; Hussain, Muhammad Asif

    2016-11-01

    Equi-atomic NiTi alloy composites reinforced with 0, 2, 4 and 6vol.% nano-hydroxyapatite (HA) were successfully synthesized using pressureless sintering. Pure Ni and Ti elements were ball milled for 10h in order to produce a mechanically alloyed equi-atomic NiTi alloy (MA-NiTi). Mechanically alloyed NiTi and HA powders were blended, compacted and then sintered for 3h at 1325K. The sintered density varied inversely with volume percent of HA reinforcement. The X-Ray diffraction spectra and SEM images showed the formation of multiple phases like NiTi, NiTi2, Ni3Ti, and Ni4Ti3. The back scattered-SEM image analysis confirmed the presence of Ni-rich and Ti-rich phases with increasing HA content. The 6vol.% HA reinforced composite showed Ni3Ti as the major phase having the highest hardness value which can be attributed to the presence of relatively harder phases along with higher HA content as a reinforcement. The composite of MA-NiTi with 2vol.% HA manifested the most desirable results in the form of better sintering density mainly due to the minute decomposition of NiTi into other phases. Therefore, the 2vol.% reinforced MA-NiTi composite can be exploited as a novel material for manufacturing biomedical implants.

  12. Pulsed-Current Electrochemical Codeposition and Heat Treatment of Ti-Dispersed Ni-Matrix Layers

    NASA Astrophysics Data System (ADS)

    Janetaisong, Pathompong; Boonyongmaneerat, Yuttanant; Techapiesancharoenkij, Ratchatee

    2016-08-01

    An electrochemical deposition is a fast and cost-efficient process to produce film or coating. In this research, Ni-Ti electrodeposition is developed by codepositing a Ti-dispersed Ni-matrix layer from a Ni-plating solution suspended with Ti particles. To enhance the coating uniformity and control the atomic composition, the pulsed current was applied to codeposit Ni-Ti layers with varying pulse duty cycles (10 to 100 pct) and frequencies (10 to 100 Hz). The microstructures and compositions of the codeposited layers were analyzed by scanning electron microscopy, X-ray diffraction, and X-ray fluorescent techniques. The pulsed current significantly improved the quality of the Ni-Ti layer as compared to a direct current. The Ni-Ti layers could be electroplated with a controlled composition within 48 to 51 at. pct of Ti. The optimal pulse duty cycle and frequency are 50 pct and 10 Hz, respectively. The standalone Ni-49Ti layers were removed from copper substrates by selective etching method and subsequently heat-treated under Ar-fed atmosphere at 1423 K (1150 °C) for 5 hours. The phase and microstructures of the post-annealed samples exhibit different Ni-Ti intermetallic compounds, including NiTi, Ni3Ti, and NiTi2. Yet, the contamination of TiN and TiO2 was also present in the post-annealed samples.

  13. Reaction layers and mechanisms for a Ti-activated braze on sapphire

    NASA Astrophysics Data System (ADS)

    Stephens, J. J.; Hosking, F. M.; Headley, T. J.; Hlava, P. F.; Yost, F. G.

    2003-12-01

    A study was conducted to understand the wetting phenomena observed in brazing of a Ti-containing active filler metal on sapphire substrates. The goal of the study was to understand the interfacial reactions that permit wetting of commercial Ag-Cu-Ti active filler metal to pure alumina, despite the lower thermodynamic stability of TiO2 relative to Al2O3. Based upon transmission electron microscope, electron microprobe, and Auger analyses, it is proposed that two coupled reactions and diffusion of reactants take place. The oxides TiO, Ti2O, and Cu3Ti3O were observed at the braze/ceramic interface. It is suggested that the complex oxide Cu3Ti3O grows at its interface with TiO, and the oxide TiO is produced by reaction of Ti and sapphire and is subsequently consumed at its interface with Cu3Ti3O. It is also suggested that Ti2O forms from Ti and TiO while cooling from the brazing cycle.

  14. Mechanical properties and microstructure of TiC/amorphous hydrocarbon nanocomposite coatings.

    SciTech Connect

    Meng, W. J.; Tittsworth, R. C.; Rehn, L. E.; Materials Science Division; Louisana State Univ.

    2000-12-01

    Using the techniques of reactive magnetron sputter deposition and inductively coupled plasma (ICP) assisted hybrid physical vapor deposition (PVD)/chemical vapor deposition (CVD), we have synthesized a wide variety of metal-free amorphous hydrocarbon (a-C:H) and Ti-containing hydrocarbon (Ti-C:H) coatings. Coating elastic modulus and hardness have been measured by the technique of instrumented nanoindentation and related to Ti and hydrogen compositions. We show that both metal and hydrogen compositions significantly influence the mechanical properties of Ti-C:H coatings. The microstructure of Ti-C:H coatings is further characterized by transmission electron microscopy (TEM), X-ray absorption near edge structure (XANES) spectroscopy, and extended X-ray absorption fine structure (EXAFS) spectroscopy. XANES spectroscopy and high-resolution TEM examination of Ti-C:H specimens shows that the dissolution limit of Ti atoms in an a-C:H matrix is between 0.9 and 2.5 at.%. Beyond the Ti dissolution limit, precipitation of nanocrystalline B1-TiC cluster occurs and Ti-C:H coatings are in fact TiC/a-C:H thin film nanocomposites. Measurements of the average Ti bonding environment in TiC/a-C:H nanocomposites by EXAFS spectroscopy are consistent with a microstructure in which bulk-like B1-TiC clusters are embedded in an a-C:H matrix.

  15. Photocatalytic degradation of methylene blue under UV light irradiation on prepared carbonaceous TiO2.

    PubMed

    Ramli, Zatil Amali Che; Asim, Nilofar; Isahak, Wan N R W; Emdadi, Zeynab; Ahmad-Ludin, Norasikin; Yarmo, M Ambar; Sopian, K

    2014-01-01

    This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC), TiO2/carbon (C), and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC) was obtained after treating TiO2/carbon with 1.0 M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TG-DTA), Brunauer-Emmet-Teller (BET), and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9 m(2) g(-1)). The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples.

  16. Structure and Formation Mechanism of Black TiO2 Nanoparticles

    DOE PAGES

    Tian, Mengkun; Mahjouri-Samani, Masoud; Eres, Gyula; ...

    2015-10-27

    The remarkable properties of black TiO2 are due to its disordered surface shell surrounding a crystalline core. However, the chemical composition and the atomic and electronic structure of the disordered shell and its relationship to the core remain poorly understood. Using advanced transmission electron microscopy methods, we show that the outermost layer of black TiO2 nanoparticles consists of a disordered Ti2O3 shell. The measurements show a transition region that connects the disordered Ti2O3 shell to the perfect rutile core consisting first of four to five monolayers of defective rutile, containing clearly visible Ti interstitial atoms, followed by an ordered reconstructionmore » layer of Ti interstitial atoms. Our data suggest that this reconstructed layer presents a template on which the disordered Ti2O3 layers form by interstitial diffusion of Ti ions. In contrast to recent reports that attribute TiO2 band-gap narrowing to the synergistic action of oxygen vacancies and surface disorder of nonspecific origin, our results point to Ti2O3, which is a narrow-band-gap semiconductor. In conclusion, as a stoichiometric compound of the lower oxidation state Ti3+ it is expected to be a more robust atomic structure than oxygen-deficient TiO2 for preserving and stabilizing Ti3+ surface species that are the key to the enhanced photocatalytic activity of black TiO2.« less

  17. A comparative first-principles study of martensitic phase transformations in TiPd2 and TiPd intermetallics.

    PubMed

    Krcmar, M; Morris, James R

    2014-04-02

    Martensitic phase transformations in TiPd2 and TiPd alloys are studied employing density-functional, first-principles calculations. We examine the transformation of tetragonal C11b TiPd2 to the low-temperature orthorhombic phase (C11b → oI6), and the transformation of cubic B2 TiPd under orthorhombic (B2→B19) and subsequent monoclinic transformations (B19→B19') as the system is cooled. We employ a theoretical approach based on a phenomenological Landau theory of the structural phase transitions and a mean-field approximation for the free energy, utilizing first-principles calculations to obtain the deformation energy as a function of strains and to deduce parameters for constructing the free energy. The predicted transition temperature for the TiPd2 C11b → oI6 transition is in good agreement with reported experimental results. To investigate the TiPd B2→B19 transformation, we employ both the Cauchy-Born rule and a soft-mode-based approach, and elucidate the importance of the coupling between lattice distortion and atomic displacements (i.e. shuffling) in the formation of the final structure. The calculated B2→B19 transition temperature for TiPd alloy agrees well with the experimental results. We also find that there exists a very small but finite (0.0005 eV/atom) energy barrier of B19 TiPd under monoclinic deformation for B19→B19' structural phase transformation.

  18. Behavior of TiO(2) released from Nano-TiO(2)-containing paint and comparison to pristine Nano-TiO(2).

    PubMed

    Al-Kattan, Ahmed; Wichser, Adrian; Zuin, Stefano; Arroyo, Yadira; Golanski, Luana; Ulrich, Andrea; Nowack, Bernd

    2014-06-17

    In the assessment of the fate and effects of engineered nanomaterials (ENM), the current focus is on studying the pristine, unaltered materials. However, ENM are incorporated into products and are released over the whole product life cycle, though mainly during the use and disposal phases. So far, released ENMs have only been characterized to a limited extent and almost nothing is known about the behavior of these materials under natural conditions. In this work we obtained material that was released from aged paint containing nano-TiO2, characterized the particulate materials, and studied their colloidal stability in media with different pH and ionic composition. A stable suspension was obtained from aged paint powder by gentle shaking in water, producing a dilute suspension of 580 μg/L TiO2 with an average particle size of 200-300 nm. Most particles in this suspension were small pieces of paint matrix that also contained nano-TiO2. Some free nano-TiO2 particles were observed by electron microscopy, but the majority was enclosed by the organic paint binder. The pristine nano-TiO2 showed the expected colloidal behavior with increasing stability with increasing pH and strong agglomeration above the isoelectric point and settling in the presence of Ca. The released TiO2 showed very small variations in particle size, ζ potential, and colloidal stability, even in the presence of 3 mM Ca. The results show that the behavior of released ENM may not necessarily be predicted by studying the pristine materials. Additionally, effect studies need to focus more on the particles that are actually released as we can expect that the toxic effect will also be markedly different between pristine and product released materials.

  19. Conductor Formation Through Phase Transformation in Ti-Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Liu, Y. S.; Lin, Y. H.; Wei, Y. S.; Liu, C. Y.

    2012-01-01

    The resistance and transmittance of Ti-oxide thin films sputtered on quartz substrates were studied. The electrical and optical properties can be changed by varying the percentage of O2 introduced during the sputtering. The lowest resistivity for the sputtered Ti-oxide thin film was 2.30 × 10-2 Ω cm for 12.5% O2, which was obtained after annealing at 400°C in ambient oxygen. The results of x-ray photoelectron spectroscopy (XPS) curve-fitting indicate that the Ti-oxide thin film contained both Ti2O3 and TiO2 phases during deposition. The Ti2O3 phase was transformed into the stable TiO2 phase during annealing. The Ti2O3-TiO2 phase transformation initiated the substitution reaction. The substitution of Ti4+ ions in the TiO2 phase for the Ti3+ ions in the Ti2O3 phase created the free electrons. This Ti2O3-TiO2 phase transformation demonstrates the potential mechanism for conduction in the annealed Ti-oxide thin films. The transmittance of the annealed Ti-oxide thin films can be as high as approximately 90% at the 400 nm wavelength with the introduction of 16.5% O2. This result indicates that the annealed Ti-oxide thin films are excellent candidates for use as transparent conducting layers for ultraviolet (UV) or near-UV light-emitting diode (LED) devices.

  20. TiO2 nanoparticle modified organ-like Ti3C2 MXene nanocomposite encapsulating hemoglobin for a mediator-free biosensor with excellent performances.

    PubMed

    Wang, Fen; Yang, ChenHui; Duan, Max; Tang, Yi; Zhu, JianFeng

    2015-12-15

    TiO2 nanoparticle modified organ-like Ti3C2 MXene (TiO2-Ti3C2) nanocomposite has been synthesized and then used to immobilize hemoglobin (Hb) to fabricate a mediator-free biosensor. The morphology and structure of TiO2-Ti3C2 nanocomposite were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Spectroscopic and electrochemical results revealed that TiO2-Ti3C2 nanocomposite is an excellent immobilization matrix with biocompatibility for redox protein, affording good protein bioactivity and stability. Due to the special organ-like hybrid structure of TiO2-Ti3C2, the direct electron transfer of Hb is facilitated and the prepared biosensors displayed good performance for the detection of H2O2 with a wide linear range of 0.1-380 μM for H2O2 (sensitivity of 447.3 μA mM(-1) cm(-2)), an extremely low detection limit of 14 nM for H2O2. Especially, numerous TiO2 nanoparticles with excellent biocompatibility on the surface of the nanocomposite may provide a protective microenvironment for Hb to make the prepared biosensor improve long-term stability. The TiO2-Ti3C2 based biosensor retains 94.6% of the initial response to H2O2 after 60-day storage. TiO2-Ti3C2 nanocomposite could be a promising matrix for the fabrication of mediator-free biosensors, and might find wide potential applications in environmental analysis and biomedical detection.

  1. Synergetic Effect of Ti(3+) and Oxygen Doping on Enhancing Photoelectrochemical and Photocatalytic Properties of TiO2/g-C3N4 Heterojunctions.

    PubMed

    Li, Kai; Huang, Zhenyu; Zeng, Xiaoqiao; Huang, Baibiao; Gao, Shanmin; Lu, Jun

    2017-04-05

    To improve the utilization of visible light and reduce photogenerated electron/hole recombination, Ti(3+) self-doped TiO2/oxygen-doped graphitic carbon nitride (Ti(3+)-TiO2/O-g-C3N4) heterojunctions were prepared via hydrothermal treatment of a mixture of g-C3N4 and titanium oxohydride sol obtained from the reaction of TiH2 with H2O2. In this way, exfoliated O-g-C3N4 and Ti(3+)-TiO2 nanoparticles were obtained. Simultaneously, strong bonding was formed between Ti(3+)-TiO2 nanoparticles and exfoliated O-g-C3N4 during the hydrothermal process. Charge transfer and recombination processes were characterized by transient photocurrent responses, electrochemical impedance test, and photoluminescence spectroscopy. The photocatalytic performances were investigated through rhodamine B degradation test under an irradiation source based on 30 W cold visible-light-emitting diode. The highest visible-light photoelectrochemical and photocatalytic activities were observed from the heterojunction with 1:2 mass ratio of Ti(3+)-TiO2 to O-g-C3N4. The photodegradation reaction rate constant based on this heterojuction is 0.0356 min(-1), which is 3.87 and 4.56 times higher than those of pristine Ti(3+)-TiO2 and pure g-C3N4, respectively. The remarkably high photoelectrochemical and photocatalytic performances of the heterojunctions are mainly attributed to the synergetic effect of efficient photogenerated electron-hole separation, decreased electron transfer resistance from interfacial chemical hydroxy residue bonds, and oxidizing groups originating from Ti(3+)-TiO2 and O-g-C3N4.

  2. Fabrication of Ni-Ti-O nanotube arrays by anodization of NiTi alloy and their potential applications.

    PubMed

    Hang, Ruiqiang; Liu, Yanlian; Zhao, Lingzhou; Gao, Ang; Bai, Long; Huang, Xiaobo; Zhang, Xiangyu; Tang, Bin; Chu, Paul K

    2014-12-18

    Nickel-titanium-oxide (Ni-Ti-O) nanotube arrays (NTAs) prepared on nearly equiatomic NiTi alloy shall have broad application potential such as for energy storage and biomedicine, but their precise structure control is a great challenge because of the high content of alloying element of Ni, a non-valve metal that cannot form a compact electronic insulating passive layer when anodized. In the present work, we systemically investigated the influence of various anodization parameters on the formation and structure of Ni-Ti-O NTAs and their potential applications. Our results show that well controlled NTAs can be fabricated during relatively wide ranges of the anodization voltage (5-90 V), electrolyte temperature (10-50°C) and electrolyte NH4F content (0.025-0.8 wt%) but within a narrow window of the electrolyte H2O content (0.0-1.0 vol%). Through modulating these parameters, the Ni-Ti-O NTAs with different diameter (15-70 nm) and length (45-1320 nm) can be produced in a controlled manner. Regarding potential applications, the Ni-Ti-O NTAs may be used as electrodes for electrochemical energy storage and non-enzymic glucose detection, and may constitute nanoscaled biofunctional coating to improve the biological performance of NiTi based biomedical implants.

  3. Nanofibrous TiO2 improving performance of mesoporous TiO2 electrode in dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Zukalová, Markéta; Kavan, Ladislav; Procházka, Jan; Zukal, Arnošt; Yum, Jun-Ho; Graetzel, Michael

    2013-05-01

    A method of direct coating of conducting glass by electrospinning was developed. Electrospun fibrous TiO2 consisting of closely packed anatase nanocrystals of 40-50 nm in size was incorporated into mesoporous TiO2 thin film stabilized by phosphorus. The mesoporous framework formed by walls with 5-6 nm TiO2 nanocrystals surrounding 20 nm mesopores exhibits extreme porosity and consequently limited number of necking points. TiO2 with fibrous morphology was found to solidify mesoporous titania and to be beneficial for the performance of corresponding photoanode in dye-sensitized solar cell (DSC). Obviously, its wire-like structure suitably interconnects mesoporous network and thus increases the electron collection efficiency from the TiO2 layer to the F-doped SnO2 electrode. The solar conversion efficiency of a DSC employing optimized photoanode consisting of nanocrystalline fibrous bottom layer, four mesoporous layers, and one nanocrystalline anatase scattering top layer sensitized with the N945 dye reached 5.35 %. This represents an improvement of about 9 % compared to the solar conversion efficiency of a DSC employing purely mesoporous TiO2 layer prepared by means of phosphorus doping (5.05 %).

  4. Fe(3+)-Doped TiO₂ Nanotube Arrays on Ti-Fe Alloys for Enhanced Photoelectrocatalytic Activity.

    PubMed

    Yu, Jiangdong; Wu, Zhi; Gong, Cheng; Xiao, Wang; Sun, Lan; Lin, Changjian

    2016-06-06

    Highly ordered, vertically oriented Fe(3+)-doped TiO₂ nanotube arrays (Fe-TNTs) were prepared on Ti-Fe alloy substrates with different Fe contents by the electrochemical anodization method. The as-prepared Fe-TNTs were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and related electrochemical techniques. XPS results demonstrated that Fe(3+) ions were successfully doped into TiO₂ nanotubes. The photoelectrochemical activity of Fe-TNTs was compared with that of pure TiO₂ nanotube arrays (TNTs). The results showed that Fe-TNTs grown on low concentration (0.5 wt %-1 wt % Fe) Ti-Fe alloys possessed higher photocurrent density than TNTs. The Fe-TNTs grown on Ti-Fe alloy containing 0.8 wt % Fe exhibited the highest photoelectrochemical activity and the photoelectrocatalytic degradation rate of methylene blue (MB) aqueous solution was significantly higher than that of TNTs.

  5. Ferroelectricity of nondoped thin HfO2 films in TiN/HfO2/TiN stacks

    NASA Astrophysics Data System (ADS)

    Nishimura, Tomonori; Xu, Lun; Shibayama, Shigehisa; Yajima, Takeaki; Migita, Shinji; Toriumi, Akira

    2016-08-01

    We report on the impact of TiN interfaces on the ferroelectricity of nondoped HfO2. Ferroelectric properties of nondoped HfO2 in TiN/HfO2/TiN stacks are shown in capacitance-voltage and polarization-voltage characteristics. The Curie temperature is also estimated to be around 500 °C. The ferroelectricity of nondoped HfO2 clearly appears by thinning HfO2 film down to ˜35 nm. We directly revealed in thermal treatments that the ferroelectric HfO2 film on TiN was maintained by covering the top surface of HfO2 with TiN, while it was followed by a phase transition to the paraelectric phase in the case of the open surface of HfO2. Thus, it is concluded that the ferroelectricity in nondoped HfO2 in this study was mainly driven by both of top and bottom TiN interfaces.

  6. Fe3+-Doped TiO2 Nanotube Arrays on Ti-Fe Alloys for Enhanced Photoelectrocatalytic Activity

    PubMed Central

    Yu, Jiangdong; Wu, Zhi; Gong, Cheng; Xiao, Wang; Sun, Lan; Lin, Changjian

    2016-01-01

    Highly ordered, vertically oriented Fe3+-doped TiO2 nanotube arrays (Fe-TNTs) were prepared on Ti-Fe alloy substrates with different Fe contents by the electrochemical anodization method. The as-prepared Fe-TNTs were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and related electrochemical techniques. XPS results demonstrated that Fe3+ ions were successfully doped into TiO2 nanotubes. The photoelectrochemical activity of Fe-TNTs was compared with that of pure TiO2 nanotube arrays (TNTs). The results showed that Fe-TNTs grown on low concentration (0.5 wt %–1 wt % Fe) Ti-Fe alloys possessed higher photocurrent density than TNTs. The Fe-TNTs grown on Ti-Fe alloy containing 0.8 wt % Fe exhibited the highest photoelectrochemical activity and the photoelectrocatalytic degradation rate of methylene blue (MB) aqueous solution was significantly higher than that of TNTs. PMID:28335234

  7. Native SrTiO3 (001) surface layer from resonant Ti L2,3 reflectance spectroscopy

    SciTech Connect

    Valvidares, Manuel; Huijben, Mark; Yu, Pu; Ramesh, Ramamoorthy; Kortright, Jeffrey

    2010-11-03

    We quantitatively model resonant Ti L2,3 reflectivity Rs,p(q, hn) from several SrTiO3 (001) single crystals having different initial surface preparations and stored in ambient conditions before and between measurements. All samples exhibit unexpected 300 K Rs(hn) - Rp(hn) anisotropy corresponding to weak linear dichroism and tetragonal distortion of the TiO6 octahedra indicating a surface layer with properties different from cubic SrTiO3. Oscillations in Rs(q) confirm a ubiquitous surface layer 2-3 nm thick that evolves over a range of time scales. Resonant optical constant spectra derived from Rs,p(hn) assuming a uniform sample are refined using a single surface layer to fit measured Rs(q). Differences in surface layer and bulk optical properties indicate that the surface is significantly depleted in Sr and enriched in Ti and O. While consistent with the tendency of SrTiO3 surfaces toward non-stoichiometry, this layer does not conform simply to existing models for the near surface region and apparently forms via room temperature surface reactions with the ambient. This new quantitative spectral modeling approach is generally applicable and has potential to study near-surface properties of a variety of systems with unique chemical and electronic sensitivities.

  8. Ferroelectric BaTiO3 thin films on Ti substrate fabricated using pulsed-laser deposition.

    PubMed

    He, J; Jiang, J C; Liu, J; Collins, G; Chen, C L; Lin, B; Giurgiutiu, V; Guo, R Y; Bhalla, A; Meletis, E I

    2010-09-01

    We report on the fabrication of ferroelectric BaTiO3 thin films on titanium substrates using pulsed laser deposition and their microstructures and properties. Electron microscopy studies reveal that BaTiO3 films are composed of crystalline assemblage of nanopillars with average cross sections from 100 nm to 200 nm. The BaTiO3 films have good interface structures and strong adhesion with respect to Ti substrates by forming a rutile TiO2 intermediate layer with a gradient microstructure. The room temperature ferroelectric polarization measurements show that the as-deposited BTO films possess nearly the same spontaneous polarization as the bulk BTO ceramics indicating formation of ferroelectric domains in the films. Successful fabrication of such ferroelectric films on Ti has significant importance for the development of new applications such as structural health monitoring spanning from aerospace to civil infrastructure. The work can be extended to integrate other ferroelectric oxide films with various promising properties to monitor the structural health of materials.

  9. TiAl3-TiN Composite Nanoparticles Produced by Hydrogen Plasma-Metal Reaction: Synthesis, Passivation, and Characterization

    PubMed Central

    Li, Ju Ying; Mei, Qing Song

    2016-01-01

    TiAl3 and TiN composite nanoparticles were continuously synthesized from Ti–48Al master alloy by hydrogen plasma-metal reaction in a N2, H2 and Ar atmosphere. The phase, morphology, and size of the nanoparticles were studied by X-ray diffraction (XRD) and transmission electronic microscopy (TEM). X-ray photoelectron spectroscopy (XPS) and evolved gas analysis (EGA) were used to analyze the surface phase constitution and oxygen content of the nanoparticles. The as-synthesized nanopowders were mainly composed of nearly spherical TiAl3 and tetragonal TiN phases, with a mean diameter of ~42 nm and mass fractions of 49.1% and 24.3%, respectively. Passivation in the atmosphere of Ar and O2 for 24 h at room temperature led to the formation of amorphous Al2O3 shells on the TiAl3 particle surface, with a mean thickness of ~5.0 nm and a mass fraction of ~23.5%, as well as TiO2 with a mass fraction of ~3.2%. PMID:28335229

  10. 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.

  11. Critical Plastic Strain as a Criterion for Failure in Ballistic Impact Experiments of U/Ti and Ti64 Alloys

    SciTech Connect

    Herrmann, B.; Shvarts, D.; Favorsky, V.; Zaretsky, E.

    2006-07-28

    Strain localization and failure in U-0.75Ti and Ti-6Al-4V alloys were studied in symmetric (rod-on-rod) and reverse ballistic (disk-on-rod) impact experiments, accompanied by VISAR monitoring of the lateral sample surface velocity. Softly-recovered samples were metallurgically examined, and the experiments were numerically simulated using an AUTODYN trade mark sign 2-D code. Satisfactory reproduction of both the measured velocity profiles and the results of metallographic examination of the damage produced by adiabatic shearing were obtained by using the Steinberg-Cochran-Guinan-type constitutive equation (calibrated in preliminary planar impact experiments) and the AUTODYN trade mark sign built-in erosion function. A good agreement was found between strains, measured by using natural markers (martensite in U/Ti and texture in Ti64), corresponding to the onset of adiabatic shearing (0.5 - 1.0) and the value of the critical plastic strain used in the simulations as a criterion for triggering the erosion function (0.6 for both alloys). In the case of Ti64 the shearing is finalized by cracking at observed strain values of 1.0 - 1.5, whereas in the U/Ti the shear strain reaches values greater by at least one order of magnitude and is terminated by void growth and coalescence.

  12. Electrochemical degradation of chlortetracycline using N-doped Ti/TiO2 photoanode under sunlight irradiations.

    PubMed

    Daghrir, Rimeh; Drogui, Patrick; Delegan, Nazar; El Khakani, My Ali

    2013-11-01

    The appearance and the persistence of pharmaceutical products in the aquatic environment urgently call for the development of an innovative and practical water treatment technology. This study deals with the development of nanostructured nitrogen-doped TiO2 photoanodes and their subsequent use for chlortetracycline (CTC) photoelectrocatalytic oxidation under visible light. The N-doped TiO2 photoanodes with different nitrogen contents were prepared by means of a radiofrequency magnetron sputtering (RF-MS) process, with the objective to tune shift their optical absorption from the UV towards the visible. The N-doped TiO2 consist of nanostructured anatase phase with average TiO2 nanocrystallite size of 29 nm. The nitrogen doping is clearly shown to produce the desired red shift of the absorption onset of the TiO2 coatings (from ~380 nm to ~550 nm). Likewise, the N-doped TiO2 are found to be highly photo-electroactive not only under the UV light but most interestingly under the visible light as well. Using the optimal N-doped photoanodes, 99.6% of CTC (100 μg/L) was successfully degraded after 180 min of treatment time with a current intensity of 0.6 A. Under these conditions, a relatively high mineralization of CTC (92.5% ± 0.26% of TOC removal and 90.3% ± 1.1% of TN removal) was achieved.

  13. Preparation of N-doped TiO2 by oxidizing TiN and its application on phenol degradation.

    PubMed

    Huang, Ji-Guo; Zhao, Xiao-Guang; Zheng, Meng-Yang; Li, Sen; Wang, Yu; Liu, Xing-Juan

    2013-01-01

    Incomplete oxidation of titanium nitride (TiN) to prepare nitrogen-doped TiO2 was verified by calcining TiN at different temperatures in air for 30 min. The as-prepared samples were characterized by X-ray diffraction, UV-Vis diffuse reflectance spectra and X-ray photoelectron spectroscopy. The results confirmed that oxidizing TiN incompletely is an effective and simple method to prepare nitrogen-doped TiO2. Photocatalytic degradation of phenol was conducted to evaluate the photocatalytic activity of as-prepared samples. The results showed that phenol can be degraded efficiently by the as-prepared samples under visible light; low phenol concentration was conducive to degradation; the optimum calcination temperature and photocatalyst dosage are 650 °C and 0.5 g/L, respectively. The effects of different light sources on phenol degradation were compared. The reusability of nitrogen-doped TiO2 was tested and the results indicated a relatively good reusability under laboratory conditions.

  14. Fabrication of Ni-Ti-O nanotube arrays by anodization of NiTi alloy and their potential applications

    PubMed Central

    Hang, Ruiqiang; Liu, Yanlian; Zhao, Lingzhou; Gao, Ang; Bai, Long; Huang, Xiaobo; Zhang, Xiangyu; Tang, Bin; Chu, Paul K.

    2014-01-01

    Nickel-titanium-oxide (Ni-Ti-O) nanotube arrays (NTAs) prepared on nearly equiatomic NiTi alloy shall have broad application potential such as for energy storage and biomedicine, but their precise structure control is a great challenge because of the high content of alloying element of Ni, a non-valve metal that cannot form a compact electronic insulating passive layer when anodized. In the present work, we systemically investigated the influence of various anodization parameters on the formation and structure of Ni-Ti-O NTAs and their potential applications. Our results show that well controlled NTAs can be fabricated during relatively wide ranges of the anodization voltage (5–90 V), electrolyte temperature (10–50°C) and electrolyte NH4F content (0.025–0.8 wt%) but within a narrow window of the electrolyte H2O content (0.0–1.0 vol%). Through modulating these parameters, the Ni-Ti-O NTAs with different diameter (15–70 nm) and length (45–1320 nm) can be produced in a controlled manner. Regarding potential applications, the Ni-Ti-O NTAs may be used as electrodes for electrochemical energy storage and non-enzymic glucose detection, and may constitute nanoscaled biofunctional coating to improve the biological performance of NiTi based biomedical implants. PMID:25520180

  15. Selective aerobic oxidation mediated by TiO(2) photocatalysis.

    PubMed

    Lang, Xianjun; Ma, Wanhong; Chen, Chuncheng; Ji, Hongwei; Zhao, Jincai

    2014-02-18

    TiO2 is one of the most studied metal oxide photocatalysts and has unparal-leled efficiency and stability. This cheap, abundant, and non-toxic material has the potential to address future environmental and energy concerns. Understanding about the photoinduced interfacial redox events on TiO2 could have profound effect on the degradation of organic pollutants, splitting of H2O into H2 and O2, and selective redox organic transformations. Scientists traditionally accept that for a semiconductor photocatalyst such as TiO2 under the illumination of light with energy larger than its band gap, two photocarriers will be created to carry out their independent reduction and oxidation processes. However, our recent discoveries indicate that it is the concerted rather than independent effect of both photocarriers of valence band hole (hvb(+)) and conduction band electron (ecb(-)) that dictate the product formation during interfacial oxidation event mediated by TiO2 photocatalysis. In this Account, we describe our recent findings on the selective oxidation of organic substrates with O2 mediated by TiO2 photocatalysis. The transfer of O-atoms from O2 to the corresponding products dominates the selective oxidation of alcohols, amines, and alkanes mediated by TiO2 photocatalysis. We ascribe this to the concerted effect of both hvb(+) and ecb(-) of TiO2 in contribution to the oxidation products. These findings imply that O2 plays a unique role in its transfer into the products rather than independent role of ecb(-) scavenger. More importantly, ecb(-) plays a crucial role to ensure the high selectivity for the oxygenation of organic substrates. We can also use the half reactions such as those of the conduction band electron of TiO2 for efficient oxidation reactions with O2. To this end, efficient selective oxidation of organic substrates such as alcohols, amines, and aromatic alkanes with O2 mediated by TiO2 photocatalysis under visible light irradiation has been achieved. In

  16. Investigation of the mechanical properties of Ti-Fe-Sn ultrafine eutectic composites by dendrite phase selection

    NASA Astrophysics Data System (ADS)

    Lee, C. H.; Kim, J. T.; Hong, S. H.; Song, G. A.; Jo, J. H.; Moon, S. C.; Kim, K. B.

    2014-05-01

    Microstructural investigation of Ti-Fe-Sn ultrafine eutectic composites reveals that β-Ti primary dendrite in eutectic matrix consists of TiFe and β-Ti for Ti72Fe22Sn6 alloy. Similarly, the Ti64Fe32Sn4 alloy and Ti68Fe23Sn9 alloy consists of TiFe and Ti3Sn micron-scale primary dendrites uniformly embedded in the TiFe and β-Ti eutectic structure. The β-Ti dendrite was formed in Ti72Fe22Sn6 alloy, the large number of shear bands propagation and makes multiple steps on the fracture surface. The Ti3Sn dendrite in Ti68Fe23Sn9 ultrafine eutectic alloy leads slip bands which induce the work hardening that have important role in plasticity during deformation. On the other hand, TiFe dendrite in Ti64Fe32Sn4 alloy was presented shear bands bypass and extinction while the propagation of shear bands. These microstructural changes lead to different deformation behavior in primary dendrite. Therefore, it is believed that the mechanical properties of Ti-Fe-Sn alloys could improve due to a different deformation behavior through the minute compositional tuning of Ti-Fe-Sn alloys.

  17. Magneto-transport in LaTi{sub 1−x}Mn{sub x}O{sub 3}/SrTiO{sub 3} oxide heterostructures

    SciTech Connect

    Kumar, Pramod Dogra, Anjana Budhani, R. C.

    2014-04-24

    We report the growth of ultrathin film of Mn doped LaTiO{sub 3} on TiO{sub 2} terminated SrTiO{sub 3} (001) substrate by pulsed laser deposition (PLD) and their electrical transport characteristics including magnetoresistance (MR). Though the replacement of Mn in LaTiO{sub 3} at the Ti site in dilute limit does not affect the metallic behaviour of films but variation in resistance is observed. Normalised resistance behaviour is explained on the basis of variation in charge carriers and increased interaction between Mn atoms in the system under investigation.

  18. Impact of Ni/Ge/Au/Ti/Au and Ti/Pt/Au collector metal on GaInP/GaAs HBT characteristics

    NASA Astrophysics Data System (ADS)

    Park, Jae-Woo; Mohammadi, Saeed; Pavlidis, Dimitris

    2000-10-01

    The collector-emitter offset voltage of GaInP/GaAs HBTs grown by chemical-beam epitaxy with reduced toxicity precursors is investigated for Ni/Ge/Au/Ti/Au and Ti/Pt/Au collector contact metals. The offset voltage for HBTs with Ti/Pt/Au collector metal is increased by 0.26 V compared to Ni/Ge/Au/Ti/Au due to the 0.26 eV barrier existing between the n-GaAs subcollector and the Ti/Pt/Au contact metal. Other parameters affected by the collector contact barrier and impacting transistor performance include DC gain, microwave and power performance.

  19. Influence of TiO2 nanofiber additives for high efficient dye-sensitized solar cells.

    PubMed

    Hwang, Kyung-Jun; Lee, Jae-Wook; Park, Ju-Young; Kim, Sun-Il

    2011-02-01

    TiO2 nanofibers were prepared from a mixture of titanium-tetra-isopropoxide and poly vinyl pyrrolidone by applying the electrospinning method. The samples were characterized by XRD, FE-SEM, TEM and BET analyses. The diameter of electrospun TiO2 nanofibers is in the range of 70 approximately 160 nm. To improve the short-circuit photocurrent, we added the TiO2 nanofibers in the TiO2 electrode of dye-sensitized solar cells (DSSCs). TiO2 nanofibers added in DSSCs can make up to 20% more conversion energy than the conventional DSSC with only TiO2 films only.

  20. EXAFS Study of Disorder in SrTiO3 Perovskite

    SciTech Connect

    Kodre, Alojz; Arcon, Iztok; Gomilsek, Jana Padeznik; Zalar, Bostjan

    2007-02-02

    Ti K-edge EXAFS spectra of SrTiO3 at room temperature and at N2 boiling point are measured to detect the Ti ion displacement above and below the antiferrodistortive phase transition occurring at Tc = 105 K. The data yield a definite value of the displacement, only slightly dependent on the temperature. The sensitive dependence of the amplitude of Ti-O-Ti focusing paths on the scattering angle is used to infer the correlation of Ti displacements. A preference to alternating displacements is indicated.

  1. Investigation into Photoconductivity in Single CNF/TiO2-Dye Core-Shell Nanowire Devices

    DTIC Science & Technology

    2010-01-01

    TiO2 ) is an attractive possible replacement for the sintered TiO2 nanoparticle network in the original dye-sensitized solar cell ( DSSC ) design due to...anatase TiO2 (CNF/ TiO2 ) is an attractive possible replacement for the sintered TiO2 nanoparticle network in the original dye-sensitized solar cell ( DSSC ...a mixture of compact fine grains several nanometers in size embedded in an amorphous phase was suggested for the TiO2 sheath (left inset of Fig. 1d

  2. Microstructure-reactivity relationship of Ti + C reactive nanomaterials

    NASA Astrophysics Data System (ADS)

    Manukyan, Khachatur V.; Lin, Ya-Cheng; Rouvimov, Sergei; McGinn, Paul J.; Mukasyan, Alexander S.

    2013-01-01

    The influence of short-term (≤10 min) high energy ball milling (HEBM) on the microstructure and reactivity of a titanium-carbon powder mixture is reported. It is proved that the mechanism of microstructural transformation in a Ti-C mixture during HEBM defines the reaction mechanism in the produced Ti/C structural energetic materials. More specifically, it is shown that after the first two minutes of dry milling (DM) in an inert (argon) atmosphere the initially crystalline graphite flakes were almost completely amorphized and uniformly distributed on the surface of the deformed titanium particles. A subsequent "cold-welding" leads to formation of Ti-(C-rich/Ti)-Ti agglomerates. TEM studies reveal that the (C-rich/Ti) composite layers consist of nano-size (20 nm) Ti particles distributed in the matrix of the amorphous carbon and thus are characterized by extremely high surface area contacts between the reagents. A rapid self-ignition of the material during DM occurs just after 9.5 min of mechanical treatment, resulting in formation of pure cubic TiC. Wet grinding (WG) of a Ti-C mixture in hexane, under otherwise identical parameters, provides more "soft" conditions, which do not allow the rapid amorphization of carbon during the first stage of grinding. As a result graphite and titanium form sandwich-like Ti/C composite particles, in which the reagents contact primarily along the boundaries of the layers. Such particles gradually transform to the TiC phase without a spontaneous reaction during the HEBM process. The reactivity, i.e., self-ignition temperature and ignition delay time, of different milling-induced microstructures, were also studied. It was found that the ignition temperature in Ti-C structural energetic material prepared under optimized HEBM conditions is ˜600 K, which is more than three times lower than that of the initial reaction mixture (Tig ˜ 1900 K). A significant decrease of the effective activation energy for interaction in the Ti-C system

  3. Grindability of cast Ti-Hf alloys.

    PubMed

    Kikuchi, Masafumi; Takahashi, Masatoshi; Sato, Hideki; Okuno, Osamu; Nunn, Martha E; Okabe, Toru

    2006-04-01

    As part of our systematic studies characterizing the properties of titanium alloys, we investigated the grindability of a series of cast Ti-Hf alloys. Alloy buttons with hafnium concentrations up to 40 mass% were made using an argon-arc melting furnace. Each button was cast into a magnesia-based mold using a dental titanium casting machine; three specimens were made for each metal. Prior to testing, the hardened surface layer was removed. The specimens were ground at five different speeds for 1 min at 0.98 N using a carborundum wheel on an electric dental handpiece. Grindability was evaluated as the volume of metal removed per minute (grinding rate) and the volume ratio of metal removed compared to the wheel material lost (grinding ratio). The data were analyzed using ANOVA. A trend of increasing grindability was found with increasing amounts of hafnium, although there was no statistical difference in the grindability with increasing hafnium contents. We also found that hafnium may be used to harden or strengthen titanium without deteriorating the grindability.

  4. Optimized nanostructured TiO2 photocatalysts

    NASA Astrophysics Data System (ADS)

    Topcu, Selda; Jodhani, Gagan; Gouma, Pelagia

    2016-07-01

    Titania is the most widely studied photocatalyst. In it’s mixed-phase configuration (anatase-rutile form) -as manifested in the commercially available P25 Degussa material- titania was previously found to exhibit the best photocatalytic properties reported for the pure system. A great deal of published research by various workers in the field have not fully explained the underlying mechanism for the observed behavior of mixed-phase titania photocatalysts. One of the prevalent hypothesis in the literature that is tested in this work involves the presence of small, active clusters of interwoven anatase and rutile crystallites or “catalytic “hot-spots””. Therefore, non-woven nanofibrous mats of titania were produced and upon calcination the mats consisted of nanostructured fibers with different anatase-rutile ratios. By assessing the photocatalytic and photoelectrochemical properties of these samples the optimized photocatalyst was determined. This consisted of TiO2 nanostructures annealed at 500˚C with an anatase /rutile content of 90/10. Since the performance of this material exceeded that of P25 complete structural characterization was employed to understand the catalytic mechanism involved. It was determined that the dominant factors controlling the photocatalytic behavior of the titania system are the relative particle size of the different phases of titania and the growth of rutile laths on anatase grains which allow for rapid electron transfer between the two phases. This explains how to optimize the response of the pure system.

  5. Pitot tube calculations with a TI-59

    SciTech Connect

    Brown, K.

    1984-06-01

    Industrial plant and stack analysis dictates that flow measurements in ducts be accurate. This is usually accomplished by running a traverse with a pitot tube across the duct or flue. A traverse is a series of measurements taken at predetermined points across the duct. The values of these measurements are calculated into point flow rates and averaged. A program for the Texas Instruments TI-59 programmable calculator follows. The program will perform calculations for an infinite number of test points, both with the standard (combined impact type) pitot tube and the S-type (combined reverse type). The type of tube is selected by inputting an indicating valve that triggers a flag in the program. To use the standard pitot tube, a 1 is input into key E. When the S-type is used, a zero is input into key E. The program output will note if the S-type had been used. Since most process systems are not at standard conditions (32/sup 0/F, 1 atm) the program will take this into account.

  6. Hexaferrite M (Co, Ti) magnetic properties optimization

    SciTech Connect

    Autissier, D.; Rousselle, D.; Podembski, A.

    1995-09-01

    Barium hexaferrites are anisotropic iron oxides which can present high values of permeability. We have studied Ba (Co, Ti){sub x}Fe{sub 12-2x}O{sub 19} compositions. Powders are synthesized using the ceramic method: stoichiometric amounts of basic components are ground and fired at high temperature (1170{degrees}C) to obtain the desired phase. The powders are then ground for 6 hours in order to reduce the particle size. The slurry is cast in a plaster matrix. This matrix is rotated between the poles of a stationary electromagnet. Fields of approximately 500 Oe are used for the orientation procedure. Samples are then sintered for different temperatures between 1200 and 1300{degrees}C. We present results (magnetization, permeability, permittivity, orientation rate) obtained for diverse compositions (1.1

  7. The Distribution of Radioactive 44Ti in Cassiopeia A

    NASA Astrophysics Data System (ADS)

    Grefenstette, Brian W.; Fryer, Chris L.; Harrison, Fiona A.; Boggs, Steven E.; DeLaney, Tracey; Laming, J. Martin; Reynolds, Stephen P.; Alexander, David M.; Barret, Didier; Christensen, Finn E.; Craig, William W.; Forster, Karl; Giommi, Paolo; Hailey, Charles J.; Hornstrup, Alan; Kitaguchi, Takao; Koglin, J. E.; Lopez, Laura; Mao, Peter H.; Madsen, Kristin K.; Miyasaka, Hiromasa; Mori, Kaya; Perri, Matteo; Pivovaroff, Michael J.; Puccetti, Simonetta; Rana, Vikram; Stern, Daniel; Westergaard, Niels J.; Wik, Daniel R.; Zhang, William W.; Zoglauer, Andreas

    2017-01-01

    The distribution of elements produced in the innermost layers of a supernova explosion is a key diagnostic for studying the collapse of massive stars. Here we present the results of a 2.4 Ms NuSTAR observing campaign aimed at studying the supernova remnant Cassiopeia A (Cas A). We perform spatially resolved spectroscopic analyses of the 44Ti ejecta, which we use to determine the Doppler shift and thus the three-dimensional (3D) velocities of the 44Ti ejecta. We find an initial 44Ti mass of (1.54 ± 0.21) × 10‑4 M⊙, which has a present-day average momentum direction of 340° ± 15° projected onto the plane of the sky (measured clockwise from celestial north) and is tilted by 58° ± 20° into the plane of the sky away from the observer, roughly opposite to the inferred direction of motion of the central compact object. We find some 44Ti ejecta that are clearly interior to the reverse shock and some that are clearly exterior to it. Where we observe 44Ti ejecta exterior to the reverse shock we also see shock-heated iron; however, there are regions where we see iron but do not observe 44Ti. This suggests that the local conditions of the supernova shock during explosive nucleosynthesis varied enough to suppress the production of 44Ti by at least a factor of two in some regions, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium.

  8. Au and Ti induced charge redistributions on monolayer WS2

    NASA Astrophysics Data System (ADS)

    Zhu, Hui-Li; Yang, Wei-Huang; Wu, Ya-Ping; Lin, Wei; Kang, Jun-Yong; Zhou, Chang-Jie

    2015-07-01

    By using the first-principles calculations, structural and electronic properties of Au and Ti adsorbed WS2 monolayers are studied systematically. For Au-adsorbed WS2, metallic interface states are induced in the middle of the band gap across the Fermi level. These interface states origin mainly from the Au-6s states. As to the Ti adsorbed WS2, some delocalized interface states appear and follow the bottom of conduction band. The Fermi level arises into the conduction band and leads to the n-type conducting behavior. The n-type interface states are found mainly come from the Ti-3d and W-5d states due to the strong Ti-S hybridization. The related partial charge densities between Ti and S atoms are much higher and increased by an order of magnitude as compared with that of Au-adsorbed WS2. Therefore, the electron transport across the Ti-adsorbed WS2 system is mainly by the resonant transport, which would further enhances the electronic transparency when monolayer WS2 contacts with metal Ti. These investigations are of significant importance in understanding the electronic properties of metal atom adsorption on monolayer WS2 and offer valuable references for the design and fabrication of 2D nanodevices. Project supported by the National Natural Science Foundation of China (Grant Nos. 91321102, 11304257, and 61227009), the Natural Science Foundation of Fujian Province, China (Grant Nos. 2011J05006, 2009J05149, and 2014J01026), the Foundation from Department of Education of Fujian Province, China (Grant No. JA09146), Huang Hui Zhen Foundation of Jimei University, China (Grant No. ZC2010014), and the Scientific Research Foundation of Jimei University, China (Grant Nos. ZQ2011008 and ZQ2009004).

  9. The Distribution of Radioactive 44Ti in Cassiopeia A

    DOE PAGES

    Grefenstette, Brian W.; Fryer, Christopher Lee; Harrison, Fiona A.; ...

    2016-12-27

    The distribution of elements produced in the inner-most layers of a supernova explosion is a key diagnostic for studying the collapse of massive stars. Here we present the results of a 2.4 Ms NuSTAR observing campaign aimed at studying the supernova remnant Cassiopeia A (Cas A). We perform spatially-resolved spectroscopic analyses of the 44Ti ejecta which we use to determine the Doppler shift and thus the three-dimensional (3D) velocities of the 44Ti ejecta. We nd an initial 44Ti mass of 1.54±0.21x10-4 M which has a present day average momentum direction of 340°±15° projected on to the plane of the skymore » (measured clockwise from Celestial North) and tilted by 58°±20° into the plane of the sky away from the observer, roughly opposite to the inferred direction of motion of the central compact object. We find some 44Ti ejecta that are clearly interior to the reverse shock and some that are clearly exterior to the reverse shock. Where we observe 44Ti ejecta exterior to the reverse shock we also see shock-heated iron; however, there are regions where we see iron but do not observe 44Ti. This suggests that the local conditions of the supernova shock during explosive nucleosynthesis varied enough to suppress the production of 44Ti in some regions by at least a factor of two, even in regions that are assumed to be the result of processes like α-rich freezeout that should produce both iron and titanium.« less

  10. Self-Organized Amorphous TiO2 Nanotube Arrays on Porous Ti Foam for Rechargeable Lithium and Sodium Ion Batteries

    SciTech Connect

    Bi, Zhonghe; Paranthaman, Mariappan Parans; Menchhofer, Paul A; Dehoff, Ryan R; Bridges, Craig A; Chi, Miaofang; Guo, Bingkun; Sun, Xiao-Guang; Dai, Sheng

    2013-01-01

    Self-organized amorphous TiO2 nanotube arrays (NTAs) were successfully fabricated on both Ti foil and porous Ti foam through electrochemical anodization techniques. The starting Ti foams were fabricated using ARCAM s Electron Beam Melting (EBM) technology. The TiO2 NTAs on Ti foam were used as anodes in lithium ion batteries; they exhibited high capacities of 103 Ahcm-2 at 10 Acm-2 and 83 Ahcm-2 at 500 Acm-2, which are two to three times higher than those achieved on the standard Ti foil, which is around 40 Ahcm-2 at 10 Acm-2 and 24 Ahcm-2 at 500 Acm-2, respectively. This improvement is mainly attributed to higher surface area of the Ti foam and higher porosity of the nanotube arrays layer grown on the Ti foam. In addition, a Na-ion half-cell composed of these NTAs anodes and Na metal showed a self-improving specific capacity upon cycling at 10 Acm-2. These results indicate that TiO2 NTAs grown on Ti porous foam are promising electrodes for Li-ion or Na-ion rechargeable batteries.

  11. Investigation of Ag-TiO2 Interfacial Reaction of Highly Stable Ag Nanowire Transparent Conductive Film with Conformal TiO2 Coating by Atomic Layer Deposition.

    PubMed

    Yeh, Ming-Hua; Chen, Po-Hsun; Yang, Yi-Ching; Chen, Guan-Hong; Chen, Hsueh-Shih

    2017-03-29

    The atomic layer deposition (ALD) technique is applied to coat Ag nanowires (NWs) with a highly uniform and conformal TiO2 layer to improve the stability and sustainability of Ag NW transparent conductive films (TCFs) at high temperatures. The TiO2 layer can be directly deposited on Ag NWs with a surface polyvinylpyrrolidone (PVP) coat that acts a bed for TiO2 seeding in the ALD process. The ALD TiO2 layer significantly enhances the thermal stability at least 100 fold when aged between 200-400 °C and also provides an extra function of violet-blue light filtration for Ag NW TCFs. Investigation into the interaction between TiO2 and Ag reveals that the conformal TiO2 shell could effectively prevent Ag from 1D-to-3D ripening. However, Ag could penetrate the conformal TiO2 shell and form nanocrystals on the TiO2 shell surface when it is aged at 400 °C. According to experimental data and thermodynamic evaluation, the Ag penetration leads to an interlayer composed of mixed Ag-Ag2O-amorphous carbon phases and TiO2-x at the Ag-TiO2 interface, which is thought to be caused by extremely high vapor pressure of Ag at the Ag-TiO2 interface at a higher temperature (e.g., 400 °C).

  12. Facile fabrication of transparent TiO2-C@TiO2-C free-standing film for visible-light photocatalytic application

    NASA Astrophysics Data System (ADS)

    Hu, Luyang; Zhang, Yumin; Zhang, Shanmei; Li, Benxia

    2017-02-01

    A transparent TiO2-C@TiO2-C free-standing film has been synthesized by two-step hydrothermal method and subsequent thermal annealing. The chemical composition and morphological features of the TiO2-C@TiO2-C film are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption measurement. The results indicate that the flower-like micro/nanostructure TiO2-C particle layers are intimately inhered to porous TiO2-C fibers. The fibers in film are interconnected each other to form a three-dimensional reticulate microstructure, and exhibit intense visible light absorption and high adsorptivity of dye molecules. The interaction between TiO2 and its surface carbon layer in TiO2-C particle promotes the generation of Ti-O-C bonds, which leads to effective charge transfer. Under visible-light irradiation, TiO2-C@TiO2-C film presents enhanced photocatalytic activity for degradation of methylene blue. This work may provide a new viewpoint for designing transparent photocatalytic film for promising applications in heterogeneous photocatalysis.

  13. 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.

  14. TiO2 nanotube arrays modified with Cr-doped SrTiO3 nanocubes for highly efficient hydrogen evolution under visible light.

    PubMed

    Jiao, Zhengbo; Zhang, Yan; Chen, Tao; Dong, Qingsong; Lu, Gongxuan; Bi, Yingpu

    2014-02-24

    In recent decades, solar-driven hydrogen production over semiconductors has attracted tremendous interest owing to the global energy and environmental crisis. Among various semiconductor materials, TiO2 exhibits outstanding photocatalytic properties and has been extensively applied in diverse photocatalytic and photoelectric systems. However, two major drawbacks limit practical applications, namely, high charge-recombination rate and poor visible-light utilization. In this work, heterostructured TiO2 nanotube arrays grafted with Cr-doped SrTiO3 nanocubes were fabricated by simply controlling the kinetics of hydrothermal reactions. It was found that coupling TiO2 nanotube arrays with regular SrTiO3 nanocubes can significantly improve the charge separation. Meanwhile, doping Cr cations into SrTiO3 nanocubes proved to be an effective and feasible approach to enhance remarkably the visible-light response, which was also confirmed by theoretical calculations. As a result, the rate of photoelectrochemical hydrogen evolution of these novel heteronanostructures is an order of magnitude larger than those of TiO2 nanotube arrays and other previously reported SrTiO3 /TiO2 nanocomposites under visible-light irradiation. Furthermore, the as-prepared Cr-doped SrTiO3 /TiO2 heterostructures exhibit excellent durability and stability, which are favorable for practical hydrogen production and photoelectric nanodevices.

  15. Effect of heat treatment on morphology, crystalline structure and photocatalysis properties of TiO 2 nanotubes on Ti substrate and freestanding membrane

    NASA Astrophysics Data System (ADS)

    Fang, Dong; Luo, Zhiping; Huang, Kelong; Lagoudas, Dimitris C.

    2011-05-01

    Highly ordered titanium oxide (TiO 2) nanotubes were prepared by electrolytic anodization of titanium electrodes. Morphological evolution and phase transformations of TiO 2 nanotubes on a Ti substrate and that of freestanding TiO 2 membranes during the calcinations process were studied by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction microscopy. The detailed results and mechanisms on the morphology and crystalline structure were presented. Our results show that a compact layer exists between the tubular layer and Ti substrate at 600 °C, and the length of the nanotubes shortens dramatically at 750 °C. The freestanding membranes have many particles on their tubes during calcinations from 450 to 900 °C. The TiO 2 nanotubes on the Ti substrate transform to rutile crystals at 600 °C, while the freestanding TiO 2 membranes retain an anatase crystal with increasing temperature to 800 °C. The photocatalytic activity of TiO 2 nanotubes on a Ti substrate annealed at different temperatures was investigated by the degradation of methyl orange in aqueous solution under UV light irradiation. Due to the anatase crystals in the tubular layer and rutile crystals in the compact layer, TiO 2 nanotubes annealed at 450 °C with pure anatase crystals have a better photocatalytic activity than those annealed at 600 °C or 750 °C.

  16. Enhanced photoelectrical performance of dye-sensitized solar cells with double-layer TiO2 on perovskite SrTiO3 substrate

    NASA Astrophysics Data System (ADS)

    Liu, Qiuhong; Sun, Qiong; Zhang, Min; Li, Yang; Zhao, Mei; Dong, Lifeng

    2016-04-01

    In this research, perovskite SrTiO3 particles are synthesized by a hydrothermal method, and TiO2 with a double-layer structure is grown on the SrTiO3 surface by a hydrolysis-condensation process. Structural characterizations reveal that TiO2 comprises of two phases: anatase film at the bottom and single-crystal rutile nanorods grown along the [110] direction on top. The TiO2-SrTiO3 composite film is investigated as photoanode material for dye-sensitized solar cells. In comparison with pure TiO2 and SrTiO3, the composite photoanode shows a much better performance in photoelectric conversion efficiency (1.35 %), which is about 2 and 100 times as efficient as pure TiO2 and SrTiO3, respectively. This indicates that the composite structure can facilitate charge carrier transfer and reduce electron-hole recombination to enhance photoelectrical properties of TiO2-based photoanode materials.

  17. Determination of TiO2 and AgTiO2 Nanoparticles in Artemia salina: Toxicity, Morphological Changes, Uptake and Depuration.

    PubMed

    Ozkan, Yesim; Altinok, Ilhan; Ilhan, Hasan; Sokmen, Munevver

    2016-01-01

    In this study, aquatic stability and toxic effects of TiO2 and AgTiO2 nanoparticles (NPs) were investigated on Artemia salina nauplii. AgTiO2 was found to be more toxic to nauplii compared to TiO2. The mortality rate in nauplii increased significantly with increasing concentrations and duration of exposure. TiO2 eliminations ranged between 27.8% and 96.5% at 50 and 1 mg/L TiO2 exposed to nauplii, respectively. Accumulation and elimination of Ag in AgTiO2 exposed nauplii were similar except at 1 mg/L AgTiO2. When NPs were mixed with water, the hydrodynamic dimensions of NPs significantly increased because of aggregation in saltwater but NP size decreased over time. NPs-exposed nauplii showed changes in eye formation, enlargement of the intestine, malformations in the outer shell and antennae loss were also observed. Since accumulation and toxicity of AgTiO2 NPs was higher than TiO2 alone, inevitably release of AgTiO2 into aqueous environments can cause ecological risks.

  18. The Formation of Ti-H Species at Interface Is Lethal to the Efficiency of TiO2-Based Dye-Sensitized Devices.

    PubMed

    Yan, Yan; Shi, Weidong; Yuan, Zhen; He, Shenggui; Li, Dongmei; Meng, Qingbo; Ji, Hongwei; Chen, Chuncheng; Ma, Wanhong; Zhao, Jincai

    2017-02-08

    TiO2-based dye-sensitization cycle is one of the basic strategies for the development of solar energy applications. Although the power conversion efficiency (PCE) of dye-sensitized devices has been improved through constant attempts, the intrinsically fatal factor that leads to the complete failure of the PCE of TiO2-mediated dye-sensitized devices has not yet been determined. Here, by using isotopically labeled MAS-(1)H NMR, ATR-FTIR spectroscopy (separate H/D and (48)Ti/(49)Ti experiments), and ESR, we revealed that the accumulative formation of Ti-H species on the TiO2 surface is the intrinsic cause of the PCE failure of TiO2-based dye-sensitization devices. Such a Ti-H species is generated from the reduction of hydrogen ions (mostly released from dye carboxyl groups or organic electrolyte) accompanied by electron injection on the surface of TiO2, which deteriorates the PCE mainly by reducing the electrical conductivity of the TiO2 (by a maximum of ∼80%) and the hydrophilic nature of the TiO2 surface (contact angle increased).

  19. In-situ SEM indentation studies of the deformation mechanisms in TiN, CrN and TiN/CrN.

    PubMed

    Rzepiejewska-Malyska, K; Parlinska-Wojtan, M; Wasmer, K; Hejduk, K; Michler, J

    2009-01-01

    In this study, the microstructure and the deformation mechanisms of TiN, CrN and multilayer TiN/CrN thin films on silicon substrates were investigated. Cross-sectional lamellas of nanoindents were prepared by focused ion beam milling to observe by transmission electron microscopy the microstructure of the as-deposited and deformed materials. TiN film exhibits nanocrystalline columns, whereas CrN shows large grains. The TiN/CrN multilayer presents microstructural features typical for both materials. A film hardness of 16.9GPa for CrN, 15.8GPa for TiN and 16.6GPa for TiN/CrN was found by the nanoindentation. Reduced modulus recorded for TiN and CrN reference coatings were 221.54 and 171.1GPa, respectively, and 218.6GPa for the multilayer coating. The deformation mechanisms were observed via in-situ scanning electron microscope nanoindentation. The TiN thin film showed short radial cracks, whereas CrN deformed through pile-up and densification of the material. For TiN/CrN multilayer pile-up and cracks were found. Transmission electron microscopy observations indicated that TiN deforms through grain boundary sliding and CrN via densification and material flow. The deformation mechanism observed in TiN/CrN multilayer was found to be a mixture of both modes.

  20. The Reductive Activation of CO2 Across a Ti=Ti Double Bond: Synthetic, Structural, and Mechanistic Studies

    PubMed Central

    2015-01-01

    The reactivity of the bis(pentalene)dititanium double-sandwich compound Ti2Pn†2 (1) (Pn† = 1,4-{SiiPr3}2C8H4) with CO2 is investigated in detail using spectroscopic, X-ray crystallographic, and computational studies. When the CO2 reaction is performed at −78 °C, the 1:1 adduct 4 is formed, and low-temperature spectroscopic measurements are consistent with a CO2 molecule bound symmetrically to the two Ti centers in a μ:η2,η2 binding mode, a structure also indicated by theory. Upon warming to room temperature the coordinated CO2 is quantitatively reduced over a period of minutes to give the bis(oxo)-bridged dimer 2 and the dicarbonyl complex 3. In situ NMR studies indicated that this decomposition proceeds in a stepwise process via monooxo (5) and monocarbonyl (7) double-sandwich complexes, which have been independently synthesized and structurally characterized. 5 is thermally unstable with respect to a μ-O dimer in which the Ti–Ti bond has been cleaved and one pentalene ligand binds in an η8 fashion to each of the formally TiIII centers. The molecular structure of 7 shows a “side-on” bound carbonyl ligand. Bonding of the double-sandwich species Ti2Pn2 (Pn = C8H6) to other fragments has been investigated by density functional theory calculations and fragment analysis, providing insight into the CO2 reaction pathway consistent with the experimentally observed intermediates. A key step in the proposed mechanism is disproportionation of a mono(oxo) di-TiIII species to yield di-TiII and di-TiIV products. 1 forms a structurally characterized, thermally stable CS2 adduct 8 that shows symmetrical binding to the Ti2 unit and supports the formulation of 4. The reaction of 1 with COS forms a thermally unstable complex 9 that undergoes scission to give mono(μ-S) mono(CO) species 10. Ph3PS is an effective sulfur transfer agent for 1, enabling the synthesis of mono(μ-S) complex 11 with a double-sandwich structure and bis(μ-S) dimer 12 in which the Ti–Ti

  1. TiS2 transformation into S-doped and N-doped TiO2 with visible-light catalytic activity

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Chen; Chien, Tzu-En; Lai, Po-Chih; Chiang, Yu-Hsien; Li, Kun-Lin; Lin, Jong-Liang

    2015-12-01

    S-doped rutile has been prepared for the first time by hydrothermal reaction of TiS2 in hydrochloric acid at a low temperature (180 °C), with the S atoms in three states of Tisbnd Ssbnd Ti, Tisbnd Ssbnd O and SO4. TiS2 in nitric acid can also be transformed into TiO2, but with mixed phases of anatase and rutile, containing nitrogen atoms at interstitial sites in the form of Tisbnd Osbnd N or Tisbnd Nsbnd O. The Ssbnd TiO2 catalyst shows a better visible-light reactivity toward adsorbed methylene blue (MB) photodegradation and hydroxylation of terephthalic acid with respect to the Nsbnd TiO2. The possible reasons leading to the high photoactivity of the Ssbnd TiO2 are discussed in terms of the incorporated sulfur states.

  2. Pressure Induced Phase Transition in PbTiO3 Studied by X-ray Absorption Spectroscopy at the Ti K edge

    SciTech Connect

    Dhaussy, A. C.; Marinel, S.; Veres, A.; Jaouen, N.; Itie, J. P.; Rogalev, A.

    2007-01-19

    The Ti-K edge X-ray Absorption Near Edge Structure (XANES) for CaTiO3 and PbTiO3 have been measured under high pressure in a diamond anvil cell at room temperature. Despite the huge absorption from the diamond cell and the sample high quality XANES allows us to observe that in CaTiO3 no change occurs when applying pressure, at the opposite of PbTiO3 in which the pre-edge features vary strongly. It allows studying the phase transition from ferroelectric to paraelectric phase in PbTiO3 from the local point of view. Under pressure the change in intensity of the pre-edge indicates qualitatively that the Ti atom is moving toward the centre of the oxygen octahedron along the c-axis.

  3. Microstructural evolution in joining of TiAl with a liquid Ti alloy

    SciTech Connect

    Blue, C.A.; Blue, R.A.; Lin, R.Y. . Dept. of Materials Science and Engineering)

    1995-01-01

    In this study, the reaction between titanium aluminide and a liquid titanium alloy, 70Ti-15Cu-15Ni in wt%, was investigated in order to reveal the behavior of TiAl during joining. The microstructural evolution of the reacted melt during solidification was also studied. Issues of concern in this study include: (1) the solidification process of the melt upon termination of heating, and (2) the diffusion of Cu and Ni into the substrate during processing. To accurately control the extent of reaction, an innovative infrared processing technique was used. Infrared processing can produce heating rates exceeding 100 C/s up to the processing temperature and cooling to below 500 C in a few seconds. Such rapid rates of processing decreases or eliminates the adverse effects associated with prolonged heating. In this study, experiments were conducted at various heating times in order to investigate the solidified zone microstructure, melt affected zone thickness, and base material microstructure. The system investigated in this study is directly related to joining of titanium aluminide with a titanium brazing alloy. Meanwhile, the evolution of the microstructure may be applied to other solid-liquid reactions of titanium alloys.

  4. Radiation effects in multilayer ohmic contacts Au-Ti-Al-Ti-n-GaN

    SciTech Connect

    Belyaev, A. E.; Boltovets, N. S.; Ivanov, V. N.; Kapitanchuk, L. M.; Konakova, R. V. Kudryk, Ya. Ya.; Lytvyn, O. S.; Milenin, V. V.; Sheremet, V. N.; Sveshnikov, Yu. N.

    2009-07-15

    Radiation effects in the Au-Ti-Al-Ti-n-GaN multilayer metallization subjected to irradiation with {sup 60}Co {gamma}-ray photons in the dose range 4 x 10{sup 6}-2 x 10{sup 7} Gy are considered, and the effect of radiation on the initial contact structures and the structures subjected to a rapid thermal annealing (RTA) at high-temperature in the nitrogen atmosphere is studied. Irradiation does not significantly affect the properties of structures that were not subjected to the heat treatment. An RTA at 700 deg. C brings about a deterioration of the contact-layer morphology. The morphological and structural transformations in the contact metallization due to the RTA are enhanced by irradiation with {gamma}-ray photons. The combined radiation-thermal treatment is conducive to the mass transfer between contacting layers. In addition, after {gamma}-ray irradiation with the dose of 2 x 10{sup 7} Gy, the oxygen-impurity atoms appear over the entire contact's structure and are observed in a large amount in the near-contact GaN region.

  5. Preparation of porous TiO 2/Ti composite membrane for immunoisolation

    NASA Astrophysics Data System (ADS)

    Minjing, Zhan; Gang, Li; Qiang, Wei; Hualei, Cui; Ling, Lin

    2008-12-01

    The TiO 2 membrane supported on porous Ti planar can be used as a kind of alternative material of immunoisolation membranes, which are presently prepared by polymeric materials, in order to overcome defects of conventional immunoisolation membranes. The composite membranes were prepared by sol-gel technique with tetrabutyl titanate and the withdrawal velocity was 4 mm/s. The circle of 'dip-coating-sintering' must be repeated five times. The retention rate of proteins and flux of glucose were used to evaluate the effect of immunoisolation. The result showed that the membranes, which were sintered under 700 °C, could completely retain the proteins with molecular weight over 156 kDa and the retention rate of BSA exceeded 85%. At the same time, the glucose and proteins, whose molecular weight were under 45 kDa, could all freely pass the membranes according to the concentration difference of both sides. However, the retention rate of proteins first increased and subsequently decreased with the increase of sintering temperature. The membranes, which were sintered at 600 °C, retained more proteins than the membranes sintered at other temperatures. So a better sintering temperature, which can be used as immunoisolation membrane, is about 600 °C.

  6. Electronic properties of free-standing TiO2 nanotube arrays fabricated by electrochemical anodization.

    PubMed

    Chen, Chi Liang; Dong, Chung-Li; Chen, Chia-Hao; Wu, Jen-Wei; Lu, Ying-Rui; Lin, Chin-Jung; Liou, Sofia Ya Hsuan; Tseng, Chuan-Ming; Kumar, Krishna; Wei, Da-Hua; Guo, Jinghua; Chou, Wu-Ching; Wu, Maw-Kuen

    2015-09-14

    Nanotubular TiO2 has attracted considerable attention owing to its unique functional properties, including high surface area and vectorial charge transport along the nanotube, making it a good photocatalytic material. Anodic TiO2-nanotube (TiNT) arrays on a Ti foil substrate were prepared by electrochemical anodic oxidation and SEM/HRTEM/XRD analyses have suggested that the walls of TiO2 tubes are formed from stacked [101] planes (anatase). Both HRTEM and XRD indicate an interplanar spacing of d101 = 0.36 nm in the wall structure. Despite the large amount of work done on nanotube synthesis, a thorough investigation of the electronic and atomic structures of free-standing TiNT arrays has not yet been carried out. X-ray absorption spectroscopy (XAS), resonant inelastic X-ray scattering (RIXS) and scanning photoelectron microscopy (SPEM) are employed herein to examine the electronic and atomic structures at the top and bottom of TiNT arrays. These analyses demonstrate the presence of mixed valence states of the Ti ions (Ti(3+) and Ti(4+)) and a structural distortion at the bottom cap region of the TiNT. Additionally, the results obtained herein suggest the formation of a defective anatase phase at the bottom cap barrier layer between the Ti foil substrate and TiNT during the growth of electrochemically anodized nanotubes.

  7. Differential effects of human and plant N-acetylglucosaminyltransferase I (GnTI) in plants.

    PubMed

    Henquet, Maurice; Heinhuis, Bas; Borst, Jan Willem; Eigenhuijsen, Jochem; Schreuder, Mariëlle; Bosch, Dirk; van der Krol, Alexander

    2010-08-01

    In plants and animals, the first step in complex type N-glycan formation on glycoproteins is catalyzed by N-acetylglucosaminyltransferase I (GnTI). We show that the cgl1-1 mutant of Arabidopsis, which lacks GnTI activity, is fully complemented by YFP-labeled plant AtGnTI, but only partially complemented by YFP-labeled human HuGnTI and that this is due to post-transcriptional events. In contrast to AtGnTI-YFP, only low levels of HuGnTI-YFP protein was detected in transgenic plants. In protoplast co-transfection experiments all GnTI-YFP fusion proteins co-localized with a Golgi marker protein, but only limited co-localization of AtGnTI and HuGnTI in the same plant protoplast. The partial alternative targeting of HuGnTI in plant protoplasts was alleviated by exchanging the membrane-anchor domain with that of AtGnTI, but in stably transformed cgl1-1 plants this chimeric GnTI still did not lead to full complementation of the cgl1-1 phenotype. Combined, the results indicate that activity of HuGnTI in plants is limited by a combination of reduced protein stability, alternative protein targeting and possibly to some extend to lower enzymatic performance of the catalytic domain in the plant biochemical environment.

  8. TEM Observation of the Ti Interlayer Between SiC Substrates During Diffusion Bonding

    NASA Technical Reports Server (NTRS)

    Tsuda, Hiroshi; Mori, Shigeo; Halbig, Michael C.; Singh, Mori

    2012-01-01

    Diffusion bonding was carried out to join SiC to SiC substrates using titanium interlayers. In this study, 10 m and 20 m thick physical vapor deposited (PVD) Ti surface coatings, and 10 and 20 m thick Ti foils were used. Diffusion bonding was performed at 1250 C for PVD Ti coatings and 1200 C for Ti foil. This study investigates the microstructures of the phases formed during diffusion bonding through TEM and selected-area diffraction analysis of a sample prepared with an FIB, which allows samples to be taken from the reacted area. In all samples, Ti3SiC2, Ti5Si3Cx and TiSi2 phases were identified. In addition, TiC and unknown phases also appeared in the samples in which Ti foils were used as interlayers. Furthermore, Ti3SiC2 phases show high concentration and Ti5Si3Cx formed less when samples were processed at a higher temperature and thinner interlayer samples were used. It appears that the formation of microcracks is caused by the presence of intermediate phase Ti5Si3Cx, which has anisotropic thermal expansion, and by the presence of an unidentified Ti-Si-C ternary phase with relatively low Si content.

  9. Substitutional and Interstitial Diffusion in alpha2-Ti3Al(O)

    NASA Technical Reports Server (NTRS)

    Copland, Evan; Young, David J.; Gleeson, Brian; Jacobson, Nathan

    2007-01-01

    The reaction between Al2O3 and alpha2-Ti3Al was studied with a series of Al2O3/alpha2-Ti3Al multiphase diffusion couples annealed at 900, 1000 and 1100 C. The diffusion-paths were found to strongly depend on alpha2- Ti3Al(O) composition. For alloys with low oxygen concentrations the reaction involved the reduction of Al2O3, the formation of a gamma-TiAl reaction-layer and diffusion of Al and O into the alpha2-Ti3Al substrate. Measured concentration profiles across the interaction-zone showed "up-hill" diffusion of O in alpha2-Ti3Al(O) indicating a significant thermodynamic interaction between O and Al, Ti or both. Diffusion coefficients for the interstitial O in alpha2-Ti3Al(O) were determined independently from the interdiffusion of Ti and Al on the substitutional lattice. Diffusion coefficients are reported for alpha2-Ti3Al(O) as well as gamma-TiAl. Interpretation of the results were aided with the subsequent measurement of the activities of Al, Ti and O in alpha 2-Ti3Al(O) by Knudsen effusion-cell mass spectrometry.

  10. Phase transformations and phase equilibria in the Co-Sn-Ti system in the crystallization interval

    NASA Astrophysics Data System (ADS)

    Fartushna, Iu.; Bulanova, M.; Ayral, R. M.; Tedenac, J. C.; Meleshevich, K.

    2016-12-01

    The Co-Sn-Ti system was studied in the crystallization interval (below 50 at% Sn) by the methods of Scanning Electron Microscopy, microprobe analysis, Differential Thermal Analysis, X-ray diffraction. The liquidus and solidus projections and the melting diagram were constructed. Only Co2TiSn(τ1) ternary compound (Heusler phase-L12) was found in equilibria with the liquid in the concentration interval studied. Taking into account our recent data, the liquidus projection is characterized by the fields of primary crystallization of (βTi), (Co), binary-based phases Ti3Sn, Ti2Sn, Ti5Sn3, Ti6Sn5, Ti2Co, TiCo, TiCo2 (c), TiCo2 (h), TiCo3, βCo3Sn2, CoSn and ternary τ1. The solidus projection is characterized by thirteen three-phase fields, which result from invariant four-phase equilibria, five are of eutectic type (E) and eight of transition type (U) and the existence of one more region Ti2Sn3+βCoSn3+(Sn) in the solidus projection is discussed.

  11. Characterization of high temperature deposited Ti-containing hydrogenated carbon thin films

    NASA Astrophysics Data System (ADS)

    Shi, B.; Meng, W. J.; Evans, R. D.

    2004-12-01

    A detailed structural and mechanical characterization was performed on Ti-containing hydrogenated amorphous carbon (Ti-C:H) thin films deposited at ˜600°C by plasma assisted hybrid chemical/physical vapor deposition. The structural and mechanical characteristics of these specimens were compared to those deposited at the lower temperature of ˜250°C. The results indicated that Ti-C :H consisted of a nanocrystalline TiC phase and a hydrogenated amorphous carbon (a-C:H) phase, and that Ti atoms were incorporated into Ti-C :H predominantly as B1-TiC. Deposition at ˜600°C promoted TiC precipitation, resulting in little Ti dissolution within the a-C :H matrix. High temperature deposited Ti-C :H specimens were found to possess lower modulus and hardness values as compared to low temperature deposited specimens, especially at low Ti compositions. This is rationalized by electron microscopy evidence of increased short and medium range graphitic order within the a-C :H matrix of high temperature deposited Ti-C :H, and supported by additional Raman spectroscopic observations. Heat treatments at 600 °C combined with Raman scattering measurements showed that the a-C :H matrix in high temperature deposited Ti-C :H specimens appears to be less structurally sensitive to additional annealing.

  12. The combination of precipitation and dispersion hardening in powder metallurgy produced Cu-Ti-Si alloy

    SciTech Connect

    Bozic, D.; Dimcic, O.; Dimcic, B. Cvijovic, I.; Rajkovic, V.

    2008-08-15

    Microstructure and microhardness properties of precipitation hardened Cu-Ti and precipitation/dispersion hardened Cu-Ti-Si alloys have been analyzed. Cu-1.2Ti and Cu-1.2Ti-3TiSi{sub 2} (wt.%) atomized powders were characterized before and after consolidation by HIP (Hot Isostatic Pressing). Rapidly solidified powders and HIP-ed compacts were subsequently subjected to thermal treatment in hydrogen at temperatures between 300 and 600 deg. C. Compared to Cu-Ti powder particles and compacts, obtained by the same procedure, the strengthening effect in Cu-1.2Ti-3TiSi{sub 2} powder particles and compacts was much greater. The binary and ternary powders both reveal properties superior to those of Cu-1.2Ti and Cu-1.2Ti-3TiSi{sub 2} compacts. Microhardness analysis as a function of the aging temperature of Cu-1.2Ti-3TiSi{sub 2} alloy shows an interaction between precipitation and dispersion hardening which offers possibilities for an application at elevated temperatures.

  13. Degradation of 4-chlorophenol in TiO2, WO3, SnO2, TiO2/WO3 and TiO2/SnO2 systems.

    PubMed

    Lin, Cheng-Fang; Wu, Chung-Hsin; Onn, Zong-Nan

    2008-06-15

    The present study was undertaken to evaluate the degradation performance of 4-chlorophenol (4-CP) using TiO2/WO3 and TiO2/SnO2 systems. A BET surface area analyzer, UV-vis spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron spectroscopy for chemical analysis (ESCA) were employed to characterize the photocatalyst. The band edge wavelength increased to 475 nm and gap energy decreased to 2.61 eV in the TiO2/WO3 system as compare to the single TiO2. Although the specific surfaces area of TiO2/WO3 decreases due to its larger size as compared to either TiO2 or WO3, the 4-CP degradation efficiency significantly increased as compared to single TiO2 or WO3 system at 435 nm wavelength. The TiO2/WO3 degradation of 4-CP at 369 nm was in fact inhibited. For TiO2/SnO2, the degradation efficiency also suffered at 369 nm, and only slightly increased compared to otherwise hardly 4-CP degraded in single TiO2 or SnO2 system. Since there is a significant accumulation of byproducts, the buildup of these intermediates on the catalyst surface may be responsible for their poor performance.

  14. Corrosion resistance appraisal of TiN, TiCN and TiAlN coatings deposited by CAE-PVD method on WC-Co cutting tools exposed to artificial sea water

    NASA Astrophysics Data System (ADS)

    Matei, A. A.; Pencea, I.; Branzei, M.; Trancă, D. E.; Ţepeş, G.; Sfăt, C. E.; Ciovica (Coman), E.; Gherghilescu, A. I.; Stanciu, G. A.

    2015-12-01

    A new advanced sintered composite cutting tool has been developed based on tungsten carbide matrix ligated with cobalt (WC-Co) additivated with tantalum carbide (TaC), titanium carbide (TiC) and niobium carbide (NbC) as grain growth inhibitors. Titanium nitride (TiN), titanium carbonitride (TiCN) and titanium aluminium nitride (TiAlN) coatings were deposited on these tools by CAE-PVD technique to find out the best solution to improve the corrosion resistance of this tool in marine environment. The electrochemical behaviours of the specimens in 3.5% NaCl water solution were estimated by potentiodynamic polarization measurements i.e. the open circuit potential (Eoc), corrosion potential (Ecorr) and corrosion current density (icorr). Wide angle X-ray diffraction (WAXD), optical microscopy (OM) and atomic force microscopy (AFM) investigations have been carried on tested and untested specimens to substantiate the corrosion resistance of the tested specimens. Based on the open circuit potential (Eoc) and corrosion potential (Ecorr) results, the tested specimens were ranked as TiN, TiAlN, TiCN and WC-Co while on corrosion current density (icorr) and protective efficiency (P) values they have been ranked as TiN, TiAlN, WC-Co and TiCN. The WAXD, MO and AFM results unambiguously show that the corrosion resistance depends on the nature and morphology of the coating.

  15. Hierarchical interfaces induce high dielectric permittivity in nanocomposites containing TiO2@BaTiO3 nanofibers

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Chen, Weiwei; Wang, Jianjun; Shen, Yang; Gu, Lin; Lin, Yuanhua; Nan, Ce-Wen

    2014-05-01

    Interface issues are common and crucial in nanocomposites or nanohybrid systems since the interface area is enormous on the nanoscale. In the 0-3 dimensional polymer nanocomposites, in which nano-inclusions (0-dimension) are embedded in a 3-dimensionally connected polymer matrix, enhanced dielectric permittivity could be induced by the interfacial polarization at the interfaces between the nano-inclusions and the polymer matrix. In this contribution, we propose and demonstrate that the topological structure of the interface plays an equally important role as the area of the interface in determining the dielectric polarization of polymer nanocomposites. TiO2 nanofibers embedded with BaTiO3 nanoparticles are prepared via electrospinning and then fused with polyvinyl difluoride (PVDF) into polymer nanocomposite films. Modulation of hierarchical interfaces is thus achieved for these nanocomposites. The confinement of these additional interfaces inside the TiO2 nanofibers leads to percolated networks formed by the interfacial regions. The dielectric permittivity of the polymer nanocomposites is thus enhanced by ~300% over the PVDF matrix at a low filler loading of 11 vol%. A phase-field simulation study indicates that the enhanced dielectric permittivity could be attributed to the increased polarization in the percolated interfacial regions inside the TiO2 nanofibers. The instantaneous electrical breakdown of the TiO2@BaTiO3 nanofibers studied by the in situ transmission electron microscopy method further reveals the striking feature that the breakdown behavior of the nanofibers changes from semiconductive to metallic with the incorporation of insulating BaTiO3 nanoparticles.Interface issues are common and crucial in nanocomposites or nanohybrid systems since the interface area is enormous on the nanoscale. In the 0-3 dimensional polymer nanocomposites, in which nano-inclusions (0-dimension) are embedded in a 3-dimensionally connected polymer matrix, enhanced dielectric

  16. In vitro biocompatibility of Ti-Mg alloys fabricated by direct current magnetron sputtering.

    PubMed

    Hieda, Junko; Niinomi, Mitsuo; Nakai, Masaaki; Cho, Ken

    2015-09-01

    Ti-xMg (x=17, 33, and 55 mass%) alloy films, which cannot be prepared by conventional melting processes owing to the absence of a solid-solution phase in the phase diagram, were prepared by direct current magnetron sputtering in order to investigate their biocompatibility. Ti and Mg films were also prepared by the same process for comparison. The crystal structures were examined by X-ray diffraction (XRD) analysis and the surfaces were analyzed by X-ray photoelectron spectroscopy. The Ti, Ti-xMg alloy, and Mg films were immersed in a 0.9% NaCl solution at 310 K for 7d to evaluate the dissolution amounts of Ti and Mg. In addition, to evaluate the formation ability of calcium phosphate in vitro, the Ti, Ti-xMg alloy, and Mg films were immersed in Hanks' solution at 310 K for 30 d. Ti and Mg form solid-solution alloys because the peaks attributed to pure Ti and Mg do not appear in the XRD patterns of any of the Ti-xMg alloy films. The surfaces of the Ti-17 Mg alloy and Ti-33 Mg alloy films contain Ti oxides and MgO, whereas MgO is the main component of the surface oxide of the Ti-55 Mg alloy and Mg films. The dissolution amounts of Ti from all films are below or near the detection limit of inductively coupled plasma-optical emission spectroscopy. On the other hand, the Ti-17 Mg alloy, Ti-33 Mg alloy, Ti-55 Mg alloy, and Mg films exhibit Mg dissolution amounts of approximately 2.5, 1.4, 21, and 41 μg/cm(2), respectively. The diffraction peaks attributed to calcium phosphate are present in the XRD patterns of the Ti-33 Mg alloy, Ti-55 Mg alloy, and Mg films after the immersion in Hanks' solution. Spherical calcium phosphate particles precipitate on the surface of the Ti-33 Mg film. However, many cracks are observed in the Ti-55 Mg film, and delamination of the film occurs after the immersion in Hanks' solution. The Mg film is dissolved in Hanks' solution and calcium phosphate particles precipitate on the glass substrate. Consequently, it is revealed that the Ti-33 Mg

  17. Influence of TiCl4 post-treatment condition on TiO2 electrode for enhancement photovoltaic efficiency of dye-sensitized solar cells.

    PubMed

    Eom, Tae Sung; Kim, Kyung Hwan; Bark, Chung Wung; Choi, Hyung Wook

    2014-10-01

    Titanium tetrachloride (TiCl4) treatment processed by chemical bath deposition is usually adopted as pre- and post-treatment for nanocrystalline titanium dioxide (TiO2) film deposition in the dye-sensitized solar cells (DSSCs) technology. TiCl4 post-treatment is a widely known method capable of improving the performance of dye-sensitized solar cells. In this work, the effect of TiCl4 post-treatment on the TiO2 electrode is proposed and compared to the untreated film. A TiO2 passivating layer was deposited on FTO glass by RF magnetron sputtering. The TiO2 sol prepared sol-gel method, nanoporous TiO2 upper layer was deposited by screen printing method on the passivating layer. TiCl4 post-treatment was deposited on the substrate by hydrolysis of TiCl4 aqueous solution. Crystalline structure was adjusted by various TiCl4 concentration and dipping time: 20 mM-150 mM and 30 min-120 min. The conversion efficiency was measured by solar simulator (100 mW/cm2). The dye-sensitized solar cell using TiCl4 post-treatment was measured the maximum conversion efficiency of 5.04% due to electron transport effectively. As a result, the DSSCs based on TiCl4 post-treatment showed better photovoltaic performance than cells made purely of TiO2 nanoparticles. The relative DSSCs devices are characterized in terms of short circuit current density, open circuit voltage, fill factor, conversion efficiency.

  18. Efficient Photocatalytic Degradation of Norfloxacin in Aqueous Media by Hydrothermally Synthesized Immobilized TiO2/Ti Films with Exposed {001} Facets.

    PubMed

    Sayed, Murtaza; Shah, Luqman Ali; Khan, Javed Ali; Shah, Noor S; Nisar, Jan; Khan, Hasan M; Zhang, Pengyi; Khan, Abdur Rahman

    2016-12-22

    In this study, a novel immobilized TiO2/Ti film with exposed {001} facets was prepared via a facile one-pot hydrothermal route for the degradation of norfloxacin from aqueous media. The effects of various hydrothermal conditions (i.e., solution pH, hydrothermal time (HT) and HF concentration) on the growth of {001} faceted TiO2/Ti film were investigated. The maximum photocatalytic performance of {001} faceted TiO2/Ti film was observed when prepared at pH 2.62, HT of 3 h and at HF concentration of 0.02 M. The as-prepared {001} faceted TiO2/Ti films were fully characterized by field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), high resolution transmission electron microscope (HR-TEM), and X-ray photoelectron spectroscopy (XPS). More importantly, the as-prepared {001} faceted TiO2/Ti film exhibited excellent photocatalytic performance toward degradation of norfloxacin in various water matrices (Milli-Q water, tap water, river water and synthetic wastewater). The individual influence of various anions (SO4(2-), HCO3(-), NO3(-), Cl(-)) and cations (K(+), Ca(2+), Mg(2+), Cu(2+), Na(+), Fe(3+)) usually present in the real water samples on the photocatalytic performance of as-prepared TiO2/Ti film with exposed {001} facet was investigated. The mechanistic studies revealed that (•)OH is mainly involved in the photocatalytic degradation of norfloxacin by {001} faceted TiO2/Ti film. In addition, norfloxacin degradation byproducts were investigated, on the basis of which degradation schemes were proposed.

  19. 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.

  20. Solution-growth and optoelectronic performance of ZnO : Cl/TiO2 and ZnO : Cl/ZnxTiOy/TiO2 core-shell nanowires with tunable shell thickness

    NASA Astrophysics Data System (ADS)

    Fan, Jiandong; Zamani, Reza; Fábrega, Cristian; Shavel, Alexey; Flox, Cristina; Ibáñez, Maria; Andreu, Teresa; López, Antonio M.; Arbiol, Jordi; Ramón Morante, Joan; Cabot, Andreu

    2012-10-01

    Arrays of vertically aligned ZnO : Cl/TiO2 and ZnO : Cl/ZnxTiOy/TiO2 core-shell nanowires (NWs) were prepared by means of the combination of two solution-growth processes. First, single-crystal ZnO NWs with controlled n-type doping were grown on conducting substrates by a low-cost, high-yield and seed-free electrochemical route. These NWs were covered by a titanium oxide shell of tunable thickness mediating successive adsorption-hydrolysis-condensation steps. Using this atomic-layer growth procedure, titania shells with controlled thickness and the anatase TiO2 phase were obtained after sintering at 450 °C. Higher sintering temperatures resulted in the formation of ZnO : Cl/ZnxTiOy/TiO2 core-shell NWs by the interdiffusion of Zn and Ti ions at the ZnO-TiO2 interface. The performance of ZnO : Cl/TiO2 and ZnO : Cl/ZnxTiOy/TiO2 core-shell NWs towards photoelectrochemical (PEC) water splitting was investigated as a function of the titania shell thickness. Furthermore, the performance of such core-shell NWs as photoelectrodes in dye-sensitized solar cells was also characterized. The TiO2 presence at the ZnO : Cl surface promoted a two-fold increase on the produced photocurrent densities, probing their potential for PEC and optoelectronic applications. Electrochemical impedance spectroscopy was used to corroborate the lower resistance for charge transfer between the NWs and the electrolyte in the presence of the TiO2 shell.

  1. C, N co-doped TiO2/TiC0.7N0.3 composite coatings prepared from TiC0.7N0.3 powder using ball milling followed by oxidation

    NASA Astrophysics Data System (ADS)

    Hao, Liang; Wang, Zhenwei; Zheng, Yaoqing; Li, Qianqian; Guan, Sujun; Zhao, Qian; Cheng, Lijun; Lu, Yun; Liu, Jizi

    2017-01-01

    Ball milling followed by heat oxidation was used to prepared C, N co-doped TiO2 coatings on the surfaces of Al2O3 balls from TiC0.7N0.3 powder. The as-prepared coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrophotometer (UV-vis). The results show that continuous TiC0.7N0.3 coatings were formed after ball milling. C, N co-doped TiO2/TiC0.7N0.3 composite coatings were prepared after the direct oxidization of TiC0.7N0.3 coatings in the atmosphere. However, TiO2 was hardly formed in the surface layer of TiC0.7N0.3 coatings within a depth less than 10 nm during the heat oxidation of TiC0.7N0.3 coatings in carbon powder. Meanwhile, the photocatalytic activity evaluation of these coatings was conducted under the irradiation of UV and visible light. All the coatings showed photocatalytic activity in the degradation of MB no matter under the irradiation of UV or visible light. The C, N co-doped TiO2/TiC0.7N0.3 composite coatings showed the most excellent performance. The enhancement under visible light irradiation should attribute to the co-doping of carbon and nitrogen, which enhances the absorption of visible light. The improvement of photocatalytic activity under UV irradiation should attribute to the synergistic effect of C, N co-doping, the formation of rutile-anatase mixed phases and the TiO2/TiC0.7N0.3 composite microstructure.

  2. The importance of melt TiO2 in affecting major and trace element partitioning between Fe-Ti oxides and lunar picritic glass melts

    NASA Astrophysics Data System (ADS)

    Dygert, Nick; Liang, Yan; Hess, Paul

    2013-04-01

    Lunar mare basalts and picritic glasses have TiO2 abundances ranging from less than 1 wt.% to over 16%. Any high-Ti mare basalt or picritic glass petrogenetic model must include Fe-Ti oxides in the mantle source or invoke Fe-Ti oxide assimilation during magma ascent to the lunar surface. We conducted partitioning experiments to investigate high field strength element (HFSE), rare earth element (REE), and transition metal distribution between Fe-Ti oxides and lunar picritic glass melts over a range of melt compositions. Our results suggest that ilmenite-melt and armalcolite-melt HFSE, Cr, and V partition coefficients (DHFSE, DCr, DV) are strongly dependent on melt TiO2 content, whereas ilmenite-melt REE partition coefficients appear to be insensitive to melt composition. As TiO2 increases in picritic glass melts, HFSE, Cr, and V activities in melt also increase and Fe-Ti oxide-melt DHFSE, DCr and DV decrease. The effect of Ti on partitioning behavior can be attributed to the formation of Fe-O-Ti melt species in high-Ti melts. Ilmenite DHFSE range from compatible in oxides in equilibrium with low-Ti melts to incompatible in oxides in equilibrium with depolymerized high-Ti picritic glass melts. DHFSE are inversely correlated with TiO2 abundance in the melt and become nearly constant for melts with more than 6.8% TiO2. We present simple partitioning models that utilize the solubility of ilmenite and armalcolite in melt to effectively predict HFSE partition coefficients across a wide range of picritic glass melt compositions. The HFSE budget of ilmenite cumulates that crystallize from the lunar magma ocean strongly depends on the composition of the magma ocean. Low-Ti and high-Ti lunar basalts can be produced by an ilmenite or armalcolite bearing hybridized mantle source, or by assimilation of late-stage magma ocean cumulates. The dependence of DHFSE and DCr on melt TiO2 is consistent with the formation of lunar Type 1 armalcolite from high TiO2 picritic glass melt

  3. Dynamics of fibronectin adsorption on TiO2 surfaces.

    PubMed

    Sousa, S R; Brás, M Manuela; Moradas-Ferreira, P; Barbosa, M A

    2007-06-19

    In the present work we analyze the dynamics of fibronectin (FN) adsorption on two different stable titanium oxides, with varied surface roughness, and chemically similar to those used in clinical practice. The two types of titanium oxide surfaces used were TiO2 sputtered on Si (TiO2 sp) and TiO2 formed on commercially pure titanium after immersion in H2O2 (TiO2 cp). Surface characterization was previously carried out using different techniques (Sousa, S. R.; Moradas-Ferreira, P.; Melo, L. V.; Saramago, B.; Barbosa, M. A. Langmuir 2004, 20 (22), 9745-9754). Imaging and roughness analysis before and after FN adsorption used atomic force microscopy (AFM) in tapping mode, in air, and in magnetic alternating current mode, in liquid (water). FN adsorption as a function of time was followed by X-ray photoelectron spectroscopy (XPS), by radiolabeling of FN with 125I (125I-FN), and by ellipsometry. Exchangeability studies were performed using FN and HSA. AFM roughness analysis revealed that, before FN adsorption, both TiO2 surfaces exhibited a lower root-mean-square (Rq) and maximum peak with the depth of the maximum valley (Rmax) roughness in air than in water, due to TiO2 hydration. After protein adsorption, the same behavior was observed for the TiO2 sp substrate, while Rq and Rmax roughness values in air and in water were similar in the case of the TiO2 cp substrate, for the higher FN concentration used. Surface roughness was always significantly higher on the TiO2 cp surfaces. AFM led to direct visualization of adsorbed FN on both surfaces tested, indicating that after 10 min of FN incubation the TiO2 sp surface was partially covered by FN. The adsorbed protein seems to form globular aggregates or ellipsoids, and FN aggregates coalesce, forming clusters as the time of adsorption and the concentration increase. Radiolabeling of FN revealed that a rapid adsorption occurs on both surfaces and the amount adsorbed increased with time, reaching a maximum after 60 min of

  4. Hierarchical interfaces induce high dielectric permittivity in nanocomposites containing TiO2@BaTiO3 nanofibers.

    PubMed

    Zhang, Xin; Chen, Weiwei; Wang, Jianjun; Shen, Yang; Gu, Lin; Lin, Yuanhua; Nan, Ce-Wen

    2014-06-21

    Interface issues are common and crucial in nanocomposites or nanohybrid systems since the interface area is enormous on the nanoscale. In the 0-3 dimensional polymer nanocomposites, in which nano-inclusions (0-dimension) are embedded in a 3-dimensionally connected polymer matrix, enhanced dielectric permittivity could be induced by the interfacial polarization at the interfaces between the nano-inclusions and the polymer matrix. In this contribution, we propose and demonstrate that the topological structure of the interface plays an equally important role as the area of the interface in determining the dielectric polarization of polymer nanocomposites. TiO2 nanofibers embedded with BaTiO3 nanoparticles are prepared via electrospinning and then fused with polyvinyl difluoride (PVDF) into polymer nanocomposite films. Modulation of hierarchical interfaces is thus achieved for these nanocomposites. The confinement of these additional interfaces inside the TiO2 nanofibers leads to percolated networks formed by the interfacial regions. The dielectric permittivity of the polymer nanocomposites is thus enhanced by ∼300% over the PVDF matrix at a low filler loading of 11 vol%. A phase-field simulation study indicates that the enhanced dielectric permittivity could be attributed to the increased polarization in the percolated interfacial regions inside the TiO2 nanofibers. The instantaneous electrical breakdown of the TiO2@BaTiO3 nanofibers studied by the in situ transmission electron microscopy method further reveals the striking feature that the breakdown behavior of the nanofibers changes from semiconductive to metallic with the incorporation of insulating BaTiO3 nanoparticles.

  5. Characterization and mechanical properties investigation of TiN-Ag films onto Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Du, Dongxing; Liu, Daoxin; Zhang, Xiaohua; Tang, Jingang; Xiang, Dinggen

    2016-03-01

    To investigate their effect on fretting fatigue (FF) resistance of a Ti-6Al-4V alloy, hard solid lubricating composite films of TiN with varying silver contents (TiN-Ag) were deposited on a Ti-6Al-4V alloy using ion-assisted magnetron sputtering. The surface morphology and structure were analyzed by atomic force microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and transmission electron microscopy. The hardness, bonding strength, and toughness of films were tested using a micro-hardness tester, scratch tester, and a repeated press-press test system that was manufactured in-house, respectively. The FF resistance of TiN-Ag composite films was studied using self-developed devices. The results show that the FF resistance of a titanium alloy can be improved by TiN-Ag composite films, which were fabricated using hard TiN coating doped with soft Ag. The FF life of Ag0.5, Ag2, Ag5, Ag10 and Ag20 composite films is 2.41, 3.18, 3.20, 2.94 and 2.87 times as great as that of the titanium alloy, respectively. This is because the composite films have the better toughness, friction lubrication, and high bonding strength. When the atomic fraction of Ag changes from 2% to 5%, the FF resistance of the composite films shows the best performance. This is attributed to the surface integrity of the composite film is sufficiently fine to prevent the initiation and early propagation of FF cracks.

  6. Correlation driven charge order at LaAlO3/SrTiO3 and LaTiO3/SrTiO3 Interfaces

    NASA Astrophysics Data System (ADS)

    Pentcheva, Rossitza

    2007-03-01

    Correlated behavior at complex oxide interfaces offers additional degrees of freedom to compensate charge imbalance not available e.g. in polar semiconductor heterostructures. This can result in electronic, charge and magnetic phases that do not exist in the bulk and offers new possibilities for device applications. For instance, the interfaces of LaTiO3 and SrTiO3 [1] as well as LaAlO3 and SrTiO3 [2] show metallic conductivity, although the respective bulk materials are Mott (LTO) and band insulating (STO, LAO). Here we present the results of material-specific correlated band theory (LDA+U) employing the FP-LAPW code in the WIEN2k implementation for a variety of (n,m) multilayers containing n LTO (or LAO) and m STO-layers. To explore the relaxation length towards bulk behavior n and m is varied between 1 and 9. We find that charge mismatch at the LTO/STO IF is accommodated by the formation of a charge and orbitally ordered (CO/OO) layer with a checkerboard arrangement of Ti^3+ and Ti^4+ and an antiferromagnetic coupling of the Ti^3+-spins [3]. Lattice relaxations lead to the observed conducting behavior. An analogous diluted layer of Ti^3+ spins is obtained for the n-type LAO/STO interface, although the corresponding bulk materials are nonmagnetic. For a structurally ideal p-type LAO/STO IF the measured insulating behavior can only be understood by a charge disproportionation on the oxygen sublattice and the formation of a CO/OO magnetic OPπ hole. Alternatively, charge compensation by oxygen vacancies and the formation of a charge conjugate F-center is considered. [1] A. Ohtomo, and H.Y. Hwang, Nature 423, 378 (2002). [2] A. Ohtomo, D.A. Muller, J.L. Grazul, and H.Y. Hwang, Nature 419, 378 (2002). [3] R. Pentcheva and W.E. Pickett, cond-mat/0608212. [4] R. Pentcheva and W.E. Pickett, Phys. Rev. B 74, 035112 (2006).

  7. Morphology and structural development of reduced anatase-TiO{sub 2} by pure Ti powder upon annealing and nitridation: Synthesis of TiO{sub x} and TiO{sub x}N{sub y} powders

    SciTech Connect

    Bolokang, A.S.; Motaung, D.E.

    2015-02-15

    It is well known that nitriding of titanium is suitable for surface coating of biomaterials and in other applications such as anti-reflective coating, while oxygen-rich titanium oxynitride has been applied in thin film resistors and photocatalysis. Thus in this work anatase was reduced with pure titanium powder during annealing in argon. This was done to avoid any metallic contamination and unwanted residual metal doping. As a result, interesting and different types of particle morphology were synthesized when the pre-milled elemental anatase and titanium powders were mixed. The formation of metastable face centred cubic and monoclinic titanium monoxide was detected by the X-ray diffraction technique. The phases were confirmed by energy dispersive X-ray spectroscopy analysis. Raman analysis revealed weak intensity peaks for samples annealed in argon as compared to those annealed under nitrogen. - Graphical abstract: Display Omitted - Highlights: • Reaction of TiO{sub 2} and Ti induced metastable FCC and monoclinic TiO{sub x}. • Compositions of mixed powder were prepared from the unmilled and pre-milled powders. • Nitridation of TiO{sub x} yielded TiO{sub x}N{sub y} phase. • Mixed morphology was observed on all three powder samples.

  8. The potential health challenges of TiO2 nanomaterials.

    PubMed

    Sha, Baoyong; Gao, Wei; Cui, Xingye; Wang, Lin; Xu, Feng

    2015-10-01

    Titanium dioxide (TiO2 ) nanomaterials (NMs) have found widespread applications owing to their attractive physical and chemical properties. As a result, the potential adverse impacts of nano-TiO2 exposure on humans have become a matter of concern. This review presents the state-of-the-art advances on the investigations of the adverse effects of NMs, including the potential exposure routes of nano-TiO2 (e.g. respiratory system, skin absorption and digestive system), the physico-chemical characterizations of nano-TiO2 (e.g. crystal structure, shape,size, zeta potential, treatment media, aggregation and agglomeration tendency, surface characteristics and coatings), risk evaluation of nanotoxicity (e.g. cytotoxicity, ecotoxicity, phototoxicity, and phytotoxicity) and potential mechanisms of adverse effects (e.g. generation of reactive oxygen species, oxidative stress and organelle dysfunction). The review aims to facilitate scientific assessments of health risks to nano-TiO2 , which would guide the safe applications of NMs in our daily life.

  9. Incorporation of chromium into TiO{sub 2} nanopowders

    SciTech Connect

    Kollbek, Kamila; Sikora, Marcin; Kapusta, Czesław; Szlachetko, Jakub; Radecka, Marta; Lyson-Sypien, Barbara; Zakrzewska, Katarzyna

    2015-04-15

    Highlights: • Nanopowders of TiO{sub 2}:Cr with different amount of Cr dopant were obtained by flame spray synthesis, FSS. • Increase in the optical absorption and a shift of the absorption edge were observed upon Cr doping. • HERFD-XANES measurements indicated that the average valence state of titanium ions was preserved. • Increasing magnetic susceptibility of a paramagnetic character was observed upon Cr doping. - Abstract: The paper reports on the results of a study of optical, electronic and magnetic properties of TiO{sub 2} nanopowders doped with Cr ions. Diffused reflectance spectra reveal an increase in the optical absorption and a shift of the absorption edge towards lower energies upon Cr doping. Direct information on the Ti electronic state and the symmetry of its nearest environment is obtained from XANES Ti K-edge spectra. Magnetic behaviour is probed by means of the temperature dependence of DC magnetic susceptibility. Increasing magnetic susceptibility of a paramagnetic character is observed upon increasing chromium doping. The Curie constant of TiO{sub 2}:10 at.% Cr sample (0.12 emu K/mol Oe) is lower than that expected for Cr{sup 3+} (0.1875 emu K/mol Oe) possibly due to the appearance of Cr{sup 4+} or the presence of the orbital contribution to the magnetic moment.

  10. Chemical vapor infiltration of TiB{sub 2} composites

    SciTech Connect

    Besmann, T.M.; Miller, J.H.; Cooley, K.C.; Lowden, R.A.; Starr, T.L.

    1993-01-01

    Efficiency of the Hall-Heroult electrolytic reduction of aluminum can be substantially improved by the use of a TiB{sub 2} cathode surface. The use of TiB{sub 2}, however, has been hampered by the brittle nature of the material and the grain-boundary attack of sintering-aid phases by molten aluminum. In the current work, TiB{sub 2} is toughened through the use of reinforcing fibers, with chemical vapor infiltration (CVI) used to produce pure TiB{sub 2}. It has been observed, however, that the formation of TiB{sub 2} from chloride precursors at fabrication temperatures below 900 to 1000{degrees}C alloys the retention of destructive levels of chlorine in the material. At higher fabrication temperatures and under appropriate infiltration conditions, as determined from the use of a process model, a TIB{sub 2}THORNEL P-25 fiber composite, 45 mm in diam and 6 mm thick, has been fabricated in 20 h. The material has been demonstrated to be stable in molten aluminum in short-duration tests.

  11. Chemical vapor infiltration of TiB[sub 2] composites

    SciTech Connect

    Besmann, T.M.; Miller, J.H.; Cooley, K.C.; Lowden, R.A. ); Starr, T.L. )

    1993-01-01

    Efficiency of the Hall-Heroult electrolytic reduction of aluminum can be substantially improved by the use of a TiB[sub 2] cathode surface. The use of TiB[sub 2], however, has been hampered by the brittle nature of the material and the grain-boundary attack of sintering-aid phases by molten aluminum. In the current work, TiB[sub 2] is toughened through the use of reinforcing fibers, with chemical vapor infiltration (CVI) used to produce pure TiB[sub 2]. It has been observed, however, that the formation of TiB[sub 2] from chloride precursors at fabrication temperatures below 900 to 1000[degrees]C alloys the retention of destructive levels of chlorine in the material. At higher fabrication temperatures and under appropriate infiltration conditions, as determined from the use of a process model, a TIB[sub 2]THORNEL P-25 fiber composite, 45 mm in diam and 6 mm thick, has been fabricated in 20 h. The material has been demonstrated to be stable in molten aluminum in short-duration tests.

  12. Water - Based TiO2 Suspensions: A Raman Study

    NASA Astrophysics Data System (ADS)

    Rangel, Roberto; Chipara, Dorina; Yust, Brian; Padilla, Desiree; Chipara, Mircea

    The antibacterial features of TiO2 are under scrutiny due to the UV radiation, which contributes to the generation of reactive oxygen species, mainly in water environments. A study of TiO2 suspensions in water and broth is reported. TiO2 has a low solubility in water. TiO2 (anatase), with average diameter of 15 nm from Nanostructured & Amorphous Materials, Inc. has been added to the fluid (water, broth) and the mixture was stirred for 1-10 h, followed by a 10-60 minutes sonication. The suspension was left to sediment for 1 day before measurements. Quasistable suspensions of TiO2 in water and broth were investigated by Raman spectroscopy using a Renishaw InVia spectrometer operating at 532 and 785 nm. The spectra of the nanofiller have been simulated by a collection of Breit-Wigner Fano line shapes and the effect of the preparation conditions (stirring and sonication time) on the parameters of Raman lines are reported. The differences are explained by observing that the sonication destroys the agglomerates of anatase resulting in a better dispersion of nanoparticles and consequently a longer sedimentation time. Sample preparation/storage have been done both under dark and UV light conditions.

  13. Corrosion behavior and microstructures of experimental Ti-Au alloys.

    PubMed

    Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo; Okuno, Osamu; Okabe, Toru

    2004-06-01

    Anodic polarization was performed in 0.9% NaCl and 1% lactic acid solutions to characterize the relationship between the corrosion behavior and microstructures of cast Ti-Au (5-40%) alloys. An abrupt increase in the current density occurred at approximately 0.6 V vs. SCE for the 30% and 40% Au alloys in the 0.9% NaCl solution. The microstructures after corrosion testing indicated that this breakdown may have been caused by the preferential dissolution of the Ti3Au. However, the potential for preferential dissolution was higher than the breakdown potential of stainless steel or Co-Cr alloy, which meant that the corrosion resistance of the Ti-Au alloys was superior. In 1% lactic acid solution, the corrosion resistance of the Ti-Au alloys was excellent, with no breakdown at any composition. In the present test solutions, the Ti-Au alloys up to 20% Au had good corrosion resistance comparable to that for pure titanium.

  14. Electrogenerated chemiluminescence of anatase TiO₂ nanotubes film.

    PubMed

    Chen, Lifen; Lu, Lili; Mo, Yan; Xu, Zemin; Xie, Shunping; Yuan, Hongyan; Xiao, Dan; Choi, Martin M F

    2011-07-15

    Highly ordered titanium dioxide (TiO(2)) nanotubes film was successfully synthesized via anodic oxidation of a Ti foil in an ammonium fluoride-based ethylene glycol solution. The electrogenerated chemiluminescence (ECL) behavior of the resulting TiO(2) nanotubes film was subsequently studied. Strong ECL emission was observed at -1.40V (vs. Ag/AgCl) and the ECL spectrum displayed three emission peaks which were bathochromatically shifted by ca. 140nm as compared to its corresponding photoluminescence (PL) emission peaks, indicating that the surface state plays an important role in the emission process. The ECL emission can also occur in a deareated solution attributing to the surface adsorbed O(2) molecules. The ECL emission intensity was quenched by dopamine and greatly enhanced in the presence of dissolved O(2) and H(2)O(2), making it possible to detect these analytes. The TiO(2) nanotubes film has been successfully applied to determine the dissolved O(2) content in river and pond water samples, the H(2)O(2) concentration in commercial disinfectant samples and the dopamine concentration in commercial dopamine injections with satisfactory results. The plausible ECL mechanisms of TiO(2) nanotubes film in aqueous solution are discussed.

  15. Effect of TiO₂ nanoparticles on the structure and activity of catalase.

    PubMed

    Zhang, Hong-Mei; Cao, Jian; Tang, Bo-Ping; Wang, Yan-Qing

    2014-08-05

    TiO₂ nanoparticles are the most widely used metal oxide nanoparticles and have oxidative toxicity. Catalase is an important antioxidant enzyme. Here the understanding of an effect of TiO₂ nanoparticles on the activity and structure of catalase is crucial to characterize the toxicity of TiO₂ nanoparticles. These experimental data revealed that TiO₂ nanoparticles could bind to catalase by the electrostatic and hydrogen bonding forces. On binding TiO₂ nanoparticles, catalase got destabilized with the decrease of α-helices content, the solvent polarity of environment around the fluorescence chromophores on catalase were also affected. In addition, TiO₂ nanoparticles also affected the activity of catalase. TiO₂ nanoparticles acted as an activator of catalase activity at a low molar concentration and as an inhibitor at a higher molar concentration. With regard to human health, the present study could provide a better understanding of the potential nanotoxicity of TiO₂ nanoparticles.

  16. Sandwich structure of Pd doped nanostructure TiO2 film as O2 sensor.

    PubMed

    Wang, Hairong; Sun, Quantao; Chen, Lei; Zhao, Yulong

    2013-09-01

    In this paper, we investigated the sensing properties of sandwich structure of TiO2/Pd/TiO2 thin films at various operating temperatures and oxygen partial pressures. The nanostructure TiO2 thin films were prepared by the sol-gel method. Various thickness of Pd buried layer was deposited by magnetron sputtering of a pure Pd target. The films were characterized using X-ray diffraction analysis and SEM. It was found that TiO2/Pd/TiO2 thin films have the p-type behavior while the pure TiO2 thin film is n-type semiconductor materials. We found that the structure of TiO2/Pd/TiO2 thin films with 10 s sputtering Pd layer has a better stability at 240 °C.

  17. Engineering of highly ordered TiO2 nanopore arrays by anodization

    NASA Astrophysics Data System (ADS)

    Wang, Huijie; Huang, Zhennan; Zhang, Li; Ding, Jie; Ma, Zhaoxia; Liu, Yong; Kou, Shengzhong; Yang, Hangsheng

    2016-07-01

    Finite element analysis was used to simulate the current density distributions in the TiO2 barrier layer formed at the initial stage of Ti anodization. The morphology modification of the barrier layer was found to induce current density distribution change. By starting the anodization with proper TiO2 barrier layer morphology, the current density distribution can be adjusted to favor the formation of either nanotube arrays or nanopore arrays of anodic TiO2. We also found that the addition of sodium acetate into the electrolyte suppressed both the field-assisted chemical dissolution of TiO2 and the TiF62- hydrolysis induced TiO2 deposition during anodization, and thus further favored the nanopore formation. Accordingly, highly ordered anodic TiO2 nanopore arrays, similar to anodic aluminum oxide nanopore arrays, were successfully prepared.

  18. The shock Hugoniot of the intermetallic alloy Ti-46.5Al-2Nb-2Cr

    SciTech Connect

    Millett, Jeremy; Gray, George T. Rusty III; Bourne, Neil

    2000-09-15

    Plate impact experiments were conducted on a {gamma}-titanium aluminide (TiAl) based ordered intermetallic alloy. Stress measurements were recorded using manganin stress gauges supported on the back of TiAl targets using polymethylmethacrylate windows. The Hugoniot in stress-particle velocity space for this TiAl alloy was deduced using impedance matching techniques. The results in this study are compared to the known Hugoniot data of the common alpha-beta engineering Ti-based alloy Ti-6Al-4V. The results of the current study on the intermetallic alloy TiAl support that TiAl possesses a significantly higher stress for a given particle velocity than the two-phase Ti-6Al-4V alloy. (c) 2000 American Institute of Physics.

  19. Water adsorption induced in-plane domain switching on BaTiO{sub 3} surface

    SciTech Connect

    Li, X.; Bai, Y.; Su, Y. J.; Wang, B. C.

    2015-09-07

    In this study, the influences of the adsorption of water molecules on the changes in the atomic and electric structures of BaTiO{sub 3} surface were investigated using ab initio calculation. Water molecules are molecularly and dissociatively adsorbed on the BaTiO{sub 3} surface, which makes electrons transfer from water molecules to the BaTiO{sub 3} surface. The redistribution of electrons in the BaTiO{sub 3} surface layers weakens the Ba-O interactions and strengthens the Ti-O interactions, so that the Ti atom shifts in TiO{sub 2} plane, i.e., an in-plane domain switching. The adsorption of water molecules on BaTiO{sub 3} surfaces also results in a reduction in the surface rumpling.

  20. Preparation and photoactivity of nanostructured anatase, rutile and brookite TiO2 thin films.

    PubMed

    Addamo, Maurizio; Bellardita, Marianna; Di Paola, Agatino; Palmisano, Leonardo

    2006-12-21

    Photoactive films consisting of pure anatase, brookite or rutile TiO2 were prepared by dip coating from water dispersions obtained by using TiCl4 as the precursor under similar mild experimental conditions.