Synthesis, structure and temperature dependent luminescence of Eu3+ doped hydroxyapatite

NASA Astrophysics Data System (ADS)

Luo, Xiaobing; Luo, Xiaoxia; Wang, Hongwei; Deng, Yue; Yang, Peixin; Tian, Yili

2018-01-01

A series of Eu3+ substituted hydroxyapatite (HA) were prepared by co-precipitation reactions. The phase, fluorescence and temperature dependent luminescence of the phosphors were investigated by X-ray diffraction (XRD) and photoluminescence (PL). It is found that the doped Eu3+ ions have entered the hexagonal lattice with no obvious secondary phase were detected by XRD. The 5D0 → 7F0 transition was clearly split into two even at room temperature. The predominate 573 nm peak illustrates Eu3+ ions occupy more Ca(II) sites. The temperature dependent luminescent results show HA:xEu might be applied as one potential optical thermometry material.

[Effects of annealing temperature on the structure and optical properties of ZnMgO films prepared by atom layer deposition].

PubMed

Sun, Dong-Xiao; Li, Jin-Hua; Fang, Xuan; Chen, Xin-Ying; Fang, Fang; Chu, Xue-Ying; Wei, Zhi-Peng; Wang, Xiao-Hua

2014-07-01

In the present paper, we report the research on the effects of annealing temperature on the crystal quality and optical properties of ZnMgO films deposited by atom layer deposition(ALD). ZnMgO films were prepared on quartz substrates by ALD and then some of the samples were treated in air ambient at different annealing temperature. The effects of annealing temperature on the crystal quality and optical properties of ZnMgO films were characterized by X-ray diffraction (XRD), photoluminescence (PL) and ultraviolet-visible (UV-Vis) absorption spectra. The XRD results showed that the crystal quality of ZnMgO films was significantly improved when the annealing temperature was 600 degrees C, meanwhile the intensity of(100) diffraction peak was the strongest. Combination of PL and UV-Vis absorption measurements showed that it can strongly promote the Mg content increasing in ZnMgO films and increase the band gap of films. So the results illustrate that suitable annealing temperature can effectively improve the crystal quality and optical properties of ZnMgO films.

The Influence of Growth Temperature on Sb Incorporation in InAsSb, and the Temperature-dependent Impact of Bi Surfactants

DTIC Science & Technology

2014-01-01

resolution X - ray diffraction (XRD) were collected for all samples, and reciprocal space maps (RSMs) were collected from selected samples. The complete data...exposure. The lines represent the model fit. 19 13 Figure 1. Triple axis x - ray diffraction from the bi-layered InAsSb structures grown on GaSb at...Applied Physics, Structural properties of bismuth‐bearing semiconductor alloys, 63 (1988) 107. 18 12 Figure Captions Figure 1. Triple axis x - ray

The effects of temperature on the crystalline properties and resistant starch during storage of white bread.

PubMed

Sullivan, William R; Hughes, Jeff G; Cockman, Russell W; Small, Darryl M

2017-08-01

Resistant starch (RS) can form during storage of foods, thereby bestowing a variety of potential health benefits. The purpose of the current study has been to determine the influence of storage temperature and time on the crystallinity and RS content of bread. Loaves of white bread were baked and stored at refrigeration, frozen and room temperatures with analysis over a period of zero to seven days. RS determination and X-ray diffraction (XRD) were used to evaluate the influence of storage temperature and time on total crystallinity and RS content. The rate of starch recrystallisation was affected by storage temperature and time, where refrigeration temperatures accelerated RS formation and total crystallinity more than storage time at both frozen and room temperature. A strong statistical model has been established between RS formation in bread and XRD patterns, having a 96.7% fit indicating the potential of XRD to measure RS concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Swinging Symmetry, Multiple Structural Phase Transitions, and Versatile Physical Properties in RECuGa3 (RE = La-Nd, Sm-Gd).

PubMed

Subbarao, Udumula; Rayaprol, Sudhindra; Dally, Rebecca; Graf, Michael J; Peter, Sebastian C

2016-01-19

The compounds RECuGa3 (RE = La-Nd, Sm-Gd) were synthesized by various techniques. Preliminary X-ray diffraction (XRD) analyses at room temperature suggested that the compounds crystallize in the tetragonal system with either the centrosymmetric space group I4/mmm (BaAl4 type) or the non-centrosymmetric space group I4mm (BaNiSn3 type). Detailed single-crystal XRD, neutron diffraction, and synchrotron XRD studies of selected compounds confirmed the non-centrosymmetric BaNiSn3 structure type at room temperature with space group I4mm. Temperature-dependent single-crystal XRD, powder XRD, and synchrotron beamline measurements showed a structural transition between centro- and non-centrosymmetry followed by a phase transition to the Rb5Hg19 type (space group I4/m) above 400 K and another transition to the Cu3Au structure type (space group Pm3̅m) above 700 K. Combined single-crystal and synchrotron powder XRD studies of PrCuGa3 at high temperatures revealed structural transitions at higher temperatures, highlighting the closeness of the BaNiSn3 structure to other structure types not known to the RECuGa3 family. The crystal structure of RECuGa3 is composed of eight capped hexagonal prism cages [RE4Cu4Ga12] occupying one rare-earth atom in each ring, which are shared through the edge of Cu and Ga atoms along the ab plane, resulting in a three-dimensional network. Resistivity and magnetization measurements demonstrated that all of these compounds undergo magnetic ordering at temperatures between 1.8 and 80 K, apart from the Pr and La compounds: the former remains paramagnetic down to 0.3 K, while superconductivity was observed in the La compound at T = 1 K. It is not clear whether this is intrinsic or due to filamentary Ga present in the sample. The divalent nature of Eu in EuCuGa3 was confirmed by magnetization measurements and X-ray absorption near edge spectroscopy and is further supported by the crystal structure analysis.

In-field X-ray and neutron diffraction studies of re-entrant charge-ordering and field induced metastability in La0.175Pr0.45Ca0.375MnO3-δ

NASA Astrophysics Data System (ADS)

Sharma, Shivani; Shahee, Aga; Yadav, Poonam; da Silva, Ivan; Lalla, N. P.

2017-11-01

Low-temperature high-magnetic field (2 K, 8 T) (LTHM) powder X-ray diffraction (XRD) and time of flight powder neutron diffraction (NPD), low-temperature transmission electron microscopic (TEM), and resistivity and magnetization measurements have been carried out to investigate the re-entrant charge ordering (CO), field induced structural phase transitions, and metastability in phase-separated La0.175Pr0.45Ca0.375MnO3-δ (LPCMO). Low-temperature TEM and XRD studies reveal that on cooling under zero-field, paramagnetic Pnma phase transforms to P21/m CO antiferromagnetic (AFM) insulating phase below ˜233 K. Unlike reported literature, no structural signature of CO AFM P21/m to ferromagnetic (FM) Pnma phase-transition during cooling down to 2 K under zero-field was observed. However, the CO phase was found to undergo a re-entrant transition at ˜40 K. Neutron diffraction studies revealed a pseudo CE type spin arrangement of the observed CO phase. The low-temperature resistance, while cooled under zero-field, shows insulator to metal like transition below ˜105 K with minima at ˜25 K. On application of field, the CO P21/m phase was found to undergo field-induced transition to FM Pnma phase, which shows irreversibility on field removal below ˜40 K. Zero-field warming XRD and NPD studies reveal that field-induced FM Pnma phase is a metastable phase, which arise due to the arrest of kinetics of the first-order phase transition of FM Pnma to CO-AFM P21/m phase, below 40 K. Thus, a strong magneto-structural coupling is observed for this system. A field-temperature (H-T) phase-diagram has been constructed based on the LTHM-XRD, which matches very nicely with the reported H-T phase-diagram constructed based on magnetic measurements. Due to the occurrence of gradual growth of the re-entrant CO phase and the absence of a clear structural signature of phase-separation of CO-AFM P21/m and FM Pnma phases, the H-T minima in the phase-diagram of the present LPCMO sample has been attributed to the strengthening of AFM interaction during re-entrant CO transition and not to glass like "dynamic to frozen" transition.

Single phase Pb0.7Bi0.3Fe0.65Nb0.35O3 multiferroic: Neutron diffraction, impedance and modulus studies

NASA Astrophysics Data System (ADS)

Dadami, Sunanda T.; Matteppanvar, Shidaling; Shivaraja, I.; Rayaprol, Sudhindra; Deshpande, S. K.; Angadi, Basavaraj

2018-04-01

The Pb0.7Bi0.3Fe0.65Nb0.35O3 (PBFNO) multiferroic solid solution was synthesized by using single step solid state reaction method. Single phase formation was confirmed through room temperature (RT) X Ray Diffraction (XRD) and Neutron Diffraction (ND). Rietveld refinement was used to perform the structural analysis using FullProf Suite program. RT XRD and ND patterns well fitted with monoclinic structure (Cm space group) and cell parameters from the ND data are found to be a = 5.6474(4) Å, b = 5.6415(3) Å, c = 3.9992(3) Å and β = 89.95(2)°. ND data at RT exhibits G-type antiferromagnetic structure. The electrical properties (impedance and modulus) of PBFNO were studied as a function of frequency (100 Hz - 5 MHz) and temperature (133 K - 293 K) by Impedance spectroscopy technique. Impedance and modulus spectroscopy studies confirm the contribution to the conductivity is from grains only and the relaxation is of non-Debye type. The PBFNO sample exhibits negative temperature coefficient of resistance (NTCR) behaviour. PBFNO is found be a potential candidate for RT applications.

Effect of different conventional melt quenching technique on purity of lithium niobate (LiNbO3) nano crystal phase formed in lithium borate glass

NASA Astrophysics Data System (ADS)

Kashif, Ismail; Soliman, Ashia A.; Sakr, Elham M.; Ratep, Asmaa

2012-01-01

The glass system (45Li2O + 45B2O3 + 10Nb2O5) was fabricated by the conventional melt quenching technique poured in water, at air, between two hot plates and droplets at the cooled surface. The glass and glass ceramics were studied by differential thermal analysis (DTA) and X-ray diffraction (XRD). The as quenched samples poured in water and between two hot plates were amorphous. The samples poured at air and on cooled surface were crystalline as established via X-ray powder diffraction (XRD) studies. Differential thermal analysis was measured. The glass transition temperature (Tg) and the crystallization temperatures were calculated. Lithium niobate (LiNbO3) was the main phase in glass ceramic poured at air, droplets at the cooled surface and the heat treated glass sample at 500, 540 and 580 °C in addition to traces from LiNb3O8. Crystallite size of the main phases determined from the X-ray diffraction peaks is in the range of <100 nm. The fraction of crystalline (LiNbO3) phase decreases with increase in the heat treatment temperature.

Synthesis and characterization of nanostructured titanium carbide for fuel cell applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Paviter; Singh, Harwinder; Singh, Bikramjeet

2016-04-13

Titanium carbide (TiC) nanoparticles have been successfully synthesized by carbo-thermic reaction of titanium and acetone at 800 °C. This method is relatively low temperature synthesis route. It can be used for large scale production of TiC. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA) techniques. XRD analysis confirmed the formation of single phase TiC. XRD analysis confirmed that the particles are spherical in shape with an average particle size of 13 nm. DTA analysis shows that the phase is stable upto 900 °C and the material can be used formore » high temperature applications.« less

Effect of Annealing Temperature on Structural and Optical Properties of Sol-Gel-Derived ZnO Thin Films

NASA Astrophysics Data System (ADS)

Arif, Mohd.; Sanger, Amit; Vilarinho, Paula M.; Singh, Arun

2018-04-01

Nanocrystalline ZnO thin films were deposited on glass substrate via sol-gel dip-coating technique then annealed at 300°C, 400°C, and 500°C for 1 h. Their optical, structural, and morphological properties were studied using ultraviolet-visible (UV-Vis) spectrophotometry, x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). XRD diffraction revealed that the crystalline nature of the thin films increased with increasing annealing temperature. The c-axis orientation improved, and the grain size increased, as indicated by increased intensity of the (002) plane peak at 2θ = 34.42° corresponding to hexagonal ZnO crystal. The average crystallite size of the thin films ranged from 13 nm to 23 nm. Increasing the annealing temperature resulted in larger crystallite size and higher crystallinity with increased surface roughness. The grain size according to SEM analysis was in good agreement with the x-ray diffraction data. The optical bandgap of the thin films narrowed with increasing annealing temperature, lying in the range of 3.14 eV to 3.02 eV. The transmission of the thin films was as high as 94% within the visible region. The thickness of the thin films was 400 nm, as measured by ellipsometry, after annealing at the different temperatures of 300°C, 400°C, and 500°C.

A Curved Image-Plate Detector System for High-Resolution Synchrotron X-ray Diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarin, P.; Haggerty, R; Yoon, W

2009-01-01

The developed curved image plate (CIP) is a one-dimensional detector which simultaneously records high-resolution X-ray diffraction (XRD) patterns over a 38.7 2{theta} range. In addition, an on-site reader enables rapid extraction, transfer and storage of X-ray intensity information in {le}30 s, and further qualifies this detector to study kinetic processes in materials science. The CIP detector can detect and store X-ray intensity information linearly proportional to the incident photon flux over a dynamical range of about five orders of magnitude. The linearity and uniformity of the CIP detector response is not compromised in the unsaturated regions of the image plate,more » regardless of saturation in another region. The speed of XRD data acquisition together with excellent resolution afforded by the CIP detector is unique and opens up wide possibilities in materials research accessible through X-ray diffraction. This article presents details of the basic features, operation and performance of the CIP detector along with some examples of applications, including high-temperature XRD.« less

Structure of chitosan thermosensitive gels containing graphene oxide

NASA Astrophysics Data System (ADS)

Tylman, Michał; Pieklarz, Katarzyna; Owczarz, Piotr; Maniukiewicz, Waldemar; Modrzejewska, Zofia

2018-06-01

The supramolecular hydrogels of chitosan and graphene oxide (GO) have been prepared at temperature of the human body, by controlling the concentration of GO and ratio of chitosan to GO. During the preparation of gels the sodium β-glycerophosphate (Na-β-GP) was used as a neutralizing agent. The structure of obtained gels was determined on the basis of FTIR spectra and XRD diffraction patterns. The results of structural studies have been referenced to gels without graphene oxide. It was found that the gels crystalline structure after the addition of GO does not change. The XRD diffraction patterns are characterized by a number of peaks associated with precipitated NaCl during drying and presence of sodium β-glycerophosphate.

Characterization of mineral phases of agricultural soil samples of Colombian coffee using Mössbauer spectroscopy and X-ray diffraction

NASA Astrophysics Data System (ADS)

Rodríguez, Humberto Bustos; Lozano, Dagoberto Oyola; Martínez, Yebrayl Antonio Rojas; Pinilla, Marlene Rivera; Alcázar, German Antonio Pérez

2012-03-01

Soil chemical analysis, X-ray diffraction (XRD) and Mössbauer spectrometry (MS) of 57Fe were used to characterize mineral phases of samples taken from the productive layer (horizon A) of agricultural coffee soil from Tolima (Colombia). Chemical analysis shows the chemical and textural parameters of samples from two different regions of Tolima, i.e., Ibagué and Santa Isabel. By XRD phases like illite (I), andesine (A) and quartz (Q) in both samples were identified. The quantity of these phases is different for the two samples. The MS spectra taken at room temperature were adjusted by using five doublets, three of them associated to Fe + 3 type sites and the other two to Fe + 2 type sites. According to their isomer shift and quadrupole splitting the presence of phases like illite (detected by DRX), nontronite and biotite (not detected by XRD) can be postulated.

Effect of aging temperature on formation of sol-gel derived fluor-hydroxyapatite nanoparticles.

PubMed

Joughehdoust, S; Behnamghader, A; Jahandideh, R; Manafi, S

2010-04-01

Synthetic hydroxyapatite (HA) has been recognized as one of the most important bone substitute materials in orthopaedics and dentistry over past few decades because of its chemical and biological similarity to the mineral phase of human bone. One solution for reduction the solubility of HA in biological environments is replacing F- by OH in HA structure and forming fluor-hydroxyapatite (FHA) solid solution. In this paper, FHA nanoparticles were successfully synthesized by a sol-gel method. Also, the influence of aging temperature on formation of FHA powder was studied. Equimolar solutions of calcium nitrate tetrahydrate, triethyl phosphite and ammonium fluoride in ethanol were used as Ca, P and F precursors. After aging at different temperatures, the synthesized powders were heat treated at 550 degrees C. The powders were investigated with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), selected area electron diffraction pattern (SAED), energy dispersive analysis of X-ray (EDAX) and zetasizer measurement. The results of XRD proved the presence of fluorapatite (FA) and HA in all samples. In addition, the formation of FHA was confirmed by FT-IR results. XRD studies also showed that the crystallites were in nanometric scale. At the same time, this result was in good agreement with the result of zetasizer analysis.

Controlled nucleation and growth of CdS nanoparticles in a polymer matrix.

PubMed

Di Luccio, Tiziana; Laera, Anna Maria; Tapfer, Leander; Kempter, Susanne; Kraus, Robert; Nickel, Bert

2006-06-29

In-situ synchrotron X-ray diffraction (XRD) was used to monitor the thermal decomposition (thermolysis) of Cd thiolates precursors embedded in a polymer matrix and the nucleation of CdS nanoparticles. A thiolate precursor/polymer solid foil was heated to 300 degrees C in the X-ray diffraction setup of beamline W1.1 at Hasylab, and the diffraction curves were each recorded at 10 degrees C. At temperatures above 240 degrees C, the precursor decomposition is complete and CdS nanoparticles grow within the polymer matrix forming a nanocomposite with interesting optical properties. The nanoparticle structural properties (size and crystal structure) depend on the annealing temperature. Transmission electron microscopy (TEM) and photoluminescence (PL) analyses were used to characterize the nanoparticles. A possible mechanism driving the structural transformation of the precursor is inferred from the diffraction features arising at the different temperatures.

Comparing two tetraalkylammonium ionic liquids. II. Phase transitions.

PubMed

Lima, Thamires A; Paschoal, Vitor H; Faria, Luiz F O; Ribeiro, Mauro C C; Ferreira, Fabio F; Costa, Fanny N; Giles, Carlos

2016-06-14

Phase transitions of the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N1444][NTf2], were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) measurements, and Raman spectroscopy. XRD and Raman spectra were obtained as a function of temperature at atmospheric pressure, and also under high pressure at room temperature using a diamond anvil cell (DAC). [N1444][NTf2] experiences glass transition at low temperature, whereas [N1114][NTf2] crystallizes or not depending on the cooling rate. Both the ionic liquids exhibit glass transition under high pressure. XRD and low-frequency Raman spectra provide a consistent physical picture of structural ordering-disordering accompanying the thermal events of crystallization, glass transition, cold crystallization, pre-melting, and melting. Raman spectra in the high-frequency range of some specific cation and anion normal modes reveal conformational changes of the molecular structures along phase transitions.

Effect of substrate temperature in the synthesis of BN nanostructures

NASA Astrophysics Data System (ADS)

Sajjad, M.; Zhang, H. X.; Peng, X. Y.; Feng, P. X.

2011-06-01

Boron nitride (BN) nanostructures were grown on molybdenum discs at different substrate temperatures using the short-pulse laser plasma deposition technique. Large numbers of randomly oriented nanorods of fiber-like structures were obtained. The variation in the length and diameter of the nanorods as a function of the substrate temperature was systematically studied. The surface morphologies of the samples were studied using scanning electron microscopy. Energy dispersive x-ray spectroscopy confirmed that both the elements boron and nitrogen are dominant in the nanostructure. The x-ray diffraction (XRD) technique was used to analyse BN phases. The XRD peak that appeared at 26° showed the presence of hexagonal BN phase, whereas the peak at 44° was related to cubic BN content in the samples. Raman spectroscopic analysis showed vibrational modes of sp2- and sp3-type bonding in the sample. The Raman spectra agreed well with XRD results.

Alteration behavior of mineral structure and hazardous elements during combustion of coal from a power plant at Huainan, Anhui, China.

PubMed

Tang, Quan; Sheng, Wanqi; Li, Liyuan; Zheng, Liugen; Miao, Chunhui; Sun, Ruoyu

2018-08-01

The alteration behavior of minerals and hazardous elements during simulated combustion (100-1200 °C) of a raw coal collected from a power plant were studied. Thermogravimetric analysis indicated that there were mainly four alteration stages during coal combustion. The transformation behavior of mineral phases of raw coal, which were detected by X-ray polycrystalline diffraction (XRD) technique, mainly relied on the combustion temperature. A series of changes were derived from the intensities of mineral (e.g. clays) diffraction peaks when temperature surpassed 600 °C. Mineral phases tended to be simple and collapsed to amorphous glass when temperature reached up to 1200 °C. The characteristics of functional groups for raw coal and high-temperature (1200 °C) ash studied by Fourier transform infrared spectroscopy (FTIR) were in accordance with the result obtained from XRD analysis. The volatilization ratios of Co, Cr, Ni and V increased consistently with the increase of combustion temperature, suggesting these elements were gradually released from the organic matter and inorganic minerals of coal. Copyright © 2018 Elsevier Ltd. All rights reserved.

Annealing effect on thermal conductivity and microhardness of carbon nanotube containing Se80Te16Cu4 glassy composites

NASA Astrophysics Data System (ADS)

Upadhyay, A. N.; Tiwari, R. S.; Singh, Kedar

2018-02-01

This study deals with the effect of thermal annealing on structural/microstructural, thermal and mechanical behavior of pristine Se80Te16Cu4 and carbon nanotubes (CNTs) containing Se80Te16Cu4 glassy composites. Pristine Se80Te16Cu4, 3 and 5 wt%CNTs-Se80Te16Cu4 glassy composites are annealed in the vicinity of glass transition temperature to onset crystallization temperature (340-380 K). X-ray diffraction (XRD) pattern revealed formation of polycrystalline phases of hexagonal CuSe and trigonal selenium. The indexed d-values in XRD patterns are in well conformity with the d-values obtained after the indexing of the ring pattern of selected area electron diffraction pattern of TEM images. The SEM investigation exhibited that the grain size of the CNTs containing Se80Te16Cu4 glassy composites increased with increasing annealing temperature and decreased at further higher annealing temperature. Thermal conductivity, microhardness exhibited a substantial increase with increasing annealing temperature of 340-360 K and slightly decreases for 380 K. The variation of thermal conductivity and microhardness can be explained by cross-linking formation and voids reduction.

The Effect of Compaction Force on the Transition to Hydrate of Anhydrous Aripiprazole.

PubMed

Togo, Taichiro; Taniguchi, Toshiya; Nakata, Yoshitaka

2018-01-01

Aripiprazole (APZ) is used to treat schizophrenia and is administered as a tablet containing the anhydrous form of APZ. In this study, the effect of compaction force on the crystal form transition was investigated. The crystalline state was observed by X-ray diffraction (XRD). APZ Anhydrous Form II was compacted into tablets. The XRD intensity of anhydrous APZ became lower with higher compressive force. The degree of crystallinity decreased with the compaction force. The powder and the compacted tablets of anhydrous APZ were stored for one week under 60°C and 75% relative humidity. The powder showed no crystal form transition after storage. For the tablets, however, XRD peaks of APZ hydrate were observed after storage. The tablets compacted with higher force showed the higher XRD diffraction intensity of hydrate form. We concluded that the crystallinity reduction of APZ Anhydrous Form II by compaction caused and accelerated the transition to hydrate under high temperature and humidity conditions. In order to manufacture crystallographically stable tablets containing anhydrous APZ, it is important to prevent this crystallinity reduction during compaction.

Is Tridymite at Gale Crater Evidence for Silicic Volcanism on Mars?

NASA Technical Reports Server (NTRS)

Morris, Richard V.; Vaniman, David T.; Ming, Douglas W.; Graff, Trevor G.; Downs, Robert T.; Fendrich, Kim; Mertzman, Stanley A.

2016-01-01

The X-ray diffraction (XRD) instrument (CheMin) onboard the MSL rover Curiosity detected 17 wt% of the SiO2 polymorph tridymite (relative to bulk sample) for the Buckskin drill sample (73 wt% SiO2) obtained from sedimentary rock in the Murray formation at Gale Crater, Mars. Other detected crystalline materials are plagioclase, sanidine, cristobalite, cation-deficient magnetite, and anhydrite. XRD amorphous material constitutes approx. 60 wt% of bulk sample, and the position of its broad diffraction peak near approx. 26 deg. 2-theta is consistent with opal-A. Tridymite is a lowpressure, high-temperature mineral (approx. 870 to 1670 deg. C) whose XRD-identified occurrence on the Earth is usually associated with silicic (e.g., rhyolitic) volcanism. High SiO2 deposits have been detected at Gale crater by remote sensing from martian orbit and interpreted as opal-A on the basis H2O and Si-OH spectral features. Proposed opal-A formation pathways include precipitation of silica from lake waters and high-SiO2 residues of acid-sulfate leaching. Tridymite is nominally anhydrous and would not exhibit these spectral features. We have chemically and spectrally analyzed rhyolitic samples from New Mexico and Iwodake volcano (Japan). The glassy (by XRD) NM samples have H2O spectral features similar to opal-A. The Iwodake sample, which has been subjected to high-temperature acid sulfate leaching, also has H2O spectral features similar to opal-A. The Iwodake sample has approx. 98 wt% SiO2 and 1% wt% TiO2 (by XRF), tridymite (>80 wt.% of crystalline material without detectable quartz by XRD), and H2O and Si-OH spectral features. These results open the working hypothesis that the opal-A-like high-SiO2 deposits at Gale crater detected from martian orbit are products of alteration associated with silicic volcanism. The presence or absence of tridymite will depend on lava crystallization temperatures (NM) and post crystallization alteration temperatures (Iwodake).

XRD and FTIR crystallinity indices in sound human tooth enamel and synthetic hydroxyapatite.

PubMed

Reyes-Gasga, José; Martínez-Piñeiro, Esmeralda L; Rodríguez-Álvarez, Galois; Tiznado-Orozco, Gaby E; García-García, Ramiro; Brès, Etienne F

2013-12-01

The crystallinity index (CI) is a measure of the percentage of crystalline material in a given sample and it is also correlated to the degree of order within the crystals. In the literature two ways are reported to measure the CI: X-ray diffraction and infrared spectroscopy. Although the CI determined by these techniques has been adopted in the field of archeology as a structural order measure in the bone with the idea that it can help e.g. in the sequencing of the bones in chronological and/or stratigraphic order, some debate remains about the reliability of the CI values. To investigate similarities and differences between the two techniques, the CI of sound human tooth enamel and synthetic hydroxyapatite (HAP) was measured in this work by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR), at room temperature and after heat treatment. Although the (CI)XRD index is related to the crystal structure of the samples and the (CI)FTIR index is related to the vibration modes of the molecular bonds, both indices showed similar qualitative behavior for heat-treated samples. At room temperature, the (CI)XRD value indicated that enamel is more crystalline than synthetic HAP, while (CI)FTIR indicated the opposite. Scanning (SEM) and transmission (TEM) images were also used to corroborate the measured CI values. © 2013.

Synchronizing flash-melting in a diamond cell with synchrotron X ray diffraction (XRD)

NASA Astrophysics Data System (ADS)

Karandikar, Amol; Boehler, Reinhard; Meng, Yue; Rod, Eric; Shen, Guoyin

2013-06-01

The major challenges in measuring melting temperatures in laser heated diamond cells are sample instability, thermal runaway and chemical reactions. To circumvent these problems, we developed a ``flash heating'' method using a modulated CW fiber laser and fast X ray detection capability at APS (Pilatus 1M detector). As an example, Pt spheres of 5 micron diameter were loaded in a single crystal sapphire encapsulation in the diamond cell at 65 GPa and heated in a single flash heating event for 20 ms to reach a desired temperature. A CCD spectrometer and the Pilatus were synchronized to measure the temperature and the XRD signal, respectively, when the sample reached the thermal steady state. Each successive flash heating was done at a higher temperature. The integrated XRD pattern, collected during and after (300 K) each heating, showed no chemical reaction up to 3639 K, the highest temperature reached in the experiment. Pt111 and 200 peak intensity variation showed gradual recrystalization and complete diminishing at about 3600 K, indicating melting. Thus, synchronized flash heating with novel sample encapsulation circumvents previous notorious problems and enables accurate melting temperature measurement in the diamond cell using synchrotron XRD probe. Affiliation 2: Geowissenschaeften, Goethe-Universitaet, Altenhoeferallee 1, D-60438 Frankfurt a.M., Germany.

Phase Compositions of Self Reinforcement Al2O3/CaAl12O19 Composite using X-ray Diffraction Data and Rietveld Technique

NASA Astrophysics Data System (ADS)

Asmi, D.; Low, I. M.; O'Connor, B.

2008-03-01

The analysis of x-ray diffraction (XRD) patterns by the Rietveld technique was tested to the quantitatively phase compositions of self reinforcement Al2O3/CaAl12O19 composite. Room-temperature XRD patterns revealed that α-Al2O3 was the only phase presence in the CA0 sample, whereas the α-Al2O3 and CaAl12O19 phases were found for CA5, CA15, CA30, and CA50 samples. The peak intensity of CA6 in the self reinforcement Al2O3/CaAl12O19 composites increased in proportion with increase in CaAl12O19 content in contrast to α-Al2O3. The diffraction patterns for CA100 sample shows minor traces of α-Al2O3 even in relatively low peak intensity. It is suggesting that the in-situ reaction sintering of raw materials were not react completely to form 100 wt% CaAl12O19 at temperature 1650 °C. Quantitative phase compositions of self reinforcement Al2O3/CaAl12O19 composites by Rietveld analysis with XRD data has been well demonstrated. The results showed that the GOF values are relatively low and the fluctuation in the difference plots shows a reasonable fit between the observed and the calculated plot.

Compaction and sintering behaviors of a Nd-Fe-B permanent magnet alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chin, T.; Hung, M.; Tsai, D.

1988-11-15

Extensive x-ray diffraction (XRD) and magnetic measurements were done on Nd/sub 15/ Fe/sub 77/ B/sub 8/ magnet alloy green compacts after cold isostatic pressing following a pulsed 2-T field (CIP) and die-pressing under a static 1.2-T perpendicular field (DP1) or parallel field (DP2), and on those after sintering. An alignment factor F, through the calculation of the integrated diffraction intensity ratio of the XRD patterns, was adopted as the effectiveness of magnetic alignment. At the green compact state, DP1 has the best alignment while CIP the worst. However, after sintering the alignment factor was such that CIP>DPI>DP2, the same ordermore » as the magnetic properties. Three mechanisms were proposed for the evolution of the alignment factor at different stages of sintering, i.e., that both the appearance of a liquid phase at low temperatures and preferred grain growth at high temperatures enhance F, while recrystallization at intermediate temperatures deteriorates F. CIP results in less-defect green compact, hence less recrystallization, leading to better resultant alignment« less

Surfactant Mediated Growth of Co on MgO(111)

NASA Astrophysics Data System (ADS)

Johnson-Steigelman, H. Trevor; Parihar, Somendra S.; Lyman, Paul F.

2010-03-01

Monolayer films of Co were deposited using an electrostatic electron-beam evaporator on single-crystal MgO(111)- √3 x√3 R 30^o substrates held at room temperature, with subsequent annealing of temperatures 400 C to 800 C. These films were characterized using low-energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and x-ray diffraction (XRD). After short anneals of 400 C, AFM, LEED, and XPS suggest that islanding has occurred at the surface. XPS and XRD indicate the presence of elemental Co. 1-2 ML films of Ag were examined as a potential surfactant to aid in the growth of smooth Co films. Despite the fact that Ag itself formed islands, it was found that the presence of Ag did have a surfactant effect upon the thin-film growth of Co on Ag/MgO(111)- √3 x√3 R 30^o. Co islands were still present, but much more smooth than islands formed without Ag. XPS and AFM suggest strongly that Ag floated to the top of these samples at temperatures above 400 ^oC.

Transformation Toughening of Composite Ceramics

DTIC Science & Technology

1992-12-31

Ca 2SiO 4 ) entiwickelt. Als Sili:ium-haltiger Prekursor i’urde has been well studied ’ 2 because of the considerable Siliziumdioxid veruiendet. Diese ...of carbon diffraction (XRD). This was after calcination for formed during the pyrolysis . The thermal decompo- I min at temperatures in the range...ques respectively. Some of the powders were also temperature for 1 min and cooled. At temperatures examined by SEM. below the pyrolysis stage the

Dependence of annealing temperature on microstructure and photoelectrical properties of vanadium oxide thin films prepared by DC reactive sputtering

NASA Astrophysics Data System (ADS)

Li, Yan; Zhang, Dongping; Wang, Bo; Liang, Guangxing; Zheng, Zhuanghao; Luo, Jingting; Cai, Xingmin; Fan, Ping

2013-12-01

Vanadium oxide thin films were prepared by DC reactive sputtering method, and the samples were annealed in Ar atmosphere under different temperature for 2 hours. The microstructure, optical and electrical properties of the as-grown and treated samples were characterized by XRD, spectrophotometer, and four-probe technique, respectively. XRD results investigated that the main content of the annealed sample are VO2 and V2O5. With annealing temperature increasing, the intensity of the VO2 phase diffraction peak strengthened. The electrical properties reveal that the annealed samples exhibit semiconductor-to-metal transition characteristic at about 40°C. Comparison of transmission spectra of the samples at room temperature and 100°C, a drastic drop in IR region is found.

Sign reversal of transformation entropy change in Co{sub 2}Cr(Ga,Si) shape memory alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Xiao, E-mail: xu@material.tohoku.ac.jp; Omori, Toshihiro; Kainuma, Ryosuke

2015-11-02

In situ X-ray diffraction (XRD) measurements and compression tests were performed on Co{sub 2}Cr(Ga,Si) shape memory alloys. The reentrant martensitic transformation behavior was directly observed during the in situ XRD measurements. The high-temperature parent phase and low-temperature reentrant parent phase were found to have a continuous temperature dependence of lattice parameter, therefore suggesting that they are the same phase in nature. Moreover, compression tests were performed on a parent-phase single crystal sample; an evolution from normal to inverse temperature dependence of critical stress for martensitic transformation was directly observed. Based on the Clausius-Clapeyron analysis, a sign reversal of entropy changemore » can be expected on the same alloy.« less

Annealing effect on the structural and dielectric properties of hematite nanoparticles

NASA Astrophysics Data System (ADS)

Kumar, Vijay; Chahal, Surjeet; Singh, Dharamvir; Kumar, Ashok; Kumar, Parmod; Asokan, K.

2018-05-01

In the present work, we have synthesized hematite (α-Fe2O3) nanoparticles by sol-gel method and sintered them at different temperatures (200 °C, 400 °C and 800 °C for six hours). The samples were then characterized using versatile characterization techniques such as X-ray diffraction (XRD), dielectric measurement and temperature dependent resistivity (RT) for their structural, dielectric and electrical properties. XRD measurements infer that intensity of peak increases with an increase in temperature resulting an increase in crystallite size. Temperature dependent resistivity also shows decrease in the resistivity of the samples. Furthermore, the dielectric measurements correspond to the increase in the dielectric constant. Based on these observations, it can be inferred that sintering temperature plays an important role in tailoring the various physical properties of hematite nanoparticles.

Magnetic and dielectric behavior of chromium substituted Co-Mg ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Jadoun, Priya; Jyoti, Prashant, B. L.; Dolia, S. N.; Bhatnagar, D.; Saxena, V. K.

2016-05-01

The chromium doped Co-Mg ferrite with composition Co0.5Mg0.5Cr0.2Fe1.8O4 has been synthesized using sol-gel auto combustion method. The crystal structure has been analyzed by X-ray diffraction (XRD) technique. XRD pattern reveals the formation of single phase cubic spinel structure. The magnetic measurements show ferromagnetic behavior at room temperature and large coercivity is observed on cooling down the temperature to 20 K. Dielectric constant (ɛ') and dielectric loss tangent (tan δ) have been determined at room temperature as a function of frequency in the frequency range 75 kHz to 80 MHz. The decrease in dielectric constant with increasing frequency attributes to Maxwell Wagner model and conduction mechanism in ferrites.

In-situ XRD and EDS method study on the oxidation behaviour of Ni-Cu sulphide ore.

PubMed

Li, Guangshi; Cheng, Hongwei; Xiong, Xiaolu; Lu, Xionggang; Xu, Cong; Lu, Changyuan; Zou, Xingli; Xu, Qian

2017-06-12

The oxidation mechanism of sulfides is the key issue during the sulphide-metallurgy process. In this study, the phase transformation and element migration were clearly demonstrated by in-situ laboratory-based X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS), respectively. The reaction sequence and a four-step oxidation mechanism were proposed and identified. The elemental distribution demonstrated that at a low temperature, the Fe atoms diffused outward and the Ni/Cu atoms migrated toward the inner core, whereas the opposite diffusion processes were observed at a higher temperature. Importantly, the unique visual presentation of the oxidation behaviour provided by the combination of in-situ XRD and EDS might be useful for optimising the process parameters to improve the Ni/Cu extraction efficiency during Ni-Cu sulphide metallurgy.

Adsorption of vitamin E on mesoporous titania nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shih, C.J., E-mail: cjshih@kmu.edu.tw; Lin, C.T.; Wu, S.M.

2010-07-15

Tri-block nonionic surfactant and titanium chloride were used as starting materials for the synthesis of mesoporous titania nanocrystallite powders. The main objective of the present study was to examine the synthesis of mesoporous titania nanocrystals and the adsorption of vitamin E on those nanocrystals using X-ray diffraction (XRD), transmission electron microscopy, and nitrogen adsorption and desorption isotherms. When the calcination temperature was increased to 300 {sup o}C, the reflection peaks in the XRD pattern indicated the presence of an anatase phase. The crystallinity of the nanocrystallites increased from 80% to 98.6% with increasing calcination temperature from 465 {sup o}C tomore » 500 {sup o}C. The N{sub 2} adsorption data and XRD data taken after vitamin E adsorption revealed that the vitamin E molecules were adsorbed in the mesopores of the titania nanocrystals.« less

Role of Ga particulates on the structure and optical properties of Y3(Al,Ga)5O12:Tb thin films prepared by PLD

NASA Astrophysics Data System (ADS)

Yousif, A.; Duvenhage, M. M.; Ntwaeaborwa, O. M.; Swart, H. C.

2018-04-01

Y3(Al,Ga)5O12:Tb thin films (70 nm) have been prepared by pulsed laser deposition on a Si (100) substrate at the substrate temperature of 300 °C. The effect of annealing time on the structural, morphological and luminescence properties of Y3(Al,Ga)5O12:Tb thin films at 800 °C were studied. The crystal structure of the samples was studied by X- ray diffraction (XRD) and showed shifts in the peak positions to lower diffraction angles for the annealed film compared to the XRD peak positions of the commercial Y3(Al,Ga)5O12:Tb powder. A new excitation band different from the original Y3(Al,Ga)5O12:Tb powder was also observed for the annealed films. The shift in the XRD pattern and the new excitation band for the annealed film suggested that the films were enriched with Ga after annealing.

Crystal Structure Variations of Sn Nanoparticles upon Heating

NASA Astrophysics Data System (ADS)

Mittal, Jagjiwan; Lin, Kwang-Lung

2018-04-01

Structural changes in Sn nanoparticles during heating below the melting point have been investigated using differential scanning calorimetry (DSC), x-ray diffraction (XRD) analysis, electron diffraction (ED), and high-resolution transmission electron microscopy (HRTEM). DSC revealed that the heat required to melt the nanoparticles (28.43 J/g) was about half compared with Sn metal (52.80 J/g), which was attributed to the large surface energy contribution for the nanoparticles. ED and XRD analyses of the Sn nanoparticles revealed increased intensity for crystal planes having large interplaner distances compared with regular crystal planes with increasing heat treatment temperature (HTT). HRTEM revealed an increase in interlayer spacing at the surface and near joints between nanoparticles with the HTT, leading to an amorphous structure of nanoparticles at the surface at 220°C. These results highlight the changes that occur in the morphology and crystal structure of Sn nanoparticles at the surface and in the interior with increase of the heat treatment temperature.

Low-temperature growth and photoluminescence property of ZnS nanoribbons.

PubMed

Zhang, Zengxing; Wang, Jianxiong; Yuan, Huajun; Gao, Yan; Liu, Dongfang; Song, Li; Xiang, Yanjuan; Zhao, Xiaowei; Liu, Lifeng; Luo, Shudong; Dou, Xinyuan; Mou, Shicheng; Zhou, Weiya; Xie, Sishen

2005-10-06

At a low temperature of 450 degrees C, ZnS nanoribbons have been synthesized on Si and KCl substrates by a simple chemical vapor deposition (CVD) method with a two-temperature-zone furnace. Zinc and sulfur powders are used as sources in the different temperature zones. X-ray diffraction (XRD), selected area electron diffraction (SEAD), and transmission electron microscopy (TEM) analysis show that the ZnS nanoribbons are the wurtzite structure, and there are two types-single-crystal and bicrystal nanoribbons. Photoluminescence (PL) spectrum shows that the spectrum mainly includes two parts: a purple emission band centering at about 390 nm and a blue emission band centering at about 445 nm with a weak green shoulder around 510 nm.

Magnetic and dielectric properties of Ca-substituted BiFeO3 nanoferrites by the sol-gel method.

PubMed

Lin, Jinpei; Guo, Zeping; Li, Mei; Lin, Qing; Huang, Kangling; He, Yun

2018-01-01

A multiferroic material can simultaneously show two or more basic magnetic properties, including ferromagnetism, antiferromagnetism, and ferroelectricity. BiFeO 3 is a multiferroic material with a rhombohedral distorted perovskite structure. Doping can reduce the volatility of Bi and greatly improve the magnetoelectric properties of BiFeO 3 . To investigate the influence of the doping content we used the following analytical methods: X-ray powder diffraction (XRD), scanning electron microscopy (SEM), microwave network analysis (PNA-N5244A), and the Superconducting Quantum Interference Device (Quantum Design MPMS) test. With the increase of Ca 2+ concentration in the solution, the grain size of Bi 1- x Ca x FeO 3 becomes smaller, showing the role of Ca 2+ ions as the dopant for fine grains. The calcination temperatures are the major causes for the saturated magnetization. The residual magnetization ( M r ) and the coercive force ( H c ) decrease linearly with the increase of x value, and due to the effect of Ca 2+ substitution at Bi 3+ sites, which causes the valence change of Fe and/or the oxygen vacancies. The XRD result indicates that the diffraction peak emerges with the increase of Ca 2+ and the main diffraction peak achieves a high angle. The best calcining temperature is 600 °C, and the morphology is very dependent on the calcining temperature.

Effect of Synthesis Parameter on Crystal Structures and Magnetic Properties of Magnesium Nickel Ferrite (Mg0.5Ni0.5Fe2O4) Nanoparticles

NASA Astrophysics Data System (ADS)

Maulia, R.; Putra, R. A.; Suharyadi, E.

2017-05-01

Mg0.5Ni0.5Fe2O4 nanoparticles have been successfully synthesized by using co-precipitation method and varying the synthesis parameter, i.e. synthesis temperature and NaOH concentration. X-ray Diffraction (XRD) pattern showed that nanoparticles have cubic spinel structures with an additional phase of γ-Fe2O3 and particle size varies within the range of 4.3 - 6.7 nm. This variation is due to the effect of various synthesis parameters. Transmission Electron Microscopy (TEM) image showed that the nanoparticles exhibited agglomeration. The observed diffraction ring from selected area electron diffraction showed that the sample was polycrystalline and confirmed the peak appearing in XRD. The coercivities showed an increasing trend with an increase in particle size from 44.7 Oe to 49.6 Oe for variation of NaOH concentration, and a decreasing trend with an increase in particle size from 46.8 to 45.1 Oe for variation of synthesis temperature. The maximum magnetization showed an increasing trend with an increase in the ferrite phase from 3.7 emu/g to 5.4 emu/g possessed in the sample with variations on NaOH concentration. The maximum magnetization for the sample with variations on synthesis temperature varied from 4.4 emu/g to 5.7 emu/g due to its crystal structures.

Dielectric properties of A- and B-site doped BaTiO 3: Effect of La and Ga

NASA Astrophysics Data System (ADS)

Gulwade, Devidas; Gopalan, Prakash

2009-06-01

Extremely small amounts of La and Ga doping on the A- and B-site of BaTiO 3, respectively, resulting in a solid solution of the type Ba 1-3xLa 2xTi 1-3yGa 4yO 3 have been investigated. The present work dwells on the influence of the individual dopants, namely La and Ga, on the dielectric properties of BaTiO 3. The compositions have been prepared by solid-state reaction. X-ray diffraction (XRD) reveals the presence of tetragonal (P4/mmm) phase. The XRD data has been analyzed using FULLPROF, a Rietveld refinement package. The microstructure have been studied by orientation imaging microscopy (OIM). The compositions have been characterized by dielectric spectroscopy between room temperature and 250 °C. Further, the nature of phase transition has been studied using high temperature XRD. The resulting compounds exhibit high dielectric constant, enhanced diffuseness and low temperature coefficient of capacitance.

Comparing two tetraalkylammonium ionic liquids. II. Phase transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lima, Thamires A.; Paschoal, Vitor H.; Faria, Luiz F. O.

Phase transitions of the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1114}][NTf{sub 2}], and methyl-tributylammonium bis(trifluoromethanesulfonyl)imide, [N{sub 1444}][NTf{sub 2}], were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) measurements, and Raman spectroscopy. XRD and Raman spectra were obtained as a function of temperature at atmospheric pressure, and also under high pressure at room temperature using a diamond anvil cell (DAC). [N{sub 1444}][NTf{sub 2}] experiences glass transition at low temperature, whereas [N{sub 1114}][NTf{sub 2}] crystallizes or not depending on the cooling rate. Both the ionic liquids exhibit glass transition under high pressure. XRD and low-frequency Raman spectra provide a consistent physical picturemore » of structural ordering-disordering accompanying the thermal events of crystallization, glass transition, cold crystallization, pre-melting, and melting. Raman spectra in the high-frequency range of some specific cation and anion normal modes reveal conformational changes of the molecular structures along phase transitions.« less

Boron-doped diamond synthesized at high-pressure and high-temperature with metal catalyst

NASA Astrophysics Data System (ADS)

Shakhov, Fedor M.; Abyzov, Andrey M.; Kidalov, Sergey V.; Krasilin, Andrei A.; Lähderanta, Erkki; Lebedev, Vasiliy T.; Shamshur, Dmitriy V.; Takai, Kazuyuki

2017-04-01

The boron-doped diamond (BDD) powder consisting of 40-100 μm particles was synthesized at 5 GPa and 1500-1600 °C from a mixture of 50 wt% graphite and 50 wt% Ni-Mn catalyst with an addition of 1 wt% or 5 wt% boron powder. The size of crystal domains of doped and non-doped diamond was evaluated as a coherent scattering region by X-ray diffraction (XRD) and using small-angle neutron scattering (SANS), being ≥180 nm (XRD) and 100 nm (SANS). Magnetic impurities of NiMnx originating from the catalyst in the synthesis, which prevent superconductivity, were detected by magnetization measurements at 2-300 K. X-ray photoelectron spectroscopy, the temperature dependence of the resistivity, XRD, and Raman spectroscopy reveal that the concentration of electrically active boron is as high as (2±1)×1020 cm-3 (0.1 at%). To the best of our knowledge, this is the highest boron content for BDD synthesized in high-pressure high-temperature process with metal catalysts.

Understanding changes in cellulose crystalline structure of lignocellulosic biomass during ionic liquid pretreatment by XRD.

PubMed

Zhang, Jiafu; Wang, Yixun; Zhang, Liye; Zhang, Ruihong; Liu, Guangqing; Cheng, Gang

2014-01-01

X-ray diffraction (XRD) was used to understand the interactions of cellulose in lignocellulosic biomass with ionic liquids (ILs). The experiment was designed in such a way that the process of swelling and solubilization of crystalline cellulose in plant cell walls was followed by XRD. Three different feedstocks, switchgrass, corn stover and rice husk, were pretreated using 1-butyl-3-methylimidazolium acetate ([C4mim][OAc]) at temperatures of 50-130°C for 6h. At a 5 wt.% biomass loading, increasing pretreatment temperature led to a drop in biomass crystallinity index (CrI), which was due to swelling of crystalline cellulose. After most of the crystalline cellulose was swollen with IL molecules, a low-order structure was found in the pretreated samples. Upon further increasing temperature, cellulose II structure started to form in the pretreated biomass samples as a result of solubilization of cellulose in [C4mim][OAc] and subsequent regeneration. Copyright © 2013 Elsevier Ltd. All rights reserved.

Single step synthesis of nanostructured boron nitride for boron neutron capture therapy

NASA Astrophysics Data System (ADS)

Singh, Bikramjeet; Singh, Paviter; Kumar, Manjeet; Thakur, Anup; Kumar, Akshay

2015-05-01

Nanostructured Boron Nitride (BN) has been successfully synthesized by carbo-thermic reduction of Boric Acid (H3BO3). This method is a relatively low temperature synthesis route and it can be used for large scale production of nanostructured BN. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA). XRD analysis confirmed the formation of single phase nanostructured Boron Nitride. SEM analysis showed that the particles are spherical in shape. DTA analysis showed that the phase is stable upto 900 °C and the material can be used for high temperature applications as well boron neutron capture therapy (BNCT).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winterrose, M.; Lucas, M; Yue, A

Synchrotron x-ray diffraction (XRD) measurements, nuclear forward scattering (NFS) measurements, and density functional theory (DFT) calculations were performed on L12-ordered Pd3Fe. Measurements were performed at 300 K at pressures up to 33 GPa, and at 7 GPa at temperatures up to 650 K. The NFS revealed a collapse of the 57Fe magnetic moment between 8.9 and 12.3 GPa at 300 K, coinciding with a transition in bulk modulus found by XRD. Heating the sample under a pressure of 7 GPa showed negligible thermal expansion from 300 to 523 K, demonstrating Invar behavior. Zero-temperature DFT calculations identified a ferromagnetic ground statemore » and showed several antiferromagnetic states had comparable energies at pressures above 20 GPa.« less

Rietveld refinement, dielectric and magnetic properties of Nb modified Bi0.80Ba0.20FeO3 ceramic

NASA Astrophysics Data System (ADS)

Jangra, Sandhaya; Sanghi, Sujata; Agarwal, Ashish; Rangi, Manisha

2018-05-01

Bi0.80Ba0.20Fe0.95Nb0.05O3 ceramic has been prepared via conventional solid state reaction method. Structure analysis was carried out by X-ray diffraction (XRD) technique at room temperature. XRD pattern confirmed the crystalline nature of prepared sample. Rietveld analysis used for further structural investigations and confirmed the existence of rhombohedral symmetry (R3c space group). The dielectric response shows dispersion at lower frequency range and becomes frequency independent at high frequency. The approximation of conduction mechanism is determined by the temperature dependent behavior of frequency exponent `s'. Fitting results suggests the applicability of small polaron conduction mechanism at lower temperatures and CBH model at higher temperature. Room temperature magnetic measurements give the evidence of significant enhancement in magnetic properties with remanent magnetization (Mr = 0.1218 emu/g) and coercive field (Hc = 3.5342 kOe).

Effects on structural, optical, and magnetic properties of pure and Sr-substituted MgFe2O4 nanoparticles at different calcination temperatures

NASA Astrophysics Data System (ADS)

Loganathan, A.; Kumar, K.

2016-06-01

In the present work, pure and Sr2+ ions substituted Mg ferrite nanoparticles (NPs) had been prepared by co-precipitation method and their structural, optical, and magnetic properties at different calcination temperatures were studied. On this purpose, thermo gravimetric and differential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy, UV-Visible diffused reflectance spectroscopy, impedance spectroscopy, and vibrating sample magnetometer were carried out. The exo- and endothermic processes of synthesized precursors were investigated by TG-DTA measurements. The structural properties of the obtained products were examined by XRD analysis and show that the synthesized NPs are in the cubic spinel structure. The existence of two bands around 578-583 and 430-436 cm-1 in FT-IR spectrum also confirmed the formation of spinel-structured ferrite NPs. The lattice constants and particle size are estimated using XRD data and found to be strongly dependent on calcination temperatures. The optical, electrical, and magnetic properties of ferrite compositions also investigated and found to be strongly dependant on calcination temperatures.

Study on the Growth Mechanism of K2Ti4O9 Crystal

NASA Astrophysics Data System (ADS)

Zhou, Xuesong; Fan, Jing; Wei, Xiaoli; Shen, Yi; Meng, Yanzhi

2018-04-01

Potassium hexatitanate (K2Ti4O9) whiskers were prepared by the kneading-drying-calcination method. After the preparation of products under different calcination temperatures and holding times, their morphology and structure were characterized by thermogravimetric and differential thermal, X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy. The XRD analysis showed that the reaction mixture was completely converted to K2Ti4O9 crystals at 800 °C when the T/K ratio was 3. Based on the analysis of LS (liquid-solid) growth mechanism, the corresponding transformation reaction mechanism during the roasting was elucidated. K2Ti4O9 whiskers grow mainly through the parallel action at a low temperature. With the increase in temperature, the series effect is obvious.

Structural and thermal properties of vanadium tellurite glasses

NASA Astrophysics Data System (ADS)

Kaur, Rajinder; Kaur, Ramandeep; Khanna, Atul; González, Fernando

2018-04-01

V2O5-TeO2 glasses containing 10 to 50 mol% V2O5 were prepared by melt quenching and characterized by X-ray diffraction (XRD), density, Differential Scanning Calorimetry (DSC) and Raman studies.XRD confirmed the amorphous nature of vanadium tellurite samples. The density of the glasses decreases and the molar volume increases on increasing the concentration of V2O5. The thermal properties, such as glass transition temperature Tg, crystallization temperature Tc, and the melting temperature Tm were measured. Tg decreases from a value of 288°C to 232°C. The changes in Tg were correlated with the number of bonds per unit volume, and the average stretching force constant. Raman spectra were used to elucidate the short-range structure of vanadium tellurite glasses.

Room temperature chemical synthesis of lead selenide thin films with preferred orientation

NASA Astrophysics Data System (ADS)

Kale, R. B.; Sartale, S. D.; Ganesan, V.; Lokhande, C. D.; Lin, Yi-Feng; Lu, Shih-Yuan

2006-11-01

Room temperature chemical synthesis of PbSe thin films was carried out from aqueous ammoniacal solution using Pb(CH3COO)2 as Pb2+ and Na2SeSO3 as Se2- ion sources. The films were characterized by a various techniques including, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fast Fourier transform (FFT) and UV-vis-NIR techniques. The study revealed that the PbSe thin film consists of preferentially oriented nanocubes with energy band gap of 0.5 eV.

In Situ Neutron Diffraction of Rare-Earth Phosphate Proton Conductors Sr/Ca-doped LaPO4 at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Al-Wahish, Amal; Al-Binni, Usama; Bridges, C. A.; Huq, A.; Bi, Z.; Paranthaman, M. P.; Tang, S.; Kaiser, H.; Mandrus, D.

Acceptor-doped lanthanum orthophosphates are potential candidate electrolytes for proton ceramic fuel cells. We combined neutron powder diffraction (NPD) at elevated temperatures up to 800° C , X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) to investigate the crystal structure, defect structure, thermal stability and surface topography. NPD shows an average bond length distortion in the hydrated samples. We employed Quasi-Elastic Neutron Scattering (QENS) and electrochemical impedance spectroscopy (EIS) to study the proton dynamics of the rare-earth phosphate proton conductors 4.2% Sr/Ca-doped LaPO4. We determined the bulk diffusion and the self-diffusion coefficients. Our results show that QENS and EIS are probing fundamentally different proton diffusion processes. Supported by the U.S. Department of Energy.

Synthesis and Properties of Ortho-Nitro-Fe Complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, A.; Mishra, Niyati; Sharma, R.

2011-07-15

Ortho-Nitro-Fe complex (Transition metal complex) has synthesized by chemical route method and properties of made complex has characterized by X-Ray diffraction (XRD), Moessbauer spectroscopy, Fourier transformation infra-red spectroscopy (FTIR) and X-Ray photoelectron spectroscopy (XPS). XRD analysis shows that sample is crystalline in nature and having particle size in the range of few nano meters. Moessbauer spectroscopy at room temperature shows the oxidation state of Iron (central metal ion) after complaxasion. FTIR spectra of the complex confirms the coordination of metal ion with ligand.

Crystal structure and physicochemical characterization of ambazone monohydrate, anhydrous, and acetate salt solvate.

PubMed

Muresan-Pop, Marieta; Braga, Dario; Pop, Mihaela M; Borodi, Gheorghe; Kacso, Irina; Maini, Lucia

2014-11-01

The crystal structures of the monohydrate and anhydrous forms of ambazone were determined by single-crystal X-ray diffraction (SC-XRD). Ambazone monohydrate is characterized by an infinite three-dimensional network involving the water molecules, whereas anhydrous ambazone forms a two-dimensional network via hydrogen bonds. The reversible transformation between the monohydrate and anhydrous forms of ambazone was evidenced by thermal analysis, temperature-dependent X-ray powder diffraction and accelerated stability at elevated temperature, and relative humidity (RH). Additionally, a novel ambazone acetate salt solvate form was obtained and its nature was elucidated by SC-XRD. Powder dissolution measurements revealed a substantial solubility and dissolution rate improvement of acetate salt solvated form in water and physiological media compared with ambazone forms. Also, the acetate salt solvate displayed good thermal and solution stability but it transformed to the monohydrate on storage at elevated temperature and RH. Our study shows that despite the requirement for controlled storage conditions, the acetate salt solvated form could be an alternative to ambazone when solubility and bioavailability improvement is critical for the clinical efficacy of the drug product. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Stable tetragonal phase and magnetic properties of Fe-doped HfO2 nanoparticles

NASA Astrophysics Data System (ADS)

Sales, T. S. N.; Cavalcante, F. H. M.; Bosch-Santos, B.; Pereira, L. F. D.; Cabrera-Pasca, G. A.; Freitas, R. S.; Saxena, R. N.; Carbonari, A. W.

2017-05-01

In this paper, the effect in structural and magnetic properties of iron doping with concentration of 20% in hafnium dioxide (HfO2) nanoparticles is investigated. HfO2 is a wide band gap oxide with great potential to be used as high-permittivity gate dielectrics, which can be improved by doping. Nanoparticle samples were prepared by sol-gel chemical method and had their structure, morphology, and magnetic properties, respectively, investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with electron back scattering diffraction (EBSD), and magnetization measurements. TEM and SEM results show size distribution of particles in the range from 30 nm to 40 nm with small dispersion. Magnetization measurements show the blocking temperature at around 90 K with a strong paramagnetic contribution. XRD results show a major tetragonal phase (94%).

Center for Thin Film Studies

DTIC Science & Technology

1991-01-22

highly oriented pyrolitic graphite ( HOPG ) for detailed studies of nucleation and of the development of surface roughness. Using a shadowing technique, we...laser to a temperature of approximately 600’C, a polycrystalline film resulted, as indicated b x-ray diffraction ( XRD ) data shown in Fig. 4. vI Figure 4...stress level rose in films deposited at colder temperatures. Development of second harmonic generation as a technique for evaluation of anisotropy in

Yttria catalyzed microstructural modifications in oxide dispersion strengthened V-4Cr-4Ti alloys synthesized by field assisted sintering technique

NASA Astrophysics Data System (ADS)

Krishnan, Vinoadh Kumar; Sinnaeruvadi, Kumaran; Verma, Shailendra Kumar; Dash, Biswaranjan; Agrawal, Priyanka; Subramanian, Karthikeyan

2017-08-01

The present work deals with synthesis, characterisation and elevated temperature mechanical property evaluation of V-4Cr-4Ti and oxide (yttria = 0.3, 0.6 and 0.9 at%) dispersion strengthened V-4Cr-4Ti alloy processed by mechanical alloying and field-assisted sintering, under optimal conditions. Microstructural parameters of both powder and sintered samples were deduced by X-ray diffraction (XRD) and further confirmed with high resolution transmission electron microscopy. Powder diffraction and electron microscopy study show that ball milling of starting elemental powders (V-4Cr-4Ti) with and without yttria addition has resulted in single phase α-V (V-4Cr-4Ti) alloy. Wherein, XRD and electron microscopy images of sintered samples have revealed phase separation (viz., Cr-V and Ti-V) and domain size reduction, with yttria addition. The reasons behind phase separation and domain size reduction with yttria addition during sintering are extensively discussed. Microhardness and high temperature compression tests were done on sintered samples. Yttria addition (0.3 and 0.6 at.%) increases the elevated temperature compressive strength and strain hardening exponent of α-V alloys. High temperature compression test of 0.9 at% yttria dispersed α-V alloy reveals a glassy behaviour.

In situ flow cell for combined X-ray absorption spectroscopy, X-ray diffraction, and mass spectrometry at high photon energies under solar thermochemical looping conditions

NASA Astrophysics Data System (ADS)

Rothensteiner, Matthäus; Jenni, Joel; Emerich, Hermann; Bonk, Alexander; Vogt, Ulrich F.; van Bokhoven, Jeroen A.

2017-08-01

An in situ/operando flow cell for transmission mode X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and combined XAS/XRD measurements in a single experiment under the extreme conditions of two-step solar thermochemical looping for the dissociation of water and/or carbon dioxide was developed. The apparatus exposes materials to relevant conditions of both the auto-reduction and the oxidation sub-steps of the thermochemical cycle at ambient temperature up to 1773 K and enables determination of the composition of the effluent gases by online quadrupole mass spectrometry. The cell is based on a tube-in-tube design and is heated by means of a focusing infrared furnace. It was tested successfully for carbon dioxide splitting. In combined XAS/XRD experiments with an unfocused beam, XAS measurements were performed at the Ce K edge (40.4 keV) and XRD measurements at 64.8 keV and 55.9 keV. Furthermore, XRD measurements with a focused beam at 41.5 keV were carried out. Equimolar ceria-hafnia was auto-reduced in a flow of argon and chemically reduced in a flow of hydrogen/helium. Under reducing conditions, all cerium(iv) was converted to cerium(iii) and a cation-ordered pyrochlore-type structure was formed, which was not stable upon oxidation in a flow of carbon dioxide.

In situ flow cell for combined X-ray absorption spectroscopy, X-ray diffraction, and mass spectrometry at high photon energies under solar thermochemical looping conditions.

PubMed

Rothensteiner, Matthäus; Jenni, Joel; Emerich, Hermann; Bonk, Alexander; Vogt, Ulrich F; van Bokhoven, Jeroen A

2017-08-01

An in situ/operando flow cell for transmission mode X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and combined XAS/XRD measurements in a single experiment under the extreme conditions of two-step solar thermochemical looping for the dissociation of water and/or carbon dioxide was developed. The apparatus exposes materials to relevant conditions of both the auto-reduction and the oxidation sub-steps of the thermochemical cycle at ambient temperature up to 1773 K and enables determination of the composition of the effluent gases by online quadrupole mass spectrometry. The cell is based on a tube-in-tube design and is heated by means of a focusing infrared furnace. It was tested successfully for carbon dioxide splitting. In combined XAS/XRD experiments with an unfocused beam, XAS measurements were performed at the Ce K edge (40.4 keV) and XRD measurements at 64.8 keV and 55.9 keV. Furthermore, XRD measurements with a focused beam at 41.5 keV were carried out. Equimolar ceria-hafnia was auto-reduced in a flow of argon and chemically reduced in a flow of hydrogen/helium. Under reducing conditions, all cerium(iv) was converted to cerium(iii) and a cation-ordered pyrochlore-type structure was formed, which was not stable upon oxidation in a flow of carbon dioxide.

Thermal and structural alternations in CuAlMnNi shape memory alloy by the effect of different pressure applications

NASA Astrophysics Data System (ADS)

Canbay, Canan Aksu; Polat, Tercan

2017-09-01

In this work the effects of the applied pressure on the characteristic transformation temperatures, the high temperature order-disorder phase transitions, the variation in diffraction peaks and the surface morphology of the CuAlMnNi shape memory alloy was investigated. The evolution of the transformation temperatures was studied by differential scanning calorimetry (DSC) with different heating and cooling rates. The differential thermal analysis measurements were performed to obtain the ordered-disordered phase transformations from room temperature to 900 °C. The characteristic transformation temperatures and the thermodynamic parameters were highly sensitive to variations in the applied pressure and also the applied pressure affected the thermodynamic parameters. The activation energy of the sample according to applied pressure values calculated by Kissinger method. The structural changes of the samples were studied by X-ray diffraction (XRD) measurements and by optical microscope observations at room temperature.

Elucidation of reaction mechanism involved in the formation of LaNiO3 from XRD and TG analysis

NASA Astrophysics Data System (ADS)

Dharmadhikari, Dipti V.; Athawale, Anjali A.

2013-06-01

The present work is focused on the synthesis and elucidation of reaction mechanism involved in the formation of LaNiO3 with the help of X-ray diffraction (XRD) and thermogravimetric (TG) analysis. LaNiO3 was synthesized by hydrothermal method by heating at 160°C under autogenous pressure for 6h. Pure phase product was obtained after calcining the hydrothermally activated product for 6h at 700°C. The various phases of the product obtained after hydrothermal treatment and calcination followed by the formation of pure phase nanocrystalline lanthanum nickel oxide could be determined from XRD analysis of the samples. The reaction mechanism and phase formation temperature has been interpreted by thermogravimetric analysis of the hydrothermally synthesized product and XRD analysis.

Current-voltage characteristics of n-AlMgZnO/p-GaN junction diodes

NASA Astrophysics Data System (ADS)

Hsueh, Kuang-Po; Cheng, Po-Wei; Cheng, Yi-Chang; Sheu, Jinn-Kong; Yeh, Yu-Hsiang; Chiu, Hsien-Chin; Wang, Hsiang-Chun

2013-03-01

This study investigates the temperature dependence of the current-voltage (I-V) characteristics of Al-doped MgxZn1-xO/p-GaN junction diodes. Specifically, this study reports the deposition of n-type Al-doped MgxZn1-xO (AMZO) films on p-GaN using a radio-frequency (RF) magnetron sputtering system followed by annealing at 700, 800, 900, and 1000 °C in a nitrogen ambient for 60 seconds, respectively. The AMZO/GaN films were thereafter analyzed using Hall measurement and the x-ray diffraction (XRD) patterns. The XRD results show that the diffraction angles of the annealed AMZO films remain the same as that of GaN without shifting. The n-AMZO/p-GaN diode with 900 °C annealing had the lowest leakage current in forward and reverse bias. However, the leakage current of the diodes did not change significantly with an increase in annealing temperatures. These findings show that the n-AMZO/p-GaN junction diode is feasible for GaN-based heterojunction bipolar transistors (HBTs) and UV light-emitting diodes (LEDs).

MBE growth of few-layer 2H-MoTe2 on 3D substrates

NASA Astrophysics Data System (ADS)

Vishwanath, Suresh; Sundar, Aditya; Liu, Xinyu; Azcatl, Angelica; Lochocki, Edward; Woll, Arthur R.; Rouvimov, Sergei; Hwang, Wan Sik; Lu, Ning; Peng, Xin; Lien, Huai-Hsun; Weisenberger, John; McDonnell, Stephen; Kim, Moon J.; Dobrowolska, Margaret; Furdyna, Jacek K.; Shen, Kyle; Wallace, Robert M.; Jena, Debdeep; Xing, Huili Grace

2018-01-01

MoTe2 is the least explored material in the Molybdenum-chalcogen family. Molecular beam epitaxy (MBE) provides a unique opportunity to tackle the small electronegativity difference between Mo and Te while growing layer by layer away from thermodynamic equilibrium. We find that for a few-layer MoTe2 grown at a moderate rate of ∼6 min per monolayer, a narrow window in temperature (above Te cell temperature) and Te:Mo ratio exists, where we can obtain pure phase 2H-MoTe2. This is confirmed using reflection high-energy electron diffraction (RHEED), Raman spectroscopy and X-ray photoemission spectroscopy (XPS). For growth on CaF2, Grazing incidence X-ray diffraction (GI-XRD) reveals a grain size of ∼90 Å and presence of twinned grains. In this work, we hypothesis the presence of excess Te incorporation in MBE grown few layer 2H-MoTe2. For film on CaF2, it is based on >2 Te:Mo stoichiometry using XPS as well as 'a' and 'c' lattice spacing greater than bulk 2H-MoTe2. On GaAs, its based on observations of Te crystallite formation on film surface, 2 × 2 superstructure observed in RHEED and low energy electron diffraction, larger than bulk c-lattice spacing as well as the lack of electrical conductivity modulation by field effect. Finally, thermal stability and air sensitivity of MBE 2H-MoTe2 is investigated by temperature dependent XRD and XPS, respectively.

High-temperature X-ray diffraction study of crystallization and phase segregation on spinel-type lithium manganese oxides

NASA Astrophysics Data System (ADS)

Komaba, Shinichi; Yabuuchi, Naoaki; Ikemoto, Sachi

2010-01-01

To study crystallization process of spinel-type Li 1+xMn 2-xO 4, in-situ high-temperature X-ray diffraction technique (HT-XRD) was utilized for the mixture consisting of Li 2CO 3 and Mn 2O 3 as starting material in the temperature range of 25-700 °C. In-situ HT-XRD analysis directly revealed that crystallization process of Li 1+xMn 2-xO 4 was significantly affected by the difference in the Li/Mn molar ratio in the precursor. Single phase of stoichiometric LiMn 2O 4 formed at 700 °C. The formation of single phase of spinel was achieved at the lower temperature than the stoichiometric sample as Li/Mn molar ratio in the precursor increased. Lattice parameter of the stoichiometric LiMn 2O 4 at 25 °C was 8.24 Å and expanded to 8.31 Å at 700 °C, which corresponds to the approximately 3% expansion in the unit cell volume. From the slope of the lattice parameter change as a function of temperatures, linear thermal expansion coefficient of the stoichiometric LiMn 2O 4 was calculated to be 1.2×10 -5 °C -1 in this temperature range. When the Li/Mn molar ratio in Li 1+xMn 2-xO 4 increased ( x > 0.1), the spinel phase segregated into the Li 1+yMn 2-yO 4 ( x > y) and Li 2MnO 3 during heating, which involved the oxygen loss from the materials. During the cooling process from 700 °C, and the segregated phase merged into Li 1+xMn 2-xO 4 with oxygen incorporation. Such trend directly observed by in-situ HT-XRD was supported by thermal gravimetric analysis as reversible weight (oxygen) loss/gain at higher temperature (500-700 °C).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winterrose, M.L.; Lucas, M.S.; Yue, A.F.

Synchrotron x-ray diffraction (XRD) measurements, nuclear forward scattering (NFS) measurements, and density functional theory (DFT) calculations were performed on L1{sub 2}-ordered Pd{sub 3}Fe. Measurements were performed at 300 K at pressures up to 33 GPa, and at 7 GPa at temperatures up to 650 K. The NFS revealed a collapse of the Fe57 magnetic moment between 8.9 and 12.3 GPa at 300 K, coinciding with a transition in bulk modulus found by XRD. Heating the sample under a pressure of 7 GPa showed negligible thermal expansion from 300 to 523 K, demonstrating Invar behavior. Zero-temperature DFT calculations identified a ferromagneticmore » ground state and showed several antiferromagnetic states had comparable energies at pressures above 20 GPa.« less

Structural and Optical properties of poly-crystalline BaTiO3 and SrTiO3 prepared via solid state route

NASA Astrophysics Data System (ADS)

Jarabana, Kanaka M.; Mishra, Ashutosh; Bisen, Supriya

2016-10-01

Polycrystalline BaTiO3 (BTO) and SrTiO3 (STO) were synthesized by solid state route method and properties of made polycrystalline were characterized by X-Ray diffraction (XRD), Raman Spectroscopy & FTIR Spectroscopy. XRD analysis shows that samples are crystalline in nature. In Raman Spectroscopy measurement, the experiment has been done with the help of JOBIN-YOVN HORIBA LABRAM HR800 single monochromator, which is coupled with a “peltier cooled” charge coupled device (CCD). Raman Spectroscopy at low temperature measurement shows the phase transition above & below the curie temperature in samples. Fourier transform Infrared spectroscopy was used to determine the Ti-O bond length position.

Single step synthesis of nanostructured boron nitride for boron neutron capture therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Bikramjeet; Singh, Paviter; Kumar, Akshay, E-mail: akshaykumar.tiet@gmail.com

2015-05-15

Nanostructured Boron Nitride (BN) has been successfully synthesized by carbo-thermic reduction of Boric Acid (H{sub 3}BO{sub 3}). This method is a relatively low temperature synthesis route and it can be used for large scale production of nanostructured BN. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA). XRD analysis confirmed the formation of single phase nanostructured Boron Nitride. SEM analysis showed that the particles are spherical in shape. DTA analysis showed that the phase is stable upto 900 °C and the material can be used for high temperature applications asmore » well boron neutron capture therapy (BNCT)« less

Electro–optical properties of poly(vinyl acetate)/polyindole composite film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhagat, D. J., E-mail: bhagatd@rediffmail.com; Dhokane, G. R.; Bajaj, N. S.

2016-05-06

In present work, electrical and optical properties of poly(vinyl acetate)/polyindole (PVAc/PIN) composite film are reported. The prepared composite was characterized via X–ray diffraction (XRD), UV–Vis spectroscopy and DC conductivity measurements. The polymer chain separation was determined using XRD analysis. An attempt has been made to study the temperature dependence of DC conductivity of PVAc/PIN composite in temperature range 308–373 K. The DC conductivity initially increases and reaches to 2.45×10–7 S/cm. The optical band gap value of composite is determined as 4.77 eV. The semiconducting nature of composite observed from electronic as well as optical band gap and Arrhenius behavior of DCmore » plot.« less

Low-temperature synthesis and structural properties of ferroelectric K 3WO 3F 3 elpasolite

NASA Astrophysics Data System (ADS)

Atuchin, V. V.; Gavrilova, T. A.; Kesler, V. G.; Molokeev, M. S.; Aleksandrov, K. S.

2010-06-01

Low-temperature ferroelectric G2 polymorph of K 3WO 3F 3 has been prepared by chemical synthesis. Structural and chemical properties of the final product have been evaluated with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Structure parameters of G2-K 3WO 3F 3 are refined by the Rietveld method from XRD data measured at room temperature (space group Cm, Z = 2, a = 8.7350(3) Å, b = 8.6808(5) Å, c = 6.1581(3) Å, β = 135.124(3) Å, V = 329.46(3) Å 3; RB = 2.47%). Partial ordering of oxygen and fluorine atoms has been found over anion positions. Mechanism of ferroelectric phase transition in A 2BMO 3F 3 oxyfluorides is discussed.

Investigation on Structural and Optical Properties of Copper Telluride Thin Films with Different Annealing Temperature

NASA Astrophysics Data System (ADS)

Nishanthini, R.; Muthu Menaka, M.; Pandi, P.; Bahavan Palani, P.; Neyvasagam, K.

The copper telluride (Cu2Te) thin film of thickness 240nm was coated on a microscopic glass substrate by thermal evaporation technique. The prepared films were annealed at 150∘C and 250∘C for 1h. The annealing effect on Cu2Te thin films was examined with different characterization methods like X-ray Diffraction Spectroscopy (XRD), Scanning Electron Microscopy (SEM), Ultra Violet-Visible Spectroscopy (UV-VIS) and Photoluminescence (PL) Spectroscopy. The peak intensities of XRD spectra were increased while increasing annealing temperature from 150∘C to 250∘C. The improved crystallinity of the thin films was revealed. However, the prepared films are exposed complex structure with better compatibility. Moreover, the shift in band gap energy towards higher energies (blue shift) with increasing annealing temperature is observed from the optical studies.

Magnetic and dielectric behavior of chromium substituted Co-Mg ferrite nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jadoun, Priya, E-mail: priya4jadoun@gmail.com; Jyoti,; Prashant, B. L.

The chromium doped Co-Mg ferrite with composition Co{sub 0.5}Mg{sub 0.5}Cr{sub 0.2}Fe{sub 1.8}O{sub 4} has been synthesized using sol-gel auto combustion method. The crystal structure has been analyzed by X-ray diffraction (XRD) technique. XRD pattern reveals the formation of single phase cubic spinel structure. The magnetic measurements show ferromagnetic behavior at room temperature and large coercivity is observed on cooling down the temperature to 20 K. Dielectric constant (ε’) and dielectric loss tangent (tan δ) have been determined at room temperature as a function of frequency in the frequency range 75 kHz to 80 MHz. The decrease in dielectric constant with increasing frequency attributesmore » to Maxwell Wagner model and conduction mechanism in ferrites.« less

Dielectric and magnetic behavior of nanocrystalline Cu{sub 0.4}Co{sub 0.6}Fe{sub 2}O{sub 4} ferrite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jadoun, Priya, E-mail: priya4jadoun@gmail.com; Sharma, Jyoti; Prashant, B. L.

2016-05-23

The mixed copper cobalt ferrite nanoparticles (Cu{sub 0.4}Co{sub 0.6}Fe{sub 2}O{sub 4}) have been synthesized by sol-gel auto combustion route with aqueous metal nitrates and citric acid as the precursor. The crystal structure has been analyzed by X-Ray diffraction (XRD) method. XRD reveals the formation of single phase cubic spinel structure. The Scanning Electron Microscopy (SEM) is used for morphological studies. The dielectric measurements at room temperature show the decrease in dielectric constant with increasing frequency which is attributed to Maxwell Wagner model and conduction mechanism in ferrites.The magnetic measurements show ferromagnetic behavior at room temperature and large coercivity is observedmore » on cooling down the temperature to 20 K.« less

Electrical properties of Mg doped ZnO nanostructure annealed at different temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohamed, R., E-mail: ruziana12@gmail.com; Mamat, M. H., E-mail: hafiz-030@yahoo.com; Rusop, M., E-mail: nanouitm@gmail.com

In this work, ZincOxide (ZnO) nanostructures doped with Mg were successfully grown on the glass substrate. Magnesium (Mg) metal element was added in the ZnO host which acts as a doping agent. Different temperature in range of 250°C to 500°C was used in order to investigate the effect of annealing temperature of ZnO thin films. Field Emission Scanning Electron Microscopy (FESEM) was used to investigate the physical characteristic of ZnO thin films. FESEM results have revealed that ZnO nanorods were grown vertically aligned. The structural properties were determined by using X-Ray Diffraction (XRD) analysis. XRD results showed Mg doped ZnOmore » thin have highest crystalinnity at 500°C annealing temperature. The electrical properties were investigating by using Current-Voltage (I-V) measurement. I-V measurement showed the electrical properties were varied at different annealing temperature. The annealing temperature at 500°C has the highest electrical conductance properties.« less

Annealing Temperature Dependent Structural and Optical Properties of RF Sputtered ZnO Thin Films.

PubMed

Sharma, Shashikant; Varma, Tarun; Asokan, K; Periasamy, C; Boolchandani, Dharmendar

2017-01-01

This work investigates the effect of annealing temperature on structural and optical properties of ZnO thin films grown over Si 100 and glass substrates using RF sputtering technique. Annealing temperature has been varied from 300 °C to 600 °C in steps of 100, and different microstructural parameters such as grain size, dislocation density, lattice constant, stress and strain have been evaluated. The structural and surface morphological characterization has been done using X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). XRD analysis reveals that the peak intensity of 002 crystallographic orientation increases with increased annealing temperature. Optical characterization of deposited films have been done using UV-Vis-NIR spectroscopy and photoluminescence spectrometer. An increase in optical bandgap of deposited ZnO thin films with increasing annealing temperature has been observed. The average optical transmittance was found to be more than 85% for all deposited films. Photoluminiscense spectra (PL) suggest that the crystalline quality of deposited film has increased at higher annealing temperature.

Role of low-temperature AlGaN interlayers in thick GaN on silicon by metalorganic vapor phase epitaxy

NASA Astrophysics Data System (ADS)

Fritze, S.; Drechsel, P.; Stauss, P.; Rode, P.; Markurt, T.; Schulz, T.; Albrecht, M.; Bläsing, J.; Dadgar, A.; Krost, A.

2012-06-01

Thin AlGaN interlayers have been grown into a thick GaN stack on Si substrates to compensate tensile thermal stress and significantly improve the structural perfection of the GaN. In particular, thicker interlayers reduce the density in a-type dislocations as concluded from x-ray diffraction (XRD) measurements. Beyond an interlayer thickness of 28 nm plastic substrate deformation occurs. For a thick GaN stack, the first two interlayers serve as strain engineering layers to obtain a crack-free GaN structure, while a third strongly reduces the XRD ω-(0002)-FWHM. The vertical strain and quality profile determined by several XRD methods demonstrates the individual impact of each interlayer.

Comparative investigation of Fourier Transform Infrared (FT-IR) spectroscopy and X-ray Diffraction (XRD) in the determination of cotton fiber crystallinity

USDA-ARS?s Scientific Manuscript database

Despite considerable efforts in developing the curve-fitting protocol to evaluate the crystallinity index (CI) from the X-ray diffraction (XRD) measurement, in its present state XRD procedure can only provide a qualitative or semi-quantitative assessment of the amounts of crystalline or amorphous po...

Structure, Elastic Constants and XRD Spectra of Extended Solids under High Pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batyrev, I. G.; Coleman, S. P.; Ciezak-Jenkins, J. A.

We present results of evolutionary simulations based on density functional calculations of a potentially new type of energetic materials called extended solids: P-N and N-H. High-density structures with covalent bonds generated using variable and fixed concentration methods were analysed in terms of thermo-dynamical stability and agreement with experimental X-ray diffraction (XRD) spectra. X-ray diffraction spectra were calculated using a virtual diffraction algorithm that computes kinematic diffraction intensity in three-dimensional reciprocal space before being reduced to a two-theta line profile. Calculated XRD patterns were used to search for the structure of extended solids present at experimental pressures by optimizing data accordingmore » to experimental XRD peak position, peak intensity and theoretically calculated enthalpy. Elastic constants has been calculated for thermodynamically stable structures of P-N system.« less

Substrate temperature effect on structural and optical properties of Bi2Te3 thin films

NASA Astrophysics Data System (ADS)

Jariwala, B. S.; Shah, D. V.; Kheraj, Vipul

2012-06-01

Structural and optical properties of Bi2Te3 thin films, thermally evaporated on well-cleaned glass substrates at different substrate temperatures, are reported here. X-ray diffraction was carried out for the structural characterization. XRD patterns of the films exhibit preferential orientation along the [0 1 5] direction for the films deposited at all the substrate temperatures together with other supported planes [2 0 5] & [1 1 0]. All other deposition conditions like thickness, deposition rate and pressure were maintained same throughout the experiment. X-ray diffraction lines confirm that the grown films are polycrystalline in nature with hexagonal crystal structure. The effect of substrate temperature on lattice constants, grain size, micro strain, number of crystallites and dislocation density have been investigated and reported in this paper. Also the substrate temperature effect on the optical property has been also investigated using the FTIR spectroscopy.

Debye–Waller coefficient of heavily deformed nanocrystalline iron1

PubMed Central

Abdellatief, M.

2017-01-01

Synchrotron radiation X-ray diffraction (XRD) patterns from an extensively ball-milled iron alloy powder were collected at 100, 200 and 300 K. The results were analysed together with those using extended X-ray absorption fine structure, measured on the same sample at liquid nitrogen temperature (77 K) and at room temperature (300 K), to assess the contribution of static disorder to the Debye–Waller coefficient (B iso). Both techniques give an increase of ∼20% with respect to bulk reference iron, a noticeably smaller difference than reported by most of the literature for similar systems. Besides good quality XRD patterns, proper consideration of the temperature diffuse scattering seems to be the key to accurate values of the Debye–Waller coefficient. Molecular dynamics simulations of nanocrystalline iron aggregates, mapped on the evidence provided by XRD in terms of domain size distribution, shed light on the origin of the observed B iso increase. The main contribution to the static disorder is given by the grain boundary, while line and point defects have a much smaller effect. PMID:28381974

Debye–Waller coefficient of heavily deformed nanocrystalline iron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scardi, P.; Rebuffi, L.; Abdellatief, M.

2017-02-17

Synchrotron radiation X-ray diffraction (XRD) patterns from an extensively ball-milled iron alloy powder were collected at 100, 200 and 300 K. The results were analysed together with those using extended X-ray absorption fine structure, measured on the same sample at liquid nitrogen temperature (77 K) and at room temperature (300 K), to assess the contribution of static disorder to the Debye–Waller coefficient (B iso). Both techniques give an increase of ~20% with respect to bulk reference iron, a noticeably smaller difference than reported by most of the literature for similar systems. Besides good quality XRD patterns, proper consideration of themore » temperature diffuse scattering seems to be the key to accurate values of the Debye–Waller coefficient. Molecular dynamics simulations of nanocrystalline iron aggregates, mapped on the evidence provided by XRD in terms of domain size distribution, shed light on the origin of the observedB isoincrease. The main contribution to the static disorder is given by the grain boundary, while line and point defects have a much smaller effect.« less

High temperature oxidation behavior of austenitic stainless steel AISI 304 in steam of nanofluids contain nanoparticle ZrO2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prajitno, Djoko Hadi, E-mail: djokohp@batan.go.id; Syarif, Dani Gustaman, E-mail: djokohp@batan.go.id

2014-03-24

The objective of this study is to evaluate high temperature oxidation behavior of austenitic stainless steel SS 304 in steam of nanofluids contain nanoparticle ZrO{sub 2}. The oxidation was performed at high temperatures ranging from 600 to 800°C. The oxidation time was 60 minutes. After oxidation the surface of the samples was analyzed by different methods including, optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD). X-ray diffraction examination show that the oxide scale formed during oxidation of stainless steel AISI 304 alloys is dominated by iron oxide, Fe{sub 2}O{sub 3}. Minor element such as Cr{sub 2}O{sub 3} ismore » also appeared in the diffraction pattern. Characterization by optical microscope showed that cross section microstructure of stainless steel changed after oxidized with the oxide scale on the surface stainless steels. SEM and x-ray diffraction examination show that the oxide of ZrO{sub 2} appeared on the surface of stainless steel. Kinetic rate of oxidation of austenite stainless steel AISI 304 showed that increasing oxidation temperature and time will increase oxidation rate.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Baozhuo; Young, Marcus L.

Many technological applications of austenitic shape memory alloys (SMAs) involve cyclical mechanical loading and unloading in order to take advantage of pseudoelasticity. In this paper, we investigated the effect of mechanical bending of pseudoelastic NiTi SMA wires using high-energy synchrotron radiation X-ray diffraction (SR-XRD). Differential scanning calorimetry was performed to identify the phase transformation temperatures. Scanning electron microscopy images show that micro-cracks in compressive regions of the wire propagate with increasing bend angle, while tensile regions tend not to exhibit crack propagation. SR-XRD patterns were analyzed to study the phase transformation and investigate micromechanical properties. By observing the various diffraction peaks such as the austenite (200) and the martensite (more » $${\\bar 1}12$$), ($${\\bar 1}03$$), ($${\\bar 1}11$$), and (101) planes, intensities and residual strain values exhibit strong anisotropy, depending upon whether the sample is in compression or tension during bending.« less

Characterization of cubic ceria?zirconia powders by X-ray diffraction and vibrational and electronic spectroscopy

NASA Astrophysics Data System (ADS)

Sánchez Escribano, Vicente; Fernández López, Enrique; Panizza, Marta; Resini, Carlo; Gallardo Amores, José Manuel; Busca, Guido

2003-10-01

The X-ray diffraction (XRD) patterns and the Infrared, Raman and UV-visible spectra of CeO 2ZrO 2 powders prepared by co-precipitation are presented. Raman spectra provide evidence for the largely predominant cubic structure of the powders with CeO 2 molar composition higher than 25%. Also skeletal IR spectra allow to distinguish cubic from tetragonal phases which are instead not easily distinguished on the basis of the XRD patterns. All mixed oxides including pure ceria are strong UV absorbers although also absorb in the violet visible region. By carefully selecting their composition and treatment temperature, the onset of the radiation that they cut off can be chosen in the 425-475 nm interval. Although they are likely metastable, the cubic phases are still pure even after heating at 1173 K for 4 h.

Preparation of Cu-doped nickel oxide thin films and their properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gowthami, V.; Meenakshi, M.; Anandhan, N.

2014-04-24

Copper doped Nickel oxide film was preferred on glass substrate by simple nebulizer technique keeping the substrate temperature at 350°C and characterized by X-ray diffraction (XRD), Photoluminescence (PL) and Four probe resistivity measurements. XRD studies indicated cubic structure and the crystallites are preferentially oriented along the [111] direction. Interesting results have been obtained from the study of PL spectra. A peak corresponding to 376nm in the emission spectra for 0%, 5% and 10% copper doped samples. The samples show sharp and strong UV emission corresponding to the near band edge emission under excitation of 275nm.

Supercritical carbon dioxide treatment as a method for polymorph preparation of deoxycholic acid.

PubMed

Tozuka, Yuichi; Kawada, Dai; Oguchi, Toshio; Yamamoto, Keiji

2003-09-16

A new polymorph of deoxycholic acid (DCA) was formed by using a supercritical carbon dioxide treatment. Deoxycholic acid crystals were stored in a pressure vessel purged with carbon dioxide at 12MPa, 60 degrees C for definite intervals. After storage for 1h in supercritical carbon dioxide (SC-CO2), new X-ray diffraction (XRD) peaks, not found in the bulk DCA crystal, were observed at 2theta = 7.4 degrees, 9.7 degrees and 14.0 degrees. The intensities of the new diffraction peaks increased with an increase in storage time, whereas the intensities of the diffraction peaks due to bulk DCA crystal decreased. On the DSC curves, the crystals obtained showed an exothermic peak at around 155 degrees C followed by the melting peak of bulk DCA crystal at 175 degrees C. By the temperature-controlled powder XRD measurement, the crystals obtained were found to be a metastable form of DCA. The polymorphs of DCA have not been reported; therefore, the SC-CO2 treatment would be a peculiar method to obtain a DCA polymorph.

X-ray absorption fine structure and x-ray diffraction studies of crystallographic grains in nanocrystalline FePd:Cu thin films

NASA Astrophysics Data System (ADS)

Krupinski, M.; Perzanowski, M.; Polit, A.; Zabila, Y.; Zarzycki, A.; Dobrowolska, A.; Marszalek, M.

2011-03-01

FePd alloys have recently attracted considerable attention as candidates for ultrahigh density magnetic storage media. In this paper we investigate FePd thin alloy film with a copper admixture composed of nanometer-sized grains. [Fe(0.9 nm)/Pd(1.1 nm)/Cu(d nm)]×5 multilayers were prepared by thermal deposition at room temperature in UHV conditions on Si(100) substrates covered by 100 nm SiO2. The thickness of the copper layer has been changed from 0 to 0.4 nm. After deposition, the multilayers were rapidly annealed at 600 °C in a nitrogen atmosphere, which resulted in the creation of the FePd:Cu alloy. The structure of alloy films obtained this way was determined by x-ray diffraction (XRD), glancing angle x-ray diffraction, and x-ray absorption fine structure (EXAFS). The measurements clearly showed that the L10 FePd:Cu nanocrystalline phase has been formed during the annealing process for all investigated copper compositions. This paper concentrates on the crystallographic grain features of FePd:Cu alloys and illustrates that the EXAFS technique, supported by XRD measurements, can help to extend the information about grain size and grain shape of poorly crystallized materials. We show that, using an appropriate model of the FePd:Cu grains, the comparison of EXAFS and XRD results gives a reasonable agreement.

Surface Characteristics of Machined NiTi Shape Memory Alloy: The Effects of Cryogenic Cooling and Preheating Conditions

NASA Astrophysics Data System (ADS)

Kaynak, Y.; Huang, B.; Karaca, H. E.; Jawahir, I. S.

2017-07-01

This experimental study focuses on the phase state and phase transformation response of the surface and subsurface of machined NiTi alloys. X-ray diffraction (XRD) analysis and differential scanning calorimeter techniques were utilized to measure the phase state and the transformation response of machined specimens, respectively. Specimens were machined under dry machining at ambient temperature, preheated conditions, and cryogenic cooling conditions at various cutting speeds. The findings from this research demonstrate that cryogenic machining substantially alters austenite finish temperature of martensitic NiTi alloy. Austenite finish ( A f) temperature shows more than 25 percent increase resulting from cryogenic machining compared with austenite finish temperature of as-received NiTi. Dry and preheated conditions do not substantially alter austenite finish temperature. XRD analysis shows that distinctive transformation from martensite to austenite occurs during machining process in all three conditions. Complete transformation from martensite to austenite is observed in dry cutting at all selected cutting speeds.

Comparing results of X-ray diffraction, µ-Raman spectroscopy and neutron diffraction when identifying chemical phases in seized nuclear material, during a comparative nuclear forensics exercise.

PubMed

Rondahl, Stina Holmgren; Pointurier, Fabien; Ahlinder, Linnea; Ramebäck, Henrik; Marie, Olivier; Ravat, Brice; Delaunay, François; Young, Emma; Blagojevic, Ned; Hester, James R; Thorogood, Gordon; Nelwamondo, Aubrey N; Ntsoane, Tshepo P; Roberts, Sarah K; Holliday, Kiel S

2018-01-01

This work presents the results for identification of chemical phases obtained by several laboratories as a part of an international nuclear forensic round-robin exercise. In this work powder X-ray diffraction (p-XRD) is regarded as the reference technique. Neutron diffraction produced a superior high-angle diffraction pattern relative to p-XRD. Requiring only small amounts of sample, µ-Raman spectroscopy was used for the first time in this context as a potentially complementary technique to p-XRD. The chemical phases were identified as pure UO 2 in two materials, and as a mixture of UO 2 , U 3 O 8 and an intermediate species U 3 O 7 in the third material.

Rietveld Refinement on X-Ray Diffraction Patterns of Bioapatite in Human Fetal Bones

PubMed Central

Meneghini, Carlo; Dalconi, Maria Chiara; Nuzzo, Stefania; Mobilio, Settimio; Wenk, Rudy H.

2003-01-01

Bioapatite, the main constituent of mineralized tissue in mammalian bones, is a calcium-phosphate-based mineral that is similar in structure and composition to hydroxyapatite. In this work, the crystallographic structure of bioapatite in human fetuses was investigated by synchrotron radiation x-ray diffraction (XRD) and microdiffraction (μ-XRD) techniques. Rietveld refinement analyses of XRD and μ-XRD data allow for quantitative probing of the structural modifications of bioapatite as functions of the mineralization process and gestational age. PMID:12609904

Structural, XPS and magnetic studies of pulsed laser deposited Fe doped Eu{sub 2}O{sub 3} thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Sandeep; Prakash, Ram, E-mail: rpgiuc@gmail.com; Choudhary, R.J.

2015-10-15

Highlights: • Growth of Fe doped Eu{sub 2}O{sub 3} thin films by PLD. • XRD and Raman’s spectroscopy used for structure confirmation. • The electronic states of Eu and Fe are confirmed by XPS. • Magnetic properties reveals room temperature magnetic ordering in deposited film. - Abstract: Fe (4 at.%) doped europium (III) oxide thin film was deposited on silicon (1 0 0) substrate by pulsed laser deposition technique. Structural, spectral and magnetic properties were studied by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and magnetization measurements. XRD and Raman spectroscopy reveal that the grown film is singlemore » phased and belongs to the cubic structure of Eu{sub 2}O{sub 3}. XPS study of the Eu{sub 1.92}Fe{sub 0.08}O{sub 3} film shows that Fe exists in Fe{sup 3+} ionic state in the film. The film exhibits magnetic ordering at room temperature.« less

Identification of a deleterious phase in photocatalyst based on Cd1 - xZnxS/Zn(OH)2 by simulated XRD patterns.

PubMed

Cherepanova, Svetlana; Markovskaya, Dina; Kozlova, Ekaterina

2017-06-01

The X-ray diffraction (XRD) pattern of a deleterious phase in the photocatalyst based on Cd 1 - x Zn x S/Zn(OH) 2 contains two relatively intense asymmetric peaks with d-spacings of 2.72 and 1.56 Å. Very small diffraction peaks with interplanar distances of (d) ≃ 8.01, 5.40, 4.09, 3.15, 2.49 and 1.35 Å are characteristic of this phase but not always observed. To identify this phase, the XRD patterns for sheet-like hydroxide β-Zn(OH) 2 and sheet-like hydrozincite Zn 5 (CO 3 ) 2 (OH) 6 as well as for turbostratic hydrozincite were simulated. It is shown that the XRD pattern calculated on the basis of the last model gives the best correspondence with experimental data. Distances between layers in the turbostratically disordered hydrozincite fluctuate around d ≃ 8.01 Å. This average layer-to-layer distance is significantly higher than the interlayer distance 6.77 Å in the ordered Zn 5 (CO 3 ) 2 (OH) 6 probably due to a deficiency of CO 3 2- anions, excess OH - and the presence of water molecules in the interlayers. It is shown by variable-temperature XRD and thermogravimetric analysis (TGA) that the nanocrystalline turbostratic nonstoichiometric hydrozincite-like phase is quite thermostable. It decomposes into ZnO in air above 473 K.

Synthesis of nanocrystalline zirconia by amorphous citrate route: structural and thermal (HTXRD) studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhagwat, Mahesh; Ramaswamy, Veda

Nanocrystalline zirconia powder with a fairly narrow particle size distribution has been synthesized by the amorphous citrate route. The sample obtained has a high BET surface area of 89 m{sup 2} g{sup -1}. Rietveld refinement of the powder X-ray diffraction (XRD) profile of the zirconia sample confirms stabilization of zirconia in the tetragonal phase with around 8% monoclinic impurity. The data show the presence of both anionic as well as cationic vacancies in the lattice. Crystallite size determined from XRD is 8 nm and is in close agreement with the particle size determined by TEM. The in situ high temperature-X-raymore » diffraction (HTXRD) study revealed high thermal stability of the mixture till around 1023 K after which the transformation of tetragonal phase into the monoclinic phase has been seen as a function of temperature till 1473 K. This transformation is accompanied by an increase in the crystallite size of the sample from 8 to 55 nm. The thermal expansion coefficients are 9.14 x 10{sup -6} K{sup -1} along 'a'- and 15.8 x 10{sup -6} K{sup -1} along 'c'-axis. The lattice thermal expansion coefficient in the temperature range 298-1623 K is 34.6 x 10{sup -6} K{sup -1}.« less

In situ micro-Raman analysis and X-ray diffraction of nickel silicide thin films on silicon.

PubMed

Bhaskaran, M; Sriram, S; Perova, T S; Ermakov, V; Thorogood, G J; Short, K T; Holland, A S

2009-01-01

This article reports on the in situ analysis of nickel silicide (NiSi) thin films formed by thermal processing of nickel thin films deposited on silicon substrates. The in situ techniques employed for this study include micro-Raman spectroscopy (microRS) and X-ray diffraction (XRD); in both cases the variations for temperatures up to 350 degrees C has been studied. Nickel silicide thin films formed by vacuum annealing of nickel on silicon were used as a reference for these measurements. In situ analysis was carried out on nickel thin films on silicon, while the samples were heated from room temperature to 350 degrees C. Data was gathered at regular temperature intervals and other specific points of interest (such as 250 degrees C, where the reaction between nickel and silicon to form Ni(2)Si is expected). The transformations from the metallic state, through the intermediate reaction states, until the desired metal-silicon reaction product is attained, are discussed. The evolution of nickel silicide from the nickel film can be observed from both the microRS and XRD in situ studies. Variations in the evolution of silicide from metal for different silicon substrates are discussed, and these include (100) n-type, (100) p-type, and (110) p-type silicon substrates.

Characterization of crystallographic properties of thin films using X-ray diffraction

NASA Astrophysics Data System (ADS)

Zoo, Yeongseok

2007-12-01

Silver (Ag) has been recognized as one of promising candidates in Ultra-Large Scale Integrated (ULSI) applications in that it has the lowest bulk electrical resistivity of all pure metals and higher electromigration resistance than other interconnect materials. However, low thermal stability on Silicon Dioxide (Si02) at high temperatures (e.g., agglomeration) is considered a drawback for the Ag metallization scheme. Moreover, if a thin film is attached on a substrate, its properties may differ significantly from that of the bulk, since the properties of thin films can be significantly affected by the substrate. In this study, the Coefficient of Thermal Expansion (CTE) and texture evolution of Ag thin films on different substrates were characterized using various analytical techniques. The experimental results showed that the CTE of the Ag thin film was significantly affected by underlying substrate and the surface roughness of substrate. To investigate the alloying effect for Ag meatallization, small amounts of Copper (Cu) were added and characterized using theta-2theta X-ray Diffraction (XRD) scan and pole figure analysis. These XRD techniques are useful for investigating the primary texture of a metal film, (111) in this study, which (111) is the notation of a specific plane in the orthogonal coordinate system. They revealed that the (111) textures of Ag and Ag(Cu) thin films were enhanced with increasing temperature. Comparison of texture profiles between Ag and Ag(Cu) thin films showed that Cu additions enhanced (111) texture in Ag thin films. Accordingly, the texture enhancement in Ag thin films by Cu addition was discussed. Strained Silicon-On-Insulator (SSOI) is being considered as a potential substrate for Complementary Metal-Oxide-Semiconductor (CMOS) technology since the induced strain results in a significant improvement in device performance. High resolution X-ray diffraction (XRD) techniques were used to characterize the perpendicular and parallel strains in SSOI layers. XRD diffraction profiles generated from the crystalline SSOI layer provided a direct measurement of the layer's strain components. In addition, it has demonstrated that the rotational misalignment between the layer and the substrate can be incorporated within the biaxial strain equations for epitaxial layers. Based on these results, the strain behavior of the SSOI layer and the relation between strained Si and SiO2 layers are discussed for annealed samples.

Structural properties and gas sensing behavior of sol-gel grown nanostructured zinc oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajyaguru, Bhargav; Gadani, Keval; Kansara, S. B.

2016-05-06

In this communication, we report the results of the studies on structural properties and gas sensing behavior of nanostructured ZnO grown using acetone precursor based modified sol-gel technique. Final product of ZnO was sintered at different temperatures to vary the crystallite size while their structural properties have been studied using X-ray diffraction (XRD) measurement performed at room temperature. XRD results suggest the single phasic nature of all the samples and crystallite size increases from 11.53 to 20.96 nm with increase in sintering temperature. Gas sensing behavior has been studied for acetone gas which indicates that lower sintered samples are moremore » capable to sense the acetone gas and related mechanism has been discussed in the light of crystallite size, crystal boundary density, defect mechanism and possible chemical reaction between gas traces and various oxygen species.« less

Magnetic properties of M0.3Fe2.7O4 (M = Fe, Zn and Mn) ferrites nanoparticles

NASA Astrophysics Data System (ADS)

Modaresi, Nahid; Afzalzadeh, Reza; Aslibeiki, Bagher; Kameli, Parviz

2018-06-01

In the present article a comparative study on the structural and magnetic properties of nano-sized M0.3Fe0.7Fe2O4 (M = Fe, Zn and Mn) ferrites have been reported. The X-ray diffraction (XRD) patterns show that the crystallite size depends on the cation distribution. The Rietveld refinement of XRD patterns using MAUD software determines the distribution of cations and unit cell dimensions. The magnetic measurements show that the maximum and minimum value of saturation magnetization is obtained for Zn and Mn doped samples, respectively. The peak temperature of AC magnetic susceptibility of Zn and Fe doped samples below 300 K shows the superparamagnetic behavior in these samples at room temperature. the AC susceptibility results confirm the presence of strong interactions between the nanoparticles which leads to a superspin glass state in the samples at low temperatures.

Electrical properties of NiAs-type MnTe films with preferred crystallographic plane of (110)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, L.; Wang, Z. H., E-mail: zhwang@imr.ac.cn; Zhang, Z. D.

2016-01-28

NiAs-type manganese telluride (MnTe) films with preferred crystallographic plane of (110) were prepared on Si/SiO{sub 2} substrates by pulsed laser deposition. X-ray diffraction (XRD) of the films was studied at different temperatures. The XRD peak of MnTe (110) films shifts to higher angle with decreasing temperature, showing the decrease of the lattice parameter. Resistivity of the films was studied in the temperature range of 2–350 K. The bump between 150 and 250 K was observed in the films, which may be related to the special s-d and p-d overlaps induced by the compressed lattice. The magnon drag effect near its Néel temperaturemore » T{sub N} and enlarged magnetic-elastic coupling below 100 K were observed and analyzed in details.« less

Influence of reaction time and synthesis temperature on the physical properties of ZnO nanoparticles synthesized by the hydrothermal method

NASA Astrophysics Data System (ADS)

Wasly, H. S.; El-Sadek, M. S. Abd; Henini, Mohamed

2018-01-01

Influence of synthesis temperature and reaction time on the structural and optical properties of ZnO nanoparticles synthesized by the hydrothermal method was investigated using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray, Fourier transform infra-red spectroscopy, and UV-visible and fluorescence spectroscopy. The XRD pattern and HR-TEM images confirmed the presence of crystalline hexagonal wurtzite ZnO nanoparticles with average crystallite size in the range 30-40 nm. Their energy gap determined by fluorescence was found to depend on the synthesis temperature and reaction time with values in the range 2.90-3.78 eV. Thermal analysis, thermogravimetric and the differential scanning calorimetry were used to study the thermal reactions and weight loss with heat of the prepared ZnO nanoparticles.

Real time neutron diffraction and NMR of the Empress II glass-ceramic system.

PubMed

O'Donnell, M D; Hill, R G; Karpukhina, N; Law, R V

2011-10-01

This study reports real time neutron diffraction on the Empress II glass-ceramic system. The commercial glass-ceramics was characterized by real time neutron diffraction, ³¹P and ²⁹Si solid-state MAS-NMR, DSC and XRD. On heating, the as-received glass ceramic contained lithium disilicate (Li₂Si₂O₅), which melted with increasing temperature. This was revealed by neutron diffraction which showed the Bragg peaks for this phase had disappeared by 958°C in agreement with thermal analysis. On cooling lithium metasilicate (Li₂SiO₃) started to form at around 916°C and a minor phase of cristobalite at around 852°C. The unit cell volume of both Li-silicate phases increased linearly with temperature at a rate of +17×10⁻³ ų.°C⁻¹. Room temperature powder X-ray diffraction (XRD) of the material after cooling confirms presence of the lithium metasilicate and cristobalite as the main phases and shows, in addition, small amount of lithium disilicate and orthophosphate. ³¹P MAS-NMR reveals presence of the lithiorthophosphate (Li₃PO₄) before and after heat treatment. The melting of lithium disilicate on heating and crystallisation of lithium metasilicate on cooling agree with endothermic and exotermic features respectively observed by DSC. ²⁹Si MAS-NMR shows presence of lithium disilicate phase in the as-received glass-ceramic, though not in the major proportion, and lithium metasilicate in the material after heat treatment. Both phases have significantly long T₁ relaxation time, especially the lithium metasilicate, therefore, a quantitative analysis of the ²⁹Si MAS-NMR spectra was not attempted. Significance. The findings of the present work demonstrate importance of the commercially designed processing parameters in order to preserve desired characteristics of the material. Processing the Empress II at a rate slower than recommended 60°C min⁻¹ or long isothermal hold at the maximal processing temperature 920°C can cause crystallization of lithium metasilicate and cristobalite instead of lithium disilicate as major phase. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Efficient graphite ring heater suitable for diamond-anvil cells to 1300 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du Zhixue; Amulele, George; Lee, Kanani K. M.

In order to generate homogeneous high temperatures at high pressures, a ring-shaped graphite heater has been developed to resistively heat diamond-anvil cell (DAC) samples up to 1300 K. By putting the heater in direct contact with the diamond anvils, this graphite heater design features the following advantages: (1) efficient heating: sample can be heated to 1300 K while the DAC body temperature remains less than 800 K, eliminating the requirement of a special alloy for the DAC; (2) compact design: the sample can be analyzed with in situ measurements, e.g., x-ray, optical, and electrical probes are possible. In particular, themore » side access of the heater allows for radial x-ray diffraction (XRD) measurements in addition to traditional axial XRD.« less

Synthesis and properties of selenium trihydride at high pressures

NASA Astrophysics Data System (ADS)

Zhang, Xiao; Xu, Wan; Wang, Yu; Jiang, Shuqing; Gorelli, Federico A.; Greenberg, Eran; Prakapenka, Vitali B.; Goncharov, Alexander F.

2018-02-01

The chemical reaction products of molecular hydrogen (H2) with selenium (Se) are studied by synchrotron x-ray diffraction (XRD) and Raman spectroscopy at high pressures. We find that a common H2Se is synthesized at 0.3 GPa using laser heating. Upon compression at 300 K, a crystal of the theoretically predicted Cccm H3Se has been grown at 4.6 GPa. At room temperature, H3Se shows a reversible phase decomposition after laser irradiation above 8.6 GPa, but remains stable up to 21 GPa. However, at 170 K Cccm H3Se persists up to 39.5 GPa based on XRD measurements, while low-temperature Raman spectra weaken and broaden above 23.1 GPa. At these conditions, the sample is visually nontransparent and shiny suggesting that metallization occurred.

Pronounced pre-martensitic anomaly in the magnetization on Ni2MnGa thin films

NASA Astrophysics Data System (ADS)

Neckel, I. T.; Müller, C.; Nobrega, K. Z.; Dartora, C. A.; Schreiner, W. H.; Mosca, D. H.

2018-05-01

We have prepared [110]-textured Ni2MnGa thin films exhibiting an unusual pre-martensitic transition accompanied by an extremely large magnetization change. The thin films were grown by molecular beam epitaxy directly on epi-ready GaAs(111)B. Crystalline structure was investigated in situ by reflection high-energy electron diffraction (RHEED) and ex situ by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the film exhibits cubic crystalline structure (L2 1) at room temperature with lattice parameter a = 5.88 Å which undergoes martensitic transition. Magnetic characterization shows ferromagnetic behavior at room temperature with Curie temperature higher than room temperature. Martensitic transformation occurs at TM ∼ 185 K. A phenomenological model based on Landau theory of phase transformation was developed to explain the anomalous pre-martensitic transition at ∼285 K.

Structure evolution of zinc oxide thin films deposited by unbalance DC magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aryanto, Didik, E-mail: didi027@lipi.go.id; Materials Research Group, Physics Department, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah; Marwoto, Putut

Zinc oxide (ZnO) thin films are deposited on corning glass substrates using unbalanced DC magnetron sputtering. The effect of growth temperature on surface morphology and crystallographic orientation of ZnO thin film is studied using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The surface morphology and crystallographic orientation of ZnO thin film are transformed against the increasing of growth temperature. The mean grain size of film and the surface roughness are inversely and directly proportional towards the growth temperature from room temperature to 300 °C, respectively. The smaller grain size and finer roughness of ZnO thin film are obtainedmore » at growth temperature of 400 °C. The result of AFM analysis is in good agreement with the result of XRD analysis. ZnO thin films deposited in a series of growth temperatures have hexagonal wurtzite polycrystalline structures and they exhibit transformations in the crystallographic orientation. The results in this study reveal that the growth temperature strongly influences the surface morphology and crystallographic orientation of ZnO thin film.« less

In-plane x-ray diffraction for characterization of monolayer and few-layer transition metal dichalcogenide films

NASA Astrophysics Data System (ADS)

Chubarov, Mikhail; Choudhury, Tanushree H.; Zhang, Xiaotian; Redwing, Joan M.

2018-02-01

There is significant interest in the growth of single crystal monolayer and few-layer films of transition metal dichalcogenides (TMD) and other 2D materials for scientific exploration and potential applications in optics, electronics, sensing, catalysis and others. The characterization of these materials is crucial in determining the properties and hence the applications. The ultra-thin nature of 2D layers presents a challenge to the use of x-ray diffraction (XRD) analysis with conventional Bragg-Brentano geometry in analyzing the crystallinity and epitaxial orientation of 2D films. To circumvent this problem, we demonstrate the use of in-plane XRD employing lab scale equipment which uses a standard Cu x-ray tube for the analysis of the crystallinity of TMD monolayer and few-layer films. The applicability of this technique is demonstrated in several examples for WSe2 and WS2 films grown by chemical vapor deposition on single crystal substrates. In-plane XRD was used to determine the epitaxial relation of WSe2 grown on c-plane sapphire and on SiC with an epitaxial graphene interlayer. The evolution of the crystal structure orientation of WS2 films on sapphire as a function of growth temperature was also examined. Finally, the epitaxial relation of a WS2/WSe2 vertical heterostructure deposited on sapphire substrate was determined. We observed that WSe2 grows epitaxially on both substrates employed in this work under all conditions studied while WS2 exhibits various preferred orientations on sapphire substrate which are temperature dependent. In contrast to the sapphire substrate, WS2 deposited on WSe2 exhibits only one preferred orientation which may provide a route to better control the orientation and crystal quality of WS2. In the case of epitaxial graphene on SiC, no graphene-related peaks were observed in in-plane XRD while its presence was confirmed using Raman spectroscopy. This demonstrates the limitation of the in-plane XRD technique for characterizing low electron density materials.

Comparing results of X-ray diffraction, µ-Raman spectroscopy and neutron diffraction when identifying chemical phases in seized nuclear material, during a comparative nuclear forensics exercise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rondahl, Stina Holmgren; Pointurier, Fabien; Ahlinder, Linnea

This work presents the results for identification of chemical phases obtained by several laboratories as a part of an international nuclear forensic round-robin exercise. In this work powder X-ray diffraction (p-XRD) is regarded as the reference technique. Neutron diffraction produced a superior high-angle diffraction pattern relative to p-XRD. Requiring only small amounts of sample, µ-Raman spectroscopy was used for the first time in this context as a potentially complementary technique to p-XRD. The chemical phases were identified as pure UO 2 in two materials, and as a mixture of UO 2, U 3O 8 and an intermediate species U 3Omore » 7 in the third material.« less

Comparing results of X-ray diffraction, µ-Raman spectroscopy and neutron diffraction when identifying chemical phases in seized nuclear material, during a comparative nuclear forensics exercise

DOE PAGES

Rondahl, Stina Holmgren; Pointurier, Fabien; Ahlinder, Linnea; ...

2018-01-24

This work presents the results for identification of chemical phases obtained by several laboratories as a part of an international nuclear forensic round-robin exercise. In this work powder X-ray diffraction (p-XRD) is regarded as the reference technique. Neutron diffraction produced a superior high-angle diffraction pattern relative to p-XRD. Requiring only small amounts of sample, µ-Raman spectroscopy was used for the first time in this context as a potentially complementary technique to p-XRD. The chemical phases were identified as pure UO 2 in two materials, and as a mixture of UO 2, U 3O 8 and an intermediate species U 3Omore » 7 in the third material.« less

Crystal structure and superconducting properties of KSr2Nb3O10

NASA Astrophysics Data System (ADS)

Kawaguchi, T.; Horigane, K.; Itoh, Y.; Kobayashi, K.; Horie, R.; Kambe, T.; Akimitsu, J.

2018-05-01

We performed X-ray diffraction (XRD) and DC magnetic susceptibility measurements to elucidate the crystal structure and superconducting properties of KSr2Nb3O10. From the diffraction pattern indexing, it was found that KSr2Nb3O10 crystallizes with monoclinic symmetry, space group P21/m(11). We succeeded in preparing high temperature (HT) and low temperature (LT) phases of KSr2Nb3O10 powder samples synthesized by a conventional solid state reaction and an ion-exchange reaction, respectively. Superconductivity was observed at 4 K by Li intercalation and it was found that the superconducting volume fraction of the LT phase ( 1.4%) is clearly larger than that of the HT phase (0.07%).

Structural properties of zirconia - in-situ high temperature XRD characterization

NASA Astrophysics Data System (ADS)

Kurpaska, Lukasz

2018-07-01

In this work, the effect of high temperature on structural properties of pure zirconium have been investigated. In-situ X-ray diffraction analysis of the oxide layer formed at temperature window 25-600 °C on pure zirconium were performed. Conducted experiment aimed at investigation of the zirconia phases developed on surface of the metallic substrate. Based on the conducted studies, possible stress state (during heating, continuous oxidation and cooling), cell parameters and HWHM factor were analyzed. A tetragonal and monoclinic phases peak shifts and intensities change were observed, suggesting that different phases react in different way upon temperature effect.

Low temperature synthesis of hexagonal ZnO nanorods and their hydrogen sensing properties

NASA Astrophysics Data System (ADS)

Qurashi, Ahsanulhaq; Faiz, M.; Tabet, N.; Alam, Mir Waqas

2011-08-01

The growth of hexagonal ZnO nanorods was demonstrated by low temperature chemical synthesis approach. X-ray diffraction (XRD) analysis revealed a wurtzite hexagonal structure of the ZnO nanorods. The optical properties were measured by UV-vis spectrophotometer at room temperature. X-ray photoelectron spectroscopy (XPS) confirmed high purity of the ZnO nanorods. The hydrogen sensor made of the ZnO nanorods showed reversible response. The hydrogen gas tests were carried out in presence of ambient air and the influence of operation temperature on the hydrogen gas sensing property of ZnO nanorods was also investigated.

Raman analysis of non stoichiometric Ni1-δO

NASA Astrophysics Data System (ADS)

Dubey, Paras; Choudhary, K. K.; Kaurav, Netram

2018-04-01

Thermal decomposition method was used to synthesize non-stoichiometric nickel oxide at different sintering temperatures upto 1100 °C. The structure of synthesized compounds were analyzed by X ray diffraction analysis (XRD) and magnetic ordering was studied with the help of Raman scattering spectroscopy for the samples sintered at different temperature. It was found that due to change in sintering temperature the stoichiometry of the sample changes and hence intensity of two magnon band changes. These results were interpreted as the decomposition temperature increases, which heals the defects present in the non-stoichiometric nickel oxide and antiferromagnetic spin correlation changes accordingly.

Effects of the Tempering and High-Pressure Torsion Temperatures on Microstructure of Ferritic/Martensitic Steel Grade 91

PubMed Central

Ganeev, Artur; Nikitina, Marina; Sitdikov, Vil; Islamgaliev, Rinat; Hoffman, Andrew; Wen, Haiming

2018-01-01

Grade 91 (9Cr-1Mo) steel was subjected to various heat treatments and then to high-pressure torsion (HPT) at different temperatures. Its microstructure was studied using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Effects of the tempering temperature and the HPT temperature on the microstructural features and microhardness in the ultrafine-grained (UFG) Grade 91 steel were researched. The study of the UFG structure formation takes into account two different microstructures observed: before HPT in both samples containing martensite and in fully ferritic samples. PMID:29671761

Preparation and physical properties of polycrystalline (Bi1-xPbx)2Sr2Ca2Cu3Oy high T c superconductors

NASA Astrophysics Data System (ADS)

Awan, M. S.; Maqsood, M.; Mirza, S. A.; Yousaf, M.; Maqsood, A.

1995-02-01

(Bi1-xPbx:)2Sr2Ca2Cu3Oy ( x = 0.3) high critical transition temperature ( T c) superconductors are synthesized by the solid-state reaction method in polycrystalline form. X-ray diffraction (XRD) studies, direct current (dc) electrical resistivity measurements, scanning electron microscopic (SEM) studies, critical current density measurements, and zero-field alternating current (ac) susceptibility measurements are performed to investigate the physical changes, structural changes, and magnetic behavior of the superconducting samples. X-ray diffraction studies show that a high T c phase exists with orthorhombic symmetry in the specimen. According to the XRD data, the lattice parameters of the high T c phase were determined as a = 0.537(1) nm, b = 0.539(1) nm, and c = 3.70(1) nm. The compound exhibits a superconducting transition at 106 ±1 K for zero resistance. The ac susceptibility measurements in zero field confirm the dc electrical resistivity results; hence both support the XRD results. The particle size and structural changes as a function of the cold-pressing and aging effect are also reported.

Influence of cobalt doping on structural and magnetic properties of BiFeO3 nanoparticles

NASA Astrophysics Data System (ADS)

Khan, U.; Adeela, N.; Javed, K.; Riaz, S.; Ali, H.; Iqbal, M.; Han, X. F.; Naseem, S.

2015-11-01

Nanocrystalline cobalt-doped bismuth ferrites with general formula of BiFe1- δ Co δ O3 (0 ≤ δ ≤ 0.1) have been synthesized using solution evaporation method. Structure and phase identification was performed with X-ray diffraction (XRD) technique. The results confirm the formation of rhombohedral-distorted Perovskite structure with R3c symmetry. A decrease in lattice parameters and an increase in X-ray density have been observed with increasing cobalt concentration in BiFeO3. Particle size determined by transmission electron microscope was in good agreement with XRD, i.e., 39 nm. Room-temperature coercivity and saturation magnetization of nanoparticles were increased up to 7.5 % of cobalt doping. Low-temperature magnetic measurements of selected sample showed increasing behavior in saturation magnetization, coercivity, effective magnetic moments, and anisotropy constant. An increase in coercivity with decrease in temperature followed theoretical model of Kneller's law, while modified Bloch's model was employed for saturation magnetization in temperature range of 5-300 K.

Characterization of pulsed laser deposition grown V2O3 converted VO2

NASA Astrophysics Data System (ADS)

Majid, Suhail; Shukla, D. K.; Rahman, F.; Gautam, Kamini; Sathe, V. G.; Choudhary, R. J.; Phase, D. M.

2016-10-01

Controllable tuning of Metal-insulator transition in VxOy thin film has been a field of extensive research. However controlled synthesis of desired Vanadium oxide phase is a challenging task. We have successfully achieved VO2 phase on Silicon substrate after post deposition annealing treatment to the PLD grown as deposited V2O3 thin films. The annealed thin film was characterized by x-ray diffraction (XRD), resistivity, Raman spectroscopy, X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) measurements. XRD confirms the crystalline nature and growth of VO2 phase in thin film. The characteristic MIT was observed from resistivity measurements and transition temperature appeared at lower value around 336 K, compared to bulk VO2. The structural transition accompanied with MIT from lower temperature monoclinic phase to higher temperature Rutile phase became evident from temperature dependent Raman measurements. Chemical state of vanadium was examined using XAS and XPS measurements which confirm the presence of +4 oxidation state of vanadium in thin film.

Poly (N-ethyl aniline)/Ag Nanocomposite as Humidity Sensor

NASA Astrophysics Data System (ADS)

Pande, Nishigandh S.; Jaspal, Dipika; Ambekar, Jalindar

Poly (N-ethyl aniline)/Ag organic-inorganic composite has been synthesized by a single step in situ chemical oxidative polymerization method. The synthesis of Poly (N-ethyl aniline)/Ag nanocomposite has been confirmed by X-ray diffraction (XRD), Ultraviolet-Vis Spectroscopy (UV-visible), Fourier transform infrared analysis (FTIR) and FE-SEM investigations. XRD spectral study exhibited major diffraction in the range 20-80∘ (2θ) and indicated the semicrystalline nature of poly (N-ethyl aniline)/Ag nanocomposite. Characteristic peaks in UV-visible and FTIR spectra of poly (N-ethyl aniline) switched to higher wave numbers in poly (N-ethyl aniline)/Ag nanocomposite. Peaks at 1789cm-1, 1595cm-1, 667cm-1 and 501cm-1 in FTIR spectrum confirmed the formation of poly (N-ethyl aniline)/Ag nanocomposite. FE-SEM photographs reported agglomerated granular particulate nature of poly (N-ethyl aniline)/Ag nanocomposite. Synthesized poly (N-ethyl aniline)/Ag nanocomposite exhibited a high response to humidity, good reproducibility and stability at room temperature. An appreciable response was shown in the presence of 40% humid atmosphere for up to successive four cycles. Composite sensitivity has been found to increase with the increasing concentration of humidity, at room temperature.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan Qingtao; Huang Kai; Ni Shibing

Well-crystalline flower- and rod-like NiS nanostructures have been synthesized by an organic-free hydrothermal process at a low temperature of 200 deg. C. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were employed to characterize the as-synthesized NiS nanostructures. The effects of temperature and reaction time on the morphology have been also investigated. The two-step flake-cracking mechanism for the formation of flower- and rod-like NiS nanostructures was discussed. The products were also investigated by photoluminescence (PL) spectroscopy.

Room-temperature synthesis and photoluminescence of hexagonal CePO4 nanorods

NASA Astrophysics Data System (ADS)

Zhu, J.; Zhang, K.; Zhao, H. Y.

2018-01-01

Hexagonal CePO4 nanorods were synthesized via a simple chemical precipitation route at room-temperature without the presence of surfactants and then characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectrometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) spectroscopy. Hexagonal CePO4 nanorods exhibit strong ultraviolet absorption and ultraviolet luminescence, which correspond to the electronic transitions between 4f and 5d state of Ce3+ ions.

Digital Image Correlation of 2D X-ray Powder Diffraction Data for Lattice Strain Evaluation

PubMed Central

Zhang, Hongjia; Sui, Tan; Daisenberger, Dominik; Fong, Kai Soon

2018-01-01

High energy 2D X-ray powder diffraction experiments are widely used for lattice strain measurement. The 2D to 1D conversion of diffraction patterns is a necessary step used to prepare the data for full pattern refinement, but is inefficient when only peak centre position information is required for lattice strain evaluation. The multi-step conversion process is likely to lead to increased errors associated with the ‘caking’ (radial binning) or fitting procedures. A new method is proposed here that relies on direct Digital Image Correlation analysis of 2D X-ray powder diffraction patterns (XRD-DIC, for short). As an example of using XRD-DIC, residual strain values along the central line in a Mg AZ31B alloy bar after 3-point bending are calculated by using both XRD-DIC and the conventional ‘caking’ with fitting procedures. Comparison of the results for strain values in different azimuthal angles demonstrates excellent agreement between the two methods. The principal strains and directions are calculated using multiple direction strain data, leading to full in-plane strain evaluation. It is therefore concluded that XRD-DIC provides a reliable and robust method for strain evaluation from 2D powder diffraction data. The XRD-DIC approach simplifies the analysis process by skipping 2D to 1D conversion, and opens new possibilities for robust 2D powder diffraction data analysis for full in-plane strain evaluation. PMID:29543728

Polymethacrylic acid as a new precursor of CuO nanoparticles

NASA Astrophysics Data System (ADS)

Hosny, Nasser Mohammed; Zoromba, Mohamed Shafick

2012-11-01

Polymethacrylic acid and its copper complexes have been synthesized and characterized. These complexes have been used as precursors to produce CuO nanoparticles by thermal decomposition in air. The stages of decompositions and the calcination temperature of the precursors have been determined from thermal analyses (TGA). The obtained CuO nanoparticles have been characterized by X-ray diffraction (XRD), scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). XRD showed a monoclinic structure with particle size 8-20 nm for the synthesized copper oxide nanoparticles. These nanoparticles are catalytically active in decomposing hydrogen peroxide and a mechanism of decomposition has been suggested.

Interplay of structural, optical and magnetic properties in Gd doped CeO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soni, S.; Dalela, S., E-mail: sdphysics@rediffmail.com; Kumar, Sudish

In this research wok systematic investigation on the synthesis, characterization, optical and magnetic properties of Ce{sub 1-x}Gd{sub x}O{sub 2} (where x=0.02, 0.04, 0.06, and 0.10) synthesized using the Solid-state method. Structural, Optical and Magnetic properties of the samples were investigated by X-ray diffraction (XRD), UV-VIS-NIR spectroscopy and VSM. Fluorite structure is confirmed from the XRD measurement on Gd doped CeO{sub 2} samples. Magnetic studies showed that the Gd doped polycrystalline samples display room temperature ferromagnetism and the ferromagnetic ordering strengthens with the Gd concentration.

Synthesis and characterization of nanocrystalline graphite from coconut shell with heating process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wachid, Frischa M., E-mail: frischamw@yahoo.com, E-mail: adhiyudhaperkasa@yahoo.com, E-mail: afandisar@yahoo.com, E-mail: nurulrosyidah92@gmail.com, E-mail: darminto@physics.its.ac.id; Perkasa, Adhi Y., E-mail: frischamw@yahoo.com, E-mail: adhiyudhaperkasa@yahoo.com, E-mail: afandisar@yahoo.com, E-mail: nurulrosyidah92@gmail.com, E-mail: darminto@physics.its.ac.id; Prasetya, Fandi A., E-mail: frischamw@yahoo.com, E-mail: adhiyudhaperkasa@yahoo.com, E-mail: afandisar@yahoo.com, E-mail: nurulrosyidah92@gmail.com, E-mail: darminto@physics.its.ac.id

Graphite were synthesized and characterized by heating process of coconut shell with varying temperature (400, 800 and 1000°C) and holding time (3 and 5 hours). After heating process, the samples were characterized by X-ray diffraction (XRD) and analyzed by X'pert HighScore Plus Software, Scanning Electron Microcope-Energy Dispersive X-Ray (SEM-EDX) and Transmission Electron Microscope-Energy Dispersive X-Ray (TEM-EDX). Graphite and londsdaelite phase were analyzed by XRD. According to EDX analysis, the sample was heated in 1000°C got the highest content of carbon. The amorphous carbon and nanocrystalline graphite were observed by SEM-EDX and TEM-EDX.

Low temperature structural and transport studies of La{sub 0.175}Pr{sub 0.45}Ca{sub 0.375}MnO{sub 3-δ}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Shivani; Shahee, Aga; Singh, Kiran

2016-05-23

The temperature (T) dependent x-ray diffraction (XRD) and resistivity measurements of La{sub 0.175}Pr{sub 0.45}Ca{sub 0.375}MnO{sub 3-δ} (LPCMO) have been performed down to 2 K to understand the structural and transport properties. From room temperature down to 220 K, LPCMO exists in orthorhombic phase with Pnma structure and at T~220 K, it transforms to charge ordered (CO) monoclinic phase with P2{sub 1}/m structure and remains as it is down to 2 K. The CO phase is evident from the occurrence of weak but well defined superlattice peaks in the XRD pattern. This structural transformation is of first order in nature asmore » evident from the phase coexistence across the transition region. These results thus clearly illustrate that LPCMO undergoes a first order structural phase transition from charge disordered orthorhombic phase to CO monoclinic phase at ~220 K, consistent with temperature dependent resistivity results. Our structural analysis of T dependent XRD data using Rietveld refinement infers that below 220 K, LPCMO forms commensurate CO monoclinic P2{sub 1}/m structure with four times structural modulation.« less

Effect of annealing temperature on optical properties of binary zinc tin oxide nano-composite prepared by sol-gel route using simple precursors: structural and optical studies by DRS, FT-IR, XRD, FESEM investigations.

PubMed

Habibi, Mohammad Hossein; Mardani, Maryam

2015-02-25

Binary zinc tin oxide nano-composite was synthesized by a facile sol-gel method using simple precursors from the solutions consisting of zinc acetate, tin(IV) chloride and ethanol. Effect of annealing temperature on optical and structural properties was investigated using X-ray diffraction (XRD), diffuse reflectance spectra (DRS), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). XRD results revealed the existence of the ZnO and SnO2 phases. FESEM results showed that binary zinc tin oxide nano-composites ranges from 56 to 60 nm in diameter at 400°C and 500°C annealing temperatures respectively. The optical band gap was increased from 2.72 eV to 3.11 eV with the increasing of the annealing temperature. FTIR results confirmed the presence of zinc oxide and tin oxide and the broad absorption peaks at 3426 and 1602 cm(-1) can be ascribed to the vibration of absorptive water, and the absorption peaks at 546, 1038 and 1410 cm(-1) are due to the vibration of Zn-O or Sn-O groups in binary zinc tin oxide. Copyright © 2014 Elsevier B.V. All rights reserved.

Temperature driven structural-memory-effects in carbon nanotubes filled with Fe3C nano crystals

NASA Astrophysics Data System (ADS)

Boi, Filippo S.; Zhang, Xiaotian; Corrias, Anna

2018-02-01

We report the observation of novel temperature-driven structural-memory-effects in carbon nanotubes (CNTs) filled with Fe3C nano-crystals. These structural-transitions were measured by means of temperature (T) dependent x-ray diffraction (XRD) in the T-range from 298 K to 12 K. A clear reversible 2θ-shift in the 002-peak of the graphitic-CNTs-walls is found with the decrease of the temperature. As determined by Rietveld refinement, such 2θ-shift translates in a not previously reported decrease in the value of the CNT graphitic c-axis with the decrease of the temperature (from 298 K to 12 K). Also, a clear reversible 2θ-shift in the 031 and 131 diffraction-peaks of Fe3C is observed within the same T-range. Rietveld refinements confirm the existence of such memory-effect and also reveal a gradual decrease of the 010-axis of Fe3C with the decrease of the temperature. These observations imply that the observed structural-memory-effect is a characteristic of CNTs when Fe3C is the encapsulated ferromagnet. The generality of such memory-effects was further confirmed by additional measurements performed on other types of CNTs characterized by continuous Fe3C-filling. XRD measurements in the T-range from 298 K to 673 K revealed also an unusual reversible decrease of the Fe3C-peak intensities with the increase of the temperature. These observations can have important implications on the magnetic data recording applications of these nanostructures by helping in better understanding the unusual temperature-dependent magnetic instabilities of iron-based nano-crystals which have been recently reported in literature.

Fabrication of Far Red Emission Phosphors Y3Al5O12:Eu(YAG:Eu) by Co-precipitation Method

NASA Astrophysics Data System (ADS)

Thu, L. D.; Trung, D. Q.; Lam, T. D.; Anh, T. X.

2016-05-01

Phosphors YAG:Eu (with seven molar percent of Eu to YAG) was synthesized by the co-precipitation method using NH3 solution as a precipitating agent. X-ray diffraction (XRD) patterns show that the samples are single phase, and the crystallinity starts forming at a sintering temperature of 1000°C. The crystallinity increases with the increasing sintered temperature. XRD studies followed by Rietveld refinement confirmed the body center cubic structure of the host lattice. The crystalline YAG:Eu showed four emission bands of europium ion with the force dipole transition ascribed to 5D0-7F4 located at 710 nm as the most dominating group (far-red emission—FR). The ratio of FR/OR (far-red/orange—red) is about 1.24 in all samples.

Characterization of melt-quenched and milled amorphous solids of gatifloxacin.

PubMed

Hattori, Yusuke; Suzuki, Ayumi; Otsuka, Makoto

2016-11-01

The objectives of this study were to characterize and investigate the differences in amorphous states of gatifloxacin. We prepared two types of gatifloxacin amorphous solids coded as M and MQ using milling and melt-quenching methods, respectively. The amorphous solids were characterized via X-ray diffraction (XRD), nonisothermal differential scanning calorimetry (DSC) and time-resolved near-infrared (NIR) spectroscopy. Both the solids displayed halo XRD patterns, the characteristic of amorphous solids; however, in the non-isothermal DSC profiles, these amorphous solids were distinguished by their crystallization and melting temperatures. The Kissinger-Akahira-Sunose plots of non-isothermal crystallization temperatures at various heating rates indicated a lower activation energy of crystallization for the amorphous solid M than that of MQ. These results support the differentiation between two amorphous states with different physical and chemical properties.

Dielectric Relaxation Behavior and AC Electrical Conductivity Study of 2-(1,2-Dihydro-7-Methyl-2-Oxoquinoline-5-yl) Malononitrile (DMOQMN)

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; El-Zaidia, E. F. M.; Darwish, A. A. A.; Salem, G. F.

2017-02-01

Dielectric relaxation and alternative current conductivity of a new organic compound 2-(1,2-dihydro-7-methyl-2-oxoquinoline-5-yl) malononitrile (DMOQMN) have been investigated. X-ray diffraction (XRD) at room temperature reveals that DMOQMN samples have a polycrystalline structure of the triclinic system. The analysis of the dielectric constant and dielectric loss index suggested the dominant polarization is performed and the Maxwell-Wagner-Sillar type polarization is dominating at low frequency and high temperature. These results have been confirmed by the XRD and dielectric modulus. The estimated relaxation time and the activation energy are 9 × 10-13 s and 0.43 eV, respectively. Our results indicated that the conduction mechanism of DMOQMN is controlled by the correlation barrier hopping (CBH) model.

A study of tantalum pentoxide Ta 2O 5 structures up to 28 GPa

DOE PAGES

Stavrou, Elissaios; Zaug, Joseph M.; Bastea, Sorin; ...

2017-05-02

In this study, tantalum pentoxide Ta 2O 5 with the orthorhombic L-Ta 2O 5 structure has been experimentally studied up to 28.3 GPa (at ambient temperature) using synchrotron angle-dispersive powder X-ray diffraction (XRD). The ambient pressure phase remains stable up to 25 GPa where with increased pressure a crystalline to amorphous phase transition occurs. A detailed equation of state (EOS), including pressure dependent lattice parameters, is reported. The results of this study were compared with a previous high-pressure XRD study by Li et al. A clear discrepancy between the ambient-pressure crystal structures and, consequently, the reported EOSs between the twomore » studies was revealed. Finally, he origin of this discrepancy is attributed to two different crystal structures used to index the XRD patterns.« less

Note: application of a pixel-array area detector to simultaneous single crystal X-ray diffraction and X-ray absorption spectroscopy measurements.

PubMed

Sun, Cheng-Jun; Zhang, Bangmin; Brewe, Dale L; Chen, Jing-Sheng; Chow, G M; Venkatesan, T; Heald, Steve M

2014-04-01

X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are two main x-ray techniques in synchrotron radiation facilities. In this Note, we present an experimental setup capable of performing simultaneous XRD and XAS measurements by the application of a pixel-array area detector. For XRD, the momentum transfer in specular diffraction was measured by scanning the X-ray energy with fixed incoming and outgoing x-ray angles. By selecting a small fixed region of the detector to collect the XRD signal, the rest of the area was available for collecting the x-ray fluorescence for XAS measurements. The simultaneous measurement of XRD and X-ray absorption near edge structure for Pr0.67Sr0.33MnO3 film was demonstrated as a proof of principle for future time-resolved pump-probe measurements. A static sample makes it easy to maintain an accurate overlap of the X-ray spot and laser pump beam.

Effect of 50 MeV Li3 + irradiation on structural and electrical properties of Mn-doped ZnO

NASA Astrophysics Data System (ADS)

Neogi, S. K.; Chattopadhyay, S.; Banerjee, Aritra; Bandyopadhyay, S.; Sarkar, A.; Kumar, Ravi

2011-05-01

The present work aims to study the effect of ion irradiation on structural and electrical properties and their correlation with the defects in the Zn1 - xMnxO-type system. Zn1 - xMnxO (x = 0.02, 0.04) samples have been synthesized by the solid-state reaction method and have been irradiated with 50 MeV Li3 + ions. The concomitant changes have been probed by x-ray diffraction (XRD), temperature-dependent electrical resistivity and positron annihilation lifetime (PAL) spectroscopy. The XRD result shows a single-phase wurtzite structure for Zn0.98Mn0.02O, whereas for the Zn0.96Mn0.04O sample an impurity phase has been found, apart from the usual peaks of ZnO. Ion irradiation removes this impurity peak. The grain size of the samples is found to be uniform. For Zn0.98Mn0.02O, the observed sharp decrease in room temperature resistivity (ρRT) with irradiation is consistent with the lowering of the full width at half maximum of the XRD peaks. However, for Zn0.96Mn0.04O, ρRT decreases for the initial fluence but increases for a further increase in fluence. All the irradiated Zn0.98Mn0.02O samples show a metal-semiconductor transition in temperature-dependent resistivity measurements at low temperature. But all the irradiated Zn0.96Mn0.04O samples show a semiconducting nature in the whole range of temperatures. Results of room temperature resistivity, XRD and PAL measurements are consistent with each other.

Effect of 50 MeV Li3+ irradiation on structural and electrical properties of Mn-doped ZnO.

PubMed

Neogi, S K; Chattopadhyay, S; Banerjee, Aritra; Bandyopadhyay, S; Sarkar, A; Kumar, Ravi

2011-05-25

The present work aims to study the effect of ion irradiation on structural and electrical properties and their correlation with the defects in the Zn(1 - x)Mn(x)O-type system. Zn(1 - x)Mn(x)O (x = 0.02, 0.04) samples have been synthesized by the solid-state reaction method and have been irradiated with 50 MeV Li(3+) ions. The concomitant changes have been probed by x-ray diffraction (XRD), temperature-dependent electrical resistivity and positron annihilation lifetime (PAL) spectroscopy. The XRD result shows a single-phase wurtzite structure for Zn(0.98)Mn(0.02)O, whereas for the Zn(0.96)Mn(0.04)O sample an impurity phase has been found, apart from the usual peaks of ZnO. Ion irradiation removes this impurity peak. The grain size of the samples is found to be uniform. For Zn(0.98)Mn(0.02)O, the observed sharp decrease in room temperature resistivity (ρ(RT)) with irradiation is consistent with the lowering of the full width at half maximum of the XRD peaks. However, for Zn(0.96)Mn(0.04)O, ρ(RT) decreases for the initial fluence but increases for a further increase in fluence. All the irradiated Zn(0.98)Mn(0.02)O samples show a metal-semiconductor transition in temperature-dependent resistivity measurements at low temperature. But all the irradiated Zn(0.96)Mn(0.04)O samples show a semiconducting nature in the whole range of temperatures. Results of room temperature resistivity, XRD and PAL measurements are consistent with each other.

Mineralogy by X-ray Diffraction on Mars: The Chemin Instrument on Mars Science Laboratory

NASA Technical Reports Server (NTRS)

Vaniman, D. T.; Bristow, T. F.; Bish, D. L.; Ming, D. W.; Blake, D. F.; Morris, R. V.; Rampe, E. B.; Chipera, S. J.; Treiman, A. H.; Morrison, S. M.;

Influence of deposition substrate temperature on the morphology and molecular orientation of chloroaluminum phthalocyanine films as well the performance of organic photovoltaic cells.

PubMed

Zheng, Yan-Qiong; Zhang, Jing; Yang, Fang; Komino, Takeshi; Wei, Bin; Zhang, Jianhua; Wang, Zixing; Pu, Wenhong; Yang, Changzhu; Adachi, Chihaya

2015-10-09

The dependence of the morphology of neat chloroaluminum phthalocyanine (ClAlPc) films on substrate temperature (Tsub) during deposition is investigated by variable angle spectroscopic ellipsometry (VASE), x-ray diffraction (XRD), and atomic force microscopy (AFM) to obtain detailed information about the molecular orientation, phase separation, and crystallinity. AFM images indicate that both grain size and root mean square (RMS) roughness noticeably increase with Tsub both in neat and blend films. Increasing Tsub from room temperature to 420 K increases the horizontal orientation of the ClAlPc molecules with an increase of the mean molecular tilt angle from 60.13° (300 K) to 65.86° (420 K). The UV-vis absorption band of the corresponding films increases and the peak wavelength slightly red shifts with the Tsub increase. XRD patterns show a clear diffraction peak at Tsub over 390 K, implying the π-stacking of interconnected ClAlPc molecules at high Tsub. Planar and bulk heterojunction (BHJ) photovoltaic cells containing pristine ClAlPc films and ClAlPc:C60 blend films fabricated at Tsub of 390 K show increases in the power conversion efficiency (ηPCE) of 28% (ηPCE = 3.12%) and 36% (ηPCE = 3.58%), respectively, relative to devices as-deposited at room temperature. The maximum short circuit current in BHJs is obtained at 390 K in the Tsub range from 300 K to 450 K.

Characterization of ZnAl cast alloys with Na addition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gancarz, Tomasz, E-mail: t.gancarz@imim.pl; Cempura, Grzegorz; Skuza, Wojciech

2016-01-15

This study was aimed at evaluating the microstructural change and thermal, electrical and mechanical properties with the addition of Na to eutectic ZnAl alloys. Solders based on eutectic ZnAl containing 0.2 to 3.0 (wt.%) of Na were developed for high temperature solder. Differential scanning calorimetry (DSC) measurements were performed to determine the melting temperatures of the alloys. Thermal linear expansion and electrical resistivity measurements were performed over − 50 °C to 300 °C and 30 °C to 300 °C temperature ranges, respectively. The microstructure of the specimens was analyzed using scanning (SEM) and transmission electron microscopy (TEM) techniques. Chemical microanalysismore » was performed by energy-dispersive X-ray spectroscopy (EDS) on SEM and TEM. The precipitates of NaZn{sub 13} were confirmed by X-ray diffraction (XRD) measurements and selected area electron diffraction (SAED) techniques. The addition of Na to eutectic ZnAl alloy increased the electrical resistivity and reduced the coefficient of thermal expansion; however, the melting point did not change. The mechanical properties, strain and microhardness increased with Na content in alloys. - Highlights: • High temperature soldering materials of ZnAl with Na were designed and characterized. • Precipitates of NaZn{sub 13}were observed and confirmed using TEM and XRD. • Addition of Na to eutectic ZnAl cussed increased mechanical properties. • NaZn{sub 13} caused increased electrical resistivity and microhardness, and reduced the CTE.« less

XRD analysis of undoped and Fe doped TiO{sub 2} nanoparticles by Williamson Hall method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bharti, Bandna; Barman, P. B.; Kumar, Rajesh, E-mail: rajesh.kumar@juit.ac.in

2015-08-28

Undoped and Fe doped titanium dioxide (TiO{sub 2}) nanoparticles were synthesized by sol-gel method at room temperature. The synthesized samples were annealed at 500°C. For structural analysis, the prepared samples were characterized by X-ray diffraction (XRD). The crystallite size of TiO{sub 2} and Fe doped TiO{sub 2} nanoparticles were calculated by Scherer’s formula, and was found to be 15 nm and 11 nm, respectively. Reduction in crystallite size of TiO{sub 2} with Fe doping was observed. The anatase phase of Fe-doped TiO{sub 2} nanoparticles was also confirmed by X-ray diffraction. By using Williamson-Hall method, lattice strain and crystallite size weremore » also calculated. Williamson–Hall plot indicates the presence of compressive strain for TiO{sub 2} and tensile strain for Fe-TiO{sub 2} nanoparticles annealed at 500°C.« less

Structural and morphological study on ZnO:Al thin films grown using DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Astuti, B.; Sugianto; Mahmudah, S. N.; Zannah, R.; Putra, N. M. D.; Marwoto, P.; Aryanto, D.; Wibowo, E.

2018-03-01

ZnO doped Al (ZnO:Al ) thin film was deposited on corning glass substrate using DC magnetron sputtering method. Depositon process of the ZnO:Al thin films was kept constant at plasma power, deposition temperature and deposition time are 40 watt, 400°C and 2 hours, respectivelly. Furthermore, for annealing process has been done on the variation of oxygen pressure are 0, 50, and 100 mTorr. X-ray diffraction (XRD), and SEM was used to characterize ZnO:Al thin film was obtained. Based on XRD characterization results of the ZnO:Al thin film shows that deposited thin film has a hexagonal structure with the dominant diffraction peak at according to the orientation of the (002) plane and (101). Finally, the crystal structure of the ZnO:Al thin films that improves with an increasing the oxygen pressure at annealing process up to 100 mTorr and its revealed by narrow FWHM value and also with dense crystal structure.

Room temperature ferromagnetism in Mn-doped NiO nanoparticles

NASA Astrophysics Data System (ADS)

Layek, Samar; Verma, H. C.

2016-01-01

Mn-doped NiO nanoparticles of the series Ni1-xMnxO (x=0.00, 0.02, 0.04 and 0.06) are successfully synthesized using a low temperature hydrothermal method. Samples up to 6% Mn-doping are single phase in nature as observed from powder x-ray diffraction (XRD) studies. Rietveld refinement of the XRD data shows that all the single phase samples crystallize in the NaCl like fcc structure with space group Fm-3m. Unit cell volume decreases with increasing Mn-doping. Pure NiO nanoparticles show weak ferromagnetism, may be due to nanosize nature. Introduction of Mn within NiO lattice improves the magnetic properties significantly. Room temperature ferromagnetism is found in all the doped samples whereas the magnetization is highest for 2% Mn-doping and then decreases with further doping. The ZFC and FC branches in the temperature dependent magnetization separate well above 350 K indicating transition temperature well above room temperature for 2% Mn-doped NiO Nanoparticle. The ferromagnetic Curie temperature is found to be 653 K for the same sample as measured by temperature dependent magnetization study using vibrating sample magnetometer (VSM) in high vacuum.

Effect of the quantity of carbonate components and sintering parameters on the quality of hydrothermally synthesized carbonate hydroxyapatite

NASA Astrophysics Data System (ADS)

Ruddyard, A. A.; Soejoko, D. S.; Nurlely

2017-07-01

Carbonated hydroxyapatite is a biomaterial with high biocompatibility with human bone, moreso than regular hydroxyapatite, making it an acceptable synthetic bone graft material. The purpose of this research is to study the effect of sintering temperature and time on carbonated hydroxyapatite samples synthesized using a hydrothermal method with CaCO3 as one of its components. The samples are then characterized using Fourier-Transform Infrared Spectroscopy, X-Ray Diffraction, and Scanning Electron Microscope. Infrared (IR) spectra showed that the CO3 content in each sample is proportional to the amount of CaCO3 used during synthesis. X-Ray Diffraction (XRD) patterns showed an increase in apatite content and a decrease in calcite content as sintering temperature and time increases, with temperature increases having a stronger effect on the samples than time increases. Calcite disappears completely after sintering at 900 °C for 2 hours.

Temperature characterization of dielectric permittivity and AC conductivity of nano copper oxide-doped polyaniline composite

NASA Astrophysics Data System (ADS)

Shubha, L. N.; Madhusudana Rao, P.

2016-06-01

The polyaniline/copper oxide (PANI/CuO) nanocomposite was prepared by mixing solutions of polyaniline and copper oxide nanoparticles in dimethyl sulfoxide (DMSO). The synthesized polymer nanocomposites were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and UV-visible spectroscopy. The characteristic peaks in XRD and UV-visible spectra confirmed the presence of CuO in the polymer structure. SEM images indicated morphological changes in the composite matrix as compared to the pristine PANI. The DC conductivity measurements were performed using two-probe method for various temperatures. AC conductivity and dielectric response of the composites were investigated in the frequency range of 102-106Hz using LCR meter. Dielectric permittivity ɛ‧(w) and dielectric loss factor ɛ‧‧(w) were investigated. It was observed that ɛ‧(w) and ɛ‧‧(w) decrease with increase in frequency at all temperatures. At a particular frequency it is observed that both ɛ‧(w) and ɛ‧‧(w) increase with increase in temperature. It was also observed that AC conductivity increased with increase in frequency and temperature.

Electrical conductivity, differential scanning calorimetry, X-ray diffraction, and 7Li nuclear magnetic resonance studies of n-C x H(2 x+1)OSO3Li ( x = 12, 14, 16, 18, and 20)

NASA Astrophysics Data System (ADS)

Hirakawa, Satoru; Morimoto, Yoshiaki; Honda, Hisashi

2015-04-01

Electrical conductivity ( σ), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) measurements of n-C x H (2 x+1) OSO 3Li ( x= 12, 14, 16, 18, and 20) crystals were performed as a function of temperature. In addition, σ, DSC, and XRD observations of n-C x H (2 x+1) OSO 3Na and n-C x H (2 x+1) OSO 3K ( x= 12, 14, 16, 18, and 20) crystals were carried out for comparison. DSC results of the salts revealed several solid-solid phase transitions with large entropy changes (Δ S). For n-C 18 H 37 OSO 3Li and n-C 20 H 41 OSO 3Li salts, each melting point produced a small Δ S mp value compared with the total entropy change in the solid phases (Δ S tr1+Δ S tr2). Additionally, Li + ion diffusion was detected in the highest temperature solid phases. For K salts, larger σ values were detected for potassium alkylsulfates compared with those reported for alkyl carboxylate. 7Li NMR spectra of n-C 18 H 37 OSO 3Li crystals recorded in the low-temperature phase showed large asymmetry parameters, suggesting the Li + ions are localized at asymmetric sites in the crystals.

Water Structure and Dynamics in Smectites: X-ray Diffraction and 2 H NMR Spectroscopy of Mg–, Ca–, Sr–, Na–, Cs–, and Pb–Hectorite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddy, U. Venkateswara; Bowers, Geoffrey M.; Loganathan, Narasimhan

2016-04-06

Variable-temperature X-ray diffraction and 2H NMR spectroscopy of the smectite mineral, hectorite, containing interlayer Na +, K +, Cs +, Mg 2+, Ca 2+, Sr 2+, and Pb 2+ equilibrated at 43% relative humidity (RH) and mixed with 2H 2O to form a paste provide a comprehensive picture of the structural environments and dynamics of interlayer 2H 2O and the relationships of these properties to interlayer hydration state, the hydration energy and polarizability of the cation, temperature, and the formation of ice-1h in the interparticle pores. The variation in basal spacing shown by the XRD data correlates well with themore » 2H NMR behavior, and the XRD data show for the first time in hectorites that crystallization of interparticle ice-1h causes a decrease in the interlayer spacing, likely due to removal of interlayer 2H 2O. The variation of the 2H NMR behavior of all the samples with decreasing temperature reflects decreasing frequencies of motion for the rotation of the 2H 2O molecules around their dipoles, reorientation of the 2H 2O molecules, and exchange of the 2H 2O molecules between interlayer sites coordinated to and not coordinated to the cations.« less

A combined temperature-dependent electron and single-crystal X-ray diffraction study of the fresnoite compound Rb 2V 4+V 25+O 8

NASA Astrophysics Data System (ADS)

Withers, Ray L.; Höche, Thomas; Liu, Yun; Esmaeilzadeh, Saeid; Keding, Ralf; Sales, Brian

2004-10-01

High-purity Rb2V3O8 has been grown and temperature-dependent electron and single-crystal X-ray diffraction used to carefully investigate its fresnoite-type reciprocal lattice. In contrast to other recently investigated representatives of the fresnoite family of compounds, Rb2V3O8 is not incommensurately modulated with an incommensurate basal plane primary modulation wave vector given by q∼0.3 <110>*. A careful low-temperature electron diffraction study has, however, revealed the existence of weak incommensurate satellite reflections characterized by the primitive primary modulation wave vector q1∼0.16c*. The reciprocal space positioning of these incommensurate satellite reflections, the overall (3+1)-d superspace group symmetry, as well as the shapes of the refined displacement ellipsoids determined from single-crystal XRD refinement, are all consistent with their arising from a distinct type of condensed rigid unit modes (RUMs) of distortion of the Rb2V3O8 parent structure.

Preparation and drug release behavior of temperature-responsive mesoporous carbons

NASA Astrophysics Data System (ADS)

Wang, Xiufang; Liu, Ping; Tian, Yong

2011-06-01

A temperature-responsive composite based on poly (N-isopropylacrylamide) (PNIPAAm) and ordered mesoporous carbons (OMCs) has been successfully prepared by a simple wetness impregnation technique. The structures and properties of the composite were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 sorption, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The results showed that the inclusion of PNIPAAm had not greatly changed the basic ordered pore structure of the OMCs. Ibuprofen (IBU) was selected as model drug, and in vitro test of IBU release exhibited a temperature-responsive controlled release delivery.

Study on the structural, optical, and electrical properties of the yellow light-emitting diode grown on free-standing (0001) GaN substrate

NASA Astrophysics Data System (ADS)

Deng, Gaoqiang; Zhang, Yuantao; Yu, Ye; Yan, Long; Li, Pengchong; Han, Xu; Chen, Liang; Zhao, Degang; Du, Guotong

2018-04-01

In this paper, GaN-based yellow light-emitting diodes (LEDs) were homoepitaxially grown on free-standing (0001) GaN substrates by metal-organic chemical vapor deposition. X-ray diffraction (XRD), photoluminescence (PL), and electroluminescence (EL) measurements were conducted to investigate the structural, optical, and electrical properties of the yellow LED. The XRD measurement results showed that the InGaN/GaN multiple quantum wells (MQWs) in the LED structure have good periodicity because the distinct MQWs related higher order satellite peaks can be clearly observed from the profile of 2θ-ω XRD scan. The low temperature (10 K) and room temperature PL measurement results yield an internal quantum efficiency of 16% for the yellow LED. The EL spectra of the yellow LED present well Gaussian distribution with relatively low linewidth (47-55 nm), indicating the homogeneous In-content in the InGaN quantum well layers in the yellow LED structure. It is believed that this work will aid in the future development of GaN on GaN LEDs with long emission wavelength.

Electrical Properties and Dipole Relaxation Behavior of Zinc-Substituted Cobalt Ferrite

NASA Astrophysics Data System (ADS)

Supriya, Sweety; Kumar, Sunil; Kar, Manoranjan

2017-12-01

Co1- x Zn x Fe2O4 ceramics with x = 0.00, 0.05, 0.10, 0.15 and 0.20 were synthesized by a modified citric acid sol-gel method. The crystalline phase of the samples was characterized by the powder x-ray diffraction technique (XRD) and the Rietveld analysis of the XRD patterns. The morphology and particle size were studied using field emission scanning electron microscopy. Fourier transform infrared spectroscopy studies were consistent with the XRD results. The impedance measurements were carried out from 100 Hz to 10 MHz at different temperatures from 40°C to 300°C. The frequency dispersion of dielectric was analyzed with a modified Debye equation. The activation energy derived from the dielectric constant and the impedance follows the Arrhenius law and are comparable with each other. The dielectric relaxation and impedance relaxation are correlated in terms of activation energy, show a good temperature stability of the dielectrics and are useful for their applications in microelectronic devices such as filters, capacitors, resonators, etc.

In situ SAXS study on size changes of platinum nanoparticles with temperature

NASA Astrophysics Data System (ADS)

Wang, W.; Chen, X.; Cai, Q.; Mo, G.; Jiang, L. S.; Zhang, K.; Chen, Z. J.; Wu, Z. H.; Pan, W.

2008-09-01

Poly(vinylpyrrolidone) (PVP)-coated platinum (Pt) nanoparticles were prepared in methanol-water reduction method. In situ small-angle X-ray scattering (SAXS) and X-ray diffraction (XRD) techniques were used to probe the size change of particles and crystallites with temperature. Tangent-by-tangent (TBT) method of SAXS data analysis was improved and used to get the particle size distribution (PSD) from SAXS intensity. Scherrer’s equation was used to derive the crystallite size from XRD pattern. Combining SAXS and XRD results, a step-like characteristic of the Pt nanoparticle growth has been found. Three stages (diffusion, aggregation, and agglomeration) can be used to describe the growth of the Pt nanoparticles and nanocrystallites. Aggregation was found to be the main growth mode of the Pt nanoparticles during heating. The maximum growth rates of Pt nanoparticles and Pt nanocrystallites, as well as the maximum aggregation degree of Pt nanocrystallites were found, respectively, at 250 °C, 350 °C and 300 °C. These results are helpful to understanding the growth mode of nanoparticles, as well as controlling the nanoparticle size.

Room Temperature Magnetic Behavior In Nanocrystalline Ni-Doped Zro2 By Microwave-Assisted Polyol Synthesis

NASA Astrophysics Data System (ADS)

Parimita Rath, Pragyan; Parhi, Pankaj Kumar; Ranjan Panda, Sirish; Priyadarshini, Barsharani; Ranjan Sahoo, Tapas

2017-08-01

This article, deals with a microwave-assisted polyol method to demonstrate a low temperature route < 250°C, to prepare a high temperature cubic zirconia phase. Powder XRD pattern shows broad diffraction peaks suggesting nanometric size of the particles. Magnetic behavior of 1-5 at% Ni doped samples show a threshold for substitutional induced room temperature ferromagnetism up to 3 at% of Ni. TGA data reveals that Ni-doped ZrO2 polyol precursors decompose exothermically below 300°C. IR data confirms the reduction of Zr(OH)4 precipitates to ZrO2, in agreement with the conclusions drawn from the TGA analysis.

Bonding temperature dependence of GaInAsP/InP laser diode grown on hydrophilically directly bonded InP/Si substrate

NASA Astrophysics Data System (ADS)

Aikawa, Masaki; Onuki, Yuya; Hayasaka, Natsuki; Nishiyama, Tetsuo; Kamada, Naoki; Han, Xu; Kallarasan Periyanayagam, Gandhi; Uchida, Kazuki; Sugiyama, Hirokazu; Shimomura, Kazuhiko

2018-02-01

The bonding-temperature-dependent lasing characteristics of 1.5 a µm GaInAsP laser diode (LD) grown on a directly bonded InP/Si substrate were successfully obtained. We have fabricated the InP/Si substrate using a direct hydrophilic wafer bonding technique at bonding temperatures of 350, 400, and 450 °C, and deposited GaInAsP/InP double heterostructure layers on this InP/Si substrate. The surface conditions, X-ray diffraction (XRD) analysis, photoluminescence (PL) spectra, and electrical characteristics after the growth were compared at these bonding temperatures. No significant differences were confirmed in X-ray diffraction analysis and PL spectra at these bonding temperatures. We realized the room-temperature lasing of the GaInAsP LD on the InP/Si substrate bonded at 350 and 400 °C. The threshold current densities were 4.65 kA/cm2 at 350 °C and 4.38 kA/cm2 at 400 °C. The electrical resistance was found to increase with annealing temperature.

Effects of growth temperatures on the physical properties of Cu2ZnSnS4 thin films deposited through spray pyrolysis for solar cell applications

NASA Astrophysics Data System (ADS)

Fadavieslam, M. R.; Keshavarz, S.

2018-02-01

This paper reports the effects of substrate temperature on the structural, optical, and electrical properties of Cu2ZnSnS4 (CZTS) thin films deposited on soda lime glass through spray pyrolysis without sulfurization. Substrate temperatures ranged from 250 to 500 °C at a step of 50 °C, and a precursor solution was prepared by dissolving copper chloride, zinc acetate, zinc chloride, and thiourea in ethanol and di-ionized water. The films were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy, ultraviolet-visible spectroscopy, and electrical resistance and Hall effect measurements, respectively, obtained by two-point probe and van der Pauw techniques. XRD revealed the formation of polycrystalline CZTS thin films and the appearance of relatively intense and sharp diffraction peaks at (112), (200), (220), and (312) of a kesterite phase with (112) preferential orientation, in which the crystalline degree increased as substrate temperature increased. Surface morphological analysis demonstrated the formation of a smooth, compact, and uniform CZTS surface. When substrate temperature increased from 250 to 500 °C, single-crystal grains increased from 6.38 to 28 nm, carrier concentration increased from 3.4 × 1017 to 2.36 × 1019 cm-3, Hall mobility increased from 30.96 to 68.52 cm2/V.S, optical band gap decreased from 1.74 to 1.14 eV, and resistivity decreased from 0.59 to 3.87 × 10-3 Ωcm. Hall effect analysis indicated that the films exhibited p-type conductivity.

Preparation of meta-stable phases of barium titanate by Sol-hydrothermal method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selvaraj, Mahalakshmi; Department of Material Science, School of Chemistry, Madurai Kamaraj University, Tamilnadu Madurai-625 021; Venkatachalapathy, V.

2015-11-15

Two low-cost chemical methods of sol–gel and the hydrothermal process have been strategically combined to fabricate barium titanate (BaTiO{sub 3}) nanopowders. This method was tested for various synthesis temperatures (100 °C to 250 °C) employing barium dichloride (BaCl{sub 2}) and titanium tetrachloride (TiCl{sub 4}) as precursors and sodium hydroxide (NaOH) as mineralizer for synthesis of BaTiO{sub 3} nanopowders. The as-prepared BaTiO{sub 3} powders were investigated for structural characteristics using x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The overall analysis indicates that the hydrothermal conditions create a gentle environment to promote the formation of crystalline phasemore » directly from amorphous phase at the very low processing temperatures investigated. XRD analysis showed phase transitions from cubic - tetragonal - orthorhombic - rhombohedral with increasing synthesis temperature and calculated grain sizes were 34 – 38 nm (using the Scherrer formula). SEM and TEM analysis verified that the BaTiO{sub 3} nanopowders synthesized by this method were spherical in shape and about 114 - 170 nm in size. The particle distribution in both SEM and TEM shows that as the reaction temperature increases from 100 °C to 250 °C, the particles agglomerate. Selective area electron diffraction (SAED) shows that the particles are crystalline in nature. The study shows that choosing suitable precursor and optimizing pressure and temperature; different meta-stable (ferroelectric) phases of undoped BaTiO{sub 3} nanopowders can be stabilized by the sol-hydrothermal method.« less

Temperature dependent surface and spectral modifications of nano V2O5 films

NASA Astrophysics Data System (ADS)

Manthrammel, M. Aslam; Fatehmulla, A.; Al-Dhafiri, A. M.; Alshammari, A. S.; Khan, Aslam

2017-03-01

Nanocrystalline V2O5 films have been deposited on glass substrates at 300°C substrate temperature using thermal evaporation technique and were subjected to thermal annealing at different temperatures 350, 400, and 550°C. X-ray diffraction (XRD) spectra exhibit sharper and broader characteristic peaks respectively indicating the rearrangement of nanocrystallite phases with annealing temperatures. Other phases of vanadium oxides started emerging with the rise in annealing temperature and the sample converted completely to VO2 (B) phase at 550°C annealing. FESEM images showed an increase in crystallite size with 350 and 400°C annealing temperatures followed by a decrease in crystallite size for the sample annealed at 550°C. Transmission spectra showed an initial redshift of the fundamental band edge with 350 and 400°C while a blue shift for the sample annealed at 550°C, which was in agreement with XRD and SEM results. The films exhibited smart window properties as well as nanorod growth at specific annealing temperatures. Apart from showing the PL and defect related peaks, PL studies also supported the observations made in the transmission spectra.

Method of Generating X-Ray Diffraction Data for Integral Detection of Twin Defects in Super-Hetero-Epitaxial Materials

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

2009-01-01

A method provides X-ray diffraction (XRD) data suitable for integral detection of a twin defect in a strained or lattice-matched epitaxial material made from components having crystal structures having symme try belonging to different space groups. The material is mounted in a n X-ray diffraction (XRD) system. In one embodiment, the XRD system's goniometer angle Omega is set equal to (Theta(sub B)-Beta) where The ta(sub B) is a Bragg angle for a designated crystal plane of the allo y that is disposed at a non-perpendicular orientation with respect to the {111) crystal plane, and Beta is the angle between the designate d crystal plane and a { 111 } crystal plane of one of the epitaxial components. The XRD system's detector angle is set equal to (Theta(su b B)+Beta). The material can be rotated through an angle of azimuthal rotation Phi about the axis aligned with the material. Using the det ector, the intensity of the X-ray diffraction is recorded at least at the angle at which the twin defect occurs.

Comparative investigation of Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) in the determination of cotton fiber crystallinity.

PubMed

Liu, Yongliang; Thibodeaux, Devron; Gamble, Gary; Bauer, Philip; VanDerveer, Don

2012-08-01

Despite considerable efforts in developing curve-fitting protocols to evaluate the crystallinity index (CI) from X-ray diffraction (XRD) measurements, in its present state XRD can only provide a qualitative or semi-quantitative assessment of the amounts of crystalline or amorphous fraction in a sample. The greatest barrier to establishing quantitative XRD is the lack of appropriate cellulose standards, which are needed to calibrate the XRD measurements. In practice, samples with known CI are very difficult to prepare or determine. In a previous study, we reported the development of a simple algorithm for determining fiber crystallinity information from Fourier transform infrared (FT-IR) spectroscopy. Hence, in this study we not only compared the fiber crystallinity information between FT-IR and XRD measurements, by developing a simple XRD algorithm in place of a time-consuming and subjective curve-fitting process, but we also suggested a direct way of determining cotton cellulose CI by calibrating XRD with the use of CI(IR) as references.

Radiation-Induced Changes in Quartz, A Mineral Analog of Nuclear Power Plant Concrete Aggregates.

PubMed

Silva, Chinthaka M; Rosseel, Thomas M; Kirkegaard, Marie C

2018-03-19

Quartz single-crystal samples consisting of α-quartz crystal structure were neutron irradiated to fluences of 5 × 10 18 , 4 × 10 19 , and 2 × 10 20 n/cm 2 (E > 0.1 MeV) at two temperatures (52 and 95 °C). The changes in the α-quartz phase as a function of these two conditions (temperature and fluence) were studied using X-ray powder diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM), and the results acquired using these complementary techniques are presented in a single place for the first time. XRD studies showed that the lattice parameters of α-quartz increased with increasing neutron flux. The lattice growth was larger for the samples that were neutron irradiated at 52 °C than at 95 °C. Moreover, an amorphous content was determined in the quartz samples neutron irradiated at 4 × 10 19 n/cm 2 , with the greater amount being in the 52 °C irradiated sample. Complete amorphization of quartz was observed at a fluence of 2 × 10 20 n/cm 2 (E > 0.1 MeV) using XRD and confirmed by TEM characterization and Raman spectroscopic studies. The cause for α-quartz lattice expansion and sample amorphization was also explored using XRD and Raman spectroscopic studies.

Synthesis of nano-sized ZnO particles by co-precipitation method with variation of heating time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Purwaningsih, S. Y., E-mail: sriyanisaputri@gmail.com; Pratapa, S.; Triwikantoro

Zinc oxide powders have been synthesized by a co-precipitation method at low temperature (85 °C), using zinc acetate dihydrate, ammonia, hydrochloric acid solutions as the reactants. A number of process parameters such as reaction temperature, solution basicity or pH and heating time are the main factors affecting the morphology and physical properties of the ZnO nanostructures. In this work the effect of heating time on the morphology and particles size were studied. The as-synthesized ZnO powders were characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The samples were also analyzed using Fourier transform infrared (FTIR). Rietveld refinementmore » of XRD data confirms that ZnO crystallizes in the hexagonal wurtzite structure with high degree of purity and the (101) plane predominant. The XRD results show that the average crystallite sizes were about 66, 27 and 12 nm for 3, 4 and 5 h of heating times, respectively. The XRD analysis indicated that a fraction of nano-sized ZnO powders were in the form of aggregates, which was also verified by TEM image. The TEM photograph demonstrated that the nano-sized ZnO particles were a pseudo-spherical shape.« less

Effect of heat treatment procedure on magnetic and magnetocaloric properties of Ni43Mn46In11 melt spun ribbons

NASA Astrophysics Data System (ADS)

Kaya, M.; Elerman, Y.; Dincer, I.

2018-07-01

The effect of heat treatment on the structural, magnetic and magnetocaloric properties of Ni43Mn46In11 melt-spun ribbons was systematically investigated using X-ray powder diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), magnetic force microscope (MFM) and magnetic measurements. From the XRD studies, tetragonal and cubic phases were detected at room temperature for as-spun, quenched and slow-cooled ribbons. Furthermore, it was observed, upon annealing martensite transition temperatures increased when compared to the as-spun ribbon. To avoid magnetic hysteresis losses in the vicinity of the structural transition region, the magnetic entropy changes-ΔS m of the investigated ribbons were evaluated from temperature-dependent magnetisation-M(T) curves on cooling for different applied magnetic fields. The maximum ΔS m value was found to be 6.79 J kg-1 K-1 for the quenched ribbon in the vicinity of structural transition region for a magnetic field change of 50 kOe.

Annealing effect on structural and optical properties of chemical bath deposited MnS thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ulutas, Cemal, E-mail: cemalulutas@hakkari.edu.tr; Gumus, Cebrail

2016-03-25

MnS thin film was prepared by the chemical bath deposition (CBD) method on commercial microscope glass substrate deposited at 30 °C. The as-deposited film was given thermal annealing treatment in air atmosphere at various temperatures (150, 300 and 450 °C) for 1 h. The MnS thin film was characterized by using X-ray diffraction (XRD), UV-vis spectrophotometer and Hall effect measurement system. The effect of annealing temperature on the structural, electrical and optical properties such as optical constants of refractive index (n) and energy band gap (E{sub g}) of the film was determined. XRD measurements reveal that the film is crystallized inmore » the wurtzite phase and changed to tetragonal Mn{sub 3}O{sub 4} phase after being annealed at 300 °C. The energy band gap of film decreased from 3.69 eV to 3.21 eV based on the annealing temperature.« less

Structural and electrical properties of Li4Ti5O12 anode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Vikram Babu, B.; Vijaya Babu, K.; Tewodros Aregai, G.; Seeta Devi, L.; Madhavi Latha, B.; Sushma Reddi, M.; Samatha, K.; Veeraiah, V.

2018-06-01

In this work we investigate Li4Ti5O12 (LTO) anode material synthesized by conventional solid state reaction method calcined at 850 °C for 16 h. Thermal analysis reveals the temperature dependence of the material properties. The phase composition, micro-morphology and elemental analysis of the compound are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectra (EDS) respectively. The results of XRD pattern possessed cubic spinel structure with space group Fd-3m. The morphological features of the powder sample are in the range of 1.1 μm. The EDS spectra confirm the constituent elemental composition of the sample. Electrical conductivity measurement at different frequencies and temperatures had been carried out; and at room temperature it is found to be 5.96 × 10-7 S/cm. Besides, for the different frequencies applied, the activation energies were calculated and obtained to be in the range of 0.2-0.4 eV.

Structural and magnetic properties of morphotropic phase boundary involved Tb 1-xGd xFe 2 compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murtaza, Adil; Yang, Sen; Zhou, Chao

2016-09-01

In the present paper, structural, magnetic and magnetostrictive properties of Tb 1-xGd xFe 2 (0 <= x <= 1.0) were studied. Synchrotron x-ray diffraction (XRD) results show the non-cubic symmetry of Tb 1-xGd xFe 2 at room temperature and composition-induced crystallographic phase transition from rhombohedral phase to tetragonal phase. The Gd concentration dependent lattice parameters, lattice distortion and change of easy magnetic direction were detected by synchrotron XRD. With the Gd concentration increases, Curie temperature Tc increases while room temperature magnetization and magnetostriction coefficient lambda(111) and the anisotropy of TbFe 2 decrease. The decrease in spontaneous magnetostriction coefficient lambda(111) withmore » increasing Gd substitution can be understood on the basis of the single-ion model; the corresponding decrease of magnetostriction for Tb 1-xGd xFe 2, and the large magnetostriction value occurs on the Tb-rich side, are ascribed to decrease of lambda(111)« less

The Effects of Vanadium Pentoxide to Oxalic Acid Ratio and Different Atmospheres on the Formation of VO2 Nanopowders Synthesized via Sol-Gel Method

NASA Astrophysics Data System (ADS)

Vostakola, Mohsen Fallah; Yekta, Bijan Eftekhari; Mirkazemi, Seyed Mohammad

2017-11-01

Thermochromic VO2 nanopowders were synthesized via the sol-gel method through mixing oxalic acid and vanadium pentoxide in ethanol. We investigated the effect of oxalic acid to vanadium pentoxide ratio on the formation of final product and found that excessive oxalic acid reduced the final product from VO2 to V2O3. Because decreasing the oxalic acid to vanadium pentoxide ratio is a time-consuming process, oxygen was introduced by using a low-porosity alumina tube. The heat treatment was performed inside an electrical tube furnace and in a variety of atmospheres, including pure nitrogen (99.999% purity) and nitrogen containing 5 vol.%, 10 vol.%, and 15 vol.% hydrogen. According to x-ray diffraction (XRD) results, the appropriate atmosphere for synthesizing VO2 nanopowder was the one which contained 10 vol.% hydrogen. In order to decrease the transition temperature in VO2 from 63.5°C to room temperature, W6+ doping was done by adding different amounts of tungstic acid sol to vanadium sol precursor. Differential scanning calorimetry (DSC) results showed that W6+ reduced the transition temperature of VO2 approximately 23°C/wt.%. Lattice straining estimated from XRD results confirmed that VO2 was doped. XRD results at 25°C and 100°C along with DSC results indicated that VO2 was transformed from a low-temperature monoclinic phase to a high-temperature rutile one along this temperature interval.

Remote X-Ray Diffraction and X-Ray Fluorescence Analysis on Planetary Surfaces

NASA Technical Reports Server (NTRS)

Blake, David F.; DeVincenzi, D. (Technical Monitor)

1999-01-01

The legacy of planetary X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) began in 1960 when W. Parish proposed an XRD instrument for deployment on the moon. The instrument was built and flight qualified, but the Lunar XRD program was cancelled shortly before the first human landing in 1969. XRF chemical data have been collected in situ by surface landers on Mars (Viking 1 & 2, Pathfinder) and Venus (Venera 13 & 14). These highly successful experiments provide critical constraints on our current understanding of surface processes and planetary evolution. However, the mineralogy, which is more critical to planetary surface science than simple chemical analysis, will remain unknown or will at best be imprecisely constrained until X-ray diffraction (XRD) data are collected. Recent progress in X-ray detector technology allows the consideration of simultaneous XRD (mineralogic analysis) and high-precision XRF (elemental analysis) in systems miniaturized to the point where they can be mounted on fixed landers or small robotic rovers. There is a variety of potential targets for XRD/XRF equipped landers within the solar system, the most compelling of which are the poles of the moon, the southern highlands of Mars and Europa.

OMVPE Growth of Quaternary (Al,Ga,In)N for UV Optoelectronics (title change from A)

DOE Office of Scientific and Technical Information (OSTI.GOV)

HAN,JUNG; FIGIEL,JEFFREY J.; PETERSEN,GARY A.

We report the growth and characterization of quaternary AlGaInN. A combination of photoluminescence (PL), high-resolution x-ray diffraction (XRD), and Rutherford backscattering spectrometry (RBS) characterizations enables us to explore the contours of constant PL peak energy and lattice parameter as functions of the quaternary compositions. The observation of room temperature PL emission at 351nm (with 20% Al and 5% In) renders initial evidence that the quaternary could be used to provide confinement for GaInN (and possibly GaN). AlGaInN/GrdnN MQW heterostructures have been grown; both XRD and PL measurements suggest the possibility of incorporating this quaternary into optoelectronic devices.

Fabrication of high-k dielectric Calcium Copper Titanate (CCTO) target by solid state route

NASA Astrophysics Data System (ADS)

Tripathy, N.; Das, K. C.; Ghosh, S. P.; Bose, G.; Kar, J. P.

2016-02-01

CaCu3Ti4O12 (CCTO) ceramic pellet of 10mm diameter has been synthesized by adopting solid state route. The structural and morphological characterization of the ceramics sample was carried out by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. XRD pattern revealed the CCTO phase formation, where as SEM micrograph shows the sample consisting of well defined grain and grain boundaries. The room temperature dielectric constant of the sample was found to be ∼ 5000 at 1kHz. After successful preparation of CCTO pellet, a 2 inch diameter CCTO sputtering target is also fabricated in order to deposit CCTO thin films for microelectronic applications.

DSC and Raman studies of silver borotellurite glasses

NASA Astrophysics Data System (ADS)

Kaur, Amandeep; Khanna, Atul; Gonzàlez, Fernando

2016-05-01

Silver borotellurite glasses of composition: xAg2O-yB2O3-(100-x-y)TeO2 (x=20-mol%, y = 0, 10, 20 and 30-mol%) were prepared and characterized by density, X-ray diffraction (XRD), differential scanning calorimetry, and Raman spectroscopy. XRD confirmed the amorphous structure of all samples. Density of glasses decreases while the glass transition temperature increases with increase in B2O3 content from 10 to 30-mol%. Raman study shows that coordination number of Te with oxygen decreases steadily from 3.42 to 3.18 on adding B2O3 due to the transformation of TeO4 into TeO3 units.

Ellipsometric study of Si(0.5)Ge(0.5)/Si strained-layer superlattices

NASA Technical Reports Server (NTRS)

Sieg, R. M.; Alterovitz, S. A.; Croke, E. T.; Harrell, M. J.

1993-01-01

An ellipsometric study of two Si(0.5)Ge(0.5)/Si strained-layer super lattices grown by MBE at low temperature (500 C) is presented, and results are compared with x ray diffraction (XRD) estimates. Excellent agreement is obtained between target values, XRD, and ellipsometry when one of two available Si(x)Ge(1-x) databases is used. It is shown that ellipsometry can be used to nondestructively determine the number of superlattice periods, layer thicknesses, Si(x)Ge(1-x) composition, and oxide thickness without resorting to additional sources of information. It was also noted that we do not observe any strain effect on the E(sub 1) critical point.

Effect of calcination temperature on phase transformation and crystallite size of copper oxide (CuO) powders

NASA Astrophysics Data System (ADS)

Ratnawulan, Fauzi, Ahmad; AE, Sukma Hayati

2017-08-01

Copper oxide powder was prepared from Copper iron from South Solok, Indonesia. The samples was dried and calcined for an hour at temperatures of 145°C, 300°C,850°C, 1000°C. Phase transformation and crystallite size of the calcined powders have been investigated as a function of calcination temperature by room-temperature X-ray diffraction (XRD). It was seen that the tenorite, CuO was successfully obtained. With increasing calcining temperature, CuO transformed from malachite Cu2(CO3)(OH)2 to tenorite phase (CuO) and crystallite size of prepared samples increased from 36 nm to 76 nm.

Time-resolved in situ powder X-ray diffraction reveals the mechanisms of molten salt synthesis.

PubMed

Moorhouse, Saul J; Wu, Yue; Buckley, Hannah C; O'Hare, Dermot

2016-11-24

We report the first use of high-energy monochromatic in situ X-ray powder diffraction to gain unprecedented insights into the chemical processes occurring during high temperature, lab-scale metal oxide syntheses. During the flux synthesis of the n = 4 Aurivillius phase, Bi 5 Ti 3 Fe 0.5 Cr 0.5 O 15 at 950 °C in molten Na 2 SO 4 we observe the progression of numerous metastable phases. Using sequential multiphase Rietveld refinement of the time-dependent in situ XRD data, we are able to obtain mechanistic understanding of this reaction under a range of conditions.

Intermediate valence to Kondo behaviour in Ce(Pt1-xIrx)2Si2 (0≤x≤1)

NASA Astrophysics Data System (ADS)

Tchoula Tchokonté, M. B.; du Plessis, P. de V.; Kaczorowski, D.

2009-10-01

Measurements of X-ray diffraction (XRD), resistivity ( ρ(T)), magnetic susceptibility ( χ(T)) and magnetization ( σ(μ0H)) are reported for the polycrystalline Ce(Pt1-xIrx)2Si2 alloy system. The unit cell volume derived from the XRD results deviates from Vegard's rule around x=0.2-0.3. χ(T) measurements show a Curie-Weiss behaviour at high temperatures for the x= 0, 0.1 and 0.2 alloys whereas the alloys with x≥0.4 exhibit broad maxima in χ(T) at intermediate temperature (e.g. at 170 K for x=0.4). The latter behaviour due to valence fluctuations as described by Sales and Wohlleben. ρ(T) data indicate Kondo lattice behaviour for x≤0.2 and fluctuating valency for x≥0.3. σ(μ0H) data indicate metamagnetic behaviour for the x=0.4 alloy.

Structural and Mössbauer analysis of pure and Ce-Dy doped cobalt ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Hashim, Mohd.; Meena, Sher Singh; Kumar, Shalendra; Ahmed, Ateeq; Bhatt, Pramod

2018-05-01

Ce and Dy doped Cobalt ferrites with the chemical composition CoCexDyxFe2-2xO4 (x = 0.00 and 0.04) were synthesized via the chemical route using citrate-gel auto-combustion method. The structural analysis has been carried out with the help of x-ray diffraction (XRD). Formation of spinel cubic structure of the ferrites was confirmed by XRD analysis. Mössbauer spectra were recorded for both samples at room temperature. Presence of the well resolved sextet spectra corresponding to A and B sub-lattice clearly shows that both the samples have ferrimagnetic ordering at room temperature. Isomer shift observed from fitting of the Mössbauer spectra infers that Fe3+ ions are in high valence state. The decrease in the hyperfine field due to the doping of Ce and Dy clearly showed that magnetic interactions diluted due to the doping of Ce and Dy ions.

Rietveld analysis of the effect of annealing atmosphere on phase evolution of nanocrystalline TiO2 powders.

PubMed

Salari, M; Rezaee, M; Chidembo, A T; Konstantinov, K; Liu, H K

2012-06-01

The structural evolution of nanocrystalline TiO2 was studied by X-ray diffraction (XRD) and the Rietveld refinement method (RRM). TiO2 powders were prepared by the sol-gel technique. Post annealing of as-synthesized powders in the temperature range from 500 degrees C to 800 degrees C under air and argon atmospheres led to the formation of TiO2 nanoparticles with mean crystallite size in the range of 37-165 nm, based on the Rietveld refinement results. It was found that the phase structure, composition, and crystallite size of the resulting particles were dependent on not only the annealing temperature, but also the annealing atmosphere. Rietveld refinement of the XRD data showed that annealing the powders under argon atmosphere promoted the polymorphic phase transformation from anatase to rutile. Field emission scanning electron microscopy (FESEM) was employed to investigate the morphology and size of the annealed powders.

Effect of thickness on optoelectrical properties of Nb-doped indium tin oxide thin films deposited by RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Li, Shi-na; Ma, Rui-xin; Ma, Chun-hong; Li, Dong-ran; Xiao, Yu-qin; He, Liang-wei; Zhu, Hong-min

2013-05-01

Niobium-doped indium tin oxide (ITO:Nb) thin films are prepared on glass substrates with various film thicknesses by radio frequency (RF) magnetron sputtering from one piece of ceramic target material. The effects of thickness (60-360 nm) on the structural, electrical and optical properties of ITO: Nb films are investigated by means of X-ray diffraction (XRD), ultraviolet (UV)-visible spectroscopy, and electrical measurements. XRD patterns show the highly oriented (400) direction. The lowest resistivity of the films without any heat treatment is 3.1×10-4Ω·cm-1, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 17.6 N·S and 1.36×1021 cm-3, respectively. Band gap energy of the films depends on substrate temperature, which varies from 3.48 eV to 3.62 eV.

Formation of silicon nanocrystals in sapphire by ion implantation and the origin of visible photoluminescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yerci, S.; Serincan, U.; Dogan, I.

2006-10-01

Silicon nanocrystals, average sizes ranging between 3 and 7 nm, were formed in sapphire matrix by ion implantation and subsequent annealing. Evolution of the nanocrystals was detected by Raman spectroscopy and x-ray diffraction (XRD). Raman spectra display that clusters in the matrix start to form nanocrystalline structures at annealing temperatures as low as 800 deg. C in samples with high dose Si implantation. The onset temperature of crystallization increases with decreasing dose. Raman spectroscopy and XRD reveal gradual transformation of Si clusters into crystalline form. Visible photoluminescence band appears following implantation and its intensity increases with subsequent annealing process. Whilemore » the center of the peak does not shift, the intensity of the peak decreases with increasing dose. The origin of the observed photoluminescence is discussed in terms of radiation induced defects in the sapphire matrix.« less

Mössbauer study of sediment alteration produced by heat treatment

NASA Astrophysics Data System (ADS)

Labenski de Kanter, F.; Duhalde, S.; Saragovi, C.; March, R. J.

1994-12-01

Pincenvent (France) cooking-place silt-like sediments have been studied by using Mössbauer spectroscopy and characterized by using X-ray diffraction (XRD). The sediments were treated at 400, 600, 800 and 1000°C under oxidizing conditions. We discuss the results and we suggest a “Mössbauer thermometer” to be used to recognize the temperatures and atmosphere ancient people used in their cooking-places.

Effect of Fe doping on structural and impedance properties of PZTFN ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Arvind, E-mail: arvindmse07311209.in@gmail.com; Pal, Vijayeta; Mishra, S. K.

2016-05-06

An attempts have been made to synthesis the ceramics Pb{sub 1-3x/2} Fe{sub x}(Zr{sub 0.52}Ti{sub 0.48}){sub 1-5y/4} NbyO{sub 3} abbreviated as (PFZTN) for x = 1-6 mol% and y = 5.5 mol% by a semi-wet route. In the present paper, we have investigated the effect of Fe doping on structural and electrical properties of the PFZTN ceramics. X-ray diffraction (XRD) patterns reveal that PFZTN ceramics are single phase in nature. However, for x = 0.05 and 0.06, a secondary phase appears as discernible from the XRD profiles. Rietveld analysis of the powder diffraction data shows the presence of coexistence of tetragonal (P4mm spacemore » group) and rhombohedral phases (R3c space group) occurs near the morphotropic phase boundary (MPB) at x ≥ = 0.05. The log-log plots show that the conductivity increases with increase of temperature. The ac conductivity becomes sensitive at high frequency region and shifted towards higher frequency side with increasing temperature. It is observed that the activation energy (Ea) decreases with increasing frequency. This complex perovskite structure can be used as a multilayer ceramic capacitors and electromechanical transducers.« less

Chemical characterization of hydroxyapatite obtained by wet chemistry in the presence of V, Co, and Cu ions.

PubMed

Moseke, Claus; Gelinsky, Michael; Groll, Jürgen; Gbureck, Uwe

2013-04-01

A model system for the precipitation of hydroxyapatite (HA) from saturated solutions at basic pH was utilized to investigate the effects of V, Co, and Cu ions on crystallography and stoichiometry of the produced apatites. X-ray diffraction (XRD) was applied to analyze phase composition and crystallinity of powders obtained with different metal ion concentrations and annealed at different sintering temperatures. This procedure used the temperature-dependent phase transitions and decompositions of calcium phosphates to analyze the particular influences of the metal ions on apatite mineralization. Comparative XRD measurements showed that all metal ion species reduced crystallinity and crystallite size of the produced apatites. Furthermore the transformation of amorphous calcium phosphate (ACP) to HA was partially inhibited, as was deduced from the formation of α-tricalcium phosphate (α-TCP) peaks in XRD patterns of the heated powders as well as from the reduced intensity of the OH stretch vibration in FTIR spectra. The thermally induced formation of β-TCP indicated a significantly reduced Ca/P ratio as compared to stoichiometric HA. This effect was more pronounced with rising metal ion content. In addition, the appearance of metal oxides in the XRD patterns of samples heated to higher temperatures indicated the incorporation of metal ions in the precipitated apatites. Peak shifts showed that both the apatitic as well as the β-TCP phase apparently had incorporated metal ions. Copyright © 2012 Elsevier B.V. All rights reserved.

Clay pigment structure characterisation as a guide for provenance determination--a comparison between laboratory powder micro-XRD and synchrotron radiation XRD.

PubMed

Švarcová, Silvie; Bezdička, Petr; Hradil, David; Hradilová, Janka; Žižak, Ivo

2011-01-01

Application of X-ray diffraction (XRD)-based techniques in the analysis of painted artworks is not only beneficial for indisputable identification of crystal constituents in colour layers, but it can also bring insight in material crystal structure, which can be affected by their geological formation, manufacturing procedure or secondary changes. This knowledge might be helpful for art historic evaluation of an artwork as well as for its conservation. By way of example of kaolinite, we show that classification of its crystal structure order based on XRD data is useful for estimation of its provenance. We found kaolinite in the preparation layer of a Gothic wall painting in a Czech church situated near Karlovy Vary, where there are important kaolin deposits. Comparing reference kaolin materials from eight various Czech deposits, we found that these can be differentiated just according to the kaolinite crystallinity. Within this study, we compared laboratory powder X-ray micro-diffraction (micro-XRD) with synchrotron radiation X-ray diffraction analysing the same real sample. We found that both techniques led to the same results.

Effects of the synthesis temperature on the crystalline structure and the magnetic properties of cobalt ferrite nanoparticles prepared via coprecipitation

NASA Astrophysics Data System (ADS)

Hutamaningtyas, Evangelin; Utari; Suharyana; Purnama, Budi; Wijayanta, Agung Tri

2016-08-01

The effects of the synthesis temperature on the crystalline structure and the magnetic properties of cobalt ferrite (CoFe2O4) nanoparticles prepared via coprecipitation are discussed. The synthesis was conducted at temperatures of 75 °C, 85 °C and 95 °C. Fourier transform infrared spectroscopy characterization related to a stretching vibration at a wavenumber of 590 cm-1 indicated the formation of a CoFe2O4 metal oxide. In addition, powder X ray diffraction (XRD) characterization proved that the metal oxide was CoFe2O4. Crystallite sizes calculated using the Scherer formula at the strongest peak of the XRD spectra of the samples synthesized at 75 °C, 85 °C and 95 °C were 32 nm, 43 nm and 50.4 nm, respectively. Finally, the results of the vibrating sample magnetometer characterization showed that the saturation magnetization decreased with increasing synthesis temperature, which is related to the dominant preference of Co2+ over Fe3+ cations at the octahedral sites.

Influence of Discharge Current on Phase Transition Properties of High Quality Polycrystalline VO2 Thin Film Fabricated by HiPIMS

PubMed Central

Lin, Tiegui; Wang, Jian; Liu, Gang; Wang, Langping; Wang, Xiaofeng; Zhang, Yufen

2017-01-01

To fabricate high-quality polycrystalline VO2 thin film with a metal–insulator transition (MIT) temperature less than 50 °C, high-power impulse magnetron sputtering with different discharge currents was employed in this study. The as-deposited VO2 films were characterized by a four-point probe resistivity measurement system, visible-near infrared (IR) transmittance spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. The resistivity results revealed that all the as-deposited films had a high resistance change in the phase transition process, and the MIT temperature decreased with the increased discharge current, where little deterioration in the phase transition properties, such as the resistance and transmittance changes, could be found. Additionally, XRD patterns at various temperatures exhibited that some reverse deformations that existed in the MIT process of the VO2 film, with a large amount of preferred crystalline orientations. The decrease of the MIT temperature with little deterioration on phase transition properties could be attributed to the reduction of the preferred grain orientations. PMID:28772990

Structural versus electrical properties of an organic-inorganic hybrid material based on sulfate

NASA Astrophysics Data System (ADS)

Ben Rached, Asma; Guionneau, Philippe; Lebraud, Eric; Mhiri, Tahar; Elaoud, Zakaria

2017-01-01

A new organo-sulfate compound is obtained by slow evaporation at room temperature and is characterized by powder and single-crystal X-ray diffraction (XRD) at variable temperatures. The benzylammonium monohydrogenosulfate of formula C6H5CH2NH3+. HSO4-, denoted (BAS), crystallizes in the monoclinic system P21/c space group with the following parameters at room temperature: a=5.623(5)Å, b=20.239(5) Å, c=8.188(5)Å, β=94.104(5)°. The crystal structure consists of infinite parallel two-dimensional planes built by HSO4- anions and C6H5CH2NH3+ cations interconnected by strong O-H….. O and N-H….. O hydrogen bonds. A phase transition is detected at 350 K by differential scanning calorimetry (DSC) and confirmed by powder XRD. Conductivity measurements using the impedance spectroscopy technique allow to determine the conductivity relaxation parameters associated with the H+ conduction from an analysis of the M"/M"max spectrum measured in a wide temperature range. Transport properties of this material appear to be due to an H+ ion hopping mechanism.

Hydrolysis of bamboo biomass by subcritical water treatment.

PubMed

Mohan, Mood; Banerjee, Tamal; Goud, Vaibhav V

2015-09-01

The aim of present study was to obtain total reducing sugars (TRS) from bamboo under subcritical water (SCW) treatment in a batch reactor at the temperature ranging from 170 °C to 220 °C and 40 min hydrolysis time. Experiments were performed to investigate the effects of temperature and time on TRS yield. The maximum TRS yield (42.21%) was obtained at lower temperature (180 °C), however longer reaction time (25 min). X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) analysis were used to characterise treated and untreated bamboo samples. The XRD profile revealed that crystallinity of bamboo increased to 71.90% with increase in temperature up to 210 °C and decreased thereafter to 70.92%. The first-order reaction kinetic model was used to fit the experimental data to obtain rate constants. From the Arrhenius plot, activation energy and pre-exponential factor at 25 min time were found to be 17.97 kJ mol(-1) and 0.154 min(-1), respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

Structure, Morphology, and Optical Properties of Amorphous and Nanocrystalline Gallium Oxide Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, S. Sampath; Rubio, E. J.; Noor-A-Alam, M.

Ga2O3 thin films were produced by sputter deposition by varying the substrate temperature (Ts) in a wide range (Ts=25-800 oC). The structural characteristics and optical properties of Ga2O3 films were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Rutherford backscattering spectrometry (RBS) and spectrophotometric measurements. The effect of growth temperature is significant on the chemistry, crystal structure and morphology of Ga2O3 films. XRD and SEM analyses indicate that the Ga2O3 films grown at lower temperatures were amorphous while those grown at Ts≥500 oC were nanocrystalline. RBS measurements indicate the well-maintained stoichiometry of Ga2O3 films atmore » Ts=300-700 oC. The spectral transmission of the films increased with increasing temperature. The band gap of the films varied from 4.96 eV to 5.17 eV for a variation in Ts in the range 25-800 oC. A relationship between microstructure and optical property is discussed.« less

The phase diagram of ammonium nitrate.

PubMed

Chellappa, Raja S; Dattelbaum, Dana M; Velisavljevic, Nenad; Sheffield, Stephen

2012-08-14

The pressure-temperature (P-T) phase diagram of ammonium nitrate (AN) [NH(4)NO(3)] has been determined using synchrotron x-ray diffraction (XRD) and Raman spectroscopy measurements. Phase boundaries were established by characterizing phase transitions to the high temperature polymorphs during multiple P-T measurements using both XRD and Raman spectroscopy measurements. At room temperature, the ambient pressure orthorhombic (Pmmn) AN-IV phase was stable up to 45 GPa and no phase transitions were observed. AN-IV phase was also observed to be stable in a large P-T phase space. The phase boundaries are steep with a small phase stability regime for high temperature phases. A P-V-T equation of state based on a high temperature Birch-Murnaghan formalism was obtained by simultaneously fitting the P-V isotherms at 298, 325, 446, and 467 K, thermal expansion data at 1 bar, and volumes from P-T ramping experiments. Anomalous thermal expansion behavior of AN was observed at high pressure with a modest negative thermal expansion in the 3-11 GPa range for temperatures up to 467 K. The role of vibrational anharmonicity in this anomalous thermal expansion behavior has been established using high P-T Raman spectroscopy.

The phase diagram of ammonium nitrate

NASA Astrophysics Data System (ADS)

Chellappa, Raja S.; Dattelbaum, Dana M.; Velisavljevic, Nenad; Sheffield, Stephen

2012-08-01

The pressure-temperature (P-T) phase diagram of ammonium nitrate (AN) [NH4NO3] has been determined using synchrotron x-ray diffraction (XRD) and Raman spectroscopy measurements. Phase boundaries were established by characterizing phase transitions to the high temperature polymorphs during multiple P-T measurements using both XRD and Raman spectroscopy measurements. At room temperature, the ambient pressure orthorhombic (Pmmn) AN-IV phase was stable up to 45 GPa and no phase transitions were observed. AN-IV phase was also observed to be stable in a large P-T phase space. The phase boundaries are steep with a small phase stability regime for high temperature phases. A P-V-T equation of state based on a high temperature Birch-Murnaghan formalism was obtained by simultaneously fitting the P-V isotherms at 298, 325, 446, and 467 K, thermal expansion data at 1 bar, and volumes from P-T ramping experiments. Anomalous thermal expansion behavior of AN was observed at high pressure with a modest negative thermal expansion in the 3-11 GPa range for temperatures up to 467 K. The role of vibrational anharmonicity in this anomalous thermal expansion behavior has been established using high P-T Raman spectroscopy.

High-temperature investigation on morphology, phase and size of iron/iron-oxide core–shell nanoclusters for radiation nanodetector

NASA Astrophysics Data System (ADS)

Khanal, Lokendra Raj; Williams, Thomas; Qiang, You

2018-06-01

Iron/iron-oxide (Fe–Fe3O4) core–shell nanoclusters (NCs) synthesized by a cluster deposition technique were subjected to a study of their high temperature structural and morphological behavior. Annealing effects have been investigated up to 800 °C in vacuum, oxygen and argon environments. The ~18 nm average size of the as-prepared NCs increases slowly in temperatures up to 500 °C in all three environments. The size increases abruptly in the argon environment but slowly in vacuum and oxygen when annealed at 800 °C. The x-ray diffraction (XRD) studies have shown that the iron core remains in the core–shell NCs only when they were annealed in the vacuum. A dramatic change in the surface morphology, an island like structure and/or a network like pattern, was observed at the elevated temperature. The as-prepared and annealed samples were analyzed using XRD, scanning electron microscopy and imageJ software for a close inspection of the temperature aroused properties. This work presents the temperature induced size growth mechanism, oxidation kinetics and phase transformation of the NCs accompanied by cluster aggregation, particle coalescence, and diffusion.

Impedance spectroscopic and dielectric properties of nanosized Y2/3Cu3Ti4O12 ceramic

NASA Astrophysics Data System (ADS)

Sharma, Sunita; Yadav, Shiv Sundar; Singh, M. M.; Mandal, K. D.

2014-11-01

Yttrium Copper Titanate (Y2/3Cu3Ti4O12) nanoceramic is structurally analogous to CaCu3Ti4O12 (CCTO). X-ray diffraction (XRD) of Y2/3Cu3Ti4O12 (YCTO) shows the presence of all normal peaks of CCTO. SEM micrograph exhibits the presence of bimodal grains of size ranging from 1-2 μm. Bright field TEM image clearly displays nanocrystalline particle which is supported by presence of a few clear rings in the corresponding selected area electron diffraction (SAED) pattern. It exhibits a high value of dielectric constant (ɛ‧ = 8434) at room temperature and 100 Hz frequency with characteristic relaxation peaks. Impedance and modulus studies revealed the presence of temperature-dependent Maxwell-Wagner type of relaxation in the ceramic.

Thermal stability in the blended lithium manganese oxide – Lithium nickel cobalt manganese oxide cathode materials: An in situ time-resolved X-Ray diffraction and mass spectroscopy study

DOE PAGES

Hu, Enyuan; Bak, Seong Min; Senanayake, Sanjaya D.; ...

2015-03-01

Thermal stabilities of a series of blended LiMn 2O 4(LMO)-LiNi 1/3Co 1/3Mn 1/3O 2 (NCM) cathode materials with different weight ratios were studied by in situ time-resolved X-ray diffraction (XRD) combined with mass spectroscopy in the temperature range of 25°C-580°C under helium atmosphere. Upon heating, the electrochemically delithiated LMO changed into Mn 3O 4 phase at around 250°C. Formation of MnO with rocksalt structure started at 520°C. This observation is in contrast to the previous report for chemically delithiate LMO in air, in which a process of λ-MnO 2 transforming to β-MnO 2 was observed. Oxygen peak was not observedmore » in all cases, presumably as a result of either consumption by the carbon or detection limit. CO 2 profile correlates well with the phase transition and indirectly suggests the oxygen release of the cathode. Introducing NCM into LMO has two effects: first, it makes the high temperature rock-salt phase formation more complicated with more peaks in CO 2 profile due to different MO (M = Ni, Mn, Co) phases; secondly, the onset temperature of CO 2 release is lowered, implying lowered oxygen release temperature. Upon heating, XRD patterns indicate the NCM part reacts first, followed by the LMO part. This confirms the better thermal stability of LMO over NCM.« less

Properties of cellulase as template molecule on chitosan—methyl methacrylate membrane

NASA Astrophysics Data System (ADS)

Lian, Qi; Zheng, Xuefang; Wu, Haixia; Song, Shitao; Wang, Dongjun

2015-12-01

In this study, a novel molecular imprinting membrane made of chitosan and methyl methacrylate (MMA) was fabricated with cellulase as template molecule and the thermal response to cellulase was characterized. The film was characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and the permeation experiment. The results showed that the space structure of the film was as similar as the cellulase. Moreover, the membrane had advanced molecular imprinting capability to cellulase comparing to pepsin and pectinase at any temperature and the film had excellent ability to identify specific template molecule (cellulase) at the synthesis temperature compared to other temperatures.

Temperature dependent x-ray diffraction and dielectric studies of multiferroic GaFeO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Rajeev; Mall, Ashish Kumar, E-mail: ashishm@iitk.ac.in; Gupta, Rajeev

2016-05-06

Polycrystalline GaFeO{sub 3} (GFO) samples were synthesized by sol-gel method. The structural and dielectric properties of GaFeO{sub 3} ceramic have been investigated by a combination of XRD and permittivity measurement. The X-ray diffraction spectra shows single phase orthorhombically distorted perovskite structure with Pc2{sub 1}n symmetry over a wide range of temperature 300 K to 600 K, with no evidence of any phase transition. Refined lattice parameters (a, b, c and V) increases with increasing temperature. Temperature dependent dielectric properties were investigated in the frequency range from 100Hz–5MHz. Impedance spectroscopy study on the sample showed that the dielectric constant and acmore » conductivity with frequency increases on increasing the temperature. Cole-Cole plots suggest that the response from grain is dominant at low temperature whereas grain boundary response overcomes as temperature increases. The relaxation activation energy (calculated from Cole-Cole plots) value is found to be 0.32 eV for the grain boundary. We believe that the oxygen ion vacancies play an important role in conduction processes at higher temperatures.« less

Optical and dielectric properties of NiFe2O4 nanoparticles under different synthesized temperature

NASA Astrophysics Data System (ADS)

Parishani, Marziye; Nadafan, Marzieh; Dehghani, Zahra; Malekfar, Rasoul; Khorrami, G. H. H.

In this research, NiFe2O4 nanoparticles was prepared via the simple sol-gel route, using different sintering temperature. This nanoparticle was characterized via X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM), and FTIR spectra. The XRD patterns show by increasing the synthesized temperature, the intensity, and broadening of peaks are decreased so the results are more crystallization and raising the size of nanoparticles. The size distribution in the histogram of the NiFe2O4 nanoparticles is 42, 96, and 315 nm at 750 °C, 850 °C, and 950 °C, respectively. The FTIR spectra were evaluated using Kramers-Kronig method. Results approved the existing of certain relations between sintering temperatures and grain size of nanoparticles. By raising the temperature from 750 °C to 950 °C, the grain size was increased from 70 nm to 300 nm and the optical constants of nanoparticles were strongly related to synthesizing temperature as well. Since by increasing temperature, both real/imaginary parts of the refractive index and dielectric function were decreased. Consequently, the transversal (TO) and longitudinal (LO) phonon frequencies are detected. The TO and LO frequencies have shifted to red frequencies by increasing reaction temperature.

High temperature electrical resistivity and Seebeck coefficient of Ge2Sb2Te5 thin films

NASA Astrophysics Data System (ADS)

Adnane, L.; Dirisaglik, F.; Cywar, A.; Cil, K.; Zhu, Y.; Lam, C.; Anwar, A. F. M.; Gokirmak, A.; Silva, H.

2017-09-01

High-temperature characterization of the thermoelectric properties of chalcogenide Ge2Sb2Te5 (GST) is critical for phase change memory devices, which utilize self-heating to quickly switch between amorphous and crystalline states and experience significant thermoelectric effects. In this work, the electrical resistivity and Seebeck coefficient are measured simultaneously as a function of temperature, from room temperature to 600 °C, on 50 nm and 200 nm GST thin films deposited on silicon dioxide. Multiple heating and cooling cycles with increasingly maximum temperature allow temperature-dependent characterization of the material at each crystalline state; this is in contrast to continuous measurements which return the combined effects of the temperature dependence and changes in the material. The results show p-type conduction (S > 0), linear S(T), and a positive Thomson coefficient (dS/dT) up to melting temperature. The results also reveal an interesting linearity between dS/dT and the conduction activation energy for mixed amorphous-fcc GST, which can be used to estimate one parameter from the other. A percolation model, together with effective medium theory, is adopted to correlate the conductivity of the material with average grain sizes obtained from XRD measurements. XRD diffraction measurements show plane-dependent thermal expansion for the cubic and hexagonal phases.

Investigation of La and Al substitution on the spontaneous polarization and lattice dynamics of the Pb(1-x)LaxTi(1-x)AlxO3 ceramics

NASA Astrophysics Data System (ADS)

Yadav, Arun Kumar; Verma, Anita; Kumar, Sunil; Srihari, Velaga; Sinha, A. K.; Reddy, V. Raghavendra; Liu, Shun Wei; Biring, Sajal; Sen, Somaditya

2018-03-01

The phase purity and crystal structure of Pb(1-x)LaxTi(1-x)AlxO3 (0 ≤ x ≤ 0.25) samples (synthesized via the sol-gel process) were confirmed using synchrotron x-ray powder diffraction (XRD) (wavelength, λ = 0.44573 Å). Rietveld analyses of powder x-ray diffraction data confirmed the tetragonal structure for compositions with x ≤ 0.18 and cubic structure for the sample with x = 0.25. Temperature-dependent XRD was performed to investigate the structural change from tetragonal to cubic structure phase transition. Raman spectroscopy at room temperature also confirmed this phase transition with compositions. Field emission scanning electron microscopy (FESEM) provided information about the surface morphology while an energy dispersive x-ray spectrometer attached with FESEM confirmed the chemical compositions of samples. Temperature and frequency dependent dielectric studies showed that the tetragonal to cubic phase transition decreased from 680 K to 175 K with an increase in the x from 0.03 to 0.25, respectively. This is correlated with the structural studies. Electric field dependent spontaneous polarization showed a proper ferroelectric loop for 0.06 ≤ x ≤ 0.18 belonging to a tetragonal phase, while for x ≥ 0.25, the spontaneous polarization vanishes. Bipolar strain versus electric field revealed a butterfly loop for 0.06 ≤ x ≤ 0.18 compositions. Energy storage efficiency initially increases nominally with substitution but beyond x = 0.18 enhances considerably.

Nonlinear electrostrictive lattice response of EuTiO3

NASA Astrophysics Data System (ADS)

Pappas, P.; Calamiotou, M.; Köhler, J.; Bussmann-Holder, A.; Liarokapis, E.

2017-07-01

An epitaxial EuTiO3 (ETO) film grown on the SrTiO3 substrate was studied at room temperature with synchrotron XRD and in situ application of an electric field (nominally up to 7.8 kV/cm) in near grazing incidence geometry, in order to monitor the response of the lattice to the field. 2D diffraction images show that apparently misoriented coherently diffracting domains are present close to the surface whereas the film diffracts more as a single crystal towards the interface. Diffraction intensity profiles recorded from the near surface region of the EuTiO3 film showed systematic modifications upon the application of the electric field, indicating that at a critical electric field (nominally above 3.1 kV/cm), there is a clear change in the lattice response to the field, which was much stronger when the field was almost parallel to the diffraction vector. The data suggest that the ETO film, nominally paraelectric at room temperature, transforms under the application of a critical electric field to piezoelectric in agreement with a theoretical analysis based on a double-well potential. In order to exclude effects arising from the substrate, this has been investigated separately and shown not to be affected by the field.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asha, S.; Sangappa,; Sanjeev, Ganesh, E-mail: ganeshanjeev@rediffmail.com

Radiation-induced changes in Bombyx mori silk fibroin (SF) films under electron irradiation were investigated and correlated with dose. SF films were irradiated in air at room temperature using 8 MeV electron beam in the range 0-150 kGy. Various properties of the irradiated SF films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Electron irradiation was found to induce changes in the physical and thermal properties, depending on the radiation dose.

Remote In-Situ Quantitative Mineralogical Analysis Using XRD/XRF

NASA Technical Reports Server (NTRS)

Blake, D. F.; Bish, D.; Vaniman, D.; Chipera, S.; Sarrazin, P.; Collins, S. A.; Elliott, S. T.

2001-01-01

X-Ray Diffraction (XRD) is the most direct and accurate method for determining mineralogy. The CHEMIN XRD/XRF instrument has shown promising results on a variety of mineral and rock samples. Additional information is contained in the original extended abstract.

Room temperature ferromagnetism of nanocrystalline Nd1.90Ni0.10O3-δ

NASA Astrophysics Data System (ADS)

Sarkar, B. J.; Mandal, J.; Dalal, M.; Bandyopadhyay, A.; Chakrabarti, P. K.

2018-05-01

Nanocrystalline sample of Ni2+ doped neodymium oxide (Nd1.90Ni0.10O3-δ, NNO) is synthesized by co-precipitation method. Analysis of X-ray diffraction (XRD) pattern by Rietveld refinement method confirms the desired phase of NNO and complete substitution of Ni2+ ions in the Nd2O3 lattice. Analyses of transmission electron microscopy (TEM) and Raman spectroscopy of NNO recorded at room temperature (RT) also substantiate this fact. Besides, no traces of impurities are found in the analyses of XRD, TEM and Raman data. Room temperature hysteresis loop of NNO suggests the presence of weak ferromagnetism (FM) in low field region ( 600 mT), but in high field region paramagnetism of the host is more prominent. Magnetization vs. temperature ( M- T) curve in the entire temperature range (300-5 K) is analyzed successfully by a combined equation generated from three-dimensional (3D) spin wave model and Curie-Weiss law, which suggests the presence of mixed paramagnetic phase together with ferromagnetic phase in the doped sample. The onset of magnetic ordering is analyzed by oxygen vacancy mediated F-center exchange (FCE) coupling mechanism.

Multivariate analysis of DSC-XRD simultaneous measurement data: a study of multistage crystalline structure changes in a linear poly(ethylene imine) thin film.

PubMed

Kakuda, Hiroyuki; Okada, Tetsuo; Otsuka, Makoto; Katsumoto, Yukiteru; Hasegawa, Takeshi

2009-01-01

A multivariate analytical technique has been applied to the analysis of simultaneous measurement data from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) in order to study thermal changes in crystalline structure of a linear poly(ethylene imine) (LPEI) film. A large number of XRD patterns generated from the simultaneous measurements were subjected to an augmented alternative least-squares (ALS) regression analysis, and the XRD patterns were readily decomposed into chemically independent XRD patterns and their thermal profiles were also obtained at the same time. The decomposed XRD patterns and the profiles were useful in discussing the minute peaks in the DSC. The analytical results revealed the following changes of polymorphisms in detail: An LPEI film prepared by casting an aqueous solution was composed of sesquihydrate and hemihydrate crystals. The sesquihydrate one was lost at an early stage of heating, and the film changed into an amorphous state. Once the sesquihydrate was lost by heating, it was not recovered even when it was cooled back to room temperature. When the sample was heated again, structural changes were found between the hemihydrate and the amorphous components. In this manner, the simultaneous DSC-XRD measurements combined with ALS analysis proved to be powerful for obtaining a better understanding of the thermally induced changes of the crystalline structure in a polymer film.

Influence of Synthesis Temperature on the Growth and Surface Morphology of Co₃O₄ Nanocubes for Supercapacitor Applications.

PubMed

Samal, Rashmirekha; Dash, Barsha; Sarangi, Chinmaya Kumar; Sanjay, Kali; Subbaiah, Tondepu; Senanayake, Gamini; Minakshi, Manickam

2017-10-31

A facile hydrothermal route to control the crystal growth on the synthesis of Co₃O₄ nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co₃O₄ nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co₃O₄ synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes.

Reentrant behaviour in polyvinyl alcohol-borax hydrogels

NASA Astrophysics Data System (ADS)

Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

2018-01-01

Polyvinyl alcohol (PVA) hydrogels, cross-linked with varying concentrations of borax, were studied with small angle neutron scattering (SANS), x-ray diffraction (XRD) and differential thermal analysis (DTA). The SANS data satisfy the Ornstein-Zernike approximation. The hydrogels are modelled as PVA chains bound by borate cross-links. Water occupies the spaces within the three-dimensional hydrogel network. The mesh size ξ indicates reentrant behaviour i.e. at first, ξ increases and later decreases as a function of borax concentration. The behaviour is explained on the basis of the balance between the charged di-diol cross-links and the shielding by free ions in the solvent. XRD and DTA show the molecular size of water in the solvent and the glass transition temperature commensurate with reentrant behaviour.

Structural and morphological study of chemically synthesized CdSe thin films

NASA Astrophysics Data System (ADS)

Agrawal, P.; Singh, Randhir; Sharma, Jeewan; Sachdeva, M.; Singh, Anupinder; Bhargava, A.

2018-05-01

Nanocrystalline CdSe thin films were prepared by Chemical Bath Deposition (CBD) method using potassium nitrilo-triacetic acid cadmium complex and sodium selenosulphite. The as deposited films were red in color, uniform and well adherent to the glass substrate. These films were strongly dependent on the deposition parameters such as bath composition, deposition temperature and time. Films were annealed at 350 °C for four hours. The morphological, structural and optical properties were studied using X-ray diffraction (XRD), UV-VIS spectrophotometer measurements, scanning electron microscopy and atomic force microscopy. The XRD analysis confirmed that films are predominantly in hexagonal phase. Scanning electron micrograph shows that the grains are uniformly spread all over the film and each grain contains many nanocrystals with spherical shapes.

DSC and Raman studies of silver borotellurite glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, Amandeep; Khanna, Atul, E-mail: atul.phy@gndu.ac.in; Gonzàlez, Fernando

2016-05-23

Silver borotellurite glasses of composition: xAg{sub 2}O-yB{sub 2}O{sub 3}-(100-x-y)TeO{sub 2} (x=20-mol%, y = 0, 10, 20 and 30-mol%) were prepared and characterized by density, X-ray diffraction (XRD), differential scanning calorimetry, and Raman spectroscopy. XRD confirmed the amorphous structure of all samples. Density of glasses decreases while the glass transition temperature increases with increase in B{sub 2}O{sub 3} content from 10 to 30-mol%. Raman study shows that coordination number of Te with oxygen decreases steadily from 3.42 to 3.18 on adding B{sub 2}O{sub 3} due to the transformation of TeO{sub 4} into TeO{sub 3} units.

Synthesis of TiN/a-Si3N4 thin film by using a Mather type dense plasma focus system

NASA Astrophysics Data System (ADS)

Hussain, T.; R., Ahmad; Khalid, N.; A. Umar, Z.; Hussnain, A.

2013-05-01

A 2.3 kJ Mather type pulsed plasma focus device was used for the synthesis of a TiN/a-Si3N4 thin film at room temperature. The film was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The XRD pattern confirms the growth of polycrystalline TiN thin film. The XPS results indicate that the synthesized film is non-stoichiometric and contains titanium nitride, silicon nitride, and a phase of silicon oxy-nitride. The SEM and AFM results reveal that the surface of the synthesized film is quite smooth with 0.59 nm roughness (root-mean-square).

Synthesis and characterization of Ce, Cu co-doped ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Harish, G. S.; Sreedhara Reddy, P.

2015-09-01

Ce, Cu co-doped ZnS nanoparticles were prepared at room temperature using a chemical co-precipitation method. The prepared nanoparticles were characterized by X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and high resolution Raman spectroscopic techniques. Transmission electron microscopy (TEM) and X-ray diffraction studies showed that the diameter of the particles was around 2-3 nm. Broadened XRD peaks revealed the formation of nanoparticles with a face centered cubic (fcc) structure. DRS studies confirmed that the band gap increased with an increase in the dopant concentration. The Raman spectra of undoped and Ce, Cu ions co-doped ZnS nanoparticles showed longitudinal optical mode and transverse optical mode. Compared with the Raman modes (276 and 351 cm-1) of undoped ZnS nanoparticles, the Raman modes of Ce, Cu co- doped ZnS nanoparticles were slightly shifted towards lower frequency. PL spectra of the samples showed remarkable enhancement in the intensity upon doping.

FTIR spectroscopic, thermal and XRD characterization of hydroxyapatite from new natural sources

NASA Astrophysics Data System (ADS)

Shaltout, Abdallah A.; Allam, Moussa A.; Moharram, Mohamed A.

2011-12-01

The inorganic constituents of 5 different plants (leaves and stalks) were investigated by using Fourier transformer infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal analysis including thermal gravimetric analysis (TGA), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC). These plants are Catha edulis (Khat), basil, mint, green tea and trifolium. The absorption bands of carbonate ions CO 32- was exhibited at 1446 cm -1, and the phosphate ions PO 43- was assigned at 1105 and 1035 cm -1. At high temperatures (600, 700 and 600 °C) further absorption bands of the phosphate ions PO 43- was assigned at the frequencies 572, 617, 962, 1043 and 1110 cm -1 and the vibrational absorption band of the carbonate ions CO 32- was assigned at 871, 1416 and 1461 cm -1. X-ray diffraction and thermal analysis confirm the obtained results of FITR. Results showed that the main inorganic constituents of C. edulis and basil leaves are hydroxyapatite whereas the hydroxyapatite content in the other plant samples is less than that in case of C. edulis and basil plant leaves.

Frequency dependent dielectric properties of combustion synthesized Dy2Ti2O7 pyrochlore oxide

NASA Astrophysics Data System (ADS)

Jeyasingh, T.; Saji, S. K.; Kavitha, V. T.; Wariar, P. R. S.

2018-05-01

Nanocrystalline pyrochlore material Dysprosium Titanate (Dy2Ti2O7) has been synthesized through a single step optimized combustion route. The phase purity and phase formation of the combustion product has been characterized using X-Ray diffraction analysis (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) analysis. X-Ray diffraction analysis (XRD) reveal that Dy2Ti2O7 is highly crystalline in nature with cubic structure in the Fd3m space group. The microstructures and average particle size of the prepared nanopowder were examined by High Resolution Transmission Electron Microscopy (HR-TEM). The optical band gap of the Dy2Ti2O7 nanoparticles is determined from the absorption spectrum, was attributed to direct allowed transitions through optical band gap of 3.98 eV. The frequency dependent dielectric measurements have been carried out on the sintered pellet in the frequency range 1 Hz-10 MHz. The measured value of dielectric constant (ℇ') was ˜ 43 and loss tangent (tan δ) was 4×10-3 at 1 MHz, at room temperature.

Green synthesis of gold and silver nanoparticles using Hibiscus rosa sinensis

NASA Astrophysics Data System (ADS)

Philip, Daizy

2010-03-01

Biological synthesis of gold and silver nanoparticles of various shapes using the leaf extract of Hibiscus rosa sinensis is reported. This is a simple, cost-effective, stable for long time and reproducible aqueous room temperature synthesis method to obtain a self-assembly of Au and Ag nanoparticles. The size and shape of Au nanoparticles are modulated by varying the ratio of metal salt and extract in the reaction medium. Variation of pH of the reaction medium gives silver nanoparticles of different shapes. The nanoparticles obtained are characterized by UV-vis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR spectroscopy. Crystalline nature of the nanoparticles in the fcc structure are confirmed by the peaks in the XRD pattern corresponding to (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes, bright circular spots in the selected area electron diffraction (SAED) and clear lattice fringes in the high-resolution TEM image. From FTIR spectra it is found that the Au nanoparticles are bound to amine groups and the Ag nanoparticles to carboxylate ion groups.

Graphene/semicrystalline-carbon derived from amylose films for supercapacitor application

NASA Astrophysics Data System (ADS)

Deraman, M.; Sazali, N. E. S.; Hanappi, M. F. Y. M.; Tajuddin, N. S. M.; Hamdan, E.; Suleman, M.; Othman, M. A. R.; Omar, R.; Hashim, M. A.; Basri, N. H.; Nor, N. S. M.; Dolah, B. N. M.; Noor, A. M.; Jasni, M. R. M.

2016-08-01

Graphene/semicrystalline-carbon in the form of carbon flakes is produced by carbonization up to 600, 700, 800, 900 and 1000°C, respectively, of the amylose films prepared by a casting method on copper foil substrate. The carbon flakes are characterized by X-ray diffraction (XRD) method to determine their microcrystallite interlayer spacing, width and stack-height; and Raman spectroscopy (RS) method to obtain structural information from the D-, D2- and G-bands peak-intensities. The XRD results show that increase in carbonization temperature lead to ~(1-3%), ~85% and ~30%increase in the microcrystallites interlayer spacing, width and stack-height, respectively, indicating that a larger growth of microcrytallite of carbon flakes occurs in the direction parallel to (001) plane or film planar surface. The specific surface area of carbon flakes estimated from the XRD results in decreases from ~4400 to ~3400 m2/g, corresponding to the specific capacitance between ~500 to ~400 F/g, which are well within the range of specific capacitance for typical electrodes carbon for supercapacitor application. The RS results show that the multilayer graphene co-exist with semicrystalline- carbon within the carbon flakes, with the multilayer graphene relative quantities increase with increasing carbonization temperature.

Structural, magnetic and electronic structural properties of Mn doped CeO2 nanoparticles

NASA Astrophysics Data System (ADS)

Kumari, Kavita; Vij, Ankush; Hashim, Mohd.; Chae, K. H.; Kumar, Shalendra

2018-05-01

Nanoparticles of Ce1-xMnxO2, (x=0.0, 0.01, and 0.05) have been synthesized by using co-precipitation method, and then characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), near edge x-ray absorption fine structure (NEXAFS) spectroscopy and dc magnetization measurements. XRD results clearly showed that the all the samples have single phase nature and exclude the presence of any secondary phase. The average particle size calculated using XRD TEM measurements found to decrease with increase in Mn doping in the range of 4.0 - 9.0 nm. The structural parameters such as strain, interplaner distance and lattice parameter is observed to decrease with increase in doping. The morphology of Ce1-xMnxO2 nanoparticles measured using TEM micrographs indicate that nanoparticle have spherical shape morphology. Magnetic hysteresis curve for Ce1-xMnxO2, (x = 0.0, 0.01, and 0.05) confirms the ferromagnetic ordering room temperature. The value of saturation magnetization is observed to decrease with increase in temperature from 10 K to 300 K. The NEXAFS spectra measured at Ce M4,5 edge reveals that Ce-ions are in +4 valance state.

[Study on Hydrothermal Preparation and Luminescence Properties of Luminescent Material BaSrMg(PO₄)₂:Eu³⁺].

PubMed

Hu, Qing-song; Zhu, Cheng-jing; Xia, Yue-yi; Wang, Li-li; Liu, Wen-han; Pan, Zai-fa

2016-02-01

Eu³⁺ doped BaSrMg (PO₄)₂ were prepared by a hydrothermal method. The crystal structure and morphology of BaSrMg(PO₄)₂:Eu³⁺ phosphor were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM). The effects of different pH values (5, 6, 7 and 8) and different reaction temperatures (120, 140, 160, 180 and 200 °C) on the crystal structure and morphology of BaSrMg(PO₄)₂:Eu³⁺ phosphor were studied in this paper. The results of XRD indicate that diffraction peaks are sharp and strong only when pH value is 6, meanwhile the FESEM shows the morphology is regular-shaped. The XRD patterns show amorphous halos superimposed with several weak sharp peaks for the samples preparing under the pH values of 5, 7 and 8. It indicates that these three samples are solid solution or mixed phases, which are in accord with the results of FESEM. From the fluorescence spectra, the peaks in the excitation spectra were assigned to the transition from ⁷F₀ to ⁵D₄, ⁵L₈, ⁵L₆ and ⁵D₂, while the peaks of emission spectra corresponding to the transition of ⁵D₁ --> ⁷F₁ and ⁵D₀-->⁷Fj (J = 0, 1, 2, 3 and 4). The strongest emission peak of the optimized phosphor located at 613 nm (⁵D0--> ⁷F₂), excited by the main excitation peak with wavelength of 394 nm. The splitting of the emission peaks changes depends on pH values and temperatures, which indicating that luminescence properties is closely related to the crystal structure and morphology of particles.

Correlation of x-ray diffraction and Mössbauer effect measurements with magnetic properties of heat-treated Cu80Co15Fe5 ribbons

NASA Astrophysics Data System (ADS)

Harris, V. G.; Rubinstein, M.; Das, B. N.; Koon, N. C.

1994-05-01

X-ray diffraction (XRD) and Mössbauer Effect (ME) measurements were performed on heat-treated Cu80Co15Fe5 melt-spun ribbons in an attempt to understand the trends in magnetic properties with heat treatment. ME measurements indicate that the majority of Fe atoms (86%) occupy sites in ferromagnetic FCC CoFe clusters after the initial quench. A heat treatment at 900 °C acts to complete the chemical separation of Fe from the Cu matrix. The presence of Co in the Cu matrix, even after high temperature anneals, provides a paramagnetic component that prohibits saturation even at high fields.

Substrate temperature effects on the structure and properties of ZnMnO films prepared by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Riascos, H.; Duque, J. S.; Orozco, S.

2017-01-01

ZnMnO thin films were grown on silicon substrates by pulsed laser deposition (PLD). Pulsed Nd:YAG laser was operated at a wavelength of 1064 nm and 100 mJ. ZnMnO thin films were deposited at the vacuum pressure of 10-5 Torr and with substrate temperature from room temperature to 600 °C. The effects of substrate temperature on the structural and Optical properties of ZnMnO thin films have been investigated by X-ray diffraction (XRD), Raman spectroscopy and Uv-vis spectroscopy. From XRD data of the samples, it can be showed that temperature substrate does not change the orientation of ZnMnO thin films. All the films prepared have a hexagonal wurtzite structure, with a dominant (002) peak around 2θ=34.44° and grow mainly along the c-axis orientation. The substrate temperature improved the crystallinity of the deposited films. Uv-vis analysis showed that, the thin films exhibit high transmittance and low absorbance in the visible region. It was found that the energy band to 300 ° C is 3.2 eV, whereas for other temperatures the values were lower. Raman reveals the crystal quality of ZnMnO thin films.

Effects of surface morphology of ZnO seed layers on growth of ZnO nanostructures prepared by hydrothermal method and annealing.

PubMed

Yim, Kwang Gug; Kim, Min Su; Leem, Jae-Young

2013-05-01

ZnO nanostructures were grown on Si (111) substrates by a hydrothermal method. Prior to growing the ZnO nanostructures, ZnO seed layers with different post-heat temperatures were prepared by a spin-coating process. Then, the ZnO nanostructures were annealed at 500 degrees C for 20 min under an Ar atmosphere. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) were carried out at room temperature (RT) to investigate the structural and optical properties of the as-grown and annealed ZnO nanostructures. The surface morphologies of the seed layers changed from a smooth surface to a mountain chain-like structure as the post-heating temperatures increased. The as-grown and annealed ZnO nanostructures exhibited a strong (002) diffraction peak. Compared to the as-grown ZnO nanostructures, the annealed ZnO nanostructures exhibited significantly strong enhancement in the PL intensity ratio by almost a factor of 2.

Monitoring of CoS 2 reactions using high-temperature XRD coupled with gas chromatography (GC)

DOE PAGES

Rodriguez, Mark A.; Coker, Eric Nicholas; Griego, James J. M.; ...

2016-04-18

High-temperature X-ray diffraction with concurrent gas chromatography (GC) was used to study cobalt disulfide cathode pellets disassembled from thermal batteries. When CoS 2 cathode materials were analyzed in an air environment, oxidation of the K(Br, Cl) salt phase in the cathode led to the formation of K 2SO 4 that subsequently reacted with the pyrite-type CoS 2 phase leading to cathode decomposition between ~260 and 450 °C. Here, independent thermal analysis experiments, i.e. simultaneous thermogravimetric analysis/differential scanning calorimetry/mass spectrometry (MS), augmented the diffraction results and support the overall picture of CoS 2 decomposition. Both gas analysis measurements (i.e. GC andmore » MS) from the independent experiments confirmed the formation of SO 2 off-gas species during breakdown of the CoS 2. In contrast, characterization of the same cathode material under inert conditions showed the presence of CoS 2 throughout the entire temperature range of analysis.« less

Aloe vera plant-extracted solution hydrothermal synthesis and magnetic properties of magnetite (Fe3O4) nanoparticles

NASA Astrophysics Data System (ADS)

Phumying, Santi; Labuayai, Sarawuth; Thomas, Chunpen; Amornkitbamrung, Vittaya; Swatsitang, Ekaphan; Maensiri, Santi

2013-06-01

Magnetite (Fe3O4) nanoparticles have been successfully synthesized by a novel hydrothermal method using ferric acetylacetonate (Fe(C5H8O2)3) and aloe vera plant-extracted solution. The influences of different reaction temperatures and times on the structure and magnetic properties of the synthesized Fe3O4 nanoparticles were investigated. The synthesized nanoparticles are crystalline and have particle sizes of ˜6-30 nm, as revealed by transmission electron microscopy (TEM). The results of X-ray diffraction (XRD), High resolution TEM (HRTEM) and selected area electron diffraction (SAED) indicate that the synthesized Fe3O4 nanoparticles have the inverse cubic spinel structure without the presence of any other phase impurities. The hysteresis loops of the Fe3O4 nanoparticles at room temperature show superparamagnetic behavior and the saturation magnetization of the Fe3O4 samples increases with increasing reaction temperature and time.

Radiation-Induced Changes in Quartz, A Mineral Analog of Nuclear Power Plant Concrete Aggregates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, Chinthaka M.; Rosseel, Thomas M.; Kirkegaard, Marie C.

Quartz single-crystal samples consisting of α-quartz crystal structure were neutron irradiated to fluences of 5 × 10 18, 4 × 10 19, and 2 × 10 20 n/cm 2 (E > 0.1 MeV) at two temperatures (52 and 95 °C). The changes in the α-quartz phase as a function of these two conditions (temperature and fluence) were studied using X-ray powder diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM), and the results acquired using these complementary techniques are presented in a single place for the first time. XRD studies showed that the lattice parameters of α-quartz increased with increasingmore » neutron flux. The lattice growth was larger for the samples that were neutron irradiated at 52 °C than at 95 °C. Moreover, an amorphous content was determined in the quartz samples neutron irradiated at 4 × 10 19 n/cm 2, with the greater amount being in the 52 °C irradiated sample. Complete amorphization of quartz was observed at a fluence of 2 × 10 20 n/cm 2 (E > 0.1 MeV) using XRD and confirmed by TEM characterization and Raman spectroscopic studies. In conclusion, the cause for α-quartz lattice expansion and sample amorphization was also explored using XRD and Raman spectroscopic studies.« less

Radiation-Induced Changes in Quartz, A Mineral Analog of Nuclear Power Plant Concrete Aggregates

DOE PAGES

Silva, Chinthaka M.; Rosseel, Thomas M.; Kirkegaard, Marie C.

2018-03-07

Quartz single-crystal samples consisting of α-quartz crystal structure were neutron irradiated to fluences of 5 × 10 18, 4 × 10 19, and 2 × 10 20 n/cm 2 (E > 0.1 MeV) at two temperatures (52 and 95 °C). The changes in the α-quartz phase as a function of these two conditions (temperature and fluence) were studied using X-ray powder diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM), and the results acquired using these complementary techniques are presented in a single place for the first time. XRD studies showed that the lattice parameters of α-quartz increased with increasingmore » neutron flux. The lattice growth was larger for the samples that were neutron irradiated at 52 °C than at 95 °C. Moreover, an amorphous content was determined in the quartz samples neutron irradiated at 4 × 10 19 n/cm 2, with the greater amount being in the 52 °C irradiated sample. Complete amorphization of quartz was observed at a fluence of 2 × 10 20 n/cm 2 (E > 0.1 MeV) using XRD and confirmed by TEM characterization and Raman spectroscopic studies. In conclusion, the cause for α-quartz lattice expansion and sample amorphization was also explored using XRD and Raman spectroscopic studies.« less

[Based on Curing Age of Calcined Coal Gangue Fine Aggregate Mortar of X-Ray Diffraction and Scanning Electron Microscopy Analysis].

PubMed

Dong, Zuo-chao; Xia, Jun-wu; Duan, Xiao-mu; Cao, Ji-chang

2016-03-01

By using X-ray diffraction (XRD) and environmental scanning electron microscope (SEM) analysis method, we stud- ied the activity of coal gangue fine aggregate under different calcination temperature. In view of the activity of the highest-700 degrees C high temperature calcined coal gangue fine aggregate mortar of hydration products, microstructure and strength were discussed in this paper, and the change laws of mortar strength with curing age (3, 7, 14, 28, 60 and 90 d) growth were analyzed. Test results showed that coal gangue fine aggregate with the increase of calcination temperature, the active gradually increases. When the calcination temperature reaches 700 degrees C, the activity of coal gangue fine aggregate is the highest. When calcining temperature continues to rise, activity falls. After 700 degrees C high temperature calcined coal gangue fine aggregate has obvious ash activity, the active components of SiO2 and Al2 O3 can be with cement hydration products in a certain degree of secondary hydration reaction. Through on the top of the activity of different curing age 700 degrees C high temperature calcined coal gangue fine aggregate mortar, XRD and SEM analysis showed that with the increase of curing age, secondary hydration reaction will be more fully, and the amount of hydration products also gradually increases. Compared with the early ages of the cement mortar, the products are more stable hydration products filling in mortar microscopic pore, which can further improve the microstructure of mortar, strengthen the interface performance of the mortar. The mortar internal structure is more uniform, calcined coal gangue fine aggregate and cement mortar are more of a strong continuous whole, which increase the later strength of hardened cement mortar, 700 degrees C high temperature calcined coal gangue fine aggregate pozzolanic effect is obvious.

Roosevelt Hot Springs, Utah FORGE X-Ray Diffraction Data

DOE Data Explorer

Nash, Greg; Jones, Clay

2018-02-07

This dataset contains X-ray diffraction (XRD) data taken from wells and outcrops as part of the DOE GTO supported Utah FORGE project located near Roosevelt Hot Springs. It contains an Excel spreadsheet with the XRD data, a text file with sample site names, types, and locations in UTM, Zone 12, NAD83 coordinates, and a GIS shapefile of the sample locations with attributes.

Relative impact of H 2 O and O 2 in the oxidation of UO 2 powders from 50 to 300 °C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donald, Scott B.; Davisson, M. Lee; Dai, Zurong

Here, we studied the reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO 2) powder at elevated temperature by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). We observed and quatified oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.

Annealing effect and photovoltaic properties of nano-ZnS/textured p-Si heterojunction.

PubMed

Ji, Liang-Wen; Hsiao, Yu-Jen; Tang, I-Tseng; Meen, Teen-Hang; Liu, Chien-Hung; Tsai, Jenn-Kai; Wu, Tien-Chuan; Wu, Yue-Sian

2013-11-09

The preparation and characterization of heterojunction solar cell with ZnS nanocrystals synthesized by chemical bath deposition method were studied in this work. The ZnS nanocrystals were characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Lower reflectance spectra were found as the annealing temperature of ZnS film increased on the textured p-Si substrate. It was found that the power conversion efficiency (PCE) of the AZO/ZnS/textured p-Si heterojunction solar cell with an annealing temperature of 250°C was η = 3.66%.

Annealing effect and photovoltaic properties of nano-ZnS/textured p-Si heterojunction

PubMed Central

2013-01-01

The preparation and characterization of heterojunction solar cell with ZnS nanocrystals synthesized by chemical bath deposition method were studied in this work. The ZnS nanocrystals were characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Lower reflectance spectra were found as the annealing temperature of ZnS film increased on the textured p-Si substrate. It was found that the power conversion efficiency (PCE) of the AZO/ZnS/textured p-Si heterojunction solar cell with an annealing temperature of 250°C was η = 3.66%. PMID:24206942

Annealing effect and photovoltaic properties of nano-ZnS/textured p-Si heterojunction

NASA Astrophysics Data System (ADS)

Ji, Liang-Wen; Hsiao, Yu-Jen; Tang, I.-Tseng; Meen, Teen-Hang; Liu, Chien-Hung; Tsai, Jenn-Kai; Wu, Tien-Chuan; Wu, Yue-Sian

2013-11-01

The preparation and characterization of heterojunction solar cell with ZnS nanocrystals synthesized by chemical bath deposition method were studied in this work. The ZnS nanocrystals were characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Lower reflectance spectra were found as the annealing temperature of ZnS film increased on the textured p-Si substrate. It was found that the power conversion efficiency (PCE) of the AZO/ZnS/textured p-Si heterojunction solar cell with an annealing temperature of 250°C was η = 3.66%.

Relative impact of H2O and O2 in the oxidation of UO2 powders from 50 to 300 °C

NASA Astrophysics Data System (ADS)

Donald, Scott B.; Davisson, M. Lee; Dai, Zurong; Roberts, Sarah K.; Nelson, Art J.

2017-12-01

The reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO2) powder at elevated temperature was studied by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). Oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice was observed and quantified. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.

Grain size effect on activation energy in spinel CoFe{sub 2}O{sub 4} ceramic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Supriya, Sweety, E-mail: sweety@iitp.ac.in; Kumar, Sunil; Kar, Manoranjan

2016-05-23

Cobalt ferrite of different average crystallites (from nanocrystallite to micro crystallites) has been prepared by the Sol-Gel Method. The X-ray diffraction (XRD) analysis confirms the cubic spinel phase with no trace of impurity phases. The effect of annealing temperature on micro structure and electric transport properties as a function of frequency and temperature has been studied. It is observed that the electric impedance and conductivity are strongly dependent on grain size. The impedance spectroscopic study is employed to understand the electrical transport properties of cobalt ferrite.

Relative impact of H 2 O and O 2 in the oxidation of UO 2 powders from 50 to 300 °C

DOE PAGES

Donald, Scott B.; Davisson, M. Lee; Dai, Zurong; ...

2017-10-04

Here, we studied the reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO 2) powder at elevated temperature by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). We observed and quatified oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.

Hydride vapor phase epitaxy of AlN using a high temperature hot-wall reactor

NASA Astrophysics Data System (ADS)

Baker, Troy; Mayo, Ashley; Veisi, Zeinab; Lu, Peng; Schmitt, Jason

2014-10-01

Aluminum nitride (AlN) was grown on c-plane sapphire substrates by hydride vapor phase epitaxy (HVPE). The experiments utilized a two zone inductively heated hot-wall reactor. The surface morphology, crystal quality, and growth rate were investigated as a function of growth temperature in the range of 1450-1575 °C. AlN templates grown to a thickness of 1 μm were optimized with double axis X-ray diffraction (XRD) rocking curve full width half maximums (FWHMs) of 135″ for the (002) and 513″ for the (102).

Transmission X-ray Diffraction (XRD) Patterns Relevant to the MSL Chemin Amorphous Component: Sulfates And Silicates

NASA Technical Reports Server (NTRS)

Morris, R. V.; Rampe, E. B.; Graff, T. G.; Archer, P. D., Jr.; Le, L.; Ming, D. W.; Sutter, B.

2015-01-01

The Mars Science Laboratory (MSL) CheMin instrument on the Curiosity rover is a transmission X-ray diffractometer (Co-Kalpha radiation source and a approx.5deg to approx.52deg 2theta range) where the analyzed powder samples are constrained to have discrete particle diameters <150 microns by a sieve. To date, diffraction patterns have been obtained for one basaltic soil (Rocknest (RN)) and four drill fines of coherent rock (John Klein (JK), Cumberland (CB), Windjana (WJ), and Confidence Hills (CH)). The CheMin instrument has detected and quantified the abundance of both primary igneous (e.g., feldspar, olivine, and pyroxene) and secondary (e.g., Ca-sulfates, hematite, akaganeite, and Fe-saponite) minerals. The diffraction patterns of all CheMin samples are also characterized by a broad diffraction band centered near 30deg 2theta and by increasing diffraction intensity (scattering continuum) from approx.15deg to approx.5deg, the 2theta minimum. Both the broad band and the scattering continuum are attributed to the presence of an XRD amorphous component. Estimates of amorphous component abundance, based on the XRD data itself and on mass-balance calculations using APXS data crystalline component chemistry derived from XRD data, martian meteorites, and/or stoichiometry [e.g., 6-9], range from approx.20 wt.% to approx.50 wt.% of bulk sample. The APXSbased calculations show that the amorphous component is rich in volatile elements (esp. SO3) and is not simply primary basaltic glass, which was used as a surrogate to model the broad band in the RN CheMin pattern. For RN, the entire volatile inventory (except minor anhydrite) is assigned to the amorphous component because no volatile-bearing crystalline phases were reported within detection limits [2]. For JK and CB, Fesaponite, basanite, and akaganeite are volatile-bearing crystalline components. Here we report transmission XRD patterns for sulfate and silicate phases relevant to interpretation of MSL-CheMin XRD amorphous components.

Structural studies of degradation process of zirconium dioxide tetragonal phase induced by grinding with dental bur

NASA Astrophysics Data System (ADS)

Piosik, A.; Żurowski, K.; Pietralik, Z.; Hędzelek, W.; Kozak, M.

2017-11-01

Zirconium dioxide has been widely used in dental prosthetics. However, the improper mechanical treatment can induce changes in the microstructure of zirconium dioxide. From the viewpoint of mechanical properties and performance, the phase transitions of ZrO2 from the tetragonal to the monoclinic phase induced by mechanical processing, are particularly undesirable. In this study, the phase transitions of yttrium stabilized zirconium dioxide (Y-TZP) induced by mechanical treatment are investigated by the scanning electron microscopy (SEM), atomic force microscopy (AFM) and powder diffraction (XRD). Mechanical stress was induced by different types of drills used presently in dentistry. At the same time the surface temperature was monitored during milling using a thermal imaging camera. Diffraction analysis allowed determination of the effect of temperature and mechanical processing on the scale of induced changes. The observed phase transition to the monoclinic phase was correlated with the methods of mechanical processing.

Structural and magnetic properties of nanocrystalline NiFe2O4 thin film prepared by spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Chavan, Apparao R.; Chilwar, R. R.; Shisode, M. V.; Hivrekar, Mahesh M.; Mande, V. K.; Jadhav, K. M.

2018-05-01

The nanocrystalline NiFe2O4 thin film has been prepared using a spray pyrolysis technique on glass substrate. The prepared thin film was characterized by using X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR), and Field Emission-Scanning Electron Microscopy (FE-SEM) characterization techniques for the structural and microstructural analysis. The magnetic property was measured using vibrating sample magnetometer (VSM) at room temperature. X-ray diffraction studies show the formation of single phase spinel structure of the thin film. The octahedral and tetrahedral vibration in the sample was studied by Fourier transform infrared (FT-IR) spectra. Magnetic hysteresis loop was recorded for thin film at room temperature. At 15 kOe, saturation magnetization (Ms) was found to increase while coercivity (Hc) decreases with thickness of the NiFe2O4 thin film.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Cheng-Jun, E-mail: cjsun@aps.anl.gov; Brewe, Dale L.; Heald, Steve M.

X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are two main x-ray techniques in synchrotron radiation facilities. In this Note, we present an experimental setup capable of performing simultaneous XRD and XAS measurements by the application of a pixel-array area detector. For XRD, the momentum transfer in specular diffraction was measured by scanning the X-ray energy with fixed incoming and outgoing x-ray angles. By selecting a small fixed region of the detector to collect the XRD signal, the rest of the area was available for collecting the x-ray fluorescence for XAS measurements. The simultaneous measurement of XRD and X-ray absorptionmore » near edge structure for Pr{sub 0.67}Sr{sub 0.33}MnO{sub 3} film was demonstrated as a proof of principle for future time-resolved pump-probe measurements. A static sample makes it easy to maintain an accurate overlap of the X-ray spot and laser pump beam.« less

Co-Precipitation Synthesis and Characterization of SrBi2Ta2O9 Ceramic

NASA Astrophysics Data System (ADS)

Afqir, Mohamed; Tachafine, Amina; Fasquelle, Didier; Elaatmani, Mohamed; Carru, Jean-Claude; Zegzouti, Abdelouahad; Daoud, Mohamed

2018-04-01

Strontium bismuth tantalate (SrBi2Ta2O9) was synthesized by a co-precipitation method. The sample was characterized by x-ray powder diffraction patterns (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results of the dielectric properties are reported at room temperature. No secondary phases were found while heating the powder at 850°C and the pure SrBi2Ta2O9 phase was formed, as revealed by XRD. The characteristic bands for SrBi2Ta2O9 were observed by FTIR at approximately 619 cm-1 and 810 cm-1. SEM micrographs for the sample displayed thin plate-like grains. The grain size was less than 1 μm and the crystallite size of about 24 nm. Dielectric response at room temperature shows that the SrBi2Ta2O9 ceramic has low loss values, and the flattening of the dielectric constant at higher frequencies. The observed Curie temperature is comparable with those reported in the literature.

Synthesis and characterization of FeSe1-xTex (x=0, 0.5, 1) superconductors

NASA Astrophysics Data System (ADS)

Zargar, Rayees A.; Hafiz, A. K.; Awana, V. P. S.

2015-08-01

In this study, FeTe1-xSex (x=0,0.5,1) samples were prepared by conventional solid state reaction method and investigated by powder XRD, SEM, Raman and resistivity measurement techniques to reveal the effect of tellurium (Te) substitution in FeSe matrix. Rietveld analysis was performed on room temperature recorded, X-ray diffraction (XRD) patterns of pure FeSe, FeTe and FeSe0.5Te0.5 which shows that all the compounds are crystallized in a tetragonal structure. SEM images show the dense surface morphology. Raman spectra recorded in the range from 100 to 700 cm-1 at ambient temperature has been interpreted by P4/nmm space group of the lattice. The variation in intensity and shift in peak positions of some phonon modes has been discussed on the basis of variation in crystalline field effect by substituting Te in FeSe lattice. The resistivity versus temperature curves reveals that FeSe becomes superconductor at 7 K and FeSe0.5Te0.5 shows superconductivity below 14 K while FeTe is non-superconducting compound.

Y 3-xMg 2AlSi 2O 12: Cex3+ phosphors - prospective for warm-white light emitting diodes

NASA Astrophysics Data System (ADS)

Katelnikovas, Arturas; Bareika, Tomas; Vitta, Pranciškus; Jüstel, Thomas; Winkler, Holger; Kareiva, Aivaras; Žukauskas, Artūras; Tamulaitis, Gintautas

2010-07-01

Y 3-xMg 2AlSi 2O 12: Cex3+ (YMASG:Ce) phosphors were synthesized by sol-gel combustion technique at different temperatures from 1400 to 1550 °C. Samples with x = 0.015, 0.03, 0.045, and 0.06 were fabricated and characterized using powder X-ray diffraction (XRD), photoluminescence spectroscopy, and fluorescence lifetime measurements in frequency domain. XRD patterns confirmed single-phase garnet crystal structure for all the samples independently of their substitutional level and annealing temperature. In respect to Y 3Al 5O 12:Ce 3+ (YAG:Ce) phosphor, which was synthesized for comparison by a different sol-gel procedure, the photoluminescence band of these garnets is red shifted, indicating a prospective for application of this novel phosphor in warm-white light emitting diodes (LEDs). The luminescence decays bi-exponentially. The main component has a characteristic decay time decreasing from 72 to of 50 ns with increasing sintering temperature and cerium content, while ˜2% of the excitation decays with a characteristic decay time of ˜8 ns.

Influence of Casting Section Thickness on Fatigue Strength of Austempered Ductile Iron

NASA Astrophysics Data System (ADS)

Olawale, J. O.; Ibitoye, S. A.

2017-10-01

The influence of casting section thickness on fatigue strength of austempered ductile iron was investigated in this study. ASTM A536 65-45-12 grade of ductile iron was produced, machined into round samples of 10, 15, 20 and 25 mm diameter, austenitized at a temperature of 820 °C, quenched into an austempering temperature (TA) of 300 and 375 °C and allowed to be isothermally transformed at these temperatures for a fixed period of 2 h. From the samples, fatigue test specimens were machined to conform to ASTM E-466. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) methods were used to characterize microstructural morphology and phase distribution of heat-treated samples. The fatigue strength decreases as the section thickness increases. The SEM image and XRD patterns show a matrix of acicular ferrite and carbon-stabilized austenite with ferrite coarsening and volume fraction of austenite reducing as the section thickness increases. The study concluded that the higher the value of carbon-stabilized austenite the higher the fatigue strength while it decreases as the ausferrite structure becomes coarse.

Facile Synthesis of Calcium Borate Nanoparticles and the Annealing Effect on Their Structure and Size

PubMed Central

Erfani, Maryam; Saion, Elias; Soltani, Nayereh; Hashim, Mansor; Wan Abdullah, Wan Saffiey B.; Navasery, Manizheh

2012-01-01

Calcium borate nanoparticles have been synthesized by a thermal treatment method via facile co-precipitation. Differences of annealing temperature and annealing time and their effects on crystal structure, particle size, size distribution and thermal stability of nanoparticles were investigated. The formation of calcium borate compound was characterized by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Thermogravimetry (TGA). The XRD patterns revealed that the co-precipitated samples annealed at 700 °C for 3 h annealing time formed an amorphous structure and the transformation into a crystalline structure only occurred after 5 h annealing time. It was found that the samples annealed at 900 °C are mostly metaborate (CaB2O4) nanoparticles and tetraborate (CaB4O7) nanoparticles only observed at 970 °C, which was confirmed by FTIR. The TEM images indicated that with increasing the annealing time and temperature, the average particle size increases. TGA analysis confirmed the thermal stability of the annealed samples at higher temperatures. PMID:23203073

Preparation, Structural and Dielectric Properties of Solution Grown Polyvinyl Alcohol(PVA) Film

NASA Astrophysics Data System (ADS)

Nangia, Rakhi; Shukla, Neeraj K.; Sharma, Ambika

2017-08-01

Flexible dielectrics with high permittivity have been investigated extensively due to their applications in electronic industry. In this work, structural and electrical characteristics of polymer based film have been analysed. Poly vinyl alcohol (PVA) film was prepared by solution casting method. X-ray diffraction (XRD) characterization technique is used to investigate the structural properties. The semi-crystalline nature has been determined by the analysis of the obtained XRD pattern. Electrical properties of the synthesized film have been analysed from the C-V and I-V curves obtained at various frequencies and temperatures. Low conductivity values confirm the insulating behaviour of the film. However, it is found that conductivity increases with temperature. Also, the dielectric permittivity is found to be higher at lower frequencies and higher temperatures, that proves PVA to be an excellent dielectric material which can be used in interface electronics. Dielectric behaviour of the film has been explained based on dipole orientations to slow and fast varying electric field. However further engineering can be done to modulate the structural, electrical properties of the film.

Phase separation in SiGe nanocrystals embedded in SiO{sub 2} matrix during high temperature annealing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mogaddam, N. A. P.; Turan, R.; Alagoz, A. S.

2008-12-15

SiGe nanocrystals have been formed in SiO{sub 2} matrix by cosputtering Si, Ge, and SiO{sub 2} independently on Si substrate. Effects of the annealing time and temperature on structural and compositional properties are studied by transmission electron microscopy, x-ray diffraction (XRD), and Raman spectroscopy measurements. It is observed that Ge-rich Si{sub (1-x)}Ge{sub x} nanocrystals do not hold their compositional uniformity when annealed at high temperatures for enough long time. A segregation process leading to separation of Ge and Si atoms from each other takes place. This process has been evidenced by a double peak formation in the XRD and Ramanmore » spectra. We attributed this phase separation to the differences in atomic size, surface energy, and surface diffusion disparity between Si and Ge atoms leading to the formation of nonhomogenous structure consist of a Si-rich SiGe core covered by a Ge-rich SiGe shell. This experimental observation is consistent with the result of reported theoretical and simulation methods.« less

Atomic-scale investigation and magnetic properties of Cu80Co20 nanowires

NASA Astrophysics Data System (ADS)

Hannour, A.; Lardé, R.; Jean, M.; Bran, J.; Pareige, P.; Le Breton, J. M.

2011-09-01

Cu80Co20 granular alloy nanowires were synthesized by electrodeposition method and investigated by x-ray diffraction (XRD), Laser Assisted Wide Angle Tomographic Atom Probe (LAWATAP), and SQUID magnetometry. XRD results reveal the existence of a fcc Cu matrix and fcc Co-rich nanograins, with a preferred orientation along the [200] direction (perpendicular to the substrate surface). The Co-rich nanograins could be coherent with the Cu matrix. 3D reconstructions of a nano-sized volume, obtained by LAWATAP, reveal the heterogeneous aspect of the Cu80Co20 nanowires: Co-rich nanoclusters with size between 2 and 10 nm are detected, and the presence of Cu and Co oxides is evidenced. Magnetization measurements indicate that the Co-rich nanoclusters are superparamagnetic, with a blocking temperature that extends up to, at least, room temperature. The presence of ferromagnetic domains at room temperature indicates that some Co-rich nanoclusters are correlated within a volume that corresponds to a so-called interacting superparamagnetic phase. As a matter of fact, by LAWATAP atomic-scale analysis, a very good correlation is obtained between microstructure and magnetic properties.

Polyaniline-Cadmium Ferrite Nanostructured Composite for Room-Temperature Liquefied Petroleum Gas Sensing

NASA Astrophysics Data System (ADS)

Kotresh, S.; Ravikiran, Y. T.; Tiwari, S. K.; Vijaya Kumari, S. C.

2017-08-01

We introduce polyaniline-cadmium ferrite (PANI-CdFe2O4) nanostructured composite as a room-temperature-operable liquefied petroleum gas (LPG) sensor. The structure of PANI and the composite prepared by chemical polymerization was characterized by Fourier-transform infrared (FT-IR) spectroscopy, x-ray diffraction (XRD) analysis, and field-emission scanning electron microscopy. Comparative XRD and FT-IR analysis confirmed CdFe2O4 embedded in PANI matrix with mutual interfacial interaction. The nanostructure of the composite was confirmed by transmission electron microscopy. A simple LPG sensor operable at room temperature, exclusively based on spin-coated PANI-CdFe2O4 nanocomposite, was fabricated with maximum sensing response of 50.83% at 1000 ppm LPG. The response and recovery time of the sensor were 50 s and 110 s, respectively, and it was stable over a period of 1 month with slight degradation of 4%. The sensing mechanism is discussed on the basis of the p- n heterojunction barrier formed at the interface of PANI and CdFe2O4.

Non-convergent ordering and displacive phase transition in pigeonite: in situ HT XRD study

NASA Astrophysics Data System (ADS)

Cámara, F.; Carpenter, M. A.; Domeneghetti, M. C.; Tazzoli, V.

A natural Ca-rich pigeonite (En47Fs43Wo10), free of augite exsolution products, was studied by in situ high-temperature single-crystal X-ray diffraction. The sample, monoclinic P21/c (a=9.719(7) Å, b=8.947(9) Å, c=5.251(3) Å, β=108.49(5), V=433.0(6) Å3), was annealed up to 1000 °C to induce a phase transition from P21/c to C2/c symmetry. Complete single-crystal X-ray diffraction data collections were carried out in situ at 650, 750, 850 and 950 °C after the crystal had reached equilibrium for the Fe-Mg intracrystalline exchange reaction at each temperature. The variation, with increasing temperature, of lattice parameters, of intensity of hkl reflections with h + k=2n + 1 (which vanish at high temperature) and of some geometrical parameters from structure refinement, showed that the displacive phase transition P21/cC2/c was continuous in character. This contrasts with the first-order character for the HT phase transition in pigeonite containing significantly less calcium.

Solid state characterization of E2101, a novel antispastic drug.

PubMed

Kushida, Ikuo; Ashizawa, Kazuhide

2002-10-01

E2101, a novel antispastic drug, was found to exist in at least two polymorphs that were confirmed by X-ray powder diffraction (XRD). These two species are designated forms I and II. The physicochemical and thermodynamic properties of these polymorphs were characterized by variable temperature XRD, thermal analysis, hygroscopicity measurements, and dissolution studies. The transition temperature was also estimated from the solubilities determined at various temperatures. The E2101 polymorphs were anhydrous and adsorbed little moisture under high humidity conditions. The melting onsets and heats of fusion for form I were 148.1 +/- 0.2 degrees C and 38.2 +/- 1.0 kJ/mol, respectively, and for form II were 139.8 +/- 0.4 degrees C and 35.2 +/- 0.5 kJ/mol, respectively. The intrinsic dissolution rate of form II in JP 2 medium was 1.5-fold faster than that of form I, corresponding to the rank order of the aqueous solubility and the enthalpy of fusion. Accordingly, form I was thought to be thermodynamically more stable than form II and thus suitable for further development. According to the thermal analysis and variable temperature XRD results, the recrystallization of form I occurred at approximately 145 degrees C after form II melted, however, no crystal transition behavior was observed below the lower melting point. The DSC thermograms at various heating rates and van't Hoff plots from the solubility studies indicated that the polymorphic pair would be monotropic. Copyright 2002 Wiley-Liss Inc. and the American Pharmaceutical Association

Photosynthetic microorganism-mediated synthesis of akaganeite (beta-FeOOH) nanorods.

PubMed

Brayner, Roberta; Yéprémian, Claude; Djediat, Chakib; Coradin, Thibaud; Herbst, Fréderic; Livage, Jacques; Fiévet, Fernand; Couté, Alain

2009-09-01

Common Anabaena and Calothrix cyanobacteria and Klebsormidium green algae are shown to form intracellularly akaganeite beta-FeOOH nanorods of well-controlled size and unusual morphology at room temperature. X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy X-ray energy dispersive spectrometry (SEM-EDS) analyses are used to investigate particle structure, size, and morphology. A mechanism involving iron-siderophore complex formation is proposed and compared with iron biomineralization in magnetotactic bacteria.

Complex study on photoluminescence properties of YAG:Ce,Gd phosphors

NASA Astrophysics Data System (ADS)

Lisitsyn, V. M.; Ju, Yangyang; Stepanov, S. A.; Soschin, N. M.

2017-05-01

Luminescence characteristics of gadolinium co-doped yttrium aluminium garnet doped with cerium phosphors were studied. In this work, powder X-ray diffraction (XRD) spectra, elemental composition analyses, excitation and emission spectra, conversion efficiency of emission phosphor, corresponding (CIE) chromaticity colour coordinates and pulsed photoluminescence decay kinetic curves were investigated, all the measurements were performed at room temperature. The properties of the phosphors were studied by comparing the composition of the phosphors and their luminescent properties.

Alternative approaches used to assess structural changes of natural zircon caused by heat treatment

NASA Astrophysics Data System (ADS)

Huong, L. T. T.; Thuyet, N. T. M.; Phan, T. L.; Tran, N.; Toan, D. N.; Thang, P. D.; Huy, B. T.

2018-03-01

It is known that large changes in the crystal structure of zircon (ZrSiO4) can be assessed through the linewidth of the characteristic Raman mode (Δν3) at 1008 cm-1. However, the use of Δν3 to assess small changes caused by heat treatment at temperatures below its decomposition temperature of 1670 °C is difficult. The present work points out that the combination of X-ray diffraction (XRD) analyses, and photoluminescence (PL) and Raman (RS) measurements with different excitation wavelengths is an effective approach to solve the above problem. In this context, we have selected natural zircon containing some rare-earth (RE) impurities, and then studied the changes in its crystal structure caused by heat treatment at temperatures Tan=400-1600 °C. XRD analyses reveal that small modifications of the unit-cell parameters occur as Tan>600 °C. Taking the intensity ratios of the ν3 mode to RE-related emissions (Iν3/IRE) or the PL intensity ratios between RE-related emissions into consideration, the similar results in good agreement with the XRD analyses are also found. We believe that the small structural changes are related to the migration and redistribution of defects and impurities, and re-crystallization of zircon. This could be further confirmed though the relation between paramagnetic and ferromagnetic signals when Tan changes.

Quantitative analysis of tridymite and cristobalite crystallized in rice husk ash by heating.

PubMed

Shinohara, Yasushi; Kohyama, Norihiko

2004-04-01

The quantities of two forms of crystalline silica, tridymite and cristobalite, in heated rice husk ash (RHA) samples were determined by X-ray diffraction (XRD) and chemical methods. Two RHA samples, containing 93% SiO2 and 2-3% K2O, were prepared from charcoaled rice husk products and heated to above 900 degrees C. The crystalline silica made up over 60-80% of the total silica in the heated RHA samples based on the XRD analysis. The crystalline phases in the two samples were somewhat different: The sample heated in the temperature range of 900 to 1,200 degrees C contained 52-62% cristobalite and 10-17% tridymite, but the other sample heated at a comparable temperature, above 1,100 degrees C, contained 46-66% tridymite and 37-16% cristobalite. Based on a correlation of lower tridymite crystallization temperature with higher potassium content, it was concluded that higher potassium levels were responsible for this difference. The pyrophosphoric acid analysis did not give exact results in the evaluation of total crystalline silica content in these RHA samples. As the combustion of rice husk was considered to cover the demands for energy and silica resource in Asian countries, cristobalite and tridymite crystallized in RHA by burning of rice husk should be assessed precisely by XRD analysis and the airborne dust in relevant workplace be controlled.

[A new method for the preparation of potassium ferrate and spectroscopic characterization].

PubMed

Zheng, Huai-li; Deng, Lin-li; Ji, Fang-ying; Jiang, Shao-jie; Zhang, Peng

2010-10-01

Calcium hypochlorite was used as the raw material for preparation of the high purity potassium ferrate. The study includes the effects of reaction temperature, recrystallization temperature, reaction time, Ca(ClO)2 dosage, and the amount of calcium hypochlorite on the yield. It was determined that when the reaction temperature was 25 degrees C, recrystallization temperature 0 degree C and reaction time 40 min, the yield was more than 75%. The purity was detected by direct spectrophotometric method to be more than 92%. The product was characterized by infrated spectrum(IR), X-ray diffraction (XRD) and ultraviolet spectrum (UV) methods and proved to be potassium ferrate that was prepared by calcium hypochlorite as the raw material.

SnS thin films deposited by chemical bath deposition, dip coating and SILAR techniques

NASA Astrophysics Data System (ADS)

Chaki, Sunil H.; Chaudhary, Mahesh D.; Deshpande, M. P.

2016-05-01

The SnS thin films were synthesized by chemical bath deposition (CBD), dip coating and successive ionic layer adsorption and reaction (SILAR) techniques. In them, the CBD thin films were deposited at two temperatures: ambient and 70 °C. The energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and optical spectroscopy techniques were used to characterize the thin films. The electrical transport properties studies on the as-deposited thin films were done by measuring the I-V characteristics, DC electrical resistivity variation with temperature and the room temperature Hall effect. The obtained results are deliberated in this paper.

Investigations on Sm- and Nb-SUBSTITUTED PZT Ceramics

NASA Astrophysics Data System (ADS)

Prakash, Chandra; Juneja, J. K.

In the present paper, we report the effect of Samarium substitution and Niobium doping on the properties of a PZT(52:48). The properties studied are: structural, dielectric and ferroelectric. The samples with chemical formula Pb0.99Sm0.01Zr0.52Ti0.48O3 were prepared by solid-state dry ceramic method. Small amount (0.5 wt%) of Nb2O5 was also added. X-ray diffraction (XRD) analysis showed formation of a single phase with tetragonal structure. Dielectric properties were studied as a function of temperature and frequency. Transition temperature, Tc, was determined from dielectric constant versus temperature plot. The material shows well-defined ferroelectric (PE) hysteresis loop.

Thermal expansion properties of Ho2Fe16.5Cr0.5

NASA Astrophysics Data System (ADS)

Dan, Shovan; Mukherjee, S.; Mazumdar, Chandan; Ranganathan, R.

2018-04-01

We report the thermal expansion behavior of Ho2Fe16.5Cr0.5 compound in the range of temperature 13-483 K, using structural parameters obtained by analyzing temperature dependent x-ray diffraction (XRD) patterns. From 13 K to 300 K, the compound shows negligible thermal expansion having the coefficient of volume expansion (αV) ∼ 10-6 K -1. The thermal expansion behavior of the studied compound can be explained by the role of magnetovolume effect (MVE) below ferrimagnetic ordering temperature (394 K), in addition to normal phononic contribution. Fe sublattice contribute to MVE, whereas both the rare earth and Fe sublattice determine the value of saturation magnetization.

High-Temperature, Perhaps Silicic, Volcanism on Mars Evidenced by Tridymite Detection in High-SiO2 Sedimentary Rock at Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Morris, R. V.; Vaniman, D. T.; Blake, D. F.; Gellert, R.; Chipera, S. J.; Rampe, E. B.; Ming, D. W.; Morrison, S. M.; Downs, R. T.; Treiman, A. H.;

In situ X-ray diffraction analysis of (CF x) n batteries: signal extraction by multivariate analysis

DOE PAGES

Rodriguez, Mark A.; Keenan, Michael R.; Nagasubramanian, Ganesan

2007-11-10

In this study, (CF x) n cathode reaction during discharge has been investigated using in situ X-ray diffraction (XRD). Mathematical treatment of the in situ XRD data set was performed using multivariate curve resolution with alternating least squares (MCR–ALS), a technique of multivariate analysis. MCR–ALS analysis successfully separated the relatively weak XRD signal intensity due to the chemical reaction from the other inert cell component signals. The resulting dynamic reaction component revealed the loss of (CF x) n cathode signal together with the simultaneous appearance of LiF by-product intensity. Careful examination of the XRD data set revealed an additional dynamicmore » component which may be associated with the formation of an intermediate compound during the discharge process.« less

In-situ determination of austenite and martensite formation in 13Cr6Ni2Mo supermartensitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bojack, A., E-mail: a.bojack@tudelft.nl; Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft; Zhao, L.

2012-09-15

In-situ analysis of the phase transformations in a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) was carried out using a thermo-magnetic technique, dilatometry and high temperature X-ray diffractometry (HT-XRD). A combination of the results obtained by the three applied techniques gives a valuable insight in the phase transformations during the austenitization treatment, including subsequent cooling, of the 13Cr6Ni2Mo supermartensitic stainless steel, where the magnetic technique offers a high accuracy in monitoring the austenite fraction. It was found by dilatometry that the austenite formation during heating takes place in two stages, most likely caused by partitioning of Ni into austenite. The in-situ evolutionmore » of the austenite fraction is monitored by high-temperature XRD and dilatometry. The progress of martensite formation during cooling was described with a Koistinen-Marburger relation for the results obtained from the magnetic and dilatometer experiments. Enhanced martensite formation at the sample surface was detected by X-ray diffraction, which is assumed to be due to relaxation of transformation stresses at the sample surface. Due to the high alloy content and high thermodynamic stability of austenite at room temperature, 4 vol.% of austenite was found to be stable at room temperature after the austenitization treatment. - Highlights: Black-Right-Pointing-Pointer We in-situ analyzed phase transformations and fractions of a 13Cr6Ni2Mo SMSS. Black-Right-Pointing-Pointer Higher accuracy of the austenite fraction was obtained from magnetic technique. Black-Right-Pointing-Pointer Austenite formation during heating takes place in two stages. Black-Right-Pointing-Pointer Enhanced martensite formation at the sample surface detected by X-ray diffraction.« less

Plasma Sprayed Hydroxyapatite Coatings: Influence of Spraying Power on Microstructure

NASA Astrophysics Data System (ADS)

Mohd, S. M.; Abd, M. Z.; Abd, A. N.

2010-03-01

The plasma sprayed hydroxyapatite (HA) coatings are used on metallic implants to enhance the bonding between the implant and bone in human body. The coating process was implemented at different spraying power for each spraying condition. The coatings formed from a rapid solidification of molten and partly molten particles that impact on the surface of substrate at high velocity and high temperature. The study was concentrated on different spraying power that is between 23 to 31 kW. The effect of different power on the coatings microstructure was investigated using scanning electron microscope (SEM) and phase composition was evaluated using X-ray diffraction (XRD) analysis. The coatings surface morphology showed distribution of molten, partially melted particles and some micro-cracks. The produced coatings were found to be porous as observed from the cross-sectional morphology. The coatings XRD results indicated the presence of crystalline phase of HA and each of the patterns was similar to the initial powder. Regardless of different spraying power, all the coatings were having similar XRD patterns.

Hydrogen Gas Sensing Characteristics of Nanostructured NiO Thin Films Synthesized by SILAR Method

NASA Astrophysics Data System (ADS)

Karaduman, Irmak; Çorlu, Tugba; Yıldırım, M. Ali; Ateş, Aytunç; Acar, Selim

2017-07-01

Nanostructured NiO thin films have been synthesized by a facile, low-cost successive ionic layer adsorption and reaction (SILAR) method, and the effects of the film thickness on their hydrogen gas sensing properties investigated. The samples were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and energy-dispersive x-ray analysis. The XRD results revealed that the crystallinity improved with increasing thickness, exhibiting polycrystalline structure. SEM studies showed that all the films covered the glass substrate well. According to optical absorption measurements, the optical bandgap decreased with increasing film thickness. The gas sensing properties of the nanostructured NiO thin films were studied as a function of operating temperature and gas concentration. The samples showed good sensing performance of H2 gas with high response. The maximum response was 75% at operating temperature of 200°C for hydrogen gas concentration of 40 ppm. These results demonstrate that nanostructured NiO thin films synthesized by the SILAR method have potential for application in hydrogen detection.

Alternating current response studies on nickel ferrite-niobium composite at room temperature

NASA Astrophysics Data System (ADS)

Reddy, L. P. Babu; Rajprakash, H. G.; Chethan, B.; Vijayakumari, S. C.; Ravikiran, Y. T.

2018-05-01

In the present research NDNF -Niobium Pentaxide doped Nickel Ferrite [NiFe2O4-Nb2O5-50%] composite was prepared by Mechano-Chemical mixing of NiFe2O4 [NF] with Nb2O5. NF and the NDNF were structurally characterized by four transform infrared spectroscopy [FTIR] and X-ray diffraction [XRD] techniques. The presence of characteristic absorption bands of NF and Nb2O5 in the FTIR spectrum of NDNF with small shift confirmed interfacial interaction of NF with Nb2O5. XRD studies also confirm interfacial interaction between NF and Nb2O5 in the composite and crystalline nature with an average crystallite size of 30nm. The Alternating Current (AC) response parameters of NF and the NDNF were comparatively studied in the frequency range 100Hz-1MHz at room temperature. Increase in AC conductivity of the NDNF has compared to NF was observed and discussed based on the electron hole exchange mechanism.

Effect of annealing on structure, morphology and optoelectronic properties of nanocrystalline CuO thin films

NASA Astrophysics Data System (ADS)

Jundale, D. M.; Pawar, S. G.; Patil, S. L.; Chougule, M. A.; Godse, P. R.; Patil, V. B.

2011-10-01

The nanocrystalline CuO thin films were prepared on glass substrates by the sol-gel method. The structural, morphological, electrical and optical properties of CuO thin films, submitted to an annealing treatment in the 400-700 °C ranges are studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Four Probe Technique and UV-visible spectroscopic. XRD measurements show that all the films are crystallized in the monoclinic phase and present a random orientation. Four prominent peaks, corresponding to the (110) phase (2θ≈32.70°), (002) phase (2θ≈35.70°), (111) phase (2θ≈38.76°) and (202) phase (2θ≈49.06°) appear on the diffractograms. The crystallite size increases with increasing annealing temperature. These modifications influence the microstructure, electrical and optical properties. The optical band gap energy decreases with increasing annealing temperature. These mean that the optical quality of CuO films is improved by annealing.

Structural characteristics and properties of the regenerated silk fibroin prepared from formic acid.

PubMed

Um, I C; Kweon, H Y; Park, Y H; Hudson, S

2001-08-20

Structural characteristics and thermal and solution properties of the regenerated silk fibroin (SF) prepared from formic acid (FU) were compared with those of SF from water (AU). According to the turbidity and shear viscosity measurement, SF formic acid solution was stable and transparent, no molecular aggregations occurred. The sample FU exhibited the beta-sheet structure, while AU random coil conformation using Fourier transform infrared (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry. The effects of methanol treatment on samples were also examined. According to the measurement of crystallinity (XRD) and crystallinity index (FTIR), the concept of long/short-range ordered structure formation was proposed. Long-range ordered crystallites are predominantly formed for methanol treated SF film while SF film cast from formic acid favors the formation of short-range ordered structure. The relaxation temperatures of SF films measured by dynamic thermomechanical analysis supported the above mechanism due to the sensitivity of relaxation temperature on the short-range order.

Study on defect properties of nanocrystalline TiO2 during phase transition by positron annihilation lifetime

NASA Astrophysics Data System (ADS)

Zheng, F.; Liu, Y.; Liu, Z.; Dai, Y.-Q.; Fang, P.-F.; Wang, S.-J.

2012-08-01

The defect properties of nanocrystalline TiO2 were investigated by positron annihilation lifetime spectroscopy (PALS) and X-ray diffraction (XRD) as a function of annealed temperature that ranged from 300 to 850 °C. Below 500 °C, the measured positron lifetimes of τ1 (200-206 ps) and τ2 (378-402 ps) revealed the existence of mono-vacancy and vacancy-clusters at grain surface and in the micro-void of intergranular region. Between 500 and 750 °C, the phase transition from anatase to rutile was probed by the variations of positron lifetime and XRD pattern. With the increasing temperature from 500 to 850 °C, the positron lifetime τ1, τ2 and its intensity I2 sharply decreased from 200 ps, 378 ps, and 60% to 135 ps, 274 ps, and 33%, respectively. The results clearly indicate that the mono-vacancy or vacancy-clusters at grain surface and micro-voids between the grains were annealed out during the phase transition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deus, R.C.; Cortés, J.A., E-mail: leandrosrr89@gmail.com; Ramirez, M.A.

Highlights: • CeO{sub 2} nanoparticles were obtained by microwave-hydrothermal method. • Rietveld refinement reveals a cubic structure. • KOH mineralizer agent exhibit weak agglomeration at low temperature and shorter time. - Abstract: The structural and photoluminescent properties at room temperature of CeO{sub 2} and La-doped CeO{sub 2} particles were undertaken. The obtained particles were synthesized by a microwave-assisted hydrothermal method (MAH) under different lanthanum contents. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), Ultra-violet spectroscopy (UV–vis) and photoluminescence (PL) measurements were carried out. XRD revealed that the powders are free of secondary phases and crystallize in themore » cubic structure. Raman data show that increasing La doping content increase oxygen vacancies due to lattice expansion. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. Lanthanum addition creates oxygen vacancies and shifts the photoluminescence in the low energy range leading to intense PL emission.« less

Structural and electrical properties of different vanadium oxide phases in thin film form synthesized using pulsed laser deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Majid, S. S., E-mail: suhailphy276@gmail.com; Rahman, F.; Shukla, D. K.

2015-06-24

We present here the structural and electrical properties of the thin films of V{sub 2}O{sub 3} (Vanadium sesquioxide) and V{sub 5}O{sub 9}. Both these oxide phases, V{sub 2}O{sub 3} and V{sub 5}O{sub 9}, have beenachieved on (001) orientedSi substrate using the V{sub 2}O{sub 5} target by optimizing the deposition parameters using pulsed laser deposition technique (PLD).Deposited films were characterized by X-ray diffraction(XRD)and four probe temperature dependent resistivity measurements. XRD studies reveal the V{sub 2}O{sub 3} and V{sub 5}O{sub 9} phases and the amount of strain present in both these films. The temperature dependency of electrical resistivity confirmed the characteristic metal-insulatormore » transitions (MIT) for both the films, V{sub 2}O{sub 3} and V{sub 5}O{sub 9}.« less

Synthesis of ZnO nanopencils using wet chemical method and its investigation as LPG sensor

NASA Astrophysics Data System (ADS)

Shimpi, Navinchandra G.; Jain, Shilpa; Karmakar, Narayan; Shah, Akshara; Kothari, D. C.; Mishra, Satyendra

2016-12-01

ZnO nanopencils (NPCs) were prepared by a novel wet chemical process, using triethanolamine (TEA) as a mild base, which is relatively simple and cost effective method as compared to hydrothermal method. ZnO NPCs were characterized using powder X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy in mid-IR and far-IR regions, X-ray Photoelectron Spectroscopy (XPS), UV-vis (UV-vis) absorption spectroscopy, room temperature Photoluminescence (PL) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). ZnO NPCs obtained, were highly pure, uniform and monodispersed.XRD pattern indicated hexagonal unit cell structure with preferred orientation along the c-axis. Sensing behaviour of ZnO NPCs was studied towards Liquefied Petroleum Gas (LPG) at different operating temperatures. The study shows that ZnO NPCs were most sensitive and promising candidate for detection of LPG at 250 °C with gas sensitivity > 60%. The high response towards LPG is due to high surface area of ZnO NPCs and their parallel alignment.

Thermal stability and electrochemical properties of PVP-protected Ru nanoparticles synthesized at room temperature

NASA Astrophysics Data System (ADS)

Kumar, Manish; Devi, Pooja; Shivling, V. D.

2017-08-01

Stable ruthenium nanoparticles (RuNPs) have been synthesized by the chemical reduction of ruthenium trichloride trihydrate (RuCl3 · 3H2O) using sodium borohydride (NaBH4) as a reductant and polyvinylpyrrolidone (PVP) as a protecting agent in the aqueous medium at room temperature. The nanoparticles thus prepared were characterized by their morphology and structural analysis from transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectroscopy, Fourier transformation infrared and thermogravimetric analysis (TGA) techniques. The TEM image suggested a homogeneous distribution of PVP-protected RuNPs having a small average diameter of 2-4 nm with a chain-like network structure. The XRD pattern also confirmed that a crystallite size is around 2 nm of PVP-protected RuNPs having a single broad peak. The thermal stability studied using TGA, indicated good stability and the electrochemical properties of these nanoparticles revealed that saturation current increases for PVP-protected RuNPs/GC.

Synthesis, structural and optical properties of PVP coated transition metal doped ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Desai, N. V.; Shaikh, I. A.; Rawal, K. G.; Shah, D. V.

2018-05-01

The room temperature photoluminescence (PL) of transition metal doped ZnS nanoparticles is investigated in the present study. The PVP coated ZnS nanoparticles doped with transition metals are synthesized by facile wet chemical co-precipitation method with the concentration of impurity 1%. The UV-Vis absorbance spectra have a peak at 324nm which shifts slightly to 321nm upon introduction of the impurity. The incorporation of the transition metal as dopant is confirmed by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The particle size and the morphology are characterized by scanning electron microscopy (SEM), XRD and UV-Vis spectroscopy. The average size of synthesized nanoparticles is about 2.6nm. The room temperature photoluminescence (PL) of undoped and doped ZnS nanoparticles show a strong and sharp peak at 782nm and 781.6nm respectively. The intensity of the PL changes with the type of doping having maximum for manganese (Mn).

Effect of RE (Nd3+, Sm3+) oxide on structural, optical properties of Na2O-Li2O-ZnO-B2O3 glass system

NASA Astrophysics Data System (ADS)

Hivrekar, Mahesh M.; Bhoyar, D. N.; Mande, V. K.; Dhole, V. V.; Solunke, M. B.; Jadhav, K. M.

2018-05-01

Zinc borate glass activated with rare earth oxide (Nd2O3, Sm2O3) of Na2O-Li2O-ZnO-B2O3 quaternary system has been prepared successfully by melt quenching method. The nucleation and growth of RE oxide were controlled temperature range 950-1000° C and rapid cooling at room temperature. The physical, structural and optical properties were characterized by using X-ray diffraction (XRD), SEM, Ultraviolet-visible spectroscopy (UV-Vis). XRD and SEM studies confirmed the amorphous nature, surface morphology of prepared zinc borate glass. The physical parameters like density, molar volume, molar mass of Nd3+, Sm3+ doped borate glass are summarized in the present article. The optical absorption spectra along with tauc's plot are presented. The optical energy band gap increases due to the addition of rare earth oxide confirming the role of network modifier.

Influence of Synthesis Temperature on the Growth and Surface Morphology of Co3O4 Nanocubes for Supercapacitor Applications

PubMed Central

Samal, Rashmirekha; Dash, Barsha; Sarangi, Chinmaya Kumar; Subbaiah, Tondepu; Senanayake, Gamini; Minakshi, Manickam

2017-01-01

A facile hydrothermal route to control the crystal growth on the synthesis of Co3O4 nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co3O4 nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co3O4 synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes. PMID:29088061

To study the effect of doping concentration of silver on structural and optical properties of cadmium oxide (CdO) nanostructure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Rajesh, E-mail: rkkaushik06@gmail.com; Dept. of Physics, Vaish College of Engineering, Rohtak-124001, Haryana; Sharma, Ashwani

The present work deals with study of structural and optical properties of Silver (Ag) doped Cadmium oxide (CdO) nanostructured synthesized by Chemical Co-precipitation Techniques followed by calcinations at small temperature. The doping concentrations were changing from 0.1 to 10 at% respectively. Structural analysis study of these calcined materials is carried out by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The optical properties of calcined samples were investigating by Fourier transformation infrared (FTIR)spectroscopy, UV-Visible Spectroscopy (UV-Vis). The structural properties analysis results revels that crystallite size are in the range of nano region and TEM results aremore » quite in accordance with XRD results.« less

Growth of bulk ZnO crystals by self-selecting CVT method

NASA Astrophysics Data System (ADS)

Fan, Long; Jiang, Tao; Xiao, TingTing; Chen, Jie; Peng, Liping; Wang, Xuemin; Yan, Dawei; Wu, Weidong

2018-05-01

Bulk ZnO crystals were grown by self-selecting CVT method using carbon as the transport agent. The crystal growth process took place on the top of the polycrystalline source material, and deep-red colored ZnO crystals of several millimeters were obtained. The as-grown crystals were characterized by X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), Raman scattering (RS) spectroscopy, visible-near infrared (VIS-NIR) spectrophotometer and room temperature photoluminescence (PL) spectroscopy. XRD results indicate good crystallinity of the ZnO crystal. The EDS analysis shows that the crystal has a stoichiometry ratio Zn: O = 52: 48. The results suggest the existence of native defects of oxygen vacancies (OV) in the as-grown ZnO samples, which is caused by the stoichiometry shift to Zn-rich.

Phase study and surface morphology of beta-alumina

NASA Astrophysics Data System (ADS)

Tak, S. K.

2018-05-01

Beta alumina ceramic is well known as a polycrystalline ceramic material. The characteristic crystal structure of beta-alumina makes it useful as a separator in sodium sulphur batteries and other electrochemical devices requiring the passage of sodium ions. β"-alumina powders for this study were prepared by zeta process. The pellets were sintered at different microwave power levels and power schedule to optimize the sintering conditions to obtain preferred β" phase with improved microstructure. Phase identification was studied by X-ray diffraction (XRD). XRD analysis shows increase in β'' phase as the sintering temperature was increased from 1400°C to 1600°C. Surface morphology of the pellets was carried out by Scanning Electron microscopy (SEM). SEM studies revealed the formation and growth of platelet grains with interconnected porosity.

Synthesis and properties of the compound: LiNi 3/5Cu 2/5VO 4

NASA Astrophysics Data System (ADS)

Ram, Moti

2009-12-01

The LiNi 3/5Cu 2/5VO 4 is synthesized by solution-based chemical method and its formation has been checked by X-ray diffraction (XRD) study. XRD study shows a tetragonal unit cell structure with lattice parameters of a = 11.6475 (18) Å, c = 2.4855 (18) Å and c/ a = 0.2134 Å. Electrical properties are verified using complex impedance spectroscopy (CIS) technique. Complex impedance analysis reveals following points: (i) the bulk contribution to electrical properties up to 200 °C, (ii) the bulk and grain boundary contribution at T ≥ 225 °C, (iii) the presence of temperature dependent electrical relaxation phenomena in the material. D.c. conductivity study indicates that electrical conduction in the material is a thermally activated process.

Synthesis and characterization of high-quality cobalt vanadate crystals and their applications in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Bhuiyan, Md. Tofajjol Hossen; Rahman, Md. Afjalur; Rahman, Md. Atikur; Sultana, Rajia; Mostafa, Md. Rakib; Tania, Asmaul Husna; Sarker, Md. Abdur Razzaque

2016-12-01

High-quality cobalt vanadate crystals have been synthesized by solid-state reaction route. Structure and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy. The XRD patterns revealed that the as prepared materials are of high crystallinity and high quality. The SEM images showed that the crystalline CoV2O6 material is very uniform and well separated, with particle (of) area 252 μm. The electronic and optical properties were investigated by impedance analyzer and UV-visible spectrophotometer. Temperature-dependent electrical resistivity was measured using four-probe technique. The crystalline CoV2O6 material is a semiconductor and its activation energy is 0.05 eV.

Preparation and optical characteristics of ZnSe nanocrystals doped glass by sol gel in situ crystallization method

NASA Astrophysics Data System (ADS)

Hao, Haiyan; Yao, Xi; Wang, Minqiang

2007-01-01

Homogeneous ZnSe nanocrystals doped SiO 2 glass was successfully prepared by sol-gel in situ crystallization method. The structure of the doped ZnSe nanocrystals was studied by X-ray diffraction (XRD). ZnSe nanocrystals in silica were about 4-10 nm analysed by transmission electron microscopy (TEM), which was consistent with the results of XRD estimated using Scherrer's formular. The quantum size effect in ZnSe nanocrystals was evidenced from the blue-shifts of the optical absorption edge, and the average size of ZnSe nanocrystals was estimated by the magnitude of blue shift according to the L.E. Brus' effective mass model. The size of ZnSe nanocrystals depending on annealing time and temperature was further discussed using XRF.

Oriented Nucleation of both Ge-Fresnoite and Benitoite/BaGe4O9 during the Surface Crystallisation of Glass Studied by Electron Backscatter Diffraction

PubMed Central

Wisniewski, Wolfgang; Patschger, Marek; Murdzheva, Steliana; Thieme, Christian; Rüssel, Christian

2016-01-01

Two glasses of the compositions 2 BaO - TiO2 - 2.75 GeO2 and 2 BaO – TiO2 –3.67 GeO2 (also known as BTG55) are annealed at temperatures from 680 to 970 °C to induce surface crystallization. The resulting samples are analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) including electron backscatter diffraction (EBSD). Ge-Fresnoite (Ba2TiGe2O8, BTG) is observed at the immediate surface of all samples and oriented nucleation is proven in both compositions. After a very fast kinetic selection, the crystal growth of BTG into the bulk occurs via highly oriented dendrites where the c-axes are oriented perpendicular to the surface. The growth of this oriented layer is finally blocked by dendritc BTG originating from bulk nucleation. The secondary phases BaTiGe3O9 (benitoite) and BaGe4O9 are also identified near the surface by XRD and localized by EBSD which additionally indicates orientation preferences for these phases. This behaviour is in contrast with previous reports from the Ba2TiSi2O8 as well as the Sr2TiSi2O8 systems. PMID:26853738

Average and local atomic-scale structure in BaZrxTi(1-x)O3 (x = 0. 10, 0.20, 0.40) ceramics by high-energy x-ray diffraction and Raman spectroscopy.

PubMed

Buscaglia, Vincenzo; Tripathi, Saurabh; Petkov, Valeri; Dapiaggi, Monica; Deluca, Marco; Gajović, Andreja; Ren, Yang

2014-02-12

High-resolution x-ray diffraction (XRD), Raman spectroscopy and total scattering XRD coupled to atomic pair distribution function (PDF) analysis studies of the atomic-scale structure of archetypal BaZrxTi(1-x)O3 (x = 0.10, 0.20, 0.40) ceramics are presented over a wide temperature range (100-450 K). For x = 0.1 and 0.2 the results reveal, well above the Curie temperature, the presence of Ti-rich polar clusters which are precursors of a long-range ferroelectric order observed below TC. Polar nanoregions (PNRs) and relaxor behaviour are observed over the whole temperature range for x = 0.4. Irrespective of ceramic composition, the polar clusters are due to locally correlated off-centre displacement of Zr/Ti cations compatible with local rhombohedral symmetry. Formation of Zr-rich clusters is indicated by Raman spectroscopy for all compositions. Considering the isovalent substitution of Ti with Zr in BaZrxTi1-xO3, the mechanism of formation and growth of the PNRs is not due to charge ordering and random fields, but rather to a reduction of the local strain promoted by the large difference in ion size between Zr(4+) and Ti(4+). As a result, non-polar or weakly polar Zr-rich clusters and polar Ti-rich clusters are randomly distributed in a paraelectric lattice and the long-range ferroelectric order is disrupted with increasing Zr concentration.

Liquid contrabands classification based on energy dispersive X-ray diffraction and hybrid discriminant analysis

NASA Astrophysics Data System (ADS)

YangDai, Tianyi; Zhang, Li

2016-02-01

Energy dispersive X-ray diffraction (EDXRD) combined with hybrid discriminant analysis (HDA) has been utilized for classifying the liquid materials for the first time. The XRD spectra of 37 kinds of liquid contrabands and daily supplies were obtained using an EDXRD test bed facility. The unique spectra of different samples reveal XRD's capability to distinguish liquid contrabands from daily supplies. In order to create a system to detect liquid contrabands, the diffraction spectra were subjected to HDA which is the combination of principal components analysis (PCA) and linear discriminant analysis (LDA). Experiments based on the leave-one-out method demonstrate that HDA is a practical method with higher classification accuracy and lower noise sensitivity than the other methods in this application. The study shows the great capability and potential of the combination of XRD and HDA for liquid contrabands classification.

Experimental determination of spin-dependent electron density by joint refinement of X-ray and polarized neutron diffraction data.

PubMed

Deutsch, Maxime; Claiser, Nicolas; Pillet, Sébastien; Chumakov, Yurii; Becker, Pierre; Gillet, Jean Michel; Gillon, Béatrice; Lecomte, Claude; Souhassou, Mohamed

2012-11-01

New crystallographic tools were developed to access a more precise description of the spin-dependent electron density of magnetic crystals. The method combines experimental information coming from high-resolution X-ray diffraction (XRD) and polarized neutron diffraction (PND) in a unified model. A new algorithm that allows for a simultaneous refinement of the charge- and spin-density parameters against XRD and PND data is described. The resulting software MOLLYNX is based on the well known Hansen-Coppens multipolar model, and makes it possible to differentiate the electron spins. This algorithm is validated and demonstrated with a molecular crystal formed by a bimetallic chain, MnCu(pba)(H(2)O)(3)·2H(2)O, for which XRD and PND data are available. The joint refinement provides a more detailed description of the spin density than the refinement from PND data alone.

X-Ray Diffraction and Fluorescence Measurements for In Situ Planetary Instruments

NASA Astrophysics Data System (ADS)

Hansford, G.; Hill, K. S.; Talboys, D.; Vernon, D.; Ambrosi, R.; Bridges, J.; Hutchinson, I.; Marinangeli, L.

2011-12-01

The ESA/NASA ExoMars mission, due for launch in 2018, has a combined X-ray fluorescence/diffraction instrument, Mars-XRD, as part of the onboard analytical laboratory. The results of some XRF (X-ray fluorescence) and XRD (X-ray diffraction) tests using a laboratory chamber with representative performance are reported. A range of standard geological reference materials and analogues were used in these tests. The XRD instruments are core components of the forthcoming NASA Mars Science Laboratory (MSL) and ESA/NASA ExoMars missions and will provide the first demonstrations of the capabilities of combined XRD/XRF instrumentation in situ on an extraterrestrial planetary surface. The University of Leicester team is part of the Italy-UK collaboration that is responsible for building the ExoMars X-ray diffraction instrument, Mars-XRD [1,2]. Mars-XRD incorporates an Fe-55 radioisotope source and three fixed-position charge-coupled devices (CCDs) to simultaneously acquire an X-ray fluorescence spectrum and a diffraction pattern providing a measurement of both elemental and mineralogical composition. The CCDs cover an angular range of 2θ = 6° to 73° enabling the analysis of a wide range of geologically important minerals including phyllosilicates, feldspars, oxides, carbonates and evaporites. The identification of hydrous minerals may help identify past Martian hydrothermal systems capable of preserving traces of life. Here we present some initial findings from XRF and XRD tests carried out at the University of Leicester using an Fe-55 source and X-ray sensitive CCD. The XRF/XRD test system consists of a single CCD on a motorised arm, an Fe-55 X-ray source, a collimator and a sample table which approximately replicate the reflection geometry of the Mars-XRD instrument. It was used to test geological reference standard materials and Martian analogues. This work was funded by the Science and Technology Facilities Council, UK. References [1] Marinangeli, L., Hutchinson, I., Baliva, A., Stevoli, A., Ambrosi, R., Critani, F., Delhez, R., Scandelli, L., Holland, A., Nelms, N. & the Mars-XRD Team, Proceedings of the 38th Lunar and Planetary Science Conference, 12 - 16 March 2007, League City, Texas, USA. [2] L. Marinangeli, I. B. Hutchinson, A. Stevoli, G. Adami, R. Ambrosi, R. Amils, V. Assis Fernandes, A. Baliva, A. T. Basilevsky, G. Benedix, P. Bland, A. J. Böttger, J. Bridges, G. Caprarelli, G. Cressey, F. Critani, N. d'Alessandro, R. Delhez, C. Domeneghetti, D. Fernandez-Remolar, R. Filippone, A. M. Fioretti, J. M. Garcia Ruiz, M. Gilmore, G. M. Hansford, G. Iezzi, R. Ingley, M. Ivanov, G. Marseguerra, L. Moroz, C. Pelliciari, P. Petrinca, E. Piluso, L. Pompilio, J. Sykes, F. Westall and the MARS-XRD Team, EPSC-DPS Joint Meeting 2011, 3 - 7 October 2011, La Cité Internationale des Congrès Nantes Métropole, Nantes, France.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madhukumar, R.; Asha, S.; Rao, B. Lakshmeesha

The gamma radiation-induced change in structural and thermal properties of Bombyx mori silk fibroin films were investigated and have been correlated with the applied radiation doses. Irradiation of samples were carried out in dry air at room temperature using Co-60 source, and radiation doses are in the range of 0 - 300 kGy. Structural and thermal properties of the irradiated silk films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA) and compared with unirradiated sample. Interesting results are discussed in this report.

Influence of electron irradiation on the structural and thermal properties of silk fibroin films

NASA Astrophysics Data System (ADS)

Asha, S.; Sangappa, Sanjeev, Ganesh

2015-06-01

Radiation-induced changes in Bombyx mori silk fibroin (SF) films under electron irradiation were investigated and correlated with dose. SF films were irradiated in air at room temperature using 8 MeV electron beam in the range 0-150 kGy. Various properties of the irradiated SF films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Electron irradiation was found to induce changes in the physical and thermal properties, depending on the radiation dose.

Influence of sulfurization temperature on Cu2ZnSnS4 absorber layer on flexible titanium substrates for thin film solar cells

NASA Astrophysics Data System (ADS)

Gokcen Buldu, Dilara; Cantas, Ayten; Turkoglu, Fulya; Gulsah Akca, Fatime; Meric, Ece; Ozdemir, Mehtap; Tarhan, Enver; Ozyuzer, Lutfi; Aygun, Gulnur

2018-02-01

In this study, the effect of sulfurization temperature on the morphology, composition and structure of Cu2ZnSnS4 (CZTS) thin films grown on titanium (Ti) substrates has been investigated. Since Ti foils are flexible, they were preferred as a substrate. As a result of their flexibility, they allow large area manufacturing and roll-to-roll processes. To understand the effects of sulfurization temperature on the CZTS formation on Ti foils, CZTS films fabricated with various sulfurization temperatures were investigated with several analyses including x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy and Raman scattering. XRD measurements showed a sharp and intense peak coming from the (112) planes of the kesterite type lattice structure (KS), which is strong evidence for good crystallinity. The surface morphologies of our thin films were investigated using SEM. Electron dispersive spectroscopy was also used for the compositional analysis of the thin films. According to these analysis, it is observed that Ti foils were suitable as substrates for the growth of CZTS thin films with desired properties and the sulfurization temperature plays a crucial role for producing good quality CZTS thin films on Ti foil substrates.

Effect of calcination temperature on microstructure and magnetic properties of Ni{sub 0.5}Zn{sub 0.25}Cu{sub 0.25} Fe{sub 2}O{sub 4} nanoparticles synthesized by sol-gel method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pransisco, Prengki, E-mail: prengkipransisco@gmail.com, E-mail: afza@petronas.com.my; Shafie, Afza, E-mail: prengkipransisco@gmail.com, E-mail: afza@petronas.com.my; Guan, Beh Hoe, E-mail: beh.hoeguan@petronas.com.my

2014-10-24

This paper examines the effect of calcination process on the structural and magnetic properties material nanostructure composite of Ni{sub 0Ð}œ‡{sub 5}Zn{sub 0Ð}œ‡{sub 25}Cu{sub 0.25} Fe{sub 2}O{sub 4} ferrites. The samples were successfully prepared by sol-gel method at different calcination temperature, which are 600°C, 700°C, 800°C and 900°C. Morphological investigation, average crystallite size and microstructure of the material were examined by using X-ray diffraction (XRD) and confirmed by high resolution transmission electron microscope (HRTEM) and field emission scanning electron microscope (FESEM). The effects of calcination temperature on the magnetic properties were calculated by using vibrating sample magnetometer (VSM). The XRD resultmore » shows single-phase cubic spinel structure with interval average size 5.9-38 nm, and grain size microstructure of the material was increasing with temperature increases. The highest magnetization saturation was reached at a temperature 800°C with value 53.89 emu/g, and the value coercive force (Hc) was inversely with the grain size.« less

Effect of Bi substitution on the magnetic and magnetocaloric properties of Ni50Mn35In15-xBix Heusler alloys

NASA Astrophysics Data System (ADS)

Aryal, Anil; Quetz, Abdiel; Pandey, Sudip; Dubenko, Igor; Stadler, Shane; Ali, Naushad

2018-05-01

The structural, magnetic, magnetocaloric, and transport properties of Ni50Mn35In15-xBix (x = 0, 0.25, 0.5, 1, 1.5) compounds has been studied through X-ray diffraction (XRD), differential scanning calorimetry, and magnetization measurements. A mixture of high temperature austenite phase (AP) and low temperature martensitic phase (MP) was observed from the XRD at room temperature. The saturation magnetization MS at 10 K was found to decrease with increasing Bi content. A shift in the martensitic transition temperature (TM) relative to the parent compound was observed with a maximum shift of ˜ 36 K for x = 1.5. Abnormal shifts in TC and TM to higher temperatures were observed at high field for x ≥ 0.5. Large magnetic entropy changes (ΔSM) of about 40 J/kg K (x = 0) and 34 J/kg K (x = 0.25) were observed at TM with H = 5 T, which reduced significantly for higher Bi concentrations. The doping of small amounts of Bi in the In sites increased the peak width of the ΔSM curves at the second order transition, leading to larger values of relative cooling power. A significant magnetoresistance (-30%) was observed near TM with ΔH = 5T for x = 0.5.

Phase transition studies in bismuth ferrite thin films synthesized via spray pyrolysis technique

NASA Astrophysics Data System (ADS)

Goyal, Ankit; Lakhotia, Harish

2013-06-01

Multiferroic are the materials, which combine two or more "ferroic" properties, ferromagnetism, ferroelectricity or ferroelasticity. BiFeO3 is the only single phase multiferroic material which possesses a high Curie temperature (TC ˜ 1103 K), and a high Neel temperature (TN ˜ 643 K) at room temperature. Normally sophisticated methods are being used to deposit thin films but here we have tried a different method Low cost Spray Pyrolysis Method to deposit BiFeO3 thin film of Glass Substrate with rhombohedral crystal structure and R3c space group. Bismuth Ferrite thin films are synthesized using Bismuth Nitrate and Iron Nitrate as precursor solutions. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to study structural analysis of prepared thin films. XRD pattern shows phase formation of BiFeO3 and SEM analysis shows formation of nanocrystals of 200 nm. High Temperature Resistivity measurements were done by using Keithley Electrometer (Two Probe system). Abrupt behavior in temperature range (313 K - 400K) has been observed in resistance studies which more likely suggests that in this transition the structure is tetragonal rather than rhombohedral. BiFeO3 is the potential active material in the next generation of ferroelectric memory devices.

Electrical properties of CZTS pellets made from microwave-processed powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghediya, Prashant R., E-mail: prashantghediya@yahoo.co.in; Chaudhuri, Tapas K.

2015-06-24

Electrical properties of the kesterite copper zinc tin sulphide (CZTS) pellets in the temperature range from 300 K to 500 K are reported. The pellets are p-type with thermoelectric power (TEP) of + 175 µV/K. Electrical conductivity (σ) increases with the temperatures and is found to be due to thermionic emission (TE) over grain boundary (GB) barriers with activation energy of 170 meV. CZTS pellets are made from micropowders synthesized by microwave irradiation of precursor solution. Formation of kesterite CZTS is confirmed by X-ray diffraction (XRD) and Raman spectroscopy. Scanning Electron Microscope (SEM) shows that powder is micron sized spherical particles.

Removal of Micrometer Size Morphological Defects and Enhancement of Ultraviolet Emission by Thermal Treatment of Ga-Doped ZnO Nanostructures

PubMed Central

Manzoor, Umair; Kim, Do K.; Islam, Mohammad; Bhatti, Arshad S.

2014-01-01

Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures. PMID:24489725

Removal of micrometer size morphological defects and enhancement of ultraviolet emission by thermal treatment of Ga-doped ZnO nanostructures.

PubMed

Manzoor, Umair; Kim, Do K; Islam, Mohammad; Bhatti, Arshad S

2014-01-01

Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures.

Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Kunj, Saurabh; Sreenivas, K.

2016-05-01

Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O2/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

Frabicating hydroxyapatite nanorods using a biomacromolecule template

NASA Astrophysics Data System (ADS)

Zhu, Aiping; Lu, Yan; Si, Yunfeng; Dai, Sheng

2011-02-01

Rod-like hydroxyapatite (HAp) nanoparticles with various aspect ratios are synthesized by means of low-temperature hydrothermal method in the presence of a N-[(2-hydroxy-3-trimethylammonium) propyl]chitosan chloride (HTCC) template. The synthesized HAps were examined by X-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FTIR) and transmission electron microscopy (TEM) techniques. The results reveal that HAps are rod-like monocrystals, where the size and morphology can be tailored by varying synthesis conditions, such as pH, hydrothermal synthesis temperature and the ratio of PO43- to the quaternary ammonium in HTCC. The mechanism of HTCC template on HAp nanorod preparation is analyzed.

Observation of ferromagnetism in Mn doped KNbO3

NASA Astrophysics Data System (ADS)

Manikandan, M.; Venkateswaran, C.

2015-06-01

Pure and Mn doped KNbO3 have been prepared by ball milling assisted ceramic method. Mn ion had been doped at Nb site to induce ferromagnetism at room temperature. X-ray diffraction (XRD) patterns reveal the formation of orthorhombic phase. High resolution scanning electron micrograph (HR-SEM) of both pure and Mn doped samples show a mixture of spherical and plate like particles. Room temperature magnetic behavior of both the samples were analyzed using vibrating sample magnetometer (VSM). 5% Mn doped KNbO3 exhibits ferromagnetic behavior. Observed ferromagnetic feature has been explained by interactions between bound magnetic polarons which are created by Mn4+ ions.

Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kunj, Saurabh, E-mail: saurabhkunj22@gmail.com; Sreenivas, K.

2016-05-23

Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O{sub 2}/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

Thermoluminescence, ESR and x-ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature thermal treatment

NASA Astrophysics Data System (ADS)

Bakshi, A. K.; Patwe, S. J.; Bhide, M. K.; Sanyal, B.; Natarajan, V.; Tyagi, A. K.; Kher, R. K.

2008-01-01

Thermoluminescence (TL), electron spin resonance (ESR) and x ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature treatment were carried out. Analysis of the TL glow curve indicated that the dosimetric glow peak at 240 °C reduces, whereas the low temperature satellite peak increases with the increase in the annealing temperature in the range 650-1000 °C. The influence of the annealing atmosphere on the TL glow curve structure was also observed. Reduction of the photoluminescence intensity of the annealed phosphor indicated that the environment of Dy3+ ions might have undergone some change due to high temperature treatment. Reduction in the ESR signal intensity corresponding to O_{3}^{-} and SO_{3}^{-} radicals was observed initially with the increase in the annealing temperaure; subsequently their intensity increased with temperature. Signals due to the SO_{4}^{-} radical vanished, when the phosphor was annealed beyond 800 °C. A signal corresponding to SH2- radicals was also observed in the ESR spectra for samples subjected to annealing in the temperature regime 800-1000 °C. XRD of the in situ annealed phosphor showed a change in the unit cell parameters. An endothermic peak at 860 °C in the DTA spectrum was observed.

Effect of annealing temperature on the properties of copper oxide films prepared by dip coating technique

NASA Astrophysics Data System (ADS)

Raship, N. A.; Sahdan, M. Z.; Adriyanto, F.; Nurfazliana, M. F.; Bakri, A. S.

2017-01-01

Copper oxide films were grown on silicon substrates by sol-gel dip coating method. In order to study the effects of annealing temperature on the properties of copper oxide films, the temperature was varied from 200 °C to 450 °C. In the process of dip coating, the substrate is withdrawn from the precursor solution with uniform velocity to obtain a uniform coating before undergoing an annealing process to make the copper oxide film polycrystalline. The physical properties of the copper oxide films were measured by an X-ray diffraction (XRD), a field emission scanning electron microscope (FESEM), an atomic force microscopy (AFM) and a four point probe instrument. From the XRD results, we found that pure cuprite (Cu2O) phase can be obtained by annealing the films annealed at 200 °C. Films annealed at 300 °C had a combination phase which consists of tenorite (CuO) and cuprite (Cu2O) phase while pure tenorite (CuO) phase can be obtained at 450 °C annealing temperature. The surface microstructure showed that the grains size is increased whereas the surface roughness is increased and then decreases by increasing in annealing temperature. The films showed that the resistivity decreased with increasing annealing temperature. Consequently, it was observed that annealing temperature has strong effects on the structural, morphological and electrical properties of copper oxide films.

Structural, magnetic and dielectric properties of polyaniline/MnCoFe2O4 nanocomposites

NASA Astrophysics Data System (ADS)

Chitra, Palanisamy; Muthusamy, Athianna; Jayaprakash, Rajan

2015-12-01

Ferromagnetic PANI containing MnCoFe2O4 nanocomposites were synthesized by in-situ chemical polymerization of aniline incorporated MnCoFe2O4 nanoparticles (20%, 10% w/w of fine powders) with and without ultrasonic treatment. The MnCoFe2O4 nanoparticles were synthesized by auto combustion method. The PANI/MnCoFe2O4 nanocomposites were characterized with Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The average particle size of the resulting PANI/MnCoFe2O4 nanocomposites was confirmed from the TEM and XRD analysis. The structure and morphology of the composites were confirmed by FT-IR spectroscopy, XRD and SEM. In addition, the electrical and magnetic properties of the nanocomposites were investigated. The PANI/MnCoFe2O4 nanocomposites under applied magnetic field exhibited the hysteresis loops of ferromagnetic nature at room temperature. The variation of Dielectric constant, Dielectric loss, and AC conductivity of PANI/MnCoFe2O4 nanocomposites at room temperature as a function of frequency in the range 50 Hz-5 MHz has been studied. Effect of ultrasonication on the PANI/MnCoFe2O4 nanocomposites was also investigated.

Effect of grain size on the magnetic properties of superparamagnetic Ni 0.5Zn 0.5Fe 2O 4 nanoparticles by co-precipitation process

NASA Astrophysics Data System (ADS)

Chen, D. G.; Tang, X. G.; Wu, J. B.; Zhang, W.; Liu, Q. X.; Jiang, Y. P.

2011-06-01

Ni 0.5Zn 0.5Fe 2O 4 (NZFO) spinel-type nanoparticles were directly fabricated by the chemical co-precipitation process using metal nitrate and acetate as precursors since nitrogen and carbon would be taken away in the forms of oxynitride and oxycarbide, respectively, after the precursors were annealed and then investigated in detail by employing X-ray diffraction (XRD), magnetic measurement and Raman spectroscopy. XRD analysis indicates that the as-prepared nanocrystals are all of a pure cubic spinel structure with their sizes ranging from 20.8 to 53.3 nm, as well as peaks of some samples shifting to lower angles due to lattice expansion. Calculations from the derived XRD data indicate that the activation energy is 30.83 kJ/mol. The magnetic measurements show that these samples are superparamagnetic. The saturation magnetization increases with annealing temperature, which may be explained by super-exchange interactions of Fe ions occurring at A- and B-sites. The variation of coercivity with particle size is interpreted on the basis of domain structure and crystal anisotropy. Furthermore, these nanoparticles exhibit a redshift phenomenon at lower temperatures seen in the Raman spectra, which could be related to ionic substitution.

Physicochemical characterization of point defects in fluorine doped tin oxide films

NASA Astrophysics Data System (ADS)

Akkad, Fikry El; Joseph, Sudeep

2012-07-01

The physical and chemical properties of spray deposited FTO films are studied using FESEM, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), electrical and optical measurements. The results of XRD measurements showed that the films are polycrystalline (grain size 20-50 nm) with Rutile structure and mixed preferred orientation along the (200) and (110) planes. An angular shift of the XRD peaks after F-doping is observed and interpreted as being due to the formation of substitutional fluorine defects (FO) in presence of high concentration of oxygen vacancies (VO) that are electrically neutral. The electrical neutrality of oxygen vacancies is supported by the observation that the electron concentration n is two orders of magnitude lower than the VO concentration calculated from chemical analyses using XPS measurements. It is shown that an agreement between XPS, XRD, and Hall effect results is possible provided that the degree of deviation from stoichiometry is calculated with the assumption that the major part of the bulk carbon content is involved in O-C bonds. High temperature thermal annealing is found to cause an increase in the FO concentration and a decrease in both n and VO concentrations with the increase of the annealing temperature. These results could be interpreted in terms of a high temperature chemical exchange reaction between the SnO2 matrix and a precipitated fluoride phase. In this reaction, fluorine is released to the matrix and Sn is trapped by the fluoride phase, thus creating substitutional fluorine FO and tin vacancy VSn defects. The enthalpy of this reaction is determined to be approximately 2.4 eV while the energy of formation of a VSn through the migration of SnSn host atom to the fluoride phase is approximately 0.45 eV.

Obtaining aluminas from the thermal decomposition of their different precursors: An {sup 27}Al MAS NMR and X-ray powder diffraction studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chagas, L.H.; De Carvalho, G.S.G.; San Gil, R.A.S.

2014-01-01

Graphical abstract: - Highlights: • We synthesized three precursors of alumina from different methods. • The calcination of the precursors generated several alumina polymorphs. • XRD and NMR were used for structural investigation of the polymorphs. • The synthesis route determines the structural and textural properties of the solids. - Abstract: A commercial sample of Boehmite was used as precursor of alumina polymorphs. For comparison, three other precursors were synthesized from different methods. Particularly, the use of excess of urea promoted a very crystalline form of basic aluminum carbonate. The characteristics of the four precursors were investigated by thermal, vibrationalmore » and X-ray powder diffraction (XRD) analysis. Additionally, the nuclear magnetic resonance, with magic angle spinning ({sup 27}Al MAS NMR), was used to verify the coordination of aluminum cations. Each precursor was calcined at various temperatures generating alumina polymorphs, which were structurally analyzed by XRD and {sup 27}Al MAS NMR. Due to interest in catalysis supports, special attention was given to the γ-Al{sub 2}O{sub 3} phase, which in addition to structural investigation was subjected to textural analysis. The results showed that, from different synthesis procedures and common route of calcination, one can obtain materials with the same composition but with different structural and textural properties, which in turn can significantly influence the performance of a supported catalyst.« less

Electrical analysis of inter-growth structured Bi4Ti3O12-Na0.5Bi4.5Ti4O15 ceramics

NASA Astrophysics Data System (ADS)

Jiang, Xiangping; Jiang, Yalin; Jiang, Xingan; Chen, Chao; Tu, Na; Chen, Yunjing

2017-06-01

Inter-growth bismuth layer-structured ferroelectrics (BLSFs), Bi4Ti3O12-Na0.5Bi4.5Ti4O15 (BIT-NBT), were successfully synthesized using the traditional solid-state reaction method. X-ray diffraction (XRD) Rietveld refinements were conducted using GSAS software. Good agreement and low residual are obtained. The XRD diffraction peaks can be well indexed into I2cm space group. The inter-growth structure was further observed in the high-resolution TEM image. Dielectric and impedance properties were measured and systematically analyzed. At the temperature range 763-923 K (below {T}{{c}}), doubly ionized oxygen vacancies (OVs) are localized and the short-range hopping leads to the relaxation processes with an activation energy of 0.79-1.01 eV. Above {T}{{c}}, the doubly charged OVs are delocalized and become free ones, which contribute to the long-range dc conduction. The reduction in relaxation species gives rise to a higher relaxation activation energy ˜1.6  eV. Project supported by the National Natural Science Foundation of China (Grant Nos. 51562014, 51262009, and 51602135).

Microstructures of GaN1-xPx layers grown on (0001) GaN substrates by gas source molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Seong, Tae-Yeon; Bae, In-Tae; Choi, Chel-Jong; Noh, D. Y.; Zhao, Y.; Tu, C. W.

1999-03-01

Transmission electron microscope (TEM), transmission electron diffraction (TED), and synchrotron x-ray diffraction (XRD) studies have been performed to investigate microstructural behavior of gas source molecular beam epitaxial GaN1-xPx layers grown on (0001) GaN/sapphire at temperatures (Tg) in the range 500-760 °C. TEM, TED, and XRD results indicate that the samples grown at Tg⩽600 °C undergo phase separation resulting in a mixture of GaN-rich and GaP-rich GaNP with zinc-blende structure. However, the samples grown at Tg⩾730 °C are found to be binary zinc-blende GaN(P) single crystalline materials. As for the 500 °C layer, the two phases are randomly oriented and distributed, whereas the 600 °C layer consists of phases that are elongated and inclined by 60°-70° clockwise from the [0001]α-GaN direction. The samples grown at Tg⩾730 °C are found to consist of two types of microdomains, namely, GaN(P)I and GaN(P)II; the former having twin relation to the latter.

The effect of sintering temperature on electrical characteristics of Fe2TiO5/Nb2O5 ceramics for NTC thermistor

NASA Astrophysics Data System (ADS)

Wiendartun, Risdiana, Fitrilawati, Siregar, R. E.

2016-02-01

A study on the fabrication of Iron Titanium Oxide (Fe2TiO5) ceramics for negative temperature coefficient (NTC) thermistors has been carried out, in order to know the effect of sintering temperature on the electrical characteristic of 1.0 % mole Nb2O5 doped Fe2TiO5 ceramics.These ceramics were made by mixing commercial powders of Fe2O3, TiO2 and Nb2O5 with proportional composition to produce Fe2TiO5 based ceramic. The raw pellet was sintered at 1000 °C, 1100 °C and 1200 °C temperature for 2 hours in air. Analysis of the microstructure and crystal structure were performed by using a scanning electron microscope (SEM) and x-ray diffraction (XRD) respectively. XRD spectra showed that the crystal structure of all ceramics of Fe2TiO5 made at various sintering temperatures are orthorhombic. The SEM images showed that the grain size of pellet ceramics increase with increasing sintering temperatures. From electrical resistances data that was measured at temperature 30-300 °C, it is found that the value of thermistor constant (B), activation energy (Ea), thermistor sensitivity (α) and room temperature resistance (RRT) decreases with respect to the increasing of sintering temperature. The fabricated Fe2TiO5 ceramics have thermistor constants (B = 6394-6959 K). This can be applied as temperature sensor, and will fulfill the market requirement.

Effect of iron doping on structural and microstructural properties of nanocrystalline ZnSnO3 thin films prepared by spray pyrolysis techniques

NASA Astrophysics Data System (ADS)

Pathan, Idris G.; Suryawanshi, Dinesh N.; Bari, Anil R.; Patil, Lalchand A.

2018-05-01

This work presents the effect of iron doping having different volume ratios (1 ml, 2.5 ml and 5 ml) on the structural, microstructural and electrical properties of zinc stannate thin films, prepared by spray pyrolysis method. These properties were characterized with X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). In our study, XRD pattern indicates that ZnSnO3 has a perovskite phase with face exposed hexahedron structure. The electron diffraction fringes observed are in consistent with the peak observed in XRD patterns. Moreover the sensor reported in our study is cost-effective, user friendly and easy to fabricate.

Growth and characterization of V2O5 nanorods deposited by spray pyrolysis at low temperatures

NASA Astrophysics Data System (ADS)

Abd-Alghafour, N. M.; Ahmed, Naser M.; Hassan, Zai.; Mohammad, Sabah M.; Bououdina, M.

2016-07-01

Vanadium pentoxide (V2O5) nanorods were deposited by spray pyrolysis on preheated glass substrates at low temperatures. The influence of substrate temperature on the crystallization of V2O5 has been investigated. X-ray diffraction analysis (XRD) revealed that the films deposited at Tsub = 300°C were orthorhombic structures with preferential along (001) direction. Formation of nanorods from substrate surface which led to the formation of films with small-sized and rod-shaped nanostructure is observed by field scanning electron microscopy. Optical transmittance in the visible range increases to reach a maximum value of about 80% for a substrate temperature of 350°C. PL spectra reveal one main broad peak centered around 540 nm with high intensity.

Low temperature nucleation of Griffiths Phase in Co doped LaMnO3 nanostructures

NASA Astrophysics Data System (ADS)

Adeela, N.; Khan, U.; Naz, S.; Iqbal, M.; Irfan, M.; Cheng, Y.

2017-11-01

We have reported magnetic properties of La1-xCoxMnO3 nanostructures synthesized by hydrothermal route. The crystal structure has been characterized by X-ray diffraction (XRD) technique, which shows rhombohedral perovskite structure at room temperature. Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) have been used to analyse morphology and chemical composition of prepared nanoparticles. Magnetic hysteresis loops of all the samples exhibit ferromagnetic behaviour at 10 K. Inverse susceptibility graphs as a function of temperature represent deviation from Curie Weiss law. The indication for short range ferromagnetic clusters well above Curie temperature is observed due to the Griffiths Phase (GP). It is proposed that the presence of GP arises from induced size effects of La and Co ions.

Effect of content silver and heat treatment temperature on morphological, optical, and electrical properties of ITO films by sol-gel technique

NASA Astrophysics Data System (ADS)

Mirzaee, Majid; Dolati, Abolghasem

2014-09-01

Silver-doped indium tin oxide thin films were synthesized using sol-gel dip-coating technique. The influence of different silver-dopant contents and annealing temperature on the electrical, optical, structural, and morphological properties of the films were characterized by means of four-point probe, UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope (XPS). XRD analysis confirmed the formation of cubic bixbyte structure of In2O3 with silver nanoparticles annealed at 350 °C. XPS analysis showed that divalent tin transformed to tetravalent tin through oxidization, and silver nanoparticles embedded into ITO matrix covered with silver oxide shell, resulting in high quality nanocomposite thin films. The embedment of polyvinylpyrrolidone inhibited the growth of silver nanoparticles and ITO annealed at 350 °C. Delafossite structure of tin-doped AgInO2 was found at higher annealing temperatures. XRD analysis and FESEM micrographs showed that the optimum temperature to prevent the formation of AgInO2 is 350 °C. The embedment of silver particles (5-10 nm) from reduction of silver ion in ITO thin films improved the electrical conductivity and optical transmittance of ITO nanolayers. The lowest stable sheet resistance of 1,952 Ω/Sq for a 321 nm thick and an average optical transmittance of 91.8 % in the visible region with a band gap of 3.43 eV were achieved for silver-doping content of 0.04 M.

Methanol incorporation in clathrate hydrates and the implications for oil and gas pipeline flow assurance and icy planetary bodies

PubMed Central

Shin, Kyuchul; Udachin, Konstantin A.; Moudrakovski, Igor L.; Leek, Donald M.; Alavi, Saman; Ratcliffe, Christopher I.; Ripmeester, John A.

2013-01-01

One of the best-known uses of methanol is as antifreeze. Methanol is used in large quantities in industrial applications to prevent methane clathrate hydrate blockages from forming in oil and gas pipelines. Methanol is also assigned a major role as antifreeze in giving icy planetary bodies (e.g., Titan) a liquid subsurface ocean and/or an atmosphere containing significant quantities of methane. In this work, we reveal a previously unverified role for methanol as a guest in clathrate hydrate cages. X-ray diffraction (XRD) and NMR experiments showed that at temperatures near 273 K, methanol is incorporated in the hydrate lattice along with other guest molecules. The amount of included methanol depends on the preparative method used. For instance, single-crystal XRD shows that at low temperatures, the methanol molecules are hydrogen-bonded in 4.4% of the small cages of tetrahydrofuran cubic structure II hydrate. At higher temperatures, NMR spectroscopy reveals a number of methanol species incorporated in hydrocarbon hydrate lattices. At temperatures characteristic of icy planetary bodies, vapor deposits of methanol, water, and methane or xenon show that the presence of methanol accelerates hydrate formation on annealing and that there is unusually complex phase behavior as revealed by powder XRD and NMR spectroscopy. The presence of cubic structure I hydrate was confirmed and a unique hydrate phase was postulated to account for the data. Molecular dynamics calculations confirmed the possibility of methanol incorporation into the hydrate lattice and show that methanol can favorably replace a number of methane guests. PMID:23661058

Methanol incorporation in clathrate hydrates and the implications for oil and gas pipeline flow assurance and icy planetary bodies.

PubMed

Shin, Kyuchul; Udachin, Konstantin A; Moudrakovski, Igor L; Leek, Donald M; Alavi, Saman; Ratcliffe, Christopher I; Ripmeester, John A

2013-05-21

One of the best-known uses of methanol is as antifreeze. Methanol is used in large quantities in industrial applications to prevent methane clathrate hydrate blockages from forming in oil and gas pipelines. Methanol is also assigned a major role as antifreeze in giving icy planetary bodies (e.g., Titan) a liquid subsurface ocean and/or an atmosphere containing significant quantities of methane. In this work, we reveal a previously unverified role for methanol as a guest in clathrate hydrate cages. X-ray diffraction (XRD) and NMR experiments showed that at temperatures near 273 K, methanol is incorporated in the hydrate lattice along with other guest molecules. The amount of included methanol depends on the preparative method used. For instance, single-crystal XRD shows that at low temperatures, the methanol molecules are hydrogen-bonded in 4.4% of the small cages of tetrahydrofuran cubic structure II hydrate. At higher temperatures, NMR spectroscopy reveals a number of methanol species incorporated in hydrocarbon hydrate lattices. At temperatures characteristic of icy planetary bodies, vapor deposits of methanol, water, and methane or xenon show that the presence of methanol accelerates hydrate formation on annealing and that there is unusually complex phase behavior as revealed by powder XRD and NMR spectroscopy. The presence of cubic structure I hydrate was confirmed and a unique hydrate phase was postulated to account for the data. Molecular dynamics calculations confirmed the possibility of methanol incorporation into the hydrate lattice and show that methanol can favorably replace a number of methane guests.

Fabrication and Characterization of CZTS Thin Films Prepared by the Sulfurization of RF-Sputtered Stacked Metal Precursors

NASA Astrophysics Data System (ADS)

Abusnina, Mohamed; Moutinho, Helio; Al-Jassim, Mowafak; DeHart, Clay; Matin, Mohammed

2014-09-01

In this work, Cu2ZnSnS4 (CZTS) thin films were prepared by the sulfurization of metal precursors deposited sequentially via radio frequency magnetron sputtering on Mo-coated soda-lime glass. The stack order of the precursors was Mo/Zn/Sn/Cu. Sputtered precursors were annealed in sulfur atmosphere with nine different conditions to study the impact of sulfurization time and substrate temperature on the structural, morphological, and optical properties of the final CZTS films. X-ray fluorescence was used to determine the elemental composition ratio of the metal precursors. Final CZTS films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). XRD and EDS were combined to investigate the films' structure and to identify the presence of secondary phases. XRD analysis indicated an improvement in film crystallinity with an increase of the substrate temperature and annealing times. Also indicated was the minimization and/or elimination of secondary phases when the films experienced longer annealing time. EDS revealed slight Sn loss in films sulfurized at 550°C; however, an increase of the sulfurization temperature to 600°C did not confirm these results. SEM study showed that films treated with higher temperatures exhibited dense morphology, indicating the completion of the sulfurization process. The estimated absorption coefficient was on the order of 104 cm-1 for all CZTS films, and the values obtained for the optical bandgap energy of the films were between 1.33 eV and 1.52 eV.

Pole Figure Explorer v. 1.8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Benthem, Mark H.

2016-05-04

This software is employed for 3D visualization of X-ray diffraction (XRD) data with functionality for slicing, reorienting, isolating and plotting of 2D color contour maps and 3D renderings of large datasets. The program makes use of the multidimensionality of textured XRD data where diffracted intensity is not constant over a given set of angular positions (as dictated by the three defined dimensional angles of phi, chi, and two-theta). Datasets are rendered in 3D with intensity as a scaler which is represented as a rainbow color scale. A GUI interface and scrolling tools along with interactive function via the mouse allowmore » for fast manipulation of these large datasets so as to perform detailed analysis of diffraction results with full dimensionality of the diffraction space.« less

Low temperature hall effect investigation of conducting polymer-carbon nanotubes composite network.

PubMed

Bahrami, Afarin; Talib, Zainal Abidin; Yunus, Wan Mahmood Mat; Behzad, Kasra; M Abdi, Mahnaz; Din, Fasih Ud

2012-11-14

Polypyrrole (PPy) and polypyrrole-carboxylic functionalized multi wall carbon nanotube composites (PPy/f-MWCNT) were synthesized by in situ chemical oxidative polymerization of pyrrole on the carbon nanotubes (CNTs). The structure of the resulting complex nanotubes was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The effects of f-MWCNT concentration on the electrical properties of the resulting composites were studied at temperatures between 100 K and 300 K. The Hall mobility and Hall coefficient of PPy and PPy/f-MWCNT composite samples with different concentrations of f-MWCNT were measured using the van der Pauw technique. The mobility decreased slightly with increasing temperature, while the conductivity was dominated by the gradually increasing carrier density.

Effect of annealing temperature on titania nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manikandan, K., E-mail: sanjaymani367@gmail.com; Arumugam, S., E-mail: sanjaymani367@gmail.com; Chandrasekaran, G.

2014-04-24

Titania polycrystalline samples are prepared by using sol-gel route hydrolyzing a alkoxide titanium precursor under acidic conditions. The as prepared samples are treated with different calcination temperatures. The anatase phase of titania forms when treated below 600°C, above that temperature the anatase phase tends to transform into the rutile phase of titania. The experimental determination of average grain size, phase formation, lattice parameters and the crystal structures of titania samples at different calcinations is done using X-ray diffraction (XRD). Fourier Transform Infra-red Spectroscopy (FTIR), UV-vis-NIR spectroscopy and Scanning Electron Microscopy (SEM) and Energy Dispersive Analysis X-ray are used to characterizemore » the samples to bring impact on the respective properties.« less

Low temperature sintered giant dielectric permittivity CaCu3Ti4O12 sol-gel synthesized nanoparticle capacitors

NASA Astrophysics Data System (ADS)

Puli, Venkata Sreenivas; Adireddy, Shiva; Kothakonda, Manish; Elupula, Ravinder; Chrisey, Douglas B.

This paper reports on synthesis of polycrystalline complex perovskite CaCu3Ti4O12 (as CCTO) ceramic powders prepared by a sol-gel auto combustion method at different sintering temperatures and sintering times, respectively. The effect of sintering time on the structure, morphology, dielectric and electrical properties of CCTO ceramics is investigated. Tuning the electrical properties via different sintering times is demonstrated for ceramic samples. X-ray diffraction (XRD) studies confirm perovskite-like structure at room temperature. Abnormal grain growth is observed for ceramic samples. Giant dielectric permittivity was realized for CCTO ceramics. High dielectric permittivity was attributed to the internal barrier layer capacitance (IBLC) model associated with the Maxwell-Wagner (MW) polarization mechanism.

Comparative examination of the microstructure and high temperature oxidation performance of NiCrBSi flame sprayed and pack cementation coatings

NASA Astrophysics Data System (ADS)

Chaliampalias, D.; Vourlias, G.; Pavlidou, E.; Skolianos, S.; Chrissafis, K.; Stergioudis, G.

2009-01-01

Coatings formed from NiCrBSi powder were deposited by thermal spray and pack cementation processes on low carbon steel. The microstructure and morphology of the coatings were studied by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Flame sprayed coatings exhibited high porosity and were mechanically bonded to the substrate while pack cementation coatings were more compact and chemically bonded to the substrate. The microhardness and the high temperature oxidation resistance of the coated samples were evaluated by a Vickers microhardness tester and by thermogravimetric measurements (TG), respectively. Pack cementation coatings showed higher hardness and were more protective to high temperature environments than the flame sprayed coatings.

The Bulk Nanocrystalline zn Produced by Mechanical Attrition

NASA Astrophysics Data System (ADS)

Zhu, X. K.; Zhao, K. Y.; Li, C. J.; Tao, J. M.; Chan, T. L.; Koch, C. C.

The purpose of experiment was to produce bulk nanocrystalline Zn by mechanical attrition. The bulk nanocrystalline Zn produced by mechanical attrition was studied. The microstructural evolution during cryomilling and subsequent room temperature milling was characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). In this paper, Nanocrystalline Zn was produced by insitu consolidation of Zn elemental powder using mechanical attrition at liquid nitrogen and room temperature. For the samples studied, the longest elongation of 65% and highest stress of 200 MPa is obtained in nanocrystalline Zn during tensile testing at the condition of strain rate (10-3 sec-1) and 20°C which is equal to 0.43 Tm (Tm is the melting temperature of pure Zn).

Synthesis and dielectric properties of zinc oxide nanoparticles using a biotemplate

DOE Office of Scientific and Technical Information (OSTI.GOV)

P, Sharmila P, E-mail: sharmilavishram@gmail.com; Tharayil, Nisha J., E-mail: nishajohntharayil@gmail.com

Zinc Oxide nanoparticles are synthesized using DNA as capping agent. Zinc oxide nanoparticles are synthesized using DNA as a capping agent. Structural and morphological characterizations are done using SEM, FTIR and XRD. The particle size and lattice parameters are calculated from the diffraction data. The optical properties are studied using UV-Vis absorption spectroscopy and bandgap variation with temperature is determined. The dielectric property of nanoparticles is studied by varying temperature and frequency. The dielectric constant and dispersion parameters are found out. Method of Cole-Cole analysis is used to study the high temperature dispersion of relaxation time. The variation of bothmore » AC and DC conductivity are studied and activation energy calculated.« less

Hexamethylenetetramine assisted hydrothermal synthesis of BiPO4 and its electrochemical properties for supercapacitors

NASA Astrophysics Data System (ADS)

Nithya, V. D.; Kalai Selvan, R.; Vasylechko, Leonid

2015-11-01

The well defined microstructures of BiPO4 were successfully synthesized by the facile hexamethylenetetramine (HMT) assisted hydrothermal method. The low temperature monoclinic BiPO4 structure with space group P21/n, were obtained from X-ray diffraction (XRD) for the pristine and HMT-assisted BiPO4 with 1, 3, 5 and 10 mmole concentration. A transformation from low temperature monazite-type phase to the high temperature SbPO4-type phase of BiPO4 was observed at the 10 mmole concentration. There was a variation in the morphology from polyhedron to octahedra-like and finally into cube shape upon an increase in concentration of HMT. The role of reaction time in the morphology of BiPO4 particles was investigated. The selected area electron diffraction (SAED) pattern elucidated the ordered dot pattern and the calculated d-spacing revealed the formation of BiPO4. An increased specific capacitance of HMT assisted materials (202 F/g) compared with pristine BiPO4 (89 F/g) at 5 mA/cm2 was observed upon morphological variation due to HMT addition.

Green synthesis of soya bean sprouts-mediated superparamagnetic Fe 3O 4 nanoparticles

NASA Astrophysics Data System (ADS)

Cai, Yan; Shen, Yuhua; Xie, Anjian; Li, Shikuo; Wang, Xiufang

2010-10-01

Superparamagnetic Fe 3O 4 nanoparticles were first synthesized via soya bean sprouts (SBS) templates under ambient temperature and normal atmosphere. The reaction process was simple, eco-friendly, and convenient to handle. The morphology and crystalline phase of the nanoparticles were determined from scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) spectra. The effect of SBS template on the formation of Fe 3O 4 nanoparticles was investigated using X-ray photoemission spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). The results indicate that spherical Fe 3O 4 nanoparticles with an average diameter of 8 nm simultaneously formed on the epidermal surface and the interior stem wall of SBS. The SBS are responsible for size and morphology control during the whole formation of Fe 3O 4 nanoparticles. In addition, the superconducting quantum interference device (SQUID) results indicate the products are superparamagnetic at room temperature, with blocking temperature ( TB) of 150 K and saturation magnetization of 37.1 emu/g.

Characterization of CuCl quantum dots grown in NaCl single crystals via optical measurements, X-ray diffraction, and transmission electron microscopy

NASA Astrophysics Data System (ADS)

Miyajima, Kensuke; Akatsu, Tatsuro; Itoh, Ken

2018-05-01

We evaluated the crystal size, shape, and alignment of the lattice planes of CuCl quantum dots (QDs) embedded in NaCl single crystals by optical measurements, X-ray diffraction (XRD) patterns, and transmission electron microscopy (TEM). We obtained, for the first time, an XRD pattern and TEM images for CuCl QDs in NaCl crystals. The XRD pattern showed that the lattice planes of the CuCl QDs were parallel to those of the NaCl crystals. In addition, the size of the QDs was estimated from the diffraction width. It was apparent from the TEM images that almost all CuCl QDs were polygonal, although some cubic QDs were present. The mean size and size distribution of the QDs were also obtained. The dot size obtained from optical measurements, XRD, and TEM image were almost consistent. Our new findings can help to reveal the growth mechanism of semiconductor QDs embedded in a crystallite matrix. In addition, this work will play an important role in progressing the study of optical phenomena originating from assembled semiconductor QDs.

First X-Ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest Aeolian Bedform at Gale Crater

NASA Technical Reports Server (NTRS)

Bish, D. L.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Sarrazin, P.; Morris, R. V.; Ming, D. W.; Treiman, A. H.; Downs, R. T.; Morrison, S. M.;

Synthesis of formamidinium lead iodide perovskite bulk single crystal and its optical properties

NASA Astrophysics Data System (ADS)

Zheng, Hongge; Duan, Junjie; Dai, Jun

2017-07-01

Formamidinium lead iodide (FAPbI3) is a promising hybrid perovskite material for optoelectronic devices. We synthesized bulk single crystal FAPbI3 by a rapid solution crystallization method. X-ray diffraction (XRD) was performed to characterize the crystal structure. Temperature-dependent photoluminescence (PL) spectra of the bulk single crystal FAPbI3 were measured from 10 to 300 K to explain PL recombination mechanism. It shows that near band edge emission blueshifts with the temperature increasing from 10 to 120 K and from 140 K to room temperature, a sudden emission band redshift demonstrates near 140 K because of the phase transition from orthorhombic phase to cubic phase. From the temperature-dependent PL spectra, the temperature coefficients of the bandgap and thermal activation energies of FAPbI3 perovskite are fitted.

Miscibility of amorphous ZrO2-Al2O3 binary alloy

NASA Astrophysics Data System (ADS)

Zhao, C.; Richard, O.; Bender, H.; Caymax, M.; De Gendt, S.; Heyns, M.; Young, E.; Roebben, G.; Van Der Biest, O.; Haukka, S.

2002-04-01

Miscibility is a key factor for maintaining the homogeneity of the amorphous structure in a ZrO2-Al2O3 binary alloy high-k dielectric layer. In the present work, a ZrO2/Al2O3 laminate thin layer has been prepared by atomic layer chemical vapor deposition on a Si (100) wafer. This layer, with artificially induced inhomogeneity (lamination), enables one to study the change in homogeneity of the amorphous phase in the ZrO2/Al2O3 system during annealing. High temperature grazing incidence x-ray diffraction (HT-XRD) was used to investigate the change in intensity of the constructive interference peak of the x-ray beams which are reflected from the interfaces of ZrO2/Al2O3 laminae. The HT-XRD spectra show that the intensity of the peak decreases with an increase in the anneal temperature, and at 800 °C, the peak disappears. The same samples were annealed by a rapid thermal process (RTP) at temperatures between 700 and 1000 °C for 60 s. Room temperature XRD of the RTP annealed samples shows a similar decrease in peak intensity. Transmission electronic microscope images confirm that the laminate structure is destroyed by RTP anneals and, just below the crystallization onset temperature, a homogeneous amorphous ZrAlxOy phase forms. The results demonstrate that the two artificially separated phases, ZrO2 and Al2O3 laminae, tend to mix into a homogeneous amorphous phase before crystallization. This observation indicates that the thermal stability of ZrO2-Al2O3 amorphous phase is suitable for high-k applications.

Thermal behavior of polyhalite: a high-temperature synchrotron XRD study

DOE PAGES

Xu, Hongwu; Guo, Xiaofeng; Bai, Jianming

2016-09-17

As an accessory mineral in marine evaporites, polyhalite, K 2MgCa 2(SO 4) 4·2H 2O, coexists with halite (NaCl) in salt formations, which have been considered as potential repositories for permanent storage of high-level nuclear wastes. However, because of the heat generated by radioactive decays in the wastes, polyhalite may dehydrate, and the released water will dissolve its neighboring salt, potentially affecting the repository integrity. Thus, studying the thermal behavior of polyhalite is important. In this paper, a polyhalite sample containing a small amount of halite was collected from the Salado formation at the WIPP site in Carlsbad, New Mexico. Tomore » determine its thermal behavior, in situ high-temperature synchrotron X-ray diffraction was conducted from room temperature to 1066 K with the sample powders sealed in a silica-glass capillary. At about 506 K, polyhalite started to decompose into water vapor, anhydrite (CaSO 4) and two langbeinite-type phases, K 2Ca x Mg 2-x (SO 4) 3, with different Ca/Mg ratios. XRD peaks of the minor halite disappeared, presumably due to its dissolution by water vapor. With further increasing temperature, the two langbeinite solid solution phases displayed complex variations in crystallinity, composition and their molar ratio and then were combined into the single-phase triple salt, K 2CaMg(SO 4) 3, at ~919 K. Rietveld analyses of the XRD data allowed determination of structural parameters of polyhalite and its decomposed anhydrite and langbeinite phases as a function of temperature. Finally, from the results, the thermal expansion coefficients of these phases have been derived, and the structural mechanisms of their thermal behavior been discussed.« less

Griffith Saponite as an Analog for Clay Minerals at Yellowknife Bay in Gale Crater, Mars: A Marker for Low-temperature Hydrothermal Processes

NASA Technical Reports Server (NTRS)

Morris, R.V.; Treiman, A. H.; Agresti, D. G.; Graff, T. G.; Achilles, C. N.; Rampe, E. B.; Bristow, T. F.; Ming, D. W.; Blake, D. F.; Vaniman, D. T.;

Effect of silver doping on the elastic properties of CdS nanoparticles

NASA Astrophysics Data System (ADS)

Dey, P. C.; Das, R.

2018-05-01

CdS and Ag doped CdS (CdS/Ag) nanoparticles have been prepared via chemical method from a Cadmium acetate precursor and Thiourea. The synthesized CdS and CdS/Ag nanoparticles have been characterized by the X-ray Diffraction and High Resolution Transmission Electron Microscope. Here, these nanoparticles have been synthesized at room temperature and all the characterization have also been done at room temperature only. The XRD results reveal that the products are crystalline with cubic zinc blende structure. HRTEM images show that the prepared nanoparticles are nearly spherical in shape. Williamson-Hall method and Size-Strain Plot (SSP) have been used to study the individual contribution of crystalline sizes and lattice strain on the peak broadening of the CdS and CdS/Ag nanoparticles. The different modified model of Williamson-Hall method such as, uniform deformation model, uniform stress deformation model and uniform energy density deformation model and SSP method have been used to calculate the different physical parameter such as lattice strain, stress and energy density for all diffraction peaks of the XRD, corresponding to the CdS and silver doped CdS (CdS/Ag). The obtained results reveal that the average particle size of the prepared CdS and CdS/Ag nanoparticles estimated from the HRTEM images, Williamson-Hall analysis and SSP method are highly correlated with each other. Further, all these result confirms that doping of Ag significantly affects the elastic properties of CdS.

High-resolution transmission electron microscopy studies of graphite materials prepared by high-temperature treatment of unburned carbon concentrates from combustion fly ashes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miguel Cabielles; Jean-Nol Rouzaud; Ana B. Garcia

2009-01-15

High-resolution transmission electron microscopy (HRTEM) has been used in this work to study the microstructural (structure and microtexture) changes occurring during the high-temperature treatment of the unburned carbon concentrates from coal combustion fly ashes. Emphasis was placed on two aspects: (i) the development of graphitic carbon structures and (ii) the disordered carbon forms remaining in the graphitized samples. In addition, by coupling HRTEM with energy-dispersive spectroscopy, the transformations with the temperature of the inorganic matter (mainly iron- and silicon-based phases) of the unburned carbon concentrates were evidenced. The HRTEM results were compared to the averaged structural order of the materialsmore » as evaluated by X-ray diffraction (XRD) and Raman spectroscopy. As indicated by XRD and Raman parameters, more-ordered materials were obtained from the unburned carbon concentrates with higher mineral/inorganic matter, thus inferring the catalytic effect of some of their components. However, the average character of the information provided by these instrumental techniques seems to be inconclusive in discriminating between carbon structures with different degrees of order (stricto sensu graphite, graphitic, turbostratic, etc.) in a given graphitized unburned carbon. Unlike XRD and Raman, HRTEM is a useful tool for imaging directly the profile of the polyaromatic layers (graphene planes), thus allowing the sample heterogeneity to be looked at, specifically the presence of disordered carbon phases. 49 refs., 9 figs., 3 tabs.« less

Electron paramagnetic resonance in Cu-doped ZnO

NASA Astrophysics Data System (ADS)

Buchheit, R.; Acosta-Humánez, F.; Almanza, O.

2016-04-01

In this work, ZnO and Cu-doped ZnO nanoparticles (Zn1-xCuxO, x = 3%), with a calcination temperature of 500∘C were synthesized using the sol-gel method. The particles were analyzed using atomic absorption spectroscopy (AAS), X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) at X-band, measurement in a temperature range from 90 K to room temperature. AAS confirmed a good correspondence between the experimental doping concentration and the theoretical value. XRD reveals the presence of ZnO phase in hexagonal wurtzite structure and a nanoparticle size for the samples synthesized. EPR spectroscopy shows the presence of point defects in both samples with g-values of g = 1.959 for shallow donors and g = 2.004 for ionized vacancies. It is important when these materials are required have been used as catalysts, as suggested that it is not necessary prepare them at higher temperature. A simulation of the Cu EPR signal using an anisotropic spin Hamiltonian was performed and showed good coincidence with the experimental spectra. It was shown that Cu2+ ions enter interstitial octahedral sites of orthorhombic symmetry in the wurtzite crystal structure. Temperature dependence of the EPR linewidth and signal intensity shows a paramagnetic behavior of the sample in the measurement range. A Néel temperature TN = 78 ± 19 K was determined.

Elucidating the Wavelength Dependence of Phonon Scattering in Nanoparticle-Matrix Composites using Phonon Spectroscopy

DTIC Science & Technology

2016-07-11

composites with x - ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Rutherford backscattering spectroscopy...RBS), particle-induced x - ray emission (PIXE), and energy dispersive x - ray spectroscopy (EDX). This work complements earlier works on CdSe...sample shows only In2Se3 and CdIn2Se4 XRD peaks (Figure 1.4e), it is stoichiometrically   Figure 1.4. X - ray diffraction patterns of (a) γ-In2Se3

FT-IR and Zeta potential measurements on TiO nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Jaiveer; Rathore, Ravi; Kaurav, Netram, E-mail: netramkaurav@yahoo.co.uk

2016-05-23

In the present investigation, ultrafine TiO particles have been synthesized successfully by thermal decomposition method. The sample was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. As-synthesized TiO nanoparticles have a cubic structure as characterized by power X-ray diffraction (XRD), which shows that TiO nanoparticles have narrow size distribution with particle size 11.5 nm. FTIR data shows a strong peak at 1300 cm{sup −1}, assignable to the Ti-O stretching vibrations mode.

Enhanced electrical properties of SrBi4Ti4O15 ceramic with addition of ZrO2

NASA Astrophysics Data System (ADS)

Mamatha, B.; Rani, G. Neeraja; Shankar, J.

2018-04-01

Polycrystalline SrBi4Ti3.95Zr0.05O15 (SBZT) ceramic was prepared by solid-state double sintering method. It was characterized by X-Ray Diffraction (XRD) and Scanning Electron Micrograph (SEM). With the increased addition of ZrO2, the electrical properties as dielectric, ferroelectric and piezoelectric were studied. From XRD, single-phase formation with orthorhombic structure was identified by the increase of ZrO2. The remnant polarization (Pr) and dielectric constant was found to be increased with the increase of ZrO2. With the increase of ZrO2, Curie temperature (Tc) was found to be decreased. The planar electromechanical coupling coefficient (Kp = 0.57) and Piezoelectric coefficient (d33 = 18 pC/N) was found to be increased with the increase of ZrO2.

Study of free radicals in gamma irradiated cellulose of cultural heritage materials using Electron Paramagnetic Resonance

NASA Astrophysics Data System (ADS)

Kodama, Yasko; Rodrigues, Orlando, Jr.; Garcia, Rafael Henrique Lazzari; Santos, Paulo de Souza; Vasquez, Pablo A. S.

2016-07-01

Main subject of this article was to study room temperature stable radicals in Co-60 gamma irradiated contemporary paper using Electron Paramagnetic Resonance spectrometer (EPR). XRD was used to study the effect of ionizing radiation on the morphology of book paper. SEM images presented regions with cellulose fibers and regions with particles agglomeration on the cellulose fibers. Those agglomerations were rich in calcium, observed by EDS. XRD analysis confirmed presence of calcium carbonate diffraction peaks. The main objective of this study was to propose a method using conventional kinetics chemical reactions for the observed radical formed by ionizing radiation. Therefore, further analyses were made to study the half-life and the kinetics of the free radical created. This method can be suitably applied to study radicals on cultural heritage objects.

Charge transport mechanism analysis of Al/CdS:Sr{sup 2+}/ITO device under dark and light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Datta, Joydeep; Das, Mrinmay; Dey, Arka

2016-05-06

In this study, we have synthesized CdS:Sr{sup 2+} by hydrothermal technique. Material property has been studied by X-ray diffraction (XRD), Scanning electron microscope (SEM) and UV-vis absorption spectroscopy. XRD data revealed that there are mixed phases of CdS and SrS in the synthesized sample. The optical band gap of the material was estimated as 3.15 eV from UV-vis data. The synthesized material has been applied in metal-semiconductor device and transport properties have been analyzed by measuring current–voltage characteristics under dark and light conditions at room temperature. Variation in different device parameters like ideality factor, barrier height and series resistance ofmore » Al/CdS:Sr{sup 2+}/ITO device were analyzed by using Cheung’s function.« less

Effect of stress, strain and optical properties in vacuum and normal annealed ZnO thin films using RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Kumar, B. Santhosh; Purvaja, K.; Harinee, N.; Venkateswaran, C.

2018-05-01

Zinc oxide thin films have been deposited on quartz substrate using RF magnetron sputtering. The deposited films were subjected to different annealing atmosphere at a fixed temperature of 500 °C for 5h. The X-ray diffraction (XRD) patterns reveals the shift in the peak of both normal annealed and vacuum annealed thin films when compared to as-deposited ZnO film. The crystallite size, intrinsic stress and other parameters were calculated from XRD data. The surface morphology of the obtained films were studied using Atomic force microscopy (AFM). From Uv-Visible spectroscopy, the peak at 374 nm of all the films is characteristics of ZnO. The structural, thermal stability and optical properties of the annealed ZnO films are discussed in detail.

Photoluminescence study of ZnS and ZnS:Pb nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Virpal,, E-mail: virpalsharma.sharma@gmail.com; Hastir, Anita; Kaur, Jasmeet

2015-05-15

Photoluminescence (PL) study of pure and 5wt. % lead doped ZnS prepared by co-precipitation method was conducted at room temperature. The prepared nanoparticles were characterized by X-ray Diffraction (XRD), UV-Visible (UV-Vis) spectrophotometer, Photoluminescence (PL) and Raman spectroscopy. XRD patterns confirm cubic structure of ZnS and PbS in doped sample. The band gap energy value increased in case of Pb doped ZnS nanoparticles. The PL spectrum of pure ZnS was de-convoluted into two peaks centered at 399nm and 441nm which were attributed to defect states of ZnS. In doped sample, a shoulder peak at 389nm and a broad peak centered atmore » 505nm were observed. This broad green emission peak originated due to Pb activated ZnS states.« less

Synthesis, characterization and antistructure modeling of Ni nano ferrite

NASA Astrophysics Data System (ADS)

Kane, S. N.; Raghuvanshi, S.; Satalkar, M.; Reddy, V. R.; Deshpande, U. P.; Tatarchuk, T. R.; Mazaleyrat, F.

2018-05-01

We report the role played by cation distribution in determining magnetic properties by comparing dry gel, thermally annealed Ni ferrite prepared by sol-gel auto-combustion technique. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Mössbauer spectroscopy were used to characterize the samples. Both XRD and Mössbauer measurements validate the formation of spinel phase with grain diameter 39.13-45.53 nm. First time antistructural modeling for Ni ferrite is reported to get information on active surface centers. Decrease of Debye temperature θD in annealed sample shows enhancement of lattice vibrations. With thermal annealing experimental and Néel magnetic moment (nBe, nBN) increases, suggesting migration of Ni2+ from B to A site with concurrent migration of Fe3+ from A to B site (non-equilibrium cationic distribution), affecting magnetic properties.

Hydrogen sensor based on Sm-doped SnO{sub 2} nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Gurpreet; Hastir, Anita; Singh, Ravi Chand, E-mail: ravichand.singh@gmail.com

2016-05-23

In this paper the effect of samarium doping on the structural and hydrogen gas sensing properties of SnO{sub 2} nanoparticles has been reported. X-ray Diffraction (XRD) results revealed tetragonal rutile structure of both undoped and Sm-doped SnO{sub 2} nanoparticles. It has been observed that doping with samarium led to reduction in crystallite size of SnO{sub 2} nanoparticles which was confirmed from XRD analysis. Shifting and broadening of Raman peaks in case of doped nanoparticles has been explained by well-known phonon confinement model. The optimum operable temperature of both the sensors was found to 400 °C and the sensor response towardsmore » hydrogen gas has been improved after doping with samarium which was attributed to increase in sensing sites for the gas adsorption.« less

Fabrication, characterization and annealing of polymer-fullerene bulk heterojunction organic solar cells

NASA Astrophysics Data System (ADS)

Sharma, Trupti; Singhal, R.; Vishnoi, R.; Biswas, S. K.

2017-05-01

The structural and optical properties of bulk heterojunction (BHJ) organic solar cell devices have been studied before and after heat treatment. The BHJ structure is fabricated by making the blend of Poly [3-hexylthiophene] (P3HT) and Phenyl C61 butyric acid methyl ester (PCBM) for active layer. After the heat treatment at 140 °C temperature, the device is characterized by X-ray diffraction (XRD) measurement, Raman spectroscopy and UV-visible absorption spectroscopy. The reduced intensity of XRD peak corresponding to (100) plane and decreased crystallite size was observed after annealing. The Raman peak intensity corresponding to C=C stretching mode and optical absorption peak intensity is also found to be reduced after the heat treatment to the device. The diminished intensitiesafter annealing may be due to diffusion of Al into active layer.

A study of structural and mechanical properties of nano-crystalline tungsten nitride film synthesis by plasma focus

NASA Astrophysics Data System (ADS)

Hussnain, Ali; Singh Rawat, Rajdeep; Ahmad, Riaz; Hussain, Tousif; Umar, Z. A.; Ikhlaq, Uzma; Chen, Zhong; Shen, Lu

2015-02-01

Nano-crystalline tungsten nitride thin films are synthesized on AISI-304 steel at room temperature using Mather-type plasma focus system. The surface properties of the exposed substrate against different deposition shots are examined for crystal structure, surface morphology and mechanical properties using X-ray diffraction (XRD), atomic force microscope, field emission scanning electron microscope and nano-indenter. The XRD results show the growth of WN and WN2 phases and the development of strain/stress in the deposited films by varying the number of deposition shots. Morphology of deposited films shows the significant change in the surface structure with different ion energy doses (number of deposition shots). Due to the effect of different ion energy doses, the strain/stress developed in the deposited film leads to an improvement of hardness of deposited films.

Vitrification of radioactive contaminated soil by means of microwave energy

NASA Astrophysics Data System (ADS)

Yuan, Xun; Qing, Qi; Zhang, Shuai; Lu, Xirui

2017-03-01

Simulated radioactive contaminated soil was successfully vitrified by microwave sintering technology and the solidified body were systematically studied by Raman, XRD and SEM-EDX. The Raman results show that the solidified body transformed to amorphous structure better at higher temperature (1200 °C). The XRD results show that the metamictization has been significantly enhanced by the prolonged holding time at 1200 °C by microwave sintering, while by conventional sintering technology other crystal diffraction peaks, besides of silica at 2θ = 27.830°, still exist after being treated at 1200 °C for much longer time. The SEM-EDX discloses the micro-morphology of the sample and the uniform distribution of Nd element. All the results show that microwave technology performs vitrification better than the conventional sintering method in solidifying radioactive contaminated soil.

Definitive Mineralogical Analysis of Mars Analog Rocks Using the CheMin XRD/XRF Instrument

NASA Technical Reports Server (NTRS)

Blake, D. F.; Sarrazin, P.; Bish, D. L.; Feldman, S.; Chipera, S. J.; Vaniman, D. T.; Collins, S.

2004-01-01

Mineral identification is a critical component of Mars Astrobiological missions. Chemical or elemental data alone are not definitive because a single elemental or chemical composition or even a single bonding type can represent a range of substances or mineral assemblages. Minerals are defined as unique structural and compositional phases that occur naturally. There are about 15,000 minerals that have been described on Earth, all uniquely identifiable via diffraction methods. There are likely many minerals yet undiscovered on Earth, and likewise on Mars. If an unknown phase is identified on Mars, it can be fully characterized by structural (X-ray Diffraction, XRD) and elemental analysis (X-ray Fluorescence, XRF) without recourse to other data because XRD relies on the principles of atomic arrangement for its determinations. XRD is the principal means of identification and characterization of minerals on Earth.

Calcination Conditions on the Properties of Porous TiO2 Film

NASA Astrophysics Data System (ADS)

Zhang, Wenjie; Pei, Xiaobei; Bai, Jiawei; He, Hongbo

2014-03-01

Porous TiO2 films were deposited on SiO2 precoated glass-slides by sol-gel method using PEG1000 as template. The strongest XRD diffraction peak at 2θ = 25.3° is attributed to [101] plane of anatase TiO2 in the film. The increases of calcination temperature and time lead to stronger diffraction peak intensity. High transmittance and blue shift of light absorption edge are the properties of the film prepared at high calcination temperature. The average pore size of the films increases with the increasing calcination temperature as the result of TiO2 crystalline particles growing up and aggregation, accompanied with higher specific surface area. Photocatalytic activity of porous TiO2 films increases with the increasing calcination temperature. The light absorption edge of the films slightly moves to longer wavelength region along with the increasing calcination time. The mesoporous film calcinated at 500 °C for 2 h has the highest transmittance, the maximum surface area, and the maximum total pore volume. Consequently, the optimum degradation activity is achieved on the porous TiO2 film calcinated at 500 °C for 2 h.

Structural and Magnetic Response in Bimetallic Core/Shell Magnetic Nanoparticles

PubMed Central

Nairan, Adeela; Khan, Usman; Iqbal, Munawar; Khan, Maaz; Javed, Khalid; Riaz, Saira; Naseem, Shahzad; Han, Xiufeng

2016-01-01

Bimagnetic monodisperse CoFe2O4/Fe3O4 core/shell nanoparticles have been prepared by solution evaporation route. To demonstrate preferential coating of iron oxide onto the surface of ferrite nanoparticles X-ray diffraction (XRD), High resolution transmission electron microscope (HR-TEM) and Raman spectroscopy have been performed. XRD analysis using Rietveld refinement technique confirms single phase nanoparticles with average seed size of about 18 nm and thickness of shell is 3 nm, which corroborates with transmission electron microscopy (TEM) analysis. Low temperature magnetic hysteresis loops showed interesting behavior. We have observed large coercivity 15.8 kOe at T = 5 K, whereas maximum saturation magnetization (125 emu/g) is attained at T = 100 K for CoFe2O4/Fe3O4 core/shell nanoparticles. Saturation magnetization decreases due to structural distortions at the surface of shell below 100 K. Zero field cooled (ZFC) and Field cooled (FC) plots show that synthesized nanoparticles are ferromagnetic till room temperature and it has been noticed that core/shell sample possess high blocking temperature than Cobalt Ferrite. Results indicate that presence of iron oxide shell significantly increases magnetic parameters as compared to the simple cobalt ferrite. PMID:28335200

Effect of Co doping on the magnetic and DC electrical properties of Mn-Zn nanoferrites

NASA Astrophysics Data System (ADS)

Khandan Fadafan, H.; Lotfi Orimi, R.; Nezhadeini, S.

2018-06-01

In this study, Cobalt-Manganese-Zinc nanoferrites with the formula CoxMn0.5-xZn0.5Fe2O4 with x = 0.0, 0.1, 0.3, and 0.5 prepared by chemical Co-precipitation method. Then the structure and morphology of the synthesized nanoparticles were characterized by X-ray diffraction (XRD) and transmitting electron microscopy (TEM), respectively. The XRD patterns indicated the formation of single-phased cubic structure of spinel ferrite in nanometer size with no minor phase. The TEM image showed the formation of nanoparticles with average size of about 40 nm and normal size distribution. The magnetic measurements of the nanoparticles were done at room temperature using a vibrating sample magnetometer (VSM). Results exhibited a super-paramagnetic like behavior for some of the samples. DC electrical resistivity measurements were carried out by two-probe technique from 25 to 250 °C and showed decreasing of the resistivity with temperature meanwhile passing a transition to form of a peak. The peaks values observed near the Curie temperatures of samples suggest that anomaly behavior can attributed to spin canting associated with the phase transition from para to ferromagnetic state at TC.

Characterization of bismuth selenide (Bi2Se3) thin films obtained by evaporating the hydrothermally synthesised nano-particles

NASA Astrophysics Data System (ADS)

Indirajith, R.; Rajalakshmi, M.; Gopalakrishnan, R.; Ramamurthi, K.

2016-03-01

Bismuth selenide (Bi2Se3) was synthesized by hydrothermal method at 200 °C and confirmed by powder X-ray diffraction (XRD) studies. The synthesized material was utilized to deposit bismuth selenide thin films at various substrate temperatures (Room Temperature-RT, 150 °C, 250 °C, 350 °C and 450 °C) by electron beam evaporation technique. XRD study confirmed the polycrystalline nature of the deposited Bi2Se3films. Optical transmittance spectra showed that the deposited (at RT) films acquire relatively high average transmittance of 60%in near infrared region (1500-2500 nm). An indirect allowed optical band gap calculated from the absorption edge for the deposited films is ranging from 0.62 to 0.8 eV. Scanning electron and atomic force microscopy analyses reveal the formation of nano-scale sized particles on the surface and that the nature of surface microstructures is influenced by the substrate temperature. Hall measurements showed improved electrical properties, for the films deposited at 350 °C which possess 2.8 times the mobility and 0.9 times the resistivity of the films deposited at RT.

Optical and superparamagnetic behavior of ZnFe2O4 nanoparticles

NASA Astrophysics Data System (ADS)

Lal, Ganesh; Punia, Khushboo; Dolia, S. N.; Kumar, Sudhish

2018-05-01

Nanoparticles of zinc ferrite have been synthesized using a low temperature citrate sol-gel route and characterized by powder X-ray diffraction (XRD), Raman & UV-Vis-NIR spectroscopic and SQUID magnetometry measurements. Analysis of XRD pattern and Raman spectrum confirmed that the synthesized ZnFe2O4 sample crystallizes in single phase fcc spinel ferrite structure and the average particle size of nanoparticles is estimated to 24nm. Optical absorption study shows that maximum photo absorption take place in the visible band and peaking in UV band at 206nm and the band gap energy is estimated to Eg = 2.1eV. Zero Field Cooled (ZFC) and Field Cooled (FC) modes of magnetization down to 5K and in fields up to 20kOe shows that ZnFe2O4 nanoparticles exhibits superparamagnetism with high magneto-crystalline anisotropy and high magnetization. Small difference of 9K between the separation temperature TS=˜30K and blocking temperature TB= 21K are suggestive of the formation of ferromagnetic clusters and a narrow particle size distribution of the nanoparticles in superparamagnetic ZnFe2O4 nanoparticles.

Preparation, quantitative surface analysis, intercalation characteristics and industrial implications of low temperature expandable graphite

NASA Astrophysics Data System (ADS)

Peng, Tiefeng; Liu, Bin; Gao, Xuechao; Luo, Liqun; Sun, Hongjuan

2018-06-01

Expandable graphite is widely used as a new functional carbon material, especially as fire-retardant; however, its practical application is limited due to the high expansion temperature. In this work, preparation process of low temperature and highly expandable graphite was studied, using natural flake graphite as raw material and KMnO4/HClO4/NH4NO3 as oxidative intercalations. The structure, morphology, functional groups and thermal properties were characterized during expanding process by Fourier transform infrared spectroscopy (FTIR), Raman spectra, thermo-gravimetry differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM). The analysis showed that by oxidation intercalation, some oxygen-containing groups were grafted on the edge and within the graphite layer. The intercalation reagent entered the graphite layer to increase the interlayer spacing. After expansion, the original flaky expandable graphite was completely transformed into worm-like expanded graphite. The order of graphite intercalation compounds (GICs) was proposed and determined to be 3 for the prepared expandable graphite, based on quantitative XRD peak analysis. Meanwhile, the detailed intercalation mechanisms were also proposed. The comprehensive investigation paved a benchmark for the industrial application of such sulfur-free expanded graphite.

Optical, structural, and nuclear scientific studies of AlGaN with high Al composition

NASA Astrophysics Data System (ADS)

Lin, Tse Yang; Chung, Yee Ling; Li, Lin; Yao, Shude; Lee, Y. C.; Feng, Zhe Chuan; Ferguson, Ian T.; Lu, Weijie

2010-08-01

AlGaN epilayers with higher Al-compositions were grown by Metalorganic Chemical Vapor Deposition (MOCVD) on (0001) sapphire. Trimethylgallium (TMGa), trimethylaluminium (TMAl) and NH3 were used as the source precursors for Ga, Al, and N, respectively. A 25 nm AlN nucleation layer was first grown at low-temperature of 590 °C at 300 Torr. Followed, AlxGa1-xN layers were grown at 1080 °C on low-temperature AlN nucleation layers. The heterostructures were characterized by a series of techniques, including x-ray diffraction (XRD), Rutherford backscattering (RBS), photoluminescence (PL), scanning electron microscopy (SEM) and Raman scattering. Precise Al compositions were determined through XRD, RBS, and SEM combined measurements. Room Temperature Raman Scattering spectra shows three major bands from AlGaN alloys, which are AlN-like, A1 longitudinal optical (LO) phonon modes, and E2 transverse optical (TO) band, respectively, plus several peak comes from the substrate. Raman spectral line shape analysis lead to an optical determination of the electrical property free carrier concentration of AlGaN. The optical properties of AlGaN with high Al composition were presented here.

Low carrier semiconductor like behavior in Lu3Ir4Ge13 single crystal

NASA Astrophysics Data System (ADS)

Kumar, Anil; Matteppanavar, Shidaling; Thamizhavel, A.; Ramakrishnan, S.

2018-04-01

Single crystal of Lu3Ir4Ge13 crystallizing in the Yb3Rh4Sn13-type cubic crystal structure has been grown by Czochralski method in a tetra-arc furnace. In this paper we report on the crystal structure, magnetic and transport properties of Lu3Ir4Ge13. The analysis of the powder x-ray diffraction (XRD) studies revealed that Lu3Ir4Ge13 crystallizes in a cubic structure with the space group Pm-3n, no. 223. The lattice parameter was obtained from the Rietveld refinement of the room temperature XRD data which amounts to 8.904 (3) Å with low R factors. The temperature dependence of the resistivity exhibited semiconductor like behavior till 1.8 K, with a broad hump around 15 - 62 K. This hump was observed in both warming and cooling cycle with a very small hysteresis, it may be due to the existence of structural transition from high - low symmetry. The temperature dependent magnetization data shows the diamagnetic behavior with an anomaly around 70 K, which is well supported by the derivative of resistivity data.

In situ supported MnOx-CeOx on carbon nanotubes for the low-temperature selective catalytic reduction of NO with NH3

NASA Astrophysics Data System (ADS)

Zhang, Dengsong; Zhang, Lei; Shi, Liyi; Fang, Cheng; Li, Hongrui; Gao, Ruihua; Huang, Lei; Zhang, Jianping

2013-01-01

The MnOx and CeOx were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH3. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H2-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH3-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO2-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods.The MnOx and CeOx were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH3. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H2-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH3-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO2-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods. Electronic supplementary information (ESI) available: SEM images and EDS analysis, TEM images, and XPS spectrum of samples. See DOI: 10.1039/c2nr33006g

X-Ray Diffraction for In-Situ Mineralogical Analysis of Planetesimals.

NASA Astrophysics Data System (ADS)

Sarrazin, P.; Blake, D. F.; Dera, P.; Downs, R. T.; Taylor, J.

2017-12-01

X-ray diffraction (XRD) is a general purpose technique for definitive, quantitative mineralogical analysis. When combined with XRF data for sample chemistry, XRD analyses yield as complete a characterization as is possible by any spacecraft-capable techniques. The MSL CheMin instrument, the first XRD instrument flown in space, has been used to establish the quantitative mineralogy of the Mars global soil, to discover the first habitable environment on another planet, and to provide the first in-situ evidence of silicic volcanism on Mars. CheMin is now used to characterize the depositional and diagenetic environments associated with the mudstone sediments of lower strata of Mt. Sharp. Conventional powder XRD requires samples comprised of small grains presented in random orientations. In CheMin, sample cells are vibrated to cause loose powder to flow within the cell, driven by granular convection, which relaxes the requirement for fine grained samples. Nevertheless, CheMin still requires mechanisms to collect, crush, sieve and deliver samples before analysis. XTRA (Extraterrestrial Regolith Analyzer) is an evolution of CheMin intended to analyze fines in as-delivered surface regolith, without sample preparation. Fine-grained regolith coats the surfaces of most airless bodies in the solar system, and because this fraction is typically comminuted from the rocky regolith, it can often be used as a proxy for the surface as a whole. HXRD (Hybrid-XRD) is concept under development to analyze rocks or soils without sample preparation. Like in CheMin, the diffracted signal is collected with direct illumination CCD's. If the material is sufficiently fine-grained, a powder XRD pattern of the characteristic X-ray tube emission is obtained, similar to CheMin or XTRA. With coarse grained crystals, the white bremsstrahlung radiation of the tube is diffracted into Laue patterns. Unlike typical Laue applications, HXRD uses the CCD's capability to distinguish energy and analyze the "colors" of each Laue spot, which enable phase identification. The concept was demonstrated with prototypes and dedicated crystallographic software was developed for identification the minerals responsible for the Laue patterns. High TRL subsystems are under development for future deployment opportunities of these new XRD instruments.

Evaluation of Cation Migration in Lanthanum Strontium Cobalt Ferrite Solid Oxide Fuel Cell Cathodes via In-operando X-ray Diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hardy, John S.; Coyle, Christopher A.; Bonnett, Jeff F.

2018-01-28

Anode-supported SOFCs with LSCF-6428 cathodes were operated at various temperatures for hundreds of hours in dry or humid (~3% water) cathode air with continuous cathode XRD. Additionally, one cell in dry air was held at OCV and another had 12% CO2 added to the humid air. Long cumulative XRD count times allowed identification of minor phases at <0.1 wt%. In humid air, performance improved during the first couple of hundred hours and Fe-rich Fe,Co spinel XRD peaks gradually shifted to lower angles while nano-nodules formed on LSCF surfaces. With 12% CO2 added, performance degraded after initial activation, unlike without CO2,more » where stability followed activation. In CO2, LSCF XRD peaks shifted indicating gradual decomposition. In dry air, fast initial degradation that decelerated over time occurred at constant current while the cell at OCV was stable. At OCV and 750°C or at constant current and 700°C in dry air, Fe-rich spinel XRD peaks shifted more slowly than in humid air tests; Co-rich Fe,Co spinel peaks shifted to higher angles; and SEM discovered smaller nano-nodules on LSCF than after humid air tests. At constant current at 750°C and 800°C in dry air, no nano-nodules or gradual changes in the XRD patterns were discovered.« less

A simple and low temperature process for super-hydrophilic rutile TiO 2 thin films growth

NASA Astrophysics Data System (ADS)

Mane, R. S.; Joo, Oh-Shim; Min, Sun-Ki; Lokhande, C. D.; Han, Sung-Hwan

2006-11-01

We investigate an environmentally friendly aqueous solution system for rutile TiO2 violet color nanocrystalline thin films growth on ITO substrate at room temperature. Film shows considerable absorption in visible region with excitonic maxima at 434 nm. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), UV-vis, water surface contact angle and energy dispersive X-ray analysis (EDX) techniques in addition to actual photo-image that shows purely rutile phase of TiO2 with violet color, super-hydrophilic and densely packed nanometer-sized spherical grains of approximate diameter 3.15 ± 0.4 nm, characterize the films. Band gap energy of 4.61 eV for direct transition was obtained for the rutile TiO2 films. Film surface shows super-hydrophilic behavior, as exhibited water contact angle was 7°. Strong visible absorption (not due to chlorine) leaves future challenge to use these films in extremely thin absorber (ETA) solar cells.

Facile synthesis of hollow Co3O4 microspheres and its use as a rapid responsive CL sensor of combustible gases.

PubMed

Teng, Fei; Yao, Wenqing; Zheng, Youfei; Ma, Yutao; Xu, Tongguang; Gao, Guizhi; Liang, Shuhui; Teng, Yang; Zhu, Yongfa

2008-09-15

The hollow Co(3)O(4) microspheres (HCMs) were prepared by the carbonaceous templates, which did not need the surface pretreatment. The chemiluminescence (CL) and catalytic properties for CO oxidation over these hollow samples were evaluated. The samples were characterized by scanning electron microscopy (SEM), energy disperse spectra (EDS), transmission electron microscopy (TEM), selected area electron diffraction (ED), X-ray diffraction (XRD), temperature-programmed desorption (TPD) and N(2) adsorption. The influences of filter' band length, flow rate of gas, test temperature, and particle structure on CL intensities were mainly investigated. It was found that compared with the solid Co(3)O(4) particles (SCPs), HCMs had a stronger CL intensity, which was ascribed to its hollow structure; and that CL properties of the catalysts were well correlated with their reaction activities. Moreover, HCMs were used to fabricate a highly sensitive gas detector, which is a rapid and effective method for the selection of catalysts or the detection of environmental deleterious gases.

Texture evolution in Oxide Dispersion Strengthened (ODS) steel tubes during pilgering process

NASA Astrophysics Data System (ADS)

Vakhitova, E.; Sornin, D.; Barcelo, F.; François, M.

2017-10-01

Oxide Dispersion Strengthened (ODS) steels are foreseen as fuel cladding material in the coming generation of Sodium Fast Reactors (SFR). Cladding tubes are manufactured by hot extrusion and subsequent cold forming steps. In this study, a 9 wt% Cr ODS steel exhibiting α-γ phase transformation at high temperature is cold formed under industrial conditions with a large section reduction in two pilgering steps. The influence of pilgering process parameters and intermediate heat treatment on the microstructure evolution is studied experimentally using Electron Backscattering Diffraction (EBSD) and X-ray Diffraction (XRD) methods. Pilgered samples show elongated grains and a high texture formation with a preferential orientation along the rolling direction. During the heat treatment, grain morphology is recovered from elongated grains to almost equiaxed ones, while the well-known α-fiber texture presents an unexpected increase in intensity. The remarkable temperature stability of this fiber is attributed to a crystallographic structure memory effect during phase transformations.

Structural analysis of bioceramic materials for denture application

NASA Astrophysics Data System (ADS)

Rauf, Nurlaela; Tahir, Dahlang; Arbiansyah, Muhammad

2016-03-01

Structural analysis has been performed on bioceramic materials for denture application by using X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscopy (SEM). XRF is using for analysis chemical composition of raw materials. XRF shows the ratio 1 : 1 : 1 : 1 between feldspar, quartz, kaolin and eggshell, respectively, resulting composition CaO content of 56.78 %, which is similar with natural tooth. Sample preparation was carried out on temperature of 800 °C, 900 °C and 1000 °C. X-ray diffraction result showed that the structure is crystalline with trigonal crystal system for SiO2 (a=b=4.9134 Å and c=5.4051 Å) and CaH2O2 (a=b=3.5925 Å and c=4.9082 Å). Based on the Scherrer's equation showed the crystallite size of the highest peak (SiO2) increase with increasing the temperature preparation. The highest hardness value (87 kg/mm2) and match with the standards of dentin hardness. The surface structure was observed by using SEM also discussed.

Biocompatibility and Surface Properties of TiO2 Thin Films Deposited by DC Magnetron Sputtering

PubMed Central

López-Huerta, Francisco; Cervantes, Blanca; González, Octavio; Hernández-Torres, Julián; García-González, Leandro; Vega, Rosario; Herrera-May, Agustín L.; Soto, Enrique

2014-01-01

We present the study of the biocompatibility and surface properties of titanium dioxide (TiO2) thin films deposited by direct current magnetron sputtering. These films are deposited on a quartz substrate at room temperature and annealed with different temperatures (100, 300, 500, 800 and 1100 °C). The biocompatibility of the TiO2 thin films is analyzed using primary cultures of dorsal root ganglion (DRG) of Wistar rats, whose neurons are incubated on the TiO2 thin films and on a control substrate during 18 to 24 h. These neurons are activated by electrical stimuli and its ionic currents and action potential activity recorded. Through X-ray diffraction (XRD), the surface of TiO2 thin films showed a good quality, homogeneity and roughness. The XRD results showed the anatase to rutile phase transition in TiO2 thin films at temperatures between 500 and 1100 °C. This phase had a grain size from 15 to 38 nm, which allowed a suitable structural and crystal phase stability of the TiO2 thin films for low and high temperature. The biocompatibility experiments of these films indicated that they were appropriated for culture of living neurons which displayed normal electrical behavior. PMID:28788667

Thermal and temporal evolution of microstructure in polycrystalline ZnO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kondal, Neha; Tiwari, Sanjiv Kumar, E-mail: sanjivkumar.tiwari@juit.ac.in

2016-05-06

Tug between electronics and spintronics has opened up new area of research named as dilute magnetic semiconductors (DMS), ZnO is one of the most reliable candidates for spintronic devices and DMS. Since, pure and transition metal doped polycrystalline ZnO shows room temperature ferromagnetism, therefore it is very important to gain insight into its microstructure (MS) evolution. We report thermal evolution of MS of pure ZnO on sintering it at 200 °C, 400 °C, 600 °C, and 800 °C in ambient atmosphere for two hours. Temporal evolution at fixed temperature was analyzed using mean field model of internal energy and entropy.more » Grain size of ZnO MS were analyzed using integral breadth method of X-ray diffraction (XRD) lines using Voigt profile fit,. XRD line corresponding to [101] plane shifts from 36.17° to 36.28° whereas grain size increases from 67.5 nm to 93.7 nm with increase of temperature from 23°C to 800°C respectively. Grain growth with increase of temperature show Arrhenius type behavior with activation energy of 30.77 kJ-mol{sup −1} and temporal growth shows diffusive behavior with exponent 0.5.« less

Synthesis of AuPd alloyed nanoparticles via room-temperature electron reduction with argon glow discharge as electron source.

PubMed

Yang, Manman; Wang, Zongyuan; Wang, Wei; Liu, Chang-Jun

2014-01-01

Argon glow discharge has been employed as a cheap, environmentally friendly, and convenient electron source for simultaneous reduction of HAuCl4 and PdCl2 on the anodic aluminum oxide (AAO) substrate. The thermal imaging confirms that the synthesis is operated at room temperature. The reduction is conducted with a short time (30 min) under the pressure of approximately 100 Pa. This room-temperature electron reduction operates in a dry way and requires neither hydrogen nor extra heating nor chemical reducing agent. The analyses using X-ray photoelectron spectroscopy (XPS) confirm all the metallic ions have been reduced. The characterization with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) shows that AuPd alloyed nanoparticles are formed. There also exist some highly dispersed Au and Pd monometallic particles that cannot be detected by XRD and transmission electron microscopy (TEM) because of their small particle sizes. The observed AuPd alloyed nanoparticles are spherical with an average size of 14 nm. No core-shell structure can be observed. The room-temperature electron reduction can be operated in a larger scale. It is an easy way for the synthesis of AuPd alloyed nanoparticles.

Precipitation hardening behaviour of Al-Mg-Si alloy processed by cryorolling and room temperature rolling

NASA Astrophysics Data System (ADS)

Hussain, Maruff; Nageswara rao, P.; Singh, Dharmendra; Jayaganthan, R.

2018-04-01

The precipitation hardenable aluminium alloy (Al-Mg-Si) plates were solutionized and subjected to rolling at room temperature and liquid nitrogen temperature (RTR, CR) up to a true strain of ∼2.7. The rolled sheets were uniformly aged at room temperature and above room temperature (125 °C) to induce precipitation. The rolled and aged samples were analysed using differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), hardness and tensile tests. The strength and ductility were simultaneously improved after controlled ageing of the cryorolled (CR) and room temperature rolled (RTR) samples. However, the increment in strength is more in RTR material than CR material with same ductility. Transmission electron microscopy analysis revealed the formation of ultrafine grains (UFG) filled with dislocations and nanosized precipitates in the CR and RTR conditions after ageing treatment. The behaviour of CR and RTR alloy is same under natural ageing conditions.

Substrate effects on photoluminescence and low temperature phase transition of methylammonium lead iodide hybrid perovskite thin films

NASA Astrophysics Data System (ADS)

Shojaee, S. A.; Harriman, T. A.; Han, G. S.; Lee, J.-K.; Lucca, D. A.

2017-07-01

We examine the effects of substrates on the low temperature photoluminescence (PL) spectra and phase transition in methylammonium lead iodide hybrid perovskite (CH3NH3PbI3) thin films. Structural characterization at room temperature with X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy indicated that while the chemical structure of films deposited on glass and quartz was similar, the glass substrate induced strain in the perovskite films and suppressed the grain growth. The luminescence response and phase transition of the perovskite thin films were studied by PL spectroscopy. The induced strain was found to affect both the room temperature and low temperature PL spectra of the hybrid perovskite films. In addition, it was found that the effects of the glass substrate inhibited a tetragonal to orthorhombic phase transition such that it occurred at lower temperatures.

Uranium oxidation kinetics monitored by in-situ X-ray diffraction

NASA Astrophysics Data System (ADS)

Zalkind, S.; Rafailov, G.; Halevy, I.; Livneh, T.; Rubin, A.; Maimon, H.; Schweke, D.

2017-03-01

The oxidation kinetics of U-0.1 wt%Cr at oxygen pressures of 150 Torr and the temperature range of 90-150 °C was studied by means of in-situ X-ray diffraction (XRD). A "breakaway" in the oxidation kinetics is found at ∼0.25 μm, turning from a parabolic to a linear rate law. At the initial stage of oxidation the growth plane of UO2(111) is the prominent one. As the oxide thickens, the growth rate of UO2(220) plane increases and both planes grow concurrently. The activation energies obtained for the oxide growth are Qparabolic = 17.5 kcal/mol and Qlinear = 19 kcal/mol. Enhanced oxidation around uranium carbide (UC) inclusions is clearly observed by scanning electron microscopy (SEM).

Raman validity for crystallite size La determination on reticulated vitreous carbon with different graphitization index

NASA Astrophysics Data System (ADS)

Baldan, M. R.; Almeida, E. C.; Azevedo, A. F.; Gonçalves, E. S.; Rezende, M. C.; Ferreira, N. G.

2007-11-01

The graphitization index provided by X-ray diffraction (XRD) and Raman spectrometry for reticulated vitreous carbon (RVC) substrates, carbonized at different heat treatment temperatures (HTT), is investigated. A systematic study of the dependence between the disorder-induced D and G Raman bands is presented. The crystallite size La was obtained for both X-ray diffraction and Raman spectrometry techniques. Particularly, the validity for La determination, from Raman spectra, is pointed out comparing the commonly used formula based on peaks amplitude ratio ( ID/ IG) and the recent proposed equation that uses the integrated intensities of D and G bands. The results discrepancy is discussed taken into account the strong contribution of the line broadening presented in carbon materials heat treated below 2000 °C.

Does Z' equal 1 or 2? Enhanced powder NMR crystallography verification of a disordered room temperature crystal structure of a p38 inhibitor for chronic obstructive pulmonary disease.

PubMed

Widdifield, Cory M; Nilsson Lill, Sten O; Broo, Anders; Lindkvist, Maria; Pettersen, Anna; Svensk Ankarberg, Anna; Aldred, Peter; Schantz, Staffan; Emsley, Lyndon

2017-06-28

The crystal structure of the Form A polymorph of N-cyclopropyl-3-fluoro-4-methyl-5-[3-[[1-[2-[2-(methylamino)ethoxy]phenyl]cyclopropyl]amino]-2-oxo-pyrazin-1-yl]benzamide (i.e., AZD7624), determined using single-crystal X-ray diffraction (scXRD) at 100 K, contains two molecules in the asymmetric unit (Z' = 2) and has regions of local static disorder. This substance has been in phase IIa drug development trials for the treatment of chronic obstructive pulmonary disease, a disease which affects over 300 million people and contributes to nearly 3 million deaths annually. While attempting to verify the crystal structure using nuclear magnetic resonance crystallography (NMRX), we measured 13 C solid-state NMR (SSNMR) spectra at 295 K that appeared consistent with Z' = 1 rather than Z' = 2. To understand this surprising observation, we used multinuclear SSNMR ( 1 H, 13 C, 15 N), gauge-including projector augmented-wave density functional theory (GIPAW DFT) calculations, crystal structure prediction (CSP), and powder XRD (pXRD) to determine the room temperature crystal structure. Due to the large size of AZD7624 (ca. 500 amu, 54 distinct 13 C environments for Z' = 2), static disorder at 100 K, and (as we show) dynamic disorder at ambient temperatures, NMR spectral assignment was a challenge. We introduce a method to enhance confidence in NMR assignments by comparing experimental 13 C isotropic chemical shifts against site-specific DFT-calculated shift distributions established using CSP-generated crystal structures. The assignment and room temperature NMRX structure determination process also included measurements of 13 C shift tensors and the observation of residual dipolar coupling between 13 C and 14 N. CSP generated ca. 90 reasonable candidate structures (Z' = 1 and Z' = 2), which when coupled with GIPAW DFT results, room temperature pXRD, and the assigned SSNMR data, establish Z' = 2 at room temperature. We find that the polymorphic Form A of AZD7624 is maintained at room temperature, although dynamic disorder is present on the NMR timescale. Of the CSP-generated structures, 2 are found to be fully consistent with the SSNMR and pXRD data; within this pair, they are found to be structurally very similar (RMSD 16 = 0.30 Å). We establish that the CSP structure in best agreement with the NMR data possesses the highest degree of structural similarity with the scXRD-determined structure (RMSD 16 = 0.17 Å), and has the lowest DFT-calculated energy amongst all CSP-generated structures with Z' = 2.

Modeling and measurements of XRD spectra of extended solids under high pressure

NASA Astrophysics Data System (ADS)

Batyrev, I. G.; Coleman, S. P.; Stavrou, E.; Zaug, J. M.; Ciezak-Jenkins, J. A.

2017-06-01

We present results of evolutionary simulations based on density functional calculations of various extended solids: N-Si and N-H using variable and fixed concentration methods of USPEX. Predicted from the evolutionary simulations structures were analyzed in terms of thermo-dynamical stability and agreement with experimental X-ray diffraction spectra. Stability of the predicted system was estimated from convex-hull plots. X-ray diffraction spectra were calculated using a virtual diffraction algorithm which computes kinematic diffraction intensity in three-dimensional reciprocal space before being reduced to a two-theta line profile. Calculations of thousands of XRD spectra were used to search for a structure of extended solids at certain pressures with best fits to experimental data according to experimental XRD peak position, peak intensity and theoretically calculated enthalpy. Comparison of Raman and IR spectra calculated for best fitted structures with available experimental data shows reasonable agreement for certain vibration modes. Part of this work was performed by LLNL, Contract DE-AC52-07NA27344. We thank the Joint DoD / DOE Munitions Technology Development Program, the HE C-II research program at LLNL and Advanced Light Source, supported by BES DOE, Contract No. DE-AC02-05CH112.

Application of glucose as a green capping agent and reductant to fabricate CuI micro/nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tavakoli, Farnosh; Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir; Ghanbari, Davood

Graphical abstract: - Highlights: • CuI nanostructures were prepared via a simple precipitation method. • Glucose as a green capping agent and reductant was applied. • The effect of glucose concentration on the morphology of CuI was investigated. • According to XRD results, pure cubic phase CuI have been formed by using glucose. - Abstract: In this work, CuI micro/nanostructures have been successfully prepared via a simple precipitation route at room temperature. By using glucose as a clean reducing agent with different concentrations, CuI micro/nanostructures with various morphologies were obtained. Besides glucose, Na{sub 2}SO{sub 3}, KBH{sub 4} and N{sub 2}H{submore » 4}·H{sub 2}O have been applied as reductant. X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectroscopy, X-ray energy dispersive spectroscopy (EDS) and Fourier transformed infrared (FT-IR) spectroscopy were used to characterize the as-produced CuI micro/nanostructures. According to the XRD results, it was found that pure cubic phase CuI have been formed by using glucose.« less

Synthesis and Characterization of Titanium Dioxide Thin Film for Sensor Applications

NASA Astrophysics Data System (ADS)

Latha, H. K. E.; Lalithamba, H. S.

2018-03-01

Titanium oxide (TiO2) nanoparticles (metal oxide semiconductor) are successfully synthesized using hydrothermal method for sensor application. Titanium dioxide and Sodium hydroxide are used as precursors. These reactants are mixed and calcinated at 400 °C to produce TiO2 nanoparticles. The crystalline structure, morphology of synthesized TiO2 nanoparticles are studied using x-ray diffraction (XRD), Fourier Transform Infrared (FTIR) analysis and scanning electron microscopy (SEM). XRD results revealed that the prepared TiO2 sample is highly crystalline, having Anatase crystal structure. FT-IR spectra peak at 475 cm‑1 indicated characteristic absorption bands of TiO2 nanoparticles. The XRD and FTIR result confirmed the formation of high purity of TiO2 nanoparticles. The SEM image shows that TiO2 nanoparticles prepared in this study are spherical in shape. Synthesized TiO2 nanoparticles are deposited on glass substrate at room temperature using E beam evaporation method to determine gauge factor and found to be 4.7. The deposited TiO2 thin films offer tremendous potential in the applications of electronic and magneto–electric devices.

Structural and magnetic properties of nanocomposite iron-containing SiCxNy films

NASA Astrophysics Data System (ADS)

Pushkarev, R. V.; Fainer, N. I.; Maurya, K. K.

2017-02-01

New ferromagnetic films with composition SiCxNyFez were synthesized using chemical vapor deposition technique. Films were deposited using ferrocene, 1,1,1,3,3,3-hexamethyldisilazane (HMDS) and hydrogen gaseous mixture. Chemical and phase composition of the films were studied by FTIR, Raman spectroscopy and X-ray diffraction with grazing incidence (GI-XRD). FTIR spectra analysis confirmed the existence of Si-C and Si-N bonds. Graphite inclusions and amorphous carbon were determined by Raman spectra analysis. The surface of the SiCxNyFez films studied by SEM is covered by nanocrystallites of iron oxide Fe3O4 phase. The main purpose of GI-XRD analysis is to describe the layered structure of the films in detail. It was shown by GI-XRD study, that phase composition of the SiCxNyFez films varies from iron oxide Fe3O4 to iron silicide Fe3Si and silicon carbide SiC with the deposition temperature growing. It was established, that SiCxNyFez films are perspective for application in the spintronic field.

A facile sol-gel strategy for the scalable synthesis of CuFe2O4 nanoparticles with enhanced infrared radiation property: Influence of the synthesis conditions

NASA Astrophysics Data System (ADS)

Hou, Haili; Xu, Guoyue; Tan, Shujuan; Zhu, Yongmei

2017-09-01

CuFe2O4 particles were successfully engineered by a facile sol-gel method. The synthesized products were characterized physically by X-ray diffraction (XRD), scanning electron microscopy (SEM). Besides, the effects of the sintering temperature and the molar ration of citric acid/the total metal cations (CA/MC) on their infrared radiant properties were investigated at the wavelength of 3-5 μm. The highest infrared emission value ca. 0.911 was obtained when the test temperature was conducted at 800 °C, indicating its potential application in infrared heating, infrared coating and drying fields.

The Effects of ph on Structural and Optical Characterization of Iron Oxide Thin Films

NASA Astrophysics Data System (ADS)

Tezel, Fatma Meydaneri; Özdemir, Osman; Kariper, I. Afşin

In this study, the iron oxide thin films have been produced by chemical bath deposition (CBD) method as a function of pH onto amorphous glass substrates. The surface images of the films were investigated with scanning electron microscope (SEM). The crystal structures, orientation of crystallization, crystallite sizes, and dislocation density i.e. structural properties of the thin films were analyzed with X-ray diffraction (XRD). The optical band gap (Eg), optical transmission (T%), reflectivity (R%), absorption coefficient (α), refraction index (n), extinction coefficient (k) and dielectric constant (ɛ) of the thin films were investigated depending on pH, deposition time, solution temperature, substrate temperature, thickness of the films by UV-VIS spectrometer.

Nonenzymatic detection of glucose using BaCuO2 thin layer

NASA Astrophysics Data System (ADS)

Ito, Takeshi; Asada, Tsuyoshi; Asai, Naoto; Shimizu, Tomohiro; Shingubara, Shoso

2017-01-01

A BaCuO2 thin layer was deposited on a glassy carbon electrode and used for the direct oxidation of glucose. The crystalline, electrochemical, and physicochemical properties that depend on the deposition temperature and deposition time were studied. X-ray diffraction (XRD) analysis showed that the thin layer was amorphous even at 400 °C. The current density of the glucose oxidation using the thin layer deposited at 200 °C was higher than those at other deposition temperatures. Under this condition, the current density increased with the glucose concentration and deposition time. These results indicate that a BaCuO2 thin layer has potential for measuring the blood glucose level without enzymes.

Formation of MoS2 inorganic fullerenes (IFs) by the reaction of MoO3 nanobelts and S.

PubMed

Li, Xiao Lin; Li, Ya Dong

2003-06-16

The reaction of MoO3 and S at temperatures higher than 300 degrees C in an argon atmosphere provides a convenient and effective method for the synthesis of MoS2 nanocrystalline substances. MoS2 nanotubes and fullerene-like nanoparticles have been obtained by the reaction at 850 degrees C under well-controlled conditions. The influences of reaction temperature and duration were carefully investigated in this paper. All of the nanostructures were characterized by Xray powder diffraction (XRD), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). A stepwise reaction model and rolling mechanism were proposed based on the experimental results.

Effect of swift heavy ion irradiation on structural and opto-electrical properties of bi-layer CdS-Bi2S3 thin films prepared by solution growth technique at room temperature

NASA Astrophysics Data System (ADS)

Shaikh, Shaheed U.; Siddiqui, Farha Y.; Desale, Deepali J.; Ghule, Anil V.; Singh, Fouran; Kulriya, Pawan K.; Sharma, Ramphal

2015-01-01

CdS-Bi2S3 bi-layer thin films have been deposited by chemical bath deposition method on Indium Tin Oxide glass substrate at room temperature. The as-deposited thin films were annealed at 250 °C in an air atmosphere for 1 h. An air annealed thin film was irradiated using Au9+ ions with the energy of 120 MeV at fluence 5×1012 ions/cm2 using tandem pelletron accelerator. The irradiation induced modifications were studied using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Raman spectroscopy, UV spectroscopy and I-V characteristics. XRD study reveals that the as-deposited thin films were nanocrystalline in nature. The decrease in crystallite size, increase in energy band gap and resistivity were observed after irradiation. Results are explained on the basis of energy deposited by the electronic loss after irradiation. The comparative results of as-deposited, air annealed and irradiated CdS-Bi2S3 bi-layer thin films are presented.

One-step synthesis and characterizations of cerium oxide nanoparticles in an ambient temperature via Co-precipitation method

NASA Astrophysics Data System (ADS)

Pujar, Malatesh S.; Hunagund, Shirajahammad M.; Desai, Vani R.; Patil, Shivaprasadgouda; Sidarai, Ashok H.

2018-04-01

We report the simple Co-precipitation method for the synthesis of Cerium oxide (CeO2) nanoparticles (NPs) in an ambient temperature. We have taken the Cerium (III) nitrate hexahydrate (Ce(NO3)3.6H2O) and Sodium hydroxide (NaOH) as the precursors. The obtained NPs were analyzed using the UV-Vis spectrophotometer, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The obtained results signify that UV-Vis spectrum exhibited a well-defined absorption peak at 274 nm and the estimated energy gap (Eg) is 4.05 eV. The FT-IR analysis provides the supporting evidence for the presence of bonding of O-H, nitrates, alcohols and O-Ce-O vibrations. The XRD result reveals that the synthesized CeO2 NPs was crystallite with cubic phase structure and the estimated average crystallite size of CeO2 NPs using Scherer's and W-H method was significantly different due to their assumptions. Further, it is purposed to study their photocatalytic biological activities.

Impedance analysis and dielectric response of anatase TiO2 nanoparticles codoped with Mn and Co ions

NASA Astrophysics Data System (ADS)

Kumar, Anand; Kashyap, Manish K.; Sabharwal, Namita; Kumar, Sarvesh; Kumar, Ashok; Kumar, Parmod; Asokan, K.

2017-11-01

In order to elucidate the effect of transition metal (TM) doping, the impedance and dielectric responses of Co and/or Mn-doped TiO2 nanocrystalline powder samples with 3% doping concentration synthesized via sol gel technique, have been analyzed. X-ray diffraction (XRD) analysis confirms the formation of tetragonal TiO2 anatase phase for all studied samples without any extra impurity phase peaks. The variation in the grain size measured from field emission scanning electron microscope (FESEM) measurements for all the samples are in accordance with the change in crystallite size as obtained from XRD. The DC resistivity for pure TiO2 nanoparticles is the highest while codoped samples exhibit low resistivity. The temperature dependent dielectric constant and dielectric loss possess step like enhancement and show the relaxation behavior. At room temperature, the dielectric function and dielectric loss decrease rapidly with increase in frequency and become almost constant at the higher frequencies. Such a decrease in dielectric loss is suitable for energy storage devices.

Milestone Report - M3FT-15OR03120215 - Recommend HIP Conditions for AgZ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruffey, Stephanie H.; Jubin, Robert Thomas

2015-09-18

The purpose of this study was to continue research to determine if HIPing could directly convert I-Ag 0Z into a suitable waste form. Fiscal year (FY) 2015 work completed studies of Phase IIA, IIB, and IIC samples. Product consistency testing (PCT) of Phase IIA samples resulted in iodine release below detection limit for six of twelve samples. This is promising and indicates that a durable waste form may be produced through HIPing even if transformation of the zeolite to a distinct mineral phase does not occur. From PCT results of Phase IIA samples, it was determined that future pressing shouldmore » be conducted at a temperature of 900°C. Phase IIC testing continued production of samples to examine the effects of multiple source materials, compositional variations, and an expanded temperature range. The density of each sample was determined and x-ray diffraction (XRD) patterns were obtained. In all cases, there was nothing in the XRD analyses to indicate the creation of any AgI-containing silicon phase; the samples were found to be largely amorphous.« less

One pot synthesis of pure micro/nano photoactive α-PbO crystals

NASA Astrophysics Data System (ADS)

Bhagat, Dharini; Waldiya, Manmohansingh; Vanpariya, Anjali; Mukhopadhyay, Indrajit

2018-05-01

The present study reports a simple, fast and cost effective precipitation technique for synthesis of pure α-PbO powder. Lead monoxide powder with tetragonal structure was synthesized chemically at an elevated temperature using lead acetate and sodium hydroxide solution bath. XRD powder diffraction was used to find the structural properties as well as phase transition from alpha to beta. Study revealed that synthesized PbO powder was crystalline with tetragonal symmetry, having an average crystallite size of 70 nm and lattice constants; a=3.97Å, b=3.97Å, and c=5.02Å. Phase transition from tetragonal to orthorhombic structure was studied by comparing the XRD data of the annealed samples in the temperature range from 200 °C to 600 °C. UV-Visible spectroscopy was used to find out the optical properties of prepared PbO powder. Diffuse reflectance and absorbance spectra confirmed the formation of α-PbO with obtained direct band gap of 1.9 eV. Synthesized lead monoxide (α-PbO) powder has promising application in energy conversion as well as energy storage applications.

Bricks in historical buildings of Toledo City: characterisation and restoration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopez-Arce, Paula; Garcia-Guinea, Javier; Gracia, Mercedes

2003-01-15

Two different types of ancient bricks (12th to 14th centuries) collected from historical buildings of Toledo (Spain) were characterised by optical microscopy, scanning electron microscopy/energy-dispersive X-ray spectrometers (SEM/EDS), electron probe microanalysis (EM), X-ray diffraction (XRD), differential thermal analysis (DTA) and {sup 57}Fe-Moessbauer spectroscopy. Physical properties such as water absorption and suction, porosity, density and compression strength were also determined. Several minerals found in the brick matrix, such as garnet, let us infer raw material sources; calcite, dolomite, illite and neoformed gehlenite and diopside phases, on temperature reached in firing; secondary calcite, on first cooling scenarios; and manganese micronodules, on latemore » pollution environments. XRD and DTA of original and refired samples supply information about firing temperatures. Additional data on firing conditions and type of the original clay are provided by the Moessbauer study. Physical properties of both types of bricks were compared and correlated with raw materials and fabric and firing technology employed. The physicochemical characterisation of these bricks provides valuable data for restoration purposes to formulate new specific bricks using neighbouring raw materials.« less

Synthesis and electrical behavior of Ni-Ti substituted Y-type hexaferrites for high frequency application

NASA Astrophysics Data System (ADS)

Ahmad, Bashir; Ashiq, Muhammad Naeem; Mumtaz, Saleem; Ali, Irshad; Najam-Ul-Haq, Muhmmad; Sadiq, Imran

2018-04-01

This article reports the fabrication of Ni-Ti doped derivatives of Sr2Co2Fe12-2xO22 by economical Sol-gel method. At room temperature X-ray diffraction (XRD) pattern of powder was obtained after sintering at 1050 °C. The XRD analysis revealed the formation of pure Sr-Y hexaferrite phase. It was found that the observed values of dielectric parameters decreased with increasing Ni-Ti substitution. The higher values of dielectric constants and dielectric loss factor at lower frequency were owing to surface charge polarization. In all the samples the resonance peaks were also observed. The observed room temperature DC electrical resistivity found to increase from 1.8x106 to 4.9x109 ohm cm. The observed activation energies values of the fabricated materials are found in 0.52-0.82 eV range. The decrease in dielectric parameters and increase in resistivity of the fabricated samples with substituents suggest these materials have worth application in micro-wave devices as such devices required highly resistive materials.

High thermal behavior of a new glass ceramic developed from silica xerogel/SnO{sub 2} composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aripin, H., E-mail: aripin@unsil.ac.id; Mitsudo, Seitaro, E-mail: mitsudo@fir.u-fukui.ac.jp; Sudiana, I. Nyoman, E-mail: sudiana75@yahoo.com

2016-02-08

In this investigation, a new glass ceramics have been produced by mixing SnO{sub 2} and amorphous silica xerogel (ASX) extracted from sago waste ash. The composition has been prepared by adding 10 mol% of SnO{sub 2} into SX. The samples have been dry pressed and sintered in the temperature range between 800 °C and 1500 °C. The effects of temperature on the crystallization of silica xerogel after adding SnO{sub 2} and their relationship to bulk density have been studied. The crystallization process of the silica xerogel/SnO{sub 2} composite has been examined by an X-ray diffraction (XRD) and the bulk density hasmore » been characterized on the basis of the experimental data obtained using Archimedes′ principle. It has been found that an addition of SnO{sub 2} confers an appreciable effect on the grain and from the interpretation of XRD patterns allow one to explain the increase in the density by an increased crystallite size of SnO{sub 2} in the composite.« less

High thermal behavior of a new glass ceramic developed from silica xerogel/SnO2 composite

NASA Astrophysics Data System (ADS)

Aripin, H.; Mitsudo, Seitaro; Sudiana, I. Nyoman; Priatna, Edvin; Sabchevski, Svilen

2016-02-01

In this investigation, a new glass ceramics have been produced by mixing SnO2 and amorphous silica xerogel (ASX) extracted from sago waste ash. The composition has been prepared by adding 10 mol% of SnO2 into SX. The samples have been dry pressed and sintered in the temperature range between 800 °C and 1500 °C. The effects of temperature on the crystallization of silica xerogel after adding SnO2 and their relationship to bulk density have been studied. The crystallization process of the silica xerogel/SnO2 composite has been examined by an X-ray diffraction (XRD) and the bulk density has been characterized on the basis of the experimental data obtained using Archimedes' principle. It has been found that an addition of SnO2 confers an appreciable effect on the grain and from the interpretation of XRD patterns allow one to explain the increase in the density by an increased crystallite size of SnO2 in the composite.

Molten salt synthesis and luminescent properties of YVO4:Ln (Ln = Eu3+, Dy3+) nanophosphors.

PubMed

Liu, Chenglu; Wang, Fang; Jia, Peiyun; Lin, Jun; Zhou, Zhiqiang

2012-01-01

Eu3+ and Dy(3+)-doped YVO4 nanocrystallites were successfully prepared at 400 degrees C in equal moles of NaNO3 and KNO3 molten salts. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electronic microscopy (TEM), photoluminescence (PL) spectrum and lifetime were used to characterize the nanocrystallites. XRD results demonstrate that NaOH concentration and annealing temperature play important roles in phase purity and crystallinity of the nanocrystallites, the optimum NaOH concentration and annealing temperature being 6:40 and 400 degrees C respectively. TEM micrographs show the nanocrystallites are well crystallized with a cubic morphology in an average grain size of about 18 nm. Upon excitation of the vanadate group at 314 nm, YVO4:Eu3+ and YVO4:Dy3+ nanocrystallites exhibit the characteristic emission of Eu3+ and Dy3+, which indicates that there is an energy transfer from the vanadate group to the rare earth ions. Moreover, the structure and luminescent properties of the nanocrystallites were compared with their bulk counterparts with same composition in detail.

Microstructure Characterization and Wear-Resistant Properties Evaluation of an Intermetallic Composite in Ni-Mo-Si System.

PubMed

Huang, Boyuan; Song, Chunyan; Liu, Yang; Gui, Yongliang

2017-02-04

Intermetallic compounds have been studied for their potential application as structural wear materials or coatings on engineering steels. In the present work, a newly designed intermetallic composite in a Ni-Mo-Si system was fabricated by arc-melting process with commercially pure metal powders as starting materials. The chemical composition of this intermetallic composite is 45Ni-40Mo-15Si (at %), selected according to the ternary alloy diagram. The microstructure was characterized using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS), and the wear-resistant properties at room temperature were evaluated under different wear test conditions. Microstructure characterization showed that the composite has a dense and uniform microstructure. XRD results showed that the intermetallic composite is constituted by a binary intermetallic compound NiMo and a ternary Mo₂Ni₃Si metal silicide phase. Wear test results indicated that the intermetallic composite has an excellent wear-resistance at room-temperature, which is attributed to the high hardness and strong atomic bonding of constituent phases NiMo and Mo₂Ni₃Si.

One Step Synthesis of NiO Nanoparticles via Solid-State Thermal Decomposition at Low-Temperature of Novel Aqua(2,9-dimethyl-1,10-phenanthroline)NiCl2 Complex

PubMed Central

Barakat, Assem; Al-Noaimi, Mousa; Suleiman, Mohammed; Aldwayyan, Abdullah S.; Hammouti, Belkheir; Ben Hadda, Taibi; Haddad, Salim F.; Boshaala, Ahmed; Warad, Ismail

2013-01-01

[NiCl2(C14H12N2)(H2O)] complex has been synthesized from nickel chloride hexahydrate (NiCl2·6H2O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 ºC in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM). PMID:24351867

Improvement of magnetic and ferroelectric properties of BiFeO{sub 3} nanoparticles on Tb and Co substitution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, A.; De, S.; Chatterjee, S.

2016-05-06

Tb and Co substituted bismuth ferrite nanoparticles (NPs) with chemical composition Bi{sub 1-x}Tb{sub x}Fe{sub 1-y}Co{sub y}O{sub 3} (x = 0, 0.05; y = 0, 0.05) have been synthesized by a sol-gel method and characterized by x-ray diffraction (XRD), Mossbauer spectroscopy, dc magnetization and electric polarization measurements. The aim of the present work is to improve ferroelectric properties of BiFeO{sub 3} by substitution of Tb{sup 3+} ions in Bi{sup 3+} site and magnetic properties by substitution of Co{sup 2+} in Fe{sup 3+} site. The XRD patterns of all prepared samples show formation of the desired phase along with a small amountmore » of impurity. Room temperature Mossbauer spectroscopic studies reveal that all samples are in magnetically ordered state. Magnetic hysteresis loops of all samples indicate a significant enhancement of magnetic moment and coercivity whereas electric polarization measurements at room temperature reveal an improvement of ferroelectric properties in the co-substituted sample.« less

Synthesis and Characterization of High c-axis ZnO Thin Film by Plasma Enhanced Chemical Vapor Deposition System and its UV Photodetector Application

PubMed Central

Chao, Chung-Hua; Wei, Da-Hua

2015-01-01

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto silicon (Si) substrates via different synthesized temperatures by using plasma enhanced chemical vapor deposition (PECVD) system. The effects of different synthesized temperatures on the crystal structure, surface morphologies and optical properties have been investigated. The X-ray diffraction (XRD) patterns indicated that the intensity of (0002) diffraction peak became stronger with increasing synthesized temperature until 400 oC. The diffraction intensity of (0002) peak gradually became weaker accompanying with appearance of (10-10) diffraction peak as the synthesized temperature up to excess of 400 oC. The RT photoluminescence (PL) spectra exhibited a strong near-band-edge (NBE) emission observed at around 375 nm and a negligible deep-level (DL) emission located at around 575 nm under high c-axis ZnO thin films. Field emission scanning electron microscopy (FE-SEM) images revealed the homogeneous surface and with small grain size distribution. The ZnO thin films have also been synthesized onto glass substrates under the same parameters for measuring the transmittance. For the purpose of ultraviolet (UV) photodetector application, the interdigitated platinum (Pt) thin film (thickness ~100 nm) fabricated via conventional optical lithography process and radio frequency (RF) magnetron sputtering. In order to reach Ohmic contact, the device was annealed in argon circumstances at 450 oC by rapid thermal annealing (RTA) system for 10 min. After the systematic measurements, the current-voltage (I-V) curve of photo and dark current and time-dependent photocurrent response results exhibited a good responsivity and reliability, indicating that the high c-axis ZnO thin film is a suitable sensing layer for UV photodetector application. PMID:26484561

Sound velocity measurements of dhcp-FeHx up to 70 GPa using inelastic X-ray scattering: Implications for the abundance of hydrogen in the Earth's core

NASA Astrophysics Data System (ADS)

Shibazaki, Y.; Ohtani, E.; Fukui, H.; Sakai, T.; Kamada, S.; Baron, A. Q.; Nishitani, N.; Hirao, N.; Takemura, K.

2011-12-01

The Earth's interior has been directly investigated by seismic wave propagation and normal mode oscillation. In particular, the distributions of density and sound velocity are available to study the Earth's core (e.g. PREM). The inner core, which is solid state, is approximately 3 % less dense than pure iron (a core density deficit), and it is considered that the core consists of iron and light elements, such as hydrogen, carbon, oxygen, silicon, and sulfur. In this work, in order to constrain the abundance of hydrogen in the Earth's core by matching the density and sound velocity of FeHx to those of PREM, we determined the compressional sound velocity of iron hydride at high pressure using inelastic X-ray scattering (IXS). The IXS experiments and in situ X-ray diffraction (XRD) experiments were conducted up to 70 GPa and room temperature. High-pressure conditions were generated using a symmetric diamond anvil cell (DAC) with tungsten gaskets. Hydrogen initially pressurized to 0.18 GPa was loaded to the sample chamber. The IXS experiments were performed at BL35XU of the SPring-8 facility in Japan. The XRD experiments at high pressure were carried out by the angle dispersive method at BL10XU of the SPring-8 facility in Japan. The each XRD pattern of FeHx was collected after each IXS measurement in order to obtain directly the density of FeHx. Over the range of pressure studied, the diffraction lines of double-hexagonal close-packed (dhcp)-FeHx were observed and there were no diffraction lines of iron. We show that FeHx follows Birch's law for Vp above 37 GPa, namely a linear dependence between velocity and density. The estimated Vp, extrapolated to core conditions, is compared with PREM. Our results provide that the Earth's inner core could contain about 0.2 wt% hydrogen.

The effect of annealing on structural, optical and electrical properties of ZnS/porous silicon composites

NASA Astrophysics Data System (ADS)

Wang, Cai-Feng; Li, Qing-Shan; Hu, Bo; Li, Wei-Bing

2009-06-01

ZnS films were prepared by pulsed laser deposition (PLD) on porous silicon (PS) substrates. This paper investigates the effect of annealing temperature on the structural, morphological, optical and electrical properties of ZnS/PS composites by x-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) and I-V characteristics. It is found that the ZnS films deposited on PS substrates were grown in preferred orientation along β-ZnS (111) direction, and the intensity of diffraction peak increases with increasing annealing temperature, which is attributed to the grain growth and the enhancement of crystallinity of ZnS films. The smooth and uniform surface of the as-prepared ZnS/PS composite becomes rougher through annealing treatment, which is related to grain growth at the higher annealing temperature. With the increase of annealing temperature, the intensity of self-activated luminescence of ZnS increases, while the luminescence intensity of PS decreases, and a new green emission located around 550 nm appeared in the PL spectra of ZnS/PS composites which is ascribed to the defect-center luminescence of ZnS. The I-V characteristics of ZnS/PS heterojunctions exhibited rectifying behavior, and the forward current increases with increasing annealing temperature.

Grafted chromium 13-membered dioxo-macrocyclic complex into aminopropyl-based nanoporous SBA-15

NASA Astrophysics Data System (ADS)

Tarlani, Aliakbar; Joharian, Monika; Narimani, Khashayar; Muzart, Jacques; Fallah, Mahtab

2013-07-01

In a new approach, chromium (III) tetraaza dioxo ligand was grafted onto functionalized SBA-15 after four step reactions by using coordinating ability of anchored amino functionalized SBA-15. After the termination of each step, the obtained product was characterized by FT-IR, low-angle X-ray diffraction (LA-XRD), N2 adsorption-desorption isotherms (Brunauer-Emmett-Teller (BET)-Barret-Joyner-Halenda (BJH)) and thermogravimetric analysis (TGA), and used as catalyst for the efficient and regioselective alcoholysis of styrene oxide to 2-alkoxy-1-phenylethanol product at ambient temperature.

The thermal stability of the carbon-palladium films for hydrogen sensor applications

NASA Astrophysics Data System (ADS)

Rymarczyk, Joanna; Czerwosz, ElŻbieta; Diduszko, Ryszard; Kozłowski, Mirosław

2017-08-01

The thermal stability of two types of C-Pd films prepared in PVD process were studied. These films are composed of Pd nanograins embedded in a multiphase carbonaceous matrix. These films were distinguished by Pd content. These films were annealed in a range of temperatures 50÷1000°C. The structural, topographical and molecular changes were studied by scanning electron microscopy (SEM), infrared spectroscopy (FTIR) and X-ray diffraction (XRD) methods. The results show that investigated films are thermally stable up to 200°C.

Analyses of Failure Mechanisms and Residual Stresses in Graphite/Polyimide Composites Subjected to Shear Dominated Biaxial Loads

NASA Technical Reports Server (NTRS)

Kumosa, M.; Predecki, P. K.; Armentrout, D.; Benedikt, B.; Rupnowski, P.; Gentz, M.; Kumosa, L.; Sutter, J. K.

2002-01-01

This research contributes to the understanding of macro- and micro-failure mechanisms in woven fabric polyimide matrix composites based on medium and high modulus graphite fibers tested under biaxial, shear dominated stress conditions over a temperature range of -50 C to 315 C. The goal of this research is also to provide a testing methodology for determining residual stress distributions in unidirectional, cross/ply and fabric graphite/polyimide composites using the concept of embedded metallic inclusions and X-ray diffraction (XRD) measurements.

Structural and dielectric properties of Zn1-xAlxO nanoparticles

NASA Astrophysics Data System (ADS)

Giri, N.; Mondal, A.; Sarkar, S.; Ray, R.

2018-05-01

Aluminium doped ZnO (AZO) nano-crystalline sample has been synthesized using chemical precipitation method with different doping concentrations. Detailed structural and morphological investigations of Zn1-xAlxO have been carried out using X-ray diffraction (XRD) and FE-SEM, respectively. Dependence of grain size of AZO with dopant concentration has been studied. Ac conductivity, dielectric constant and dielectric loss of Zn1-xAlxO (0 ≤ x ≤ 0.1) are investigated as a function of frequency (ω) and doping concentration (x) at room temperature.

Structural and thermal properties of γ - irradiated Bombyx mori silk fibroin films

NASA Astrophysics Data System (ADS)

Madhukumar, R.; Asha, S.; Sarojini, B. K.; Somashekar, R.; Rao, B. Lakshmeesha; Shivananda, C. S.; Harish, K. V.; Sangappa

2015-06-01

The gamma radiation-induced change in structural and thermal properties of Bombyx mori silk fibroin films were investigated and have been correlated with the applied radiation doses. Irradiation of samples were carried out in dry air at room temperature using Co-60 source, and radiation doses are in the range of 0 - 300 kGy. Structural and thermal properties of the irradiated silk films were studied using X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA) and compared with unirradiated sample. Interesting results are discussed in this report.

Structure and thermal decomposition of sulfated β-cyclodextrin intercalated in a layered double hydroxide

NASA Astrophysics Data System (ADS)

Wang, Ji; Wei, Min; Rao, Guoying; Evans, David G.; Duan, Xue

2004-01-01

The sodium salt of hexasulfated β-cyclodextrin has been synthesized and intercalated into a magnesium-aluminum layered double hydroxide by ion exchange. The structure, composition and thermal decomposition behavior of the intercalated material have been studied by variable temperature X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma emission spectroscopy (ICP), and thermal analysis (TG-DTA) and a model for the structure has been proposed. The thermal stability of the intercalated sulfated β-cyclodextrin is significantly enhanced compared with the pure form before intercalation.

Synthesis and magnetic properties of nickel nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Jaiveer, E-mail: jaiveer24singh@gmail.com, E-mail: netramkaurav@yahoo.co.uk; Patel, Tarachand; Okram, Gunadhor S.

2016-05-23

Monodisperse nickel nanoparticles (Ni-NPs) were synthesized via a thermal decomposition process. The NPs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). They were spherical with mean diameter of 4 nm. Zero field cooled (ZFC) and field cooled (FC) magnetization versus temperature data displayed interesting magnetic interactions. ZFC showed a peak at 4.49 K, indicating the super paramagnetic behavior. Magnetic anisotropic constant was estimated to be 4.62×10{sup 5} erg/cm{sup 3} and coercive field was 168 Oe at 3 K.

The growth of ZnO nanostructures using Arginine

NASA Astrophysics Data System (ADS)

Singh, Baljinder; Moudgil, Lovika; Singh, Gurinder; Kaura, Aman

2018-05-01

The growth mechanism of Zinc oxide (ZnO) nanomaterial with amino acid (Arginine) is explained at different shapes. The present study of ZnO nanostructures (NSs) in the presence of Arginine has enabled us to not only determine the growth mechanism of ZnO NSs but also to determine the effect of Arginine at different temperature of reactants. The synthesized samples are characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Results reveal that Arginine is responsible for formation of NSs. Based on these results, a plausible mechanism is explained.

The Evolution of Structural Order as a Measure of Thermal History of Coke in the Blast Furnace

NASA Astrophysics Data System (ADS)

Lundgren, Maria; Khanna, Rita; Ökvist, Lena Sundqvist; Sahajwalla, Veena; Björkman, Bo

2014-04-01

Investigations were carried out on cokes heat treated in the laboratory and on cokes extracted from the experimental blast furnace (EBF) raceway and hearth. X-ray diffraction (XRD) measurements were performed to investigate changes in structural order ( L c), chemical transformations in coke ash along with comparative thermodynamic equilibrium studies and the influence of melt. Three data processing approaches were used to compute L c values as a function of temperature and time and linear correlations were established between L c and heat treatment temperatures during laboratory investigations. These were used to estimate temperatures experienced by coke in various regions of EBF and estimated raceway temperatures were seen to follow the profile of combustion peak. The MgAl2O4 spinel was observed in coke submerged in slag during laboratory studies and in cokes found further into the raceway. Coke in contact with hot metal showed XRD peaks corresponding to presence of Fe3Si. The intensity of SiO2 peak in coke ash was seen to decrease with increasing temperature and disappeared at around 1770 K (1500 °C) due to the formation of SiC. This study has shown that the evolution of structural order and chemical transformations in coke could be used to estimate its thermal history in blast furnaces.

Effect of sintering temperature on physical, structural and optical properties of wollastonite based glass-ceramic derived from waste soda lime silica glasses

NASA Astrophysics Data System (ADS)

Almasri, Karima Amer; Sidek, Hj. Ab Aziz; Matori, Khamirul Amin; Zaid, Mohd Hafiz Mohd

The impact of different sintering temperatures on physical, optical and structural properties of wollastonite (CaSiO3) based glass-ceramics were investigated for its potential application as a building material. Wollastonite based glass-ceramics was provided by a conventional melt-quenching method and followed by a controlled sintering process. In this work, soda lime silica glass waste was utilized as a source of silicon. The chemical composition and physical properties of glass were characterized by using Energy Dispersive X-ray Fluorescence (EDXRF) and Archimedes principle. The Archimedes measurement results show that the density increased with the increasing of sintering temperature. The generation of CaSiO3, morphology, size and crystal phase with increasing the heat-treatment temperature were examined by field emission scanning electron microscopy (FESEM), Fourier transforms infrared reflection spectroscopy (FTIR), and X-ray diffraction (XRD). The average calculated crystal size gained from XRD was found to be in the range 60 nm. The FESEM results show a uniform distribution of particles and the morphology of the wollastonite crystal is in relict shapes. The appearance of CaO, SiO2, and Ca-O-Si bands disclosed from FTIR which showed the formation of CaSiO3 crystal phase. In addition to the calculation of the energy band gap which found to be increased with increasing sintering temperature.

Temperature dependent dielectric relaxation and ac-conductivity of alkali niobate ceramics studied by impedance spectroscopy

NASA Astrophysics Data System (ADS)

Yadav, Abhinav; Mantry, Snigdha Paramita; Fahad, Mohd.; Sarun, P. M.

2018-05-01

Sodium niobate (NaNbO3) ceramics is prepared by conventional solid state reaction method at sintering temperature 1150 °C for 4 h. The structural information of the material has been investigated by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FE-SEM). The XRD analysis of NaNbO3 ceramics shows an orthorhombic structure. The FE-SEM micrograph of NaNbO3 ceramics exhibit grains with grain sizes ranging between 1 μm to 5 μm. The surface coverage and average grain size of NaNbO3 ceramics are found to be 97.6 % and 2.5 μm, respectively. Frequency dependent electrical properties of NaNbO3 is investigated from room temperature to 500 °C in wide frequency range (100 Hz-5 MHz). Dielectric constant, ac-conductivity, impedance, modulus and Nyquist analysis are performed. The observed dielectric constant (1 kHz) at transition temperature (400 °C) are 975. From conductivity analysis, the estimated activation energy of NaNbO3 ceramics is 0.58 eV at 10 kHz. The result of Nyquist plot shows that the electrical behavior of NaNbO3 ceramics is contributed by grain and grain boundary responses. The impedance and modulus spectrum asserts that the negative temperature coefficient of resistance (NTCR) behavior and non-Debye type relaxation in NaNbO3.

A study of the phase transition behaviour of [(NH4)0.63Li0.37]2TeBr6

NASA Astrophysics Data System (ADS)

Karray, R.; Linda, D.; Van Der Lee, A.; Ben Salah, A.; Kabadou, A.

2012-02-01

The mixed hexabromotellurate [(NH4)0.63Li0.37]2TeBr6, presenting at room temperature a K2PtCl6-type structure with space group Fm bar 3 m, exhibits three anomalies at 195, 395 and 498 K in the differential scanning calorimetry diagram. Different techniques: dielectric investigation, High-temperature X-ray powder diffraction and infrared spectroscopic study, in the range temperature (300-470) K are applied to explore the phase transition around 395 K. Combining XRD, dielectric and differential scanning calorimetry (DSC) results, no phase transition leading to a super-ionic conductivity phase is found. At high temperature, [(NH4)0.63Li0.37]2TeBr6 is characterized by a medium conductivity σ453≈ 10-4 Ω-1m-1.

Tuning operating temperature of BaSnO3 gas sensor for reducing and oxidizing gases

NASA Astrophysics Data System (ADS)

Kumar, Sachin; Pugh, David; Dasgupta, Daipayan; Sarin, Neha; Parkin, Ivan; Luthra, Vandna

2018-05-01

Barium stannate (BaSnO3) was prepared by solid state ceramic route. The crystalline phase of the prepared sample was confirmed by X-Ray Diffraction (XRD) pattern. Gas sensing behaviour of barium stannate was investigated for reducing and oxidizing gases; such as butane, ethanol, CO and NO2; from 5 ppm to 50 ppm levels of concentration. Barium stannate sensors were optimized for highest responsiveness by varying operating temperature between 270 °C to 550 °C. Its highest response was observed for ethanol at 300°C. The gas sensing response of ethanol was better than other gases at all the operating temperatures. Such studies in conjunction with gas sensing tests can be used for setting the optimum operating temperatures and can be used for low concentration ethanol sensing applications.

Room temperature ferromagnetism and luminescent behavior of Ni doped ZnO nanoparticles prepared by coprecipitation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arora, Deepawali; Mahajan, Aman; Kaur, Parvinder

2016-05-23

The samples of Zn{sub 1-x}Ni{sub x}O (x= 0.00 and 0.05) were prepared using coprecipitation method and annealed at different temperatures. The effect of Ni ion substitution on the structural and optical properties has been studied using X-ray Diffraction, UV-Visible, Photoluminescence and Magnetic measurements. XRD measurements demonstrate that all the prepared samples are wurtzite polycrystalline single phase in nature, ruling out the presence of any secondary phase formation. Ultraviolet visible measurements showed a decrease in band gap with the increase in annealing temperature and doping concentration. The PL data shows the red shift in all the samples and luminescence quenching withmore » Ni doping. Compared to undoped ZnO, Ni doped ZnO showed room temperature ferromagnetism.« less

Quantifying Morphological Features of α-U3O8 with Image Analysis for Nuclear Forensics.

PubMed

Olsen, Adam M; Richards, Bryony; Schwerdt, Ian; Heffernan, Sean; Lusk, Robert; Smith, Braxton; Jurrus, Elizabeth; Ruggiero, Christy; McDonald, Luther W

2017-03-07

Morphological changes in U 3 O 8 based on calcination temperature have been quantified enabling a morphological feature to serve as a signature of processing history in nuclear forensics. Five separate calcination temperatures were used to synthesize α-U 3 O 8 , and each sample was characterized using powder X-ray diffraction (p-XRD) and scanning electron microscopy (SEM). The p-XRD spectra were used to evaluate the purity of the synthesized U-oxide; the morphological analysis for materials (MAMA) software was utilized to quantitatively characterize the particle shape and size as indicated by the SEM images. Analysis comparing the particle attributes, such as particle area at each of the temperatures, was completed using the Kolmogorov-Smirnov two sample test (K-S test). These results illustrate a distinct statistical difference between each calcination temperature. To provide a framework for forensic analysis of an unknown sample, the sample distributions at each temperature were compared to randomly selected distributions (100, 250, 500, and 750 particles) from each synthesized temperature to determine if they were statistically different. It was found that 750 particles were required to differentiate between all of the synthesized temperatures with a confidence interval of 99.0%. Results from this study provide the first quantitative morphological study of U-oxides, and reveals the potential strength of morphological particle analysis in nuclear forensics by providing a framework for a more rapid characterization of interdicted uranium oxide samples.

Novel Sample-handling Approach for XRD Analysis with Minimal Sample Preparation

NASA Technical Reports Server (NTRS)

Sarrazin, P.; Chipera, S.; Bish, D.; Blake, D.; Feldman, S.; Vaniman, D.; Bryson, C.

2004-01-01

Sample preparation and sample handling are among the most critical operations associated with X-ray diffraction (XRD) analysis. These operations require attention in a laboratory environment, but they become a major constraint in the deployment of XRD instruments for robotic planetary exploration. We are developing a novel sample handling system that dramatically relaxes the constraints on sample preparation by allowing characterization of coarse-grained material that would normally be impossible to analyze with conventional powder-XRD techniques.

In situ study of maize starch gelatinization under ultra-high hydrostatic pressure using X-ray diffraction.

PubMed

Yang, Zhi; Gu, Qinfen; Hemar, Yacine

2013-08-14

The gelatinization of waxy (very low amylose) and high-amylose maize starches by ultra-high hydrostatic pressure (up to 6 GPa) was investigated in situ using synchrotron X-ray powder diffraction on samples held in a diamond anvil cell (DAC). The starch pastes, made by mixing starch and water in a 1:1 ratio, were pressurized and measured at room temperature. X-ray diffraction pattern showed that at 2.7 GPa waxy starch, which displayed A-type XRD pattern at atmospheric pressure, exhibited a faint B-type-like pattern. The B-type crystalline structures of high-amylose starch were not affected even when 1.5 GPa pressure was applied. However, both waxy and high-amylose maize starches can be fully gelatinized at 5.9 GPa and 5.1 GPa, respectively. In the case of waxy maize starch, upon release of pressure (to atmospheric pressure) crystalline structure appeared as a result of amylopectin aggregation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of Annealing Temperature on Properties of Ti-Ga-Doped ZnO Films Deposited on Flexible Substrates.

PubMed

Chen, Tao-Hsing; Chen, Ting-You

2015-11-03

An investigation is performed into the optical, electrical, and microstructural properties of Ti-Ga-doped ZnO films deposited on polyimide (PI) flexible substrates and then annealed at temperatures of 300 °C, 400 °C, and 450 °C, respectively. The X-ray diffraction (XRD) analysis results show that all of the films have a strong (002) Ga doped ZnO (GZO) preferential orientation. As the annealing temperature is increased to 400 °C, the optical transmittance increases and the electrical resistivity decreases. However, as the temperature is further increased to 450 °C, the transmittance reduces and the resistivity increases due to a carbonization of the PI substrate. Finally, the crystallinity of the ZnO film improves with an increasing annealing temperature only up to 400 °C and is accompanied by a smaller crystallite size and a lower surface roughness.

The role of annealing temperature variation on ZnO nanorods array deposited on TiO2 seed layer

NASA Astrophysics Data System (ADS)

Asib, N. A. M.; Aadila, A.; Afaah, A. N.; Rusop, M.; Khusaimi, Z.

2018-05-01

Seed layer of Titanium dioxide (TiO2) by sol-gel spin coating technique were coated on glass substrate to grow Zinc oxide nanorods (ZNR) by solution-immersion method. The fabricated ZNR were annealed at various temperatures ranged from 400 to 600° C. FESEM images revealed that smaller ZNR were densely grown at optimum temperature of 450 and 500°C. Meanwhile, for all samples a dominant (0 0 2) diffraction peak of ZNR recorded by XRD patterns was at 34.4° which corresponding to hexagonal ZNR with a wurtzite structure. UV-Vis absorbance spectra showed the maximum absorption properties at UV region were detected at 450 and 500°C. The samples also showed high absorbance values at visible region.

Flake like V{sub 2}O{sub 5} nanoparticles for ethanol sensing at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chitra, M.; Uthayarani, K.; Rajasekaran, N.

2016-05-23

The versatile redox property of vanadium oxide explores it in various applications like catalysis, electrochromism, electrochemistry, energy storage, sensors, microelectronics, batteries etc., In this present work, vanadium oxide was prepared via hydrothermal route followed by calcination. The structural and lattice parameters were analysed from the powder X-ray diffraction (XRD) pattern. The morphology and the composition of the sample were obtained from Field emission Scanning electron microscopic (FeSEM) and Energy Dispersive X-ray (EDAX) Spectrometric analysis respectively. The sensitivity, response – recovery time of the sample towards ethanol (0 ppm – 300 ppm) sensing at room temperature was measured and the present investigation onmore » vanadium oxide nanoparticles over the flakes shows better sensitivity (30%) at room temperature.« less

Pulsed laser deposition of lithium niobate thin films

NASA Astrophysics Data System (ADS)

Canale, L.; Girault-Di Bin, C.; Cosset, F.; Bessaudou, A.; Celerier, A.; Decossas, J.-Louis; Vareille, J.-C.

2000-12-01

Pulsed laser deposition of Lithium Niobate thin films onto sapphire (0001) substrates is reported. Thin films composition and structure have been determined using Rutherford Backscattermg Spectroscopy (RBS) and X-ray diffraction ( XRD) experiments. The influe:nce of deposition parameters such as substrate temperature, oxygen pressure and target to substrate distance on the composition and the structure of the films has been studied. Deposition temperature is found to be an important parameter which enables us to grow LiNbO3 films without the Li deficient phase LiNb3O8. Nearly stoichiometric thin fihns have been obtained for an oxygen pressure of 0. 1 Ton and a substrate temperature of 800°C. Under optimized conditions the (001) preferential orientation of growth, suitable for most optical applications, has been obtained.

Polymer nanocomposite dielectric and electrical properties with quantum dots nanofiller

NASA Astrophysics Data System (ADS)

Ahmed, R. M.; Morsi, R. M. M.

2017-10-01

Nanocomposite films of different contents of CdSe/ZnS quantum dots nanoparticles embedded in hosting matrix of polyvinyl chloride (PVC) were prepared by simple solution casting method. Electrical and dielectric properties of nanocomposites films were investigated in the temperature range 323-393 (K) and at frequencies (50-2000) kHz. The frequency dependence of AC conductivity was following the universal power law. The values of the frequency exponent, s, revealed that the conduction mechanism at low temperature is considered by small polaron tunneling model, whereas at high temperature, it is related to CBH model. The activation energy values (ΔE) were depending on nanoparticle concentration as well as frequency. Also, X-ray diffraction (XRD) enabled approximately estimating the average particle size of the nanoparticles incorporated in PVC.

Final Report for X-ray Diffraction Sample Preparation Method Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ely, T. M.; Meznarich, H. K.; Valero, T.

WRPS-1500790, “X-ray Diffraction Saltcake Sample Preparation Method Development Plan/Procedure,” was originally prepared with the intent of improving the specimen preparation methodology used to generate saltcake specimens suitable for XRD-based solid phase characterization. At the time that this test plan document was originally developed, packed powder in cavity supports with collodion binder was the established XRD specimen preparation method. An alternate specimen preparation method less vulnerable, if not completely invulnerable to preferred orientation effects, was desired as a replacement for the method.

Metastable and equilibrium phase formation in sputter-deposited Ti/Al multilayer thin films

NASA Astrophysics Data System (ADS)

Lucadamo, G.; Barmak, K.; Lavoie, C.; Cabral, C., Jr.; Michaelsen, C.

2002-06-01

The sequence and kinetics of metastable and equilibrium phase formation in sputter deposited multilayer thin films was investigated by combining in situ synchrotron x-ray diffraction (XRD) with ex situ electron diffraction and differential scanning calorimetry (DSC). The sequence included both cubic and tetragonal modifications of the equilibrium TiAl3 crystal structure. Values for the formation activation energies of the various phases in the sequence were determined using the XRD and DSC data obtained here, as well as activation energy data reported in the literature.

Effects of graphene oxide concentration on optical properties of ZnO/RGO nanocomposites and their application to photocurrent generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azarang, Majid, E-mail: azarangmajid@gmail.com, E-mail: azarang@phys.usb.ac.ir; Department of Physics, University of Sistan and Baluchestan, 98135-674 Zahedan; Shuhaimi, Ahmad

2014-08-28

The effects of different concentrations of graphene oxide (GO) on the structure and optical properties of ZnO nanoparticles (NPs) were investigated. The nanocomposites were synthesized via the sol-gel method in a gelatin medium. X-ray diffraction patterns (XRD) and Fourier transform infrared spectroscopy indicated that the GO sheets were reduced and changed to reduced GO (RGO) during the calcination of the nanocomposites at 400 °C. In addition, the XRD patterns of the NPs indicated a hexagonal (wurtzite) structure for all the products. Microscopic studies showed that the NPs were decorated and dispersed on the RGO sheets very well. However, these studies revealedmore » that the RGO concentration had an effect on the crystal growth process for the ZnO NPs. Furthermore, these studies showed that the NPs could be grown with a single crystal quality in an optimum RGO concentration. According to the XRD results that were obtained from pure ZnO NPs, the calcinations temperature was decreased by the RGO. UV–vis and room temperature photoluminescence studies showed that the optical properties of the ZnO/RGO nanocomposite were affected by the RGO concentration. Finally, the obtained ZnO/RGO nanocomposite was used to generate a photocurrent. Observations showed that the photocurrent intensity of the nanocomposite was significantly increased by increasing the RGO, with an optimum RGO concentration.« less

Effect of bismuth doping on the structural and magnetic properties of zinc-ferrite nanoparticles prepared by a microwave combustion method

NASA Astrophysics Data System (ADS)

Shoushtari, Morteza Zargar; Emami, Akram; Ghahfarokhi, Seyed Ebrahim Mosavi

2016-12-01

In this study, we examine the bismuth doping effect on the structural, magnetic and microstructural properties of zinc-ferrite nanoparticles (ZnFe2-xBixO4 with x=0.0, 0.02, 0.04, 0.06, 0.1, 0.15) which have been prepared by a microwave combustion method. The structural, morphological and electromagnetic properties and also Curie temperature of the samples were examined by x-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM), vibrating sample magnetometer (VSM), and LCR meter, respectively. In order to measure the energy band gap, the FTIR spectra of the samples were also considered. The XRD patterns of the samples revealed that all of them are ZnFe2O4 structure and no additional peak was observed in their patterns. This implied that the samples were single-phase up to bismuth solubility of 0.15 in Zinc-Ferrite. The results of XRD patterns also showed that the value lattice parameter increases with increasing the bismuth doping. The FESEM results revealed an ascending trend in the size of the nanoparticles. Also considering the VSM results characterized that an increasing the bismuth doping leads to lower the saturation magnetization. The Curie temperatures of the samples were reduced as a result of increasing the amount of bismuth.

Effect of thermal annealing on the phase evolution of silver tungstate in Ag/WO₃ films.

PubMed

Bose, R Jolly; Sreedharan, R Sreeja; Krishnan, R Resmi; Reddy, V R; Gupta, Mukul; Ganesan, V; Sudheer, S K; Pillai, V P Mahadevan

2015-06-15

Silver/tungsten oxide multi-layer films are deposited over quartz substrates by RF magnetron sputtering technique and the films are annealed at temperatures 200, 400 and 600°C. The effect of thermal annealing on the phase evolution of silver tungstate phase in Ag/WO3 films is studied extensively using techniques like X-ray diffraction, micro-Raman analysis, atomic force microscopy and photoluminescence studies. The XRD pattern of the as-deposited film shows only the peaks of cubic phase of silver. The film annealed at 200°C shows the presence of XRD peaks corresponding to orthorhombic phase of Ag2WO4 and peaks corresponding to cubic phase of silver with reduced intensity. It is found that, as annealing temperature increases, the volume fraction of Ag decreases and that of Ag2WO4 phase increases and becomes highest at a temperature of 400°C. When the temperature increases beyond 400°C, the volume fraction of Ag2WO4 decreases, due to its decomposition into silver and oxygen deficient phase Ag2W4O13. The micro-Raman spectra of the annealed films show the characteristic bands of tungstate phase which is in agreement with XRD analysis. The surface morphology of the films studied by atomic force microscopy reveals that the particle size and r.m.s roughness are highest for the sample annealed at 400°C. In the photoluminescence study, the films with silver tungstate phase show an emission peak in blue region centered around the wavelength 441 nm (excitation wavelength 256 nm). Copyright © 2015 Elsevier B.V. All rights reserved.

Reduction of mixed Mn-Zr oxides: in situ XPS and XRD studies.

PubMed

Bulavchenko, O A; Vinokurov, Z S; Afonasenko, T N; Tsyrul'nikov, P G; Tsybulya, S V; Saraev, A A; Kaichev, V V

2015-09-21

A series of mixed Mn-Zr oxides with different molar ratios Mn/Zr (0.1-9) have been prepared by coprecipitation of manganese and zirconium nitrates and characterized by X-ray diffraction (XRD) and BET methods. It has been found that at concentrations of Mn below 30 at%, the samples are single-phase solid solutions (MnxZr1-xO2-δ) based on a ZrO2 structure. X-ray photoelectron spectroscopy (XPS) measurements showed that manganese in these solutions exists mainly in the Mn(4+) state on the surface. An increase in Mn content mostly leads to an increase in the number of Mn cations in the structure of solid solutions; however, a part of the manganese cations form Mn2O3 and Mn3O4 in the crystalline and amorphous states. The reduction of these oxides with hydrogen was studied by a temperature-programmed reduction technique, in situ XRD, and near ambient pressure XPS in the temperature range from 100 to 650 °C. It was shown that the reduction of the solid solutions MnxZr1-xO2-δ proceeds via two stages. During the first stage, at temperatures between 100 and 500 °C, the Mn cations incorporated into the solid solutions MnxZr1-xO2-δ undergo partial reduction. During the second stage, at temperatures between 500 and 700 °C, Mn cations segregate on the surface of the solid solution. In the samples with more than 30 at% Mn, the reduction of manganese oxides was observed: Mn2O3 → Mn3O4 → MnO.

An X-ray diffraction method for semiquantitative mineralogical analysis of Chilean nitrate ore

USGS Publications Warehouse

Jackson, J.C.; Ericksent, G.E.

1997-01-01

Computer analysis of X-ray diffraction (XRD) data provides a simple method for determining the semiquantitative mineralogical composition of naturally occurring mixtures of saline minerals. The method herein described was adapted from a computer program for the study of mixtures of naturally occurring clay minerals. The program evaluates the relative intensities of selected diagnostic peaks for the minerals in a given mixture, and then calculates the relative concentrations of these minerals. The method requires precise calibration of XRD data for the minerals to be studied and selection of diffraction peaks that minimize inter-compound interferences. The calculated relative abundances are sufficiently accurate for direct comparison with bulk chemical analyses of naturally occurring saline mineral assemblages.

An x-ray diffraction method for semiquantitative mineralogical analysis of chilean nitrate ore

USGS Publications Warehouse

John, C.; George, J.; Ericksen, E.

1997-01-01

Computer analysis of X-ray diffraction (XRD) data provides a simple method for determining the semiquantitative mineralogical composition of naturally occurring mixtures of saline minerals. The method herein described was adapted from a computer program for the study of mixtures of naturally occurring clay minerals. The program evaluates the relative intensities of selected diagnostic peaks for the minerals in a given mixture, and then calculates the relative concentrations of these minerals. The method requires precise calibration of XRD data for the minerals to be studied and selection of diffraction peaks that minimize inter-compound interferences. The calculated relative abundances are sufficiently accurate for direct comparison with bulk chemical analyses of naturally occurring saline mineral assemblages.

Synthesis and characterization thin films of conductive polymer (PANI) for optoelectronic device application

NASA Astrophysics Data System (ADS)

Jarad, Amer N.; Ibrahim, Kamarulazizi; Ahmed, Nasser M.

2016-07-01

In this work we report preparation and investigation of structural and optical properties of polyaniline conducting polymer. By using sol-gel in spin coating technique to synthesize thin films of conducting polymer polyaniline (PANI). Conducting polymer polyaniline was synthesized by the chemical oxidative polymerization of aniline monomers. The thin films were characterized by technique: Hall effect, High Resolution X-ray diffraction (HR-XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), and UV-vis spectroscopy. Polyaniline conductive polymer exhibit amorphous nature as confirmed by HR-XRD. The presence of characteristic bonds of polyaniline was observed from FTIR spectroscopy technique. Electrical and optical properties revealed that (p-type) conductivity PANI with room temperature, the conductivity was 6.289×10-5 (Ω.cm)-1, with tow of absorption peak at 426,805 nm has been attributed due to quantized size of polyaniline conducting polymer.

Synthesis H-Zeolite catalyst by impregnation KI/KIO3 and performance test catalyst for biodiesel production

NASA Astrophysics Data System (ADS)

Widayat, W.; Rizky Wicaksono, Adit; Hakim Firdaus, Lukman; Okvitarini, Ndaru

2016-02-01

The objective of this research is to produce H-catalyst catalyst that was impregnated with KI/KIO3. The catalyst was analyzed about surface area, X-Ray Diffraction (XRD) and performance test of catalyst for biodiesel production. An H-Zeolite catalyst was synthesized from natural zeolite with chemical treatment processing, impregnation KI/KIO3 and physical treatment. The results shows that the surface area of the catalyst by 27.236 m2/g at a concentration of 5% KI. XRD analysis shows peak 2-θ at 23.627o indicating that KI was impregnated on H-zeolite catalyst. The catalyst was tested in production of biodiesel using palm oil with conventional methods for 3 hour at temperature of 70-80 oC. The result for conversion Fatty Acid Methyl Ester (FAME) reached maximum value on 87.91% under production process using catalyst 5% KIO3-H zeolite.

Structure, wettability and thermal degradation of new fluoro-oligomer modified nanoclays.

PubMed

Valsecchi, R; Viganò, M; Levi, M; Turri, S

2008-04-01

Quaternary ammonium salts based on monofunctionalized Perfluoropolyether (PFPE) oligomers were synthesized and used for the cation exchange process of sodium Montmorillonite nanoclays. The new fluoromodified nanoclays were characterized through X-rays diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), termogravimetric analysis (TGA), differential scanning calorimetry (DSC), electronic microscopy (SEM-EDS), and contact angle measurements (CA). In particular XRD showed rather complex patterns (presence of higher order reflections) which allowed the calculation of basal spacings, regularly increasing with the molecular weight of the fluorinated macrocation. Both IR and SEM confirmed the presence of fluorinated segments at clays interface, while TGA showed a limited thermal stability with an onset of degradation temperature which seems not dependent on the molecular weight of the macrocation. CA measurements showed a peculiar behaviour, with evident dynamic hysteresis phenomena and surface tension components quite different from those of commercially available, organomodified clays.

A High Sensitivity Isopropanol Vapor Sensor Based on Cr₂O₃-SnO₂ Heterojunction Nanocomposites via Chemical Precipitation Route.

PubMed

Jawaher, K Rackesh; Indirajith, R; Krishnan, S; Robert, R; Pasha, S K Khadheer; Deshmukh, Kalim; Sastikumar, D; Das, S Jerome

2018-08-01

Cr2O3-SnO2 heterojunction nanocomposites were prepared via chemical precipitation method. The prepared samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra and Field Emission Electron Microscopy (FESEM). The XRD spectrum confirms the presence of both tetragonal rutile SnO2 and rhombohedral corundum Cr2O3 structure. Further investigation into the gas sensing performances of the prepared Cr2O3-SnO2 nanocomposites exhibited an enhanced sensitivity towards VOPs such as isopropanol, acetone, ethanol and formaldehyde. Especially, isopropanol vapor sensor shows excellent sensitivity at an operating temperature of 100 °C. The highest sensitivity for Cr2O3-SnO2 heterojunction nanocomposites indicate that these materials can be a good candidate for the production of high-performance isopropanol sensors.

Extracellular biosynthesis of gold and silver nanoparticles using Krishna tulsi ( Ocimum sanctum) leaf

NASA Astrophysics Data System (ADS)

Philip, Daizy; Unni, C.

2011-05-01

Aqueous extract of Ocimum sanctum leaf is used as reducing agent for the environmentally friendly synthesis of gold and silver nanoparticles. The nanoparticles were characterized using UV-vis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. These methods allow the synthesis of hexagonal gold nanoparticles having size ∼30 nm showing two surface plasmon resonance (SPR) bands by changing the relative concentration of HAuCl 4 and the extract. Broadening of SPR is observed at larger quantities of the extract possibly due to biosorption of gold ions. Silver nanoparticles with size in the range 10-20 nm having symmetric SPR band centered around 409 nm are obtained for the colloid synthesized at room temperature at a pH of 8. Crystallinity of the nanoparticles is confirmed from the XRD pattern. Biomolecules responsible for capping are different in gold and silver nanoparticles as evidenced by the FTIR spectra.

Synchrotron Radiation XRD Analysis of Indialite in Y-82094 Ungrouped Carbonaceous Chondrite

NASA Technical Reports Server (NTRS)

Mikouchi, T.; Hagiya, K.; Sawa, N.; Kimura, M.; Ohsumi, K.; Komatsu, M.; Zolensky, M.

2016-01-01

Y-82094 is an ungrouped type 3.2 carbonaceous chondrite, with abundant chondrules making 78 vol.% of the rock. Among these chondrules, an unusual porphyritic Al-rich magnesian chondrule is reported that consists of a cordierite-like phase, Al-rich orthopyroxene, cristobalite, and spinel surrounded by an anorthitic mesostasis. The reported chemical formula of the cordierite-like phase is Na(0.19)Mg(1.95)Fe(0.02)Al(3.66)Si(5.19)O18, which is close to stoichiometric cordierite (Mg2Al3[AlSi5O18]). Although cordierite can be present in Al-rich chondrules, it has a high temperature polymorph (indialite) and it is therefore necessary to determine whether it is cordierite or indialite in order to better constrain its formation conditions. In this abstract we report on our synchrotron radiation X-ray diffraction (SR-XRD) study of the cordierite-like phase in Y-82094.

Synthesis, growth and characterization of 3-nitroacetanilide—A new organic nonlinear optical crystal by Bridgman technique

NASA Astrophysics Data System (ADS)

Lenin, M.; Ramasamy, P.

2008-10-01

Single crystals of 3-nitroacetanilide, an organic nonlinear optical material has been grown by the Bridgman-Stockbarger method. The single crystal X-ray diffraction (XRD) data revealed the noncentrosymmetric crystal structure, which is an essential criterion for second harmonic generation. The crystalline nature of the grown crystals was confirmed using powder XRD techniques. The functional group of the compound is identified by FTIR spectrum. The thermal stability and its tendency to grow as single crystal in solution and in melt have been identified for the new title compound. The UV-vis spectrum of mNAA shows the lower optical cut off at 400 nm and was transparent in the visible region. The second harmonic generation efficiency was found using Kurtz powder technique. The dielectric constant and dielectric loss of the crystal were measured as a function of frequency and temperature, and the results are discussed.

Isosorbide, a green plasticizer for thermoplastic starch that does not retrogradate.

PubMed

Battegazzore, Daniele; Bocchini, Sergio; Nicola, Gabriele; Martini, Eligio; Frache, Alberto

2015-03-30

Isosorbide is a non-toxic biodegradable diol derived from bio-based feedstock. It can be used for preparing thermoplastic starch through a semi-industrial process of extrusion. Isosorbide allows some technological advantages with respect to classical plasticizers: namely, direct mixing with starch, energy savings for the low processing temperature required and lower water uptake. Indeed, maize starch was directly mixed with the solid plasticizer and direct fed in the main hopper of a co-rotating twin screw extruder. Starch plasticization was assessed by X-ray diffraction (XRD) and dynamic-mechanical analysis (DMTA). Oxygen permeability, water uptake and mechanical properties were measured at different relative humidity (R.H.) values. These three properties turned out to be highly depending on the R.H. No retrogradation and changing of the material properties were occurred from XRD and DMTA after 9 months. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bioapatite Recrystallization During Burning and its Effects on Phosphate Stable Oxygen Isotope Composition

NASA Astrophysics Data System (ADS)

Munro, L. E.; Longstaffe, F. J.; White, C. D.

2003-04-01

Stable oxygen isotopic compositions of phosphate from mammal bones are commonly used in palaeoenvironmental reconstructions. However, preservation of the primary bone oxygen isotopic composition is of concern during post-mortem alteration. Particularly in studies of archaeological interest, bone samples are often obtained from contexts where they have been heated, either in middens, or near hearths. Hence, in addition to alteration resulting from natural diagenetic processes, burning may also have contributed to modification of the primary oxygen isotopic signal. Various techniques can be employed to evaluate the degree of preservation of bone during burning. Anthropologists commonly use colour comparisons (Munsell Colour Chart) to assess the temperature of burning. Recrystallization of the carbonated hydroxyapatite, i.e., bioapatite, in bone is more rigorously assessed using X-ray diffraction and infra-red spectroscopy. In this study, freshly deceased (6<8 months) white-tailed deer leg bones (Odocoileus virginianus) were collected from Pinery Provincial Park, Ontario, Canada. Each long bone was sectioned, incrementally burned, colour-typed, ground to a standardized grain-size (45<63mm), and analysed using differential thermal analysis (DTA), thermogravimetric analysis (TGA), rotating anode X-ray diffraction (XRD), and Fourier transform infra-red spectroscopy (FTIR). Heating temperatures ranged from 25 to 900^oC, increasing in intervals of 25^oC. Two major stages of weight loss were recorded in the DTA/TGA data, 25-260^oC representing dehydration, and 270-600^oC reflecting incineration of organic matter. The end-product (900^oC) resembled pure hydroxyapatite. XRD patterns of the bioapatite remained virtually unchanged from 25-250^oC, after which peak intensity, sharpness and the XRD crystallinity index (XRD CI) increased from 0.80 at 250^oC to 1.26 at 900^oC. FTIR patterns showed analogous behaviour, demonstrating minimal fluctuations in the FTIR crystallinity index (FTIR CI) from 2.86 at 25^oC to 2.56 at 250^oC, and then an overall increasing trend from 2.54 at 275^oC to a maximum of 4.72 at 825^oC as v4PO4 peak splitting intensified. Initial results show that the δ18O (VSMOW) values of bioapatite phosphate decreased from 15.0 ppm at 300^oC to 10.6 ppm at 750^oC. These data suggest that primary phosphate oxygen isotopic compositions can be significantly altered during burning, even when only modest changes in crystallinity are indicated by XRD or FTIR.

X-ray diffraction and X-ray K absorption near edge studies of copper (II) complexes with amino acids

NASA Astrophysics Data System (ADS)

Sharma, P. K.; Mishra, Ashutosh; Malviya, Varsha; Kame, Rashmi; Malviya, P. K.

2017-05-01

Synthesis of copper (II) complexes [CuL1L2X].nH2O, where n=1, 2,3 (X=Cl,Br,NO3) (L1is 2,2’-bipyridine and L2 is L-tyrosine) by the chemical root method. The XRD data for the samples have been recorded. EXAFS spectra have also been recorded at the K-edge of Cu using the dispersive beam line BL-8 at 2.5 Gev Indus-2 Synchrotron radiation source at RRCAT, Indore, India. XRD and EXAFS data have been analysed using the computer software. X-ray diffraction studies of all complexes indicate their crystalline nature. Lattice parameter, bond length, particle size have been determined from XRD data.

Ostwald ripening and interparticle-diffraction effects for illite crystals

USGS Publications Warehouse

Eberl, D.D.; Srodon, J.

1988-01-01

The Warren-Averbach method, an X-ray diffraction (XRD) method used to measure mean particle thickness and particle-thickness distribution, is used to restudy sericite from the Silverton caldera. Apparent particle-thickness distributions indicate that the clays may have undergone Ostwald ripening and that this process has modified the K-Ar ages of the samples. The mechanism of Ostwald ripening can account for many of the features found for the hydrothermal alteration of illite. Expandabilities measured by the XRD peak-position method for illite/smectites (I/S) from various locations are smaller than expandabilities measured by transmission electron microscopy (TEM) and by the Warren-Averbach (W-A) method. This disparity is interpreted as being related to the presence of nonswelling basal surfaces that form the ends of stacks of illite particles (short-stack effect), stacks that, according to the theory of interparticle diffraction, diffract as coherent X-ray scattering domains. -from Authors

Rapid green synthesis of spherical gold nanoparticles using Mangifera indica leaf

NASA Astrophysics Data System (ADS)

Philip, Daizy

2010-11-01

This paper reports the rapid biological synthesis of spherical gold nanoparticles at room temperature using fresh/dry leaf extract of Mangifera indica. This is a simple, cost-effective, stable for long time and reproducible aqueous synthesis method to obtain a self-assembly of nearly monodispersed Au nanoparticles of size ˜20 nm and 17 nm. The nanoparticles were obtained within 2 min of addition of the extract to the solution of HAuCl 4·3H 2O and the colloid is found to be stable for more than 5 months. Smaller and more uniformly distributed particles could be obtained with dried leaf extract. The nanoparticles obtained are characterized by UV-vis, transmission electron microscopy (TEM) and X-ray diffraction (XRD). Crystalline nature of the nanoparticles in the fcc structure is confirmed by the peaks in the XRD pattern corresponding to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes, bright circular spots in the selected area electron diffraction (SAED) and clear lattice fringes in the high-resolution TEM image. The possible biomolecules responsible for efficient stabilization are suggested by studying the FTIR spectrum of the sample. This environmentally benign method provides much faster synthesis and colloidal stability comparable to those of chemical reduction.

Neoteric environmental detoxification of organic pollutants and pathogenic microbes via green synthesized ZnO nanoparticles.

PubMed

Jaffri, Shaan Bibi; Ahmad, Khuram Shahzad

2018-06-13

Present study has for the first time reported Prunus cerasifera leaf extract mediated zinc oxide nanoparticles in a green and one pot synthetic mode without utilization of any chemical reducing agents. Synthesized nanoparticles were analyzed by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), fourier transmission infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). UV-Vis peak was detected at 380 nm due to surface plasmon resonance (SPR). Variety of biomolecules were revealed by FTIR involved in reduction cum stabilization of zinc oxide nanoparticles. Wurtzite hexagonal geometry with an average crystallite size of 12 nm was obtained from XRD diffraction pattern. SEM exhibited size ranges of 80-100 nm and 60- 100 nm for 200 ℃ and 600 ℃ calcination temperatures. Synthesized nanoparticles were used as bio-cleaning photocatalysts against organic pollutants i.e. bromocresol green, bromophenol blue, methyl red and methyl blue, which yielded pseudo first order reaction kinetics (R 2 = 0.98, 0.92, 0.92, 0.90 respectively). Pollutants expressed higher degradation percentages in less than 14 min in direct solar irradiance. Moreover, synthesized nanoparticles were tested against resistant microbes i.e. Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Aspergillus terreus, Penicillium chrysogenum, Fusarium solani, Lasiodiplodia theobromae, Xanthomonas axonopodis pv. citri and Psuedomonas syringae for development of new generation of antimicrobial agents.

Ultra-low thermal conductivity of TlIn5Se8 and structure of the new complex chalcogenide Tl0.98In13.12Se16.7Te2.3

NASA Astrophysics Data System (ADS)

Lefèvre, Robin; Berthebaud, David; Pérez, Olivier; Pelloquin, Denis; Boudin, Sophie; Gascoin, Franck

2017-06-01

TlIn5Se8 has been synthesized by means of solid-state reaction and densified by Spark Plasma Sintering. The compound is a semiconductor with a band gap of 1.62 eV estimated from reflectance measurements. Its thermal conductivity is about 0.45 W m-1. K-1 in the temperature range 300-673 K, an extremely low value attributed to its complex pseudo-1D structure reminiscent of the pseudo-hollandite. While attempting to dope TlIn5Se8 with Te, a new complex chalcogenide was discovered and characterized by the combination of TEM and XRD diffraction. It belongs to the A2In12X19 family, crystallizing in the R 3 ̅:H space group. Single crystal X-ray diffraction study led to a refined composition of Tl0.98In13.12Se16.7Te2.3 with cell parameters: a=13.839(5) Å and c=35.18(3) Å. A static disorder is found on one indium site situated in an octahedral environment. The single crystal XRD study is in agreement with TEM analyses in STEM-HAADF image mode that do not show any extended defects or disorder at atomic scale.

Recognizing ancient papyri by a combination of spectroscopic, diffractional and chromatographic analytical tools

PubMed Central

Łojewska, J.; Rabin, I.; Pawcenis, D.; Bagniuk, J.; Aksamit-Koperska, M. A.; Sitarz, M.; Missori, M.; Krutzsch, M.

2017-01-01

Ancient papyri are a written heritage of culture that flourished more than 3000 years ago in Egypt. One of the most significant collections in the world is housed in the Egyptian Museum and Papyrus Collection in Berlin, from where the samples for our investigation come. The papyrologists, curators and conservators of such collections search intensely for the analytical detail that would allow ancient papyri to be distinguished from modern fabrications, in order to detect possible forgeries, assess papyrus deterioration state, and improve the design of storage conditions and conservation methods. This has become the aim of our investigation. The samples were studied by a number of methods, including spectroscopic (FTIR, fluorescent-FS, Raman) diffractional (XRD) and chromatographic (size exclusion chromatography-SEC), selected in order to determine degradation parameters: overall oxidation of lignocellulosic material, degree of polymerization and crystallinity of cellulose. The results were correlated with those obtained from carefully selected model samples including modern papyri and paper of different composition aged at elevated temperature in humid air. The methods were classified in the order SEC > FS > FTIR > XRD, based on their effectiveness in discriminating the state of papyri degradation. However, the most trustworthy evaluation of the age of papyri samples should rely on several methods. PMID:28382971

Recognizing ancient papyri by a combination of spectroscopic, diffractional and chromatographic analytical tools.

PubMed

Łojewska, J; Rabin, I; Pawcenis, D; Bagniuk, J; Aksamit-Koperska, M A; Sitarz, M; Missori, M; Krutzsch, M

2017-04-06

Ancient papyri are a written heritage of culture that flourished more than 3000 years ago in Egypt. One of the most significant collections in the world is housed in the Egyptian Museum and Papyrus Collection in Berlin, from where the samples for our investigation come. The papyrologists, curators and conservators of such collections search intensely for the analytical detail that would allow ancient papyri to be distinguished from modern fabrications, in order to detect possible forgeries, assess papyrus deterioration state, and improve the design of storage conditions and conservation methods. This has become the aim of our investigation. The samples were studied by a number of methods, including spectroscopic (FTIR, fluorescent-FS, Raman) diffractional (XRD) and chromatographic (size exclusion chromatography-SEC), selected in order to determine degradation parameters: overall oxidation of lignocellulosic material, degree of polymerization and crystallinity of cellulose. The results were correlated with those obtained from carefully selected model samples including modern papyri and paper of different composition aged at elevated temperature in humid air. The methods were classified in the order SEC > FS > FTIR > XRD, based on their effectiveness in discriminating the state of papyri degradation. However, the most trustworthy evaluation of the age of papyri samples should rely on several methods.

Structural changes in shock compressed silicon observed using time-resolved x-ray diffraction at the Dynamic Compression Sector

NASA Astrophysics Data System (ADS)

Turneaure, Stefan; Zdanowicz, E.; Sinclair, N.; Graber, T.; Gupta, Y. M.

2015-06-01

Structural changes in shock compressed silicon were observed directly using time-resolved x-ray diffraction (XRD) measurements at the Dynamic Compression Sector at the Advanced Photon Source. The silicon samples were impacted by polycarbonate impactors accelerated to velocities greater than 5 km/s using a two-stage light gas gun resulting in impact stresses of about 25 GPa. The 23.5 keV synchrotron x-ray beam passed through the polycarbonate impactor, the silicon sample, and an x-ray window (polycarbonate or LiF) at an angle of 30 degrees relative to the impact plane. Four XRD frames (~ 100 ps snapshots) were obtained with 153.4 ns between frames near the time of impact. The XRD measurements indicate that in the peak shocked state, the silicon samples completely transformed to a high-pressure phase. XRD results for both shocked polycrystalline silicon and single crystal silicon will be presented and compared. Work supported by DOE/NNSA.

Effect of intrinsic zinc oxide coating on the properties of Al-doped zinc oxide nanorod arrays

NASA Astrophysics Data System (ADS)

Saidi, S. A.; Mamat, M. H.; Ismail, A. S.; Malek, M. F.; Yusoff, M. M.; Sin, N. D. Md.; Zoolfakar, A. S.; Khusaimi, Z.; Rusop, M.

2018-05-01

The aim of this study was to explore the influence of intrinsic zinc oxide (ZnO) coating fabricated by a simple immersion method. X-ray powder diffraction (XRD) analysis indicated that the Al-doped ZnO nanorod arrays films had a hexagonal wurtzite structure, similar to that of an intrinsic ZnO coating. Structural properties of the samples were characterised using field emission scanning electron microscopy (FESEM; JEOL JSM-7600F) and optical properties using X-ray diffraction (XRD). The XRD results showed that all films were crystallized under hexagonal wurtzite structure and presented a preferential orientation along the c-axis (002) was obtained. The XRD results showed that the intrinsic ZnO coating material had a strong orientation, whereas the ZnO was randomly oriented. Overall these results indicate that intrinsic ZnO coating are pontetial for the creation of functional materials such as barrier protection, optoelectronic devices, humidity sensor and ultraviolet photoconductive sensor.

Characterization of nanocrystalline ZnO:Al films by sol-gel spin coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gareso, P. L., E-mail: pgareso@gmail.com; Rauf, N., E-mail: pgareso@gmail.com; Juarlin, E., E-mail: pgareso@gmail.com

2014-09-25

Nanocrystalline ZnO films doped with aluminium by sol-gel spin coating method have been investigated using optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. ZnO films were prepared using zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}@@‡2H{sub 2}O), ethanol, and diethanolamine (DEA) as a starting material, solvent, and stabilizer, respectively. For doped films, AlCl{sub 3} was added to the mixture. The ZnO:Al films were deposited on a transparent conductive oxide (TCO) substrate using spin coating technique at room temperature with a rate of 3000 rpm in 30 sec. The deposited films were annealed at various temperatures from 400°C to 600°C during 60 minutes.more » The transmittance UV-Vis measurement results showed that after annealing at 400°C, the energy band gap profile of nanocrystalline ZnO:Al film was a blue shift. This indicated that the band gap of ZnO:Al increased after annealing due to the increase of crystalline size. As the annealing temperature increased the bandgap energy was a constant. In addition to this, there was a small oscillation occurring after annealing compared to the as–grown samples. In the case of X-RD measurements, the crystalinity of the films were amorphous before annealing, and after annealing the crystalinity became enhance. Also, X-RD results showed that structure of nanocrystalline ZnO:Al films were hexagonal polycrystalline with lattice parameters are a = 3.290 Å and c = 5.2531 Å.« less

Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

PubMed

Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

2015-11-28

Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors.

Influence of incubation temperature on biofilm formation and corrosion of carbon steel by Serratia marcescens

NASA Astrophysics Data System (ADS)

Harimawan, Ardiyan; Devianto, Hary; Kurniawan, Ignatius Chandra; Utomo, Josephine Christine

2017-01-01

Microbial induced corrosion (MIC) or biocorrosion is one type of corrosion, directly or indirectly influenced by microbial activities, by forming biofilm and adhering on the metal surface. When forming biofilm, the microorganisms can produce extracellular products which influence the cathodic and anodic reactions on metal surfaces. This will result in electrochemical changes in the interface between the biofilm and the metal surface, leading to corrosion and deterioration of the metal. MIC might be caused by various types of microorganism which leads to different corrosion mechanism and reaction kinetics. Furthermore, this process will also be influenced by various environmental conditions, such as pH and temperature. This research is aimed to determine the effect of incubation temperature on corrosion of carbon steel caused by Serratia marcescens in a mixture solution of synthetic seawater with Luria Bertani medium with a ratio of 4:1. The incubation was performed for 19 days with incubation temperature of 30, 37, and 50°C. The analyses of biofilm were conducted by total plate count (TPC), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Biofilm was found to be evenly growth on the surface and increasing with increasing incubation temperature. It consists of functional group of alcohol, alkane, amine, nitro, sulfate, carboxylic acid, and polysulfide. The analyses of the corrosion were conducted by gravimetric and X-ray diffraction (XRD). Higher incubation temperature was found to increase the corrosion rate. However, the corrosion products were not detected by XRD analysis.

Temperature dependence of the crystalline quality of AlN layer grown on sapphire substrates by metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Li, Xiao-Hang; Wei, Yong O.; Wang, Shuo; Xie, Hongen; Kao, Tsung-Ting; Satter, Md. Mahbub; Shen, Shyh-Chiang; Douglas Yoder, P.; Detchprohm, Theeradetch; Dupuis, Russell D.; Fischer, Alec M.; Ponce, Fernando A.

2015-03-01

We studied temperature dependence of crystalline quality of AlN layers at 1050-1250 °C with a fine increment step of around 18 °C. The AlN layers were grown on c-plane sapphire substrates by metalorganic chemical vapor deposition (MOCVD) and characterized by X-ray diffraction (XRD) ω-scans and atomic force microscopy (AFM). At 1050-1068 °C, the templates exhibited poor quality with surface pits and higher XRD (002) and (102) full-width at half-maximum (FWHM) because of insufficient Al atom mobility. At 1086 °C, the surface became smooth suggesting sufficient Al atom mobility. Above 1086 °C, the (102) FWHM and thus edge dislocation density increased with temperatures which may be attributed to the shorter growth mode transition from three-dimension (3D) to two-dimension (2D). Above 1212 °C, surface macro-steps were formed due to the longer diffusion length of Al atoms than the expected step terrace width. The edge dislocation density increased rapidly above 1212 °C, indicating this temperature may be a threshold above which the impact of the transition from 3D to 2D is more significant. The (002) FWHM and thus screw dislocation density were insensitive to the temperature change. This study suggests that high-quality AlN/sapphire templates may be potentially achieved at temperatures as low as 1086 °C which is accessible by most of the III-nitride MOCVD systems.

Synthesis and characterization of hollow spherical copper phosphide (Cu 3P) nanopowders

NASA Astrophysics Data System (ADS)

Liu, Shuling; Qian, Yitai; Xu, Liqiang

2009-03-01

In this paper, hollow spherical Cu 3P nanopowders were synthesized by using copper sulfate pentahydrate (CuSO 4ṡ5H 2O) and yellow phosphorus in a mixed solvent of glycol, ethanol and water at 140-180 ∘C for 12 h. X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), electron diffraction pattern (ED) and transmission electronic microscopy (TEM) studies show that the as-synthesized nanocrystal is pure hexagonal phase Cu 3P with a hollow spherical morphology. Based on the TEM observations, a possible aggregation growth mechanism was proposed for the formation of Cu 3P hollow structures. Meanwhile, the effects of some key factors such as solvents, reaction temperature and reaction time on the final formation of the Cu 3P hollow structure were also discussed.

La-Sr-Ni-Co-O based perovskite-type solid solutions as catalyst precursors in the CO 2 reforming of methane

NASA Astrophysics Data System (ADS)

Valderrama, Gustavo; Kiennemann, Alain; Goldwasser, Mireya R.

La 1- xSr xNi 0.4Co 0.6O 3 and La 0.8Sr 0.2Ni 1- yCo yO 3 solid solutions with perovskite-type structure were synthesized by the sol-gel resin method and used as catalytic precursors in the dry reforming of methane with CO 2 to syngas, between 873 and 1073 K at atmospheric pressure under continuous flow of reactant gases with CH 4/CO 2 = 1 ratio. These quaternary oxides were characterized by X-ray diffraction (XRD), BET specific surface area and temperature-programmed reduction (TPR) techniques. XRD analyses of the more intense diffraction peaks and cell parameter measurements showed formation of La-Sr-Ni-Co-O solid solutions with La 0.9Sr 0.1CoO 3 and/or La 0.9Sr 0.1NiO 3 as the main crystallographic phases present on the solids depending on the degree of substitution. TPR analyses showed that Sr doping decreases the temperature of reduction via formation of intermediary species producing Ni 0, Co 0 with particle sizes in the range of nanometers over the SrO and La 2O 3 phases. These metallic nano particles highly dispersed in the solid matrix are responsible for the high activity shown during the reaction and avoid carbon formation. The presence of Sr in doping quantities also promotes the secondary reactions of carbon formation and water-gas shift in a very small extension during the dry reforming reaction.

Study of Crystallinity Index (CrI) of Oil Palm Frond Pretreatment using Aqueous [EMIM][OAc] in a Closed System

NASA Astrophysics Data System (ADS)

Abu Darim, R.; Azizan, A.; Salihon, J.

2018-05-01

The objective of this preliminary study is to identify the Crystalinity Index (CrI) of Oil Palm Frond (OPF) pretreated with 40% concentration of 1-ethyl-3-methylimidazolium acetate ionic liquid ([EMIM][OAc]) in a closed system. The morphology and structural changes of the pretreated OPF were examined by using Fourier Transform Infrared Spectrometer (FTIR) and X-Ray Diffraction (XRD). The pretreatment process was carried out in triplicates by loading 40% of [EMIM][OAc] concentration with 10 wt% of OPF loading in the Bio-ionic liquid-reactor. The pretreatment process was conducted for 3 hours with working volume of 70 mL and temperature of 110°C. A Bio-ionic liquid reactor was purposely designed for the lignocellulosic pretreatment by using aqueous ionic liquid at high temperature (higher than boiling point of water). The CrI of OPF pretreated with 40% concentration of [EMM][OAc] in a closed system observed was 9% lower from the untreated OPF and the result showed significant difference with 95% confidence level. Further examination of the untreated and pretreated OPF by using XRD showed that the diffraction pattern of the pretreated OPF samples was decreasing compared to the untreated OPF. The characteristic of the FTIR spectra of the pretreated OPF showed the presence of the cellulose I and occurrence of amorphous cellulosic in the samples. The findings from this study are expected to improve knowledge on pretreatment of OPF by using aqueous [EMIM][OAc] as a green economically viable process for future renewable energy.

YAlO3:Ce3+ powders: Synthesis, characterization, thermoluminescence and optical studies

NASA Astrophysics Data System (ADS)

Parganiha, Yogita; Kaur, Jagjeet; Dubey, Vikas; Shrivastava, Ravi

2015-09-01

Yttrium aluminum perovskite (YAP) is a promising high temperature ceramic material, known for its mechanical, structural and optical properties. YAP's also known as an ideal host material for solid-state lasers and phosphors. In this work, Ce3+ doped YAlO3 phosphors were synthesized by solid state reaction method, which is very suitable technique for large scale production. A prepared phosphor was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Photoluminescence spectra and Thermoluminescence (TL) glow curve study. The starting reagents used for sample preparation are Y2O3, Al2O3 and CeO2, boric acid used as a flux. Ratio of Y:Al was 1:1 which shows perovskite structure confirmed by the X-ray diffraction (XRD) study. The entire prepared sample was studied by PL excitation and emission spectra. Prominent peak at 446 nm (blue emission) which shows broad emission spectra of photoluminescence. It proves that prepared phosphor can act as a single host for blue emission of light and can be used for display applications. Commission Internationale de I'Eclairage (CIE) techniques proves the blue emission of light (x = .148, y = .117). TL glow curve analysis of prepared phosphor shows the prominent peak at 189 °C for the variable UV exposure time and high temperature peak shows the more stability and less fading in the prepared phosphor. Kinetic data of prepared phosphor were evaluated by peak shape method for variable UV exposure time (5-25 min).

Unified Theory for Decoding the Signals from X-Ray Florescence and X-Ray Diffraction of Mixtures.

PubMed

Chung, Frank H

2017-05-01

For research and development or for solving technical problems, we often need to know the chemical composition of an unknown mixture, which is coded and stored in the signals of its X-ray fluorescence (XRF) and X-ray diffraction (XRD). X-ray fluorescence gives chemical elements, whereas XRD gives chemical compounds. The major problem in XRF and XRD analyses is the complex matrix effect. The conventional technique to deal with the matrix effect is to construct empirical calibration lines with standards for each element or compound sought, which is tedious and time-consuming. A unified theory of quantitative XRF analysis is presented here. The idea is to cancel the matrix effect mathematically. It turns out that the decoding equation for quantitative XRF analysis is identical to that for quantitative XRD analysis although the physics of XRD and XRF are fundamentally different. The XRD work has been published and practiced worldwide. The unified theory derives a new intensity-concentration equation of XRF, which is free from the matrix effect and valid for a wide range of concentrations. The linear decoding equation establishes a constant slope for each element sought, hence eliminating the work on calibration lines. The simple linear decoding equation has been verified by 18 experiments.

Size-dependent magnetic anisotropy of PEG coated Fe3O4 nanoparticles; comparing two magnetization methods

NASA Astrophysics Data System (ADS)

Nayek, C.; Manna, K.; Imam, A. A.; Alqasrawi, A. Y.; Obaidat, I. M.

2018-02-01

Understanding the size dependent magnetic anisotropy of iron oxide nanoparticles is essential for the successful application of these nanoparticles in several technological and medical fields. PEG-coated iron oxide (Fe3O4) nanoparticles with core diameters of 12 nm, 15 nm, and 16 nm were synthesized by the usual co-precipitation method. The morphology and structure of the nanoparticles were investigated using transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD). Magnetic measurements were conducted using a SQUID. The effective magnetic anisotropy was calculated using two methods from the magnetization measurements. In the first method the zero-field-cooled magnetization versus temperature measurements were used at several applied magnetic fields. In the second method we used the temperature-dependent coercivity curves obtained from the zero-field-cooled magnetization versus magnetic field hysteresis loops. The role of the applied magnetic field on the effective magnetic anisotropy, calculated form the zero-field-cooled magnetization versus temperature measurements, was revealed. The size dependence of the effective magnetic anisotropy constant Keff obtained by the two methods are compared and discussed.

Synthesis and characterization of nanosized lithium manganate and its derivatives

NASA Astrophysics Data System (ADS)

Iqbal, Muhammad Javed; Zahoor, Sabia

Spinel lithium manganese oxide, LiMn 2O 4 and its derivatives are prepared by the sol-gel method. The lattice constant of the pure material is calculated as 8.23 Å. Different transition metal cations of chromium, iron, cobalt, nickel, copper and zinc (0.05 and 0.15 M) are doped in place of manganese in the LiMn 2O 4. X-ray powder diffraction data show that the spinel framework preserved its integrity upon doping. Formation of a single phase and the purity of the samples are confirmed by X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The crystallite size of the samples is calculated by use of the Scherrer formula and is found to be within a range of 43-66 nm. The electrical conductivity of the samples is determined over a temperature range of 200-300 K by means of four-point probe method. An increasing trend of conductivity with increase in temperature is noted for all the samples. The parent compound LiMn 2O 4 has a conductivity value of 3.47 × 10 -4 ohm -1 cm -1 at room temperature. This value increases on doping with the above-mentioned transition metal cations.

Investigations on Cu2+-substituted Ni-Zn ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Amarjeet; Kumar, Vinod

2016-11-01

CuxNi(1-x)/2Zn(1-x)/2Fe2O4 (x = 0.1, 0.3 and 0.5) nanoparticles were prepared by chemical co-precipitation method. The developed nanoparticles were characterized for structural properties by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Peak position in the X-ray diffraction pattern confirmed the single spinel phase of the developed particles. Infrared (IR) spectroscopy in mid-IR range showed the presence of characteristic absorption bands corresponding to octahedral and tetrahedral bonds in the spinel structure of prepared samples. Thermo-gravimetric analysis (TGA) measurements showed a considerable weight loss in the developed samples above 700∘C. Frequency dependence of the electrical properties of the developed material pellets was studied in the frequency range of 1 kHz-5 MHz. Temperature dependence of the dielectric constant of Cu0.1Ni0.45Zn0.45Fe2O4 was studied at different temperatures, i.e. at 425, 450 and 475 K, in the frequency range of 1 kHz-5 MHz. It was found that the electrical conductivity decreases with increasing Cu2+ ion content while it increases with the increase in temperature.

Microstructural development of a gas-atomized and hot-pressed super-α2 alloy

NASA Astrophysics Data System (ADS)

Xu, R.; Cui, Y. Y.; Xu, D. M.; Li, D.; Li, Q. C.; Hu, Z. Q.

1996-08-01

A variety of heat treatments have been employed to explore the microstructure in Ti-25Al-10Nb-3V-lMo alloy prepared by gas atomization and hot pressing. These treatments include quenching by oil cooling and water cooling and aging at temperatures between 530 °C and 950 °C. Quenching transformations from the β-phase field include the formation of O phase in oil quenching and β (disordered) + O phase in water quenching. The metastable β phase decomposes into O + “Ω”, O, or α2 + βo/B2 phase when the as-quenched alloy is aged at various temperatures. By comparing the selection area diffraction patterns, it has been found that the ordered w phase in the alloy studied in this article is distinct in structure to the “Ω type” ( P3m1) and B82 phase which are formed in the parent matrix of the ordered β(B2,D03) phases. It has also been shown by X-ray diffraction (XRD) analyses that the lattice parameters of the as-aged O phase do not remain constant in the alloy at various temperatures.

Structure and Dynamics Investigations of Sr/Ca-Doped LaPO 4 Proton Conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

al-Wahish, Amal; al-Binni, U.; Tetard, L.

Proton conductors loom out of the pool of candidate materials with great potential to boost hydrogen alternatives to fossil-based resources for energy. Acceptor doped lanthanum orthophosphates are considered for solid oxide fuel cells (SOFCs) for their potential stability and conductivity at high temperature. By exploring the crystal and defect structure of x% Sr/Ca-doped LaPO 4 with different nominal Sr/Ca concentrations (x = 0 – 10) with Neutron powder diffraction (NPD) and X-ray powder diffraction (XRD), we confirm that Sr/Ca-doped LaPO 4 can exist as self-supported structures at high temperatures during solid oxide fuel cell operation. Thermal stability, surface topography, sizemore » distribution are also studied to better understand the proton conductivity for dry and wet compounds obtained at sintering temperatures ranging from 1200 to 1400 °C using a combination of scanning electron microscopy (SEM), Atomic Force Microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS). In conclusion, the results suggest that Sr doped samples exhibit the highest proton conductivity of our samples and illustrate the impact of material design and versatile characterization schemes on the development of proton conductors with superior functionality.« less

Simple X-ray diffraction algorithm for direct determination of cotton crystallinity

USDA-ARS?s Scientific Manuscript database

Traditionally, XRD had been used to study the crystalline structure of cotton celluloses. Despite considerable efforts in developing the curve-fitting protocol to evaluate the crystallinity index (CI), in its present state, XRD measurement can only provide a qualitative or semi-quantitative assessme...

Structural and physical property study of sol-gel synthesized CoFe2-xHoxO4 nano ferrites

NASA Astrophysics Data System (ADS)

Patankar, K. K.; Ghone, D. M.; Mathe, V. L.; Kaushik, S. D.

2018-05-01

CoFe2-xHoxO4 (x = 0.00, 0.05, 0.10, 0.15, 0.20) ferrites were prepared by the suitably modified Sol-Gel technique. X-ray diffraction (XRD) analysis revealed that the substituted samples show phase pure formation till 10% substitution, which is far higher phase pure than the earlier reports. Upon further substitution an inevitable secondary phase of HoFeO3 along with the spinel phase despite regulating synthesis parameters in the sol-gel reaction route. These results are further corroborated more convincingly by room temperature neutron diffraction. Morphological features of the ferrites were studied by Scanning Electron Microscopy (SEM). The magnetic parameters viz. the saturation magnetization (Ms), coercivity (Hc) and remanence (Mr) were determined from room temperature isothermal magnetization. These parameters were found to decrease with increase in Ho substitution. The decrease in magnetization is analyzed in the light of exchange interactions between rare earth and transition metal ions. Magnetostriction measurements revealed interesting results and the presence of a secondary phase was found to be responsible for decreased measu-red magnetostriction values. The solubility limit of Ho in CoFe2O4 lattice is also reflected from the X-ray and neutron diffraction analysis and magnetostriction studies.

A Practical Guide for the Preparation of Specimens for X-ray Fluorescence and X-ray Diffraction Analysis (by V. E. Buhrke, R. Jenkins, and D. K. Smith)

NASA Astrophysics Data System (ADS)

Rudman, Reuben

1999-06-01

Wiley-VCH: New York, 1998. xxiv + 333 pp. ISBN 0-471-19458-1. $79.95. I would have subtitled this book "All You Ever Wanted To Know about ...Sample Preparation". Although its principal thrust is geared towards the analytical chemist in an X-ray diffraction (XRD) or X-ray fluorescence (XRF) service laboratory, this text will be of use primarily as a reference source in all milieus dealing with undergraduate research projects and advanced laboratory courses in physical and analytical chemistry. It contains dozens of suggestions for preparing randomly oriented small samples of nearly anything. For example, rocks and minerals, soft organics and hard ceramics, radioactive and liquid materials, metals and oils are all treated. As the availability of XRD and XRF equipment has increased, so has the use of these techniques in the teaching schedule. Many undergraduate laboratory and research projects utilizing these methods have been described in the literature and are found in laboratory textbooks. Very often, especially with the increasingly common use of automated computer-controlled instrumentation, sample preparation has become the key experimental technique required for successful data collection. However, it is not always easy to prepare the statistically random distribution of small particles (crystallites) that is required by these methods. A multitude of techniques have been developed over the past 70 years, but many of them have been handed down by word of mouth or are scattered throughout the literature. This book represents an attempt to systematically describe the theory and practice of sample preparation. This excellent guide to the intricacies of sample preparation begins with a description of statistical sampling methods and the principles of grinding techniques. After a discussion of XRF specimen preparation, which includes pressing pellets, fusion methods, crucible selection and handling very small samples, detailed descriptions for handling rocks, minerals, cements, metals, oils, and vegetation [sic] are given. The preparation of XRD samples is described for various diffraction equipment geometries (utilizing both counter and film detectors), including specific information regarding the use of flat specimens and slurries, the use of internal standards, and the effects of crystallite size on the diffraction pattern. Methods for handling ceramics, clays, zeolites, air-sensitive samples, thin films, and plastics are described, along with the special handling requirements for materials to be studied by high-pressure, high-temperature, or low-temperature techniques. One whole chapter is devoted to the equipment used in specimen preparation, including grinders, pulverizers, presses, specimen holders, repair of platinumware, and sources of all types of special equipment. Did you ever want to know where to get a Plattner steel mortar or a micronizing mill or soft-glass capillary tubes with 0.01-mm wall thickness? It's all here in this monograph. The book ends with a good glossary of terms, a general bibliography in addition to the extensive list of references following each of its 9 chapters, and an index. It will be of help in many areas of spectroscopy and analytical chemistry, as well as in XRD and XRF analyses.

Thermal analysis of calcium sulfate dihydrate sources used to manufacture gypsum wallboard

DOE PAGES

Engbrecht, Dick C.; Hirschfeld, Deidre A.

2016-07-27

Gypsum wallboard has been used for over 100 years as a barrier to the spread of fire in residential and commercial structures. The gypsum molecule, CaSO 4·2H 2O, provides two crystalline waters that are released upon heating providing an endothermic effect. Manufacturers have recognized that the source of the gypsum ore is a factor that affects all aspects of its performance; thus, it is hypothesized that the impurities present in the gypsum ore are the causes of the performance differences. Differential Thermal Analysis/Thermogravimetric Analysis (DTA/TGA) and X-ray Diffraction (XRD) were used in this paper to compare and characterize samples ofmore » gypsum ore representing sources of natural, synthetic from a Flue Gas Desulfurization process (FGD) and blends thereof. The hemihydrate phase of representative natural, FGD, and reagent grade calcium sulfate were rehydrated with distilled water and evaluated by DTA/TGA. Analysis of the data shows distinct areas of similarity separated by the conversion to anhydrite ~250 °C. Compositional reconstructions based on DTA/TGA and XRD data were compared and although, the results were comparable, the DTA/TGA suggests thermally active compounds that were not detected by XRD. Anhydrite, silica and halite were reported by XRD but were not thermally reactive in the temperature range evaluated by DTA/TGA (ambient to 1050 °C). Finally, the presence of carbonate compounds (e.g., calcite and dolomite) were indicated by XRD and estimated from the thermal decomposition reaction ~700 °C.« less

Magnetoresistance behavior in nanobulk assembled Bi2Se3 topological insulator

NASA Astrophysics Data System (ADS)

Bera, Sumit; Behera, P.; Mishra, A. K.; Krishnan, M.; Patidar, Manju Mishra; Singh, Durgesh; Venkatesh, R.; Phase, D. M.; Ganesan, V.

2018-05-01

Temperature and magnetic field dependent magnetoresistance (MR) including structural, morphological studies of Bi2Se3 nanoflower like structure synthesized by microwave assisted solvothermal method has been investigated. Powder X-ray diffraction (XRD) has confirmed the formation of single phase. Morphology of the material shows nanoflower kind of structures with edge to edge size of around 4 µm and such occurrences are quite high. The temperature dependent resistance invokes a metallic behavior up to a certain lower temperature, below which it follows -ln(T) behavior that has been elucidated in literature using electron-electron interaction and weak anti-localization effects. High temperature magnetoresistance is consistent with parabolic field dependence indicating a classical magnetoresistance in metals as a result of Lorenz force. In low temperature regime magnetoresistance as a function of magnetic field at different temperatures obeys power law near low field which indicates a three dimensional weak-antilocalization. A linear magnetoresistance at low temperature and high magnetic field shows the domination of surface state conduction.

Characterization of Low Firing Temperature Ceramic Glaze Using Phuket MSW and Soda Lime Cullet

NASA Astrophysics Data System (ADS)

Ketboonruang, P.; Jinawat, S.; Kashima, D. P.; Wasanapiarnpong, T.; Sujaridworakun, P.; Buggakuptav, W.; Traipol, N.; Jiemsirilers, S.

2011-10-01

The normal firing temperature of ceramic products is around 1200 °C. In order to reduce firing temperature, industrial wastes were utilized in ceramic glaze. Phuket municipal solid waste (MSW), soda lime cullet, and borax were used as raw materials for low firing temperature glazes. The glaze compositions were designed using a triaxial diagram. Stoneware ceramic body was glazed then fired at 1000 and 1150 °C for 15 minutes. Morphology and phase composition of glazes were analyzed by Scanning electron microscopy (SEM-EDS) and X-ray diffraction (XRD). Thermal expansion compatibility of Stoneware body and glazes were investigated using a dilatometer. Melting behaviour of selected glaze was analyzed by heating stage microscopy. Phuket MSW and Soda lime glass cullet can be used in high percentage as major raw materials for low firing temperature ceramic glaze that show good texture and vitrified at lower firing temperature without using any commercial ceramic frits. The firing temperature can be reduced up to 150 °C in this study.

PyXRD v0.6.7: a free and open-source program to quantify disordered phyllosilicates using multi-specimen X-ray diffraction profile fitting

NASA Astrophysics Data System (ADS)

Dumon, M.; Van Ranst, E.

2016-01-01

This paper presents a free and open-source program called PyXRD (short for Python X-ray diffraction) to improve the quantification of complex, poly-phasic mixed-layer phyllosilicate assemblages. The validity of the program was checked by comparing its output with Sybilla v2.2.2, which shares the same mathematical formalism. The novelty of this program is the ab initio incorporation of the multi-specimen method, making it possible to share phases and (a selection of) their parameters across multiple specimens. PyXRD thus allows for modelling multiple specimens side by side, and this approach speeds up the manual refinement process significantly. To check the hypothesis that this multi-specimen set-up - as it effectively reduces the number of parameters and increases the number of observations - can also improve automatic parameter refinements, we calculated X-ray diffraction patterns for four theoretical mineral assemblages. These patterns were then used as input for one refinement employing the multi-specimen set-up and one employing the single-pattern set-ups. For all of the assemblages, PyXRD was able to reproduce or approximate the input parameters with the multi-specimen approach. Diverging solutions only occurred in single-pattern set-ups, which do not contain enough information to discern all minerals present (e.g. patterns of heated samples). Assuming a correct qualitative interpretation was made and a single pattern exists in which all phases are sufficiently discernible, the obtained results indicate a good quantification can often be obtained with just that pattern. However, these results from theoretical experiments cannot automatically be extrapolated to all real-life experiments. In any case, PyXRD has proven to be useful when X-ray diffraction patterns are modelled for complex mineral assemblages containing mixed-layer phyllosilicates with a multi-specimen approach.

Investigation of irradiation effects induced by self-ion in 6H-SiC combining RBS/C, Raman and XRD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chaabane, Nihed; Debelle, Aurelien; Sattonnay, Gael

2012-01-01

Single crystals of 6H-SiC were irradiated at room temperature and 670 K with 4 MeV C ions at two fluences: 1015 and 1016 cm2 (0.16 and 1.6 dpa at the damage peak). Damage accumulation was studied by a combination of X-ray diffraction (XRD), Raman spectroscopy and Rutherford backscattering spectrometry in channelling geometry (RBS/C) along the [0001] direction. The irradiated layer is found to be composed of a low damage region up to 1.5 lm followed by a region where the disorder level is higher, consistent with SRIM predictions. At room temperature and low fluence, typically 1015 cm2, the strain depthmore » profile follows the dpa depth distribution (with a maximum value of 2%). The disorder is most likely due to small defect clusters. When increasing the fluence up to 1016 cm2, a buried amorphous layer forms, as indicated by e.g. Raman results where the Si C bands become broader or even disappear. At a higher irradiation temperature of 670 K, amorphization is not observed at the same fluence, revealing a dynamic annealing process. However, results tend to suggest that the irradiated layer is highly heterogeneous and composed of different types of defects.« less

The effects of pore structure on the behavior of water in lignite coal and activated carbon.

PubMed

Nwaka, Daniel; Tahmasebi, Arash; Tian, Lu; Yu, Jianglong

2016-09-01

The effects of physical structure (pore structure) on behavior of water in lignite coal and activated carbon (AC) samples were investigated by using Differential Scanning Calorimetry (DSC) and low-temperature X-ray diffraction (XRD) techniques. AC samples with different pore structures were prepared at 800°C in steam and the results were compared with that of parent lignite coal. The DSC results confirmed the presence of two types of freezable water that freeze at -8°C (free water) and -42°C (freezable bound water). A shift in peak position of free water (FW) towards lower temperature was observed in AC samples compared to the lignite coal with decreasing water loading. The amount of free water (FW) increased with increasing gasification conversion. The amounts of free and freezable bound water (FBW) in AC samples were calculated and correlated to pore volume and average pore size. The amount of FW in AC samples is well correlated to the pore volume and average pore size of the samples, while an opposite trend was observed for FBW. The low-temperature XRD analysis confirmed the existence of non-freezable water (NFW) in coal and AC with the boundary between the freezable and non-freezable water (NFW) determined. Copyright © 2016 Elsevier Inc. All rights reserved.

Insight into the Am-O Phase Equilibria: A Thermodynamic Study Coupling High-Temperature XRD and CALPHAD Modeling.

PubMed

Epifano, Enrica; Guéneau, Christine; Belin, Renaud C; Vauchy, Romain; Lebreton, Florent; Richaud, Jean-Christophe; Joly, Alexis; Valot, Christophe; Martin, Philippe M

2017-07-03

In the frame of minor actinide transmutation, americium can be diluted in UO 2 and (U, Pu)O 2 fuels burned in fast neutron reactors. The first mandatory step to foresee the influence of Am on the in-reactor behavior of transmutation targets or fuel is to have fundamental knowledge of the Am-O binary system and, in particular, of the AmO 2-x phase. In this study, we coupled HT-XRD (high-temperature X-ray diffraction) experiments with CALPHAD thermodynamic modeling to provide new insights into the structural properties and phase equilibria in the AmO 2-x -AmO 1.61+x -Am 2 O 3 domain. Because of this approach, we were able for the first time to assess the relationships between temperature, lattice parameter, and hypostoichiometry for fcc AmO 2-x . We showed the presence of a hyperstoichiometric existence domain for the bcc AmO 1.61+x phase and the absence of a miscibility gap in the fcc AmO 2-x phase, contrary to previous representations of the phase diagram. Finally, with the new experimental data, a new CALPHAD thermodynamic model of the Am-O system was developed, and an improved version of the phase diagram is presented.

Gas sensing behaviour of Cr{sub 2}O{sub 3} and W{sup 6+}: Cr{sub 2}O{sub 3} nanoparticles towards acetone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohli, Nipin, E-mail: nipinkohli82@yahoo.com; Hastir, Anita; Singh, Ravi Chand

2016-05-23

This paper reports the acetone gas sensing properties of Cr{sub 2}O{sub 3} and 2% W{sup 6+} doped Cr{sub 2}O{sub 3} nanoparticles. The simple cost-effective hydrolysis assisted co-precipitation method was adopted. Synthesized samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. XRD revealed that synthesized nanoparticles have corundum structure. The lattice parameters have been calculated by Rietveld refinement; and strain and crystallite size have been calculated by using the Williamson-Hall plots. For acetone gas sensing properties, the nanoparticles were applied as thick film onto alumina substrate and tested at different operating temperatures. The results showedmore » that the optimum operating temperature of both the gas sensors is 250°C. At optimum operating temperature, the response of Cr{sub 2}O{sub 3} and 2% W{sup 6+} doped Cr{sub 2}O{sub 3} gas sensor towards 100 ppm acetone was found to be 25.5 and 35.6 respectively. The investigations revealed that the addition of W{sup 6+} as a dopant enhanced the sensing response of Cr{sub 2}O{sub 3} nanoparticles appreciably.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Pei; Fang, Z. Zak; Koopman, Mark

Hydrogen has been investigated for decades as a temporary alloying element to refine the microstructure of Ti-6Al-4V, and is now being used in a novel powder metallurgy method known as "hydrogen sintering and phase transformation". Pseudo-binary phase diagrams of (Ti-6Al-4V)-xH have been studied and developed, but are not well established due to methodological limitations. In this paper, in situ studies of phase transformations during hydrogenation and dehydrogenation of (Ti-6Al-4V)-xH alloys were conducted using high-energy synchrotron X-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The eutectoid phase transformation of β ↔ α + δ was observed in themore » (Ti-6Al-4V)-xH alloy via in situ synchrotron XRD at 211 °C with a hydrogen concentration of 37.5 at.% (measured using TGA-DSC). The relationships of hydrogen composition to partial pressure and temperature were investigated in the temperature range 450-900°C. Based on these results, a partial pseudo-binary phase diagram of (Ti-6Al-4V)-xH is proposed for hydrogen compositions up to 60 at.% in the temperature range 100-900°C. Using the data collected in real time under controlled parameters of temperature, composition and hydrogen partial pressure, this work characterizes relevant phase transformations and microstructural evolution for practical titanium-hydrogen technologies of Ti-6Al-4V.« less

Point defects in Cu 2ZnSnSe 4(CZTSe): Resonant X-ray diffraction study of the low-temperature order/disorder transition

DOE PAGES

Schelhas, L. T.; Stone, K. H.; Harvey, S. P.; ...

2017-07-25

We report that the interest in Cu 2ZnSn(S,Se) 4 (CZTS) for photovoltaic applications is motivated by similarities to Cu(In,Ga)Se 2 while being comprised of non-toxic and earth abundant elements. However, CZTS suffers from a V oc deficit, where the V oc is much lower than expected based on the band gap, which may be the result of a high concentration of point-defects in the CZTS lattice. Recently, reports have observed a low-temperature order/disorder transition by Raman and optical spectroscopies in CZTS films and is reported to describe the ordering of Cu and Zn atoms in the CZTS crystal structure. Tomore » directly determine the level of Cu/Zn ordering, we have used resonant-XRD, a site, and element specific probe of long range order. We used CZTSe films annealed just below and quenched from just above the transition temperature; based on previous work, the Cu and Zn should be ordered and highly disordered, respectively. Our data show that there is some Cu/Zn ordering near the low temperature transition but significantly less than high chemical order expected from Raman. Finally, to understand both our resonant-XRD results and the Raman results, we present a structural model that involves antiphase domain boundaries and accommodates the excess Zn within the CZTS lattice.« less

Role of Oxides and Porosity on High-Temperature Oxidation of Liquid-Fueled HVOF Thermal-Sprayed Ni50Cr Coatings

NASA Astrophysics Data System (ADS)

Song, B.; Bai, M.; Voisey, K. T.; Hussain, T.

2017-02-01

High chromium content in Ni50Cr thermally sprayed coatings can generate a dense and protective scale at the surface of coating. Thus, the Ni50Cr coating is widely used in high-temperature oxidation and corrosion applications. A commercially available gas atomized Ni50Cr powder was sprayed onto a power plant steel (ASME P92) using a liquid-fueled high velocity oxy-fuel thermal spray with three processing parameters in this study. Microstructure of as-sprayed coatings was examined using oxygen content analysis, mercury intrusion porosimetry, scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). Short-term air oxidation tests (4 h) of freestanding coatings (without boiler steel substrate) in a thermogravimetric analyzer at 700 °C were performed to obtain the kinetics of oxidation of the as-sprayed coating. Long-term air oxidation tests (100 h) of the coated substrates were performed at same temperature to obtain the oxidation products for further characterization in detail using SEM/EDX and XRD. In all samples, oxides of various morphologies developed on top of the Ni50Cr coatings. Cr2O3 was the main oxidation product on the surface of all three coatings. The coating with medium porosity and medium oxygen content has the best high-temperature oxidation performance in this study.

Ion beam modification of structural and optical properties of GeO2 thin films deposited at various substrate temperatures using pulsed laser deposition

NASA Astrophysics Data System (ADS)

Rathore, Mahendra Singh; Vinod, Arun; Angalakurthi, Rambabu; Pathak, A. P.; Singh, Fouran; Thatikonda, Santhosh Kumar; Nelamarri, Srinivasa Rao

2017-11-01

High energy heavy ion irradiation-induced modification of high quality crystalline GeO2 thin films grown at different substrate temperatures ranging from 100 to 500 °C using pulsed laser deposition has been investigated. The pristine films were irradiated with 100 MeV Ag7+ ions at fixed fluence of 1 × 1013 ions/cm2. These pristine and irradiated films have been characterized using X-ray diffraction, atomic force microscopy, Raman spectroscopy, Fourier transform infrared and photoluminescence spectroscopy. The XRD and Raman results of pristine films confirm the formation of hexagonal structure of GeO2 films, whereas the irradiation eliminates all the peaks except major GeO2 peak of (101) plane. It is evident from the XRD results that crystallite size changes with substrate temperature and SHI irradiation. The surface morphology of films was studied by AFM. The functional group of pristine and irradiated films was investigated by IR transmission spectra. Pristine films exhibited strong photoluminescence around 342 and 470 nm due to oxygen defects and a red shift in the PL bands is observed after irradiation. Possible mechanism of tuning structural and optical properties of pristine as well as irradiated GeO2 films with substrate temperature and ion beam irradiation has been reported in detail.

Synthesis of Carbon Nanotubes and Nanospheres from Coconut Fibre and the Role of Synthesis Temperature on Their Growth

NASA Astrophysics Data System (ADS)

Adewumi, Gloria A.; Inambao, Freddie; Eloka-Eboka, Andrew; Revaprasadu, Neerish

2018-07-01

Carbon nanotubes (CNT) and carbon nanospheres were successfully synthesized from coconut fibre-activated carbon. The biomass was first carbonized then physically activated, followed by treatment using ethanol vapor at 700°C to 1100°C at 100°C intervals. The effect of synthesis temperature on the formation of the nanomaterials was studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectrometry, x-ray diffraction (XRD), Fourier transform infrared microscopy (FTIR) and thermogravimetric analysis. SEM analysis revealed that nanospheres were formed at higher temperatures of 1000°C and 1100°C, while lower temperatures of 800°C and 900°C favored the growth of CNT. At 700°C, however, no tubes or spheres were formed. TEM and FTIR were used to observe spectral features, such as the peak positions, intensity and bandwidth, which are linked to some structural properties of the samples investigated. All these observations provided facts on the nanosphere and nanotube dimensions, vibrational modes and the degree of purity of the obtained samples. The TEM results show spheres of diameter in the range 50 nm to 250 nm while the tubes had diameters between 50 nm to 100 nm. XRD analysis reveals the materials synthesized are amorphous in nature with a hexagonal graphite structure.

Synthesis of Carbon Nanotubes and Nanospheres from Coconut Fibre and the Role of Synthesis Temperature on Their Growth

NASA Astrophysics Data System (ADS)

Adewumi, Gloria A.; Inambao, Freddie; Eloka-Eboka, Andrew; Revaprasadu, Neerish

2018-04-01

Carbon nanotubes (CNT) and carbon nanospheres were successfully synthesized from coconut fibre-activated carbon. The biomass was first carbonized then physically activated, followed by treatment using ethanol vapor at 700°C to 1100°C at 100°C intervals. The effect of synthesis temperature on the formation of the nanomaterials was studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive x-ray spectrometry, x-ray diffraction (XRD), Fourier transform infrared microscopy (FTIR) and thermogravimetric analysis. SEM analysis revealed that nanospheres were formed at higher temperatures of 1000°C and 1100°C, while lower temperatures of 800°C and 900°C favored the growth of CNT. At 700°C, however, no tubes or spheres were formed. TEM and FTIR were used to observe spectral features, such as the peak positions, intensity and bandwidth, which are linked to some structural properties of the samples investigated. All these observations provided facts on the nanosphere and nanotube dimensions, vibrational modes and the degree of purity of the obtained samples. The TEM results show spheres of diameter in the range 50 nm to 250 nm while the tubes had diameters between 50 nm to 100 nm. XRD analysis reveals the materials synthesized are amorphous in nature with a hexagonal graphite structure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pawar, C. S., E-mail: charudutta-p@yahoo.com; Gujar, M. P.; Mathe, V. L.

Nano crystalline Nickel Zinc ferrite (Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4}) thin films were synthesized by Sol Gel method for gas response. The phase and microstructure of the obtained Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The nanostructured Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film shows single spinel phase. Magnetic study was obtained with the help of VSM. The effects of working temperature on the gas response were studied. The results reveal that the Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film gas sensor shows good selectivity to chlorine gas at roommore » temperature. The sensor shows highest sensitivity (∼50%) at room temperature, indicating its application in detecting chlorine gas at room temperature in the future.« less

Effect of annealing temperature on optical and electrical properties of ZrO2-SnO2 based nanocomposite thin films

NASA Astrophysics Data System (ADS)

Anitha, V. S.; Lekshmy, S. Sujatha; Berlin, I. John; Joy, K.

2014-01-01

Transparent nanocomposite ZrO2-SnO2 thin films were prepared by sol-gel dip-coating technique. Films were annealed at 500°C, 800°C and 1200°C respectively. X-ray diffraction(XRD) spectra showed a mixture of three phases: tetragonal ZrO2 and SnO2 and orthorhombic ZrSnO4. The grain size of all the three phases' increased with annealing temperature. An average transmittance greater than 85%(in UV-Visible region) is observed for all the films. The band gap for the films decreased from 4.79 eV to 4.62 eV with increase in annealing temperature from 500 to 1200 °C. The electrical resistivity increased with increase in annealing temperature. Such composite ZrO2-SnO2 films can be used in many applications and in optoelectronic devices.

The influence of sintering temperature on microstructure and mechanical properties of Ni-Al intermetallics fabricated by SPS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thömmes, A., E-mail: thoemmes.alexander@gmail.com; Shevtsova, L. I., E-mail: edeliya2010@mail.ru; Laptev, I. S., E-mail: ilya-laptev-nstu@mail.ru

2015-10-27

In the present study PN85Yu15 was used as elemental powder to produce a sintered compound with Ni3Al as main phase. The Spark Plasma Sintering (SPS) technique is used to compact the powders. The powder was sintered in a temperature range between 1000°C and 1150°C to observe the influence of the sintering temperature on the microstructure and the mechanical properties. The microstructure was observed with optical microscope (OM), the phase composition was characterized by X-ray diffraction (XRD) technique. Density and microhardness were observed and compared the values with the results of other researchers. The compressive-, density- and microhardness tests show asmore » clear result that with increasing the sintering temperature nearly all properties become better and also the microstructure studies show that porous places become less.« less

Low temperature growth of ZnO nanorods array via solution-immersion on TiO2 seed layer

NASA Astrophysics Data System (ADS)

Asib, N. A. M.; Aadila, A.; Afaah, A. N.; Rusop, M.; Khusaimi, Z.

2018-05-01

In this work, TiO2:ZNR thin films were successfully fabricated on glass substrates at low temperatures of 75 to 90°C. The substrates were coated with titanium dioxide (TiO2) using sol-gel spin coating, which act as seed layer to grow zinc oxide nanorods (ZNR) by solution-immersion method. At 90 and 95° C, ZNR with hexagonal tip are well dispersed without any aggregation and exhibit more uniform nanorods array as observed using FESEM. The diffraction peak intensity of the (0 0 2)-plane increased as the temperature increased, indicating improved orientation in the c-axis direction of the ZNR as detected in XRD patterns. From UV-Vis absorbance spectra, it was found that the samples has higher absorption properties at middle range of immersion temperatures; 80, 85 and 90°C.

Sintering and microstructure of silicon carbide ceramic with Y3Al5O12 added by sol-gel method*

PubMed Central

Guo, Xing-zhong; Yang, Hui

2005-01-01

Silicon carbide (SiC) ceramic with YAG (Y3Al5O12) additive added by sol-gel method was liquid-phase sintered at different sintering temperatures, and the sintering mechanism and microstructural characteristics of resulting silicon carbide ceramics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and elemental distribution of surface (EDS). YAG (yttrium aluminum garnet) phase formed before the sintering and its uniform distribution in the SiC/YAG composite powder decreased the sintering temperature and improved the densification of SiC ceramic. The suitable sintering temperature was 1860 °C with the specimen sintered at this temperature having superior sintering and mechanical properties, smaller crystal size and fewer microstructure defects. Three characteristics of improved toughness of SiC ceramic with YAG added by sol-gel method were microstructural densification, main-crack deflection and crystal ‘bridging’. PMID:15682507

Elevated transition temperature in Ge doped VO2 thin films

NASA Astrophysics Data System (ADS)

Krammer, Anna; Magrez, Arnaud; Vitale, Wolfgang A.; Mocny, Piotr; Jeanneret, Patrick; Guibert, Edouard; Whitlow, Harry J.; Ionescu, Adrian M.; Schüler, Andreas

2017-07-01

Thermochromic GexV1-xO2+y thin films have been deposited on Si (100) substrates by means of reactive magnetron sputtering. The films were then characterized by Rutherford backscattering spectrometry (RBS), four-point probe electrical resistivity measurements, X-ray diffraction, and atomic force microscopy. From the temperature dependent resistivity measurements, the effect of Ge doping on the semiconductor-to-metal phase transition in vanadium oxide thin films was investigated. The transition temperature was shown to increase significantly upon Ge doping (˜95 °C), while the hysteresis width and resistivity contrast gradually decreased. The precise Ge concentration and the film thickness have been determined by RBS. The crystallinity of phase-pure VO2 monoclinic films was confirmed by XRD. These findings make the use of vanadium dioxide thin films in solar and electronic device applications—where higher critical temperatures than 68 °C of pristine VO2 are needed—a viable and promising solution.

Characterization of LaF 3 coatings prepared at different temperatures and rates

NASA Astrophysics Data System (ADS)

Yu, Hua; Shen, Yanming; Cui, Yun; Qi, Hongji; Shao, JianDa; Fan, ZhengXiu

2008-01-01

LaF 3 thin films were prepared by thermal boat evaporation at different substrate temperatures and various deposition rates. X-ray diffraction (XRD), Lambda 900 spectrophotometer and X-ray photoelectron spectroscopy (XPS) were employed to study crystal structure, transmittance and chemical composition of the coatings, respectively. Laser-induce damage threshold (LIDT) was determined by a tripled Nd:YAG laser system with a pulse width of 8 ns. It is found that the crystal structure became more perfect and the refractive index increased gradually with the temperature rising. The LIDT was comparatively high at high temperature. In the other hand, the crystallization status also became better and the refractive index increased when the deposition rate enhanced at a low level. If the rate was super rapid, the crystallization worsened instead and the refractive index would lessen greatly. On the whole, the LIDT decreased with increasing rate.

Study of the glassy magnetic behaviour and charge-ordering phase transitions in La0.75Ca0.25FeO3-δ perovskite

NASA Astrophysics Data System (ADS)

Abdel-Khalek, E. K.; Mohamed, E. A.; Salem, A. F.

2017-06-01

In this work, La0.75Ca0.25FeO3-δ perovskite sample was prepared by the coprecipitation method. The nanoparticle was found to crystallize in the orthorhombic (Pbnm) phase as confirmed by X-ray diffraction (XRD) and transmission electron microscopic (TEM). The oxygen non-stoichiometry (δ) and magnetic states of iron ions (three magnetic sextets and non-magnetic doublet) were investigated by Mössbauer spectroscopy at room temperature (RT). The shape of the magnetic hysteresis loop of the sample reveals the existence of a weak ferromagnetism at RT. The magnetization vs. temperature curves, measured in the 9 to 200 K range, showed that the sample exhibits two magnetic-phase transition temperatures at 29 K (Tg) and 120 K (TCO). The magnetization isotherms, M (H), around these magnetic-phase transition temperatures for the sample are analyzed.

Measurement of fundamental illite particle thicknesses by X-ray diffraction using PVP-10 intercalation

USGS Publications Warehouse

Eberl, D.D.; Nüesch, R.; Šucha, Vladimír; Tsipursky, S.

1998-01-01

The thicknesses of fundamental illite particles that compose mixed-layer illite-smectite (I-S) crystals can be measured by X-ray diffraction (XRD) peak broadening techniques (Bertaut-Warren-Averbach [BWA] method and integral peak-width method) if the effects of swelling and XRD background noise are eliminated from XRD patterns of the clays. Swelling is eliminated by intercalating Na-saturated I-S with polyvinylpyrrolidone having a molecular weight of 10,000 (PVP-10). Background is minimized by using polished metallic silicon wafers cut perpendicular to (100) as a substrate for XRD specimens, and by using a single-crystal monochromator. XRD measurements of PVP-intercalated diagenetic, hydrothermal and low-grade metamorphic I-S indicate that there are at least 2 types of crystallite thickness distribution shapes for illite fundamental particles, lognormal and asymptotic; that measurements of mean fundamental illite particle thicknesses made by various techniques (Bertant-Warren-Averbach, integral peak width, fixed cation content, and transmission electron microscopy [TEM]) give comparable results; and that strain (small differences in layer thicknesses) generally has a Gaussian distribution in the log-normal-type illites, but is often absent in the asymptotic-type illites.

Application of graphene oxide-poly (vinyl alcohol) polymer nanocomposite for memory devices

NASA Astrophysics Data System (ADS)

Kaushal, Jyoti; Kaur, Ravneet; Sharma, Jadab; Tripathi, S. K.

2018-05-01

Significant attention has been gained by polymer nanocomposites because of their possible demands in future electronic memory devices. In the present work, device based on Graphene Oxide (GO) and polyvinyl alcohol (PVA) has been made and examined for the memory device application. The prepared Graphene oxide (GO) and GO-PVA nanocomposite (NC) has been characterized by X-ray Diffraction (XRD). GO nanosheets show the diffraction peak at 2θ = 11.60° and the interlayer spacing of 0.761 nm. The XRD of GO-PVA NC shows the diffraction peak at 2θ =18.56°. The fabricated device shows bipolar switching behavior having ON/OFF current ratio ˜102. The Write-Read-Erase-Read (WRER) cycles test shows that the Al/GO-PVA/Ag device has good stability and repeatability.

Impact of physical and chemical parameters on the hydroxyapatite nanopowder synthesized by chemical precipitation method

NASA Astrophysics Data System (ADS)

Thu Trang Pham, Thi; Phuong Nguyen, Thu; Pham, Thi Nam; Phuong Vu, Thi; Tran, Dai Lam; Thai, Hoang; Thanh Dinh, Thi Mai

2013-09-01

In this paper, the synthesis of hydroxyapatite (HAp) nanopowder was studied by chemical precipitation method at different values of reaction temperature, settling time, Ca/P ratio, calcination temperature, (NH4)2HPO4 addition rate, initial concentration of Ca(NO3)2 and (NH4)2HPO4. Analysis results of properties, morphology, structure of HAp powder from infrared (IR) spectra, x-ray diffraction (XRD), energy dispersive x-ray (EDX) spectra and scanning electron microscopy (SEM) indicated that the synthesized HAp powder had cylinder crystal shape with size less than 100 nm, single-phase structure. The variation of the synthesis conditions did not affect the morphology but affected the size of HAp crystals.

Sulfide semiconductor materials prepared by high-speed electrodeposition and discussion of electrochemical reaction mechanism

NASA Astrophysics Data System (ADS)

Okamoto, Naoki; Kataoka, Kentaro; Saito, Takeyasu

2017-07-01

A manufacturing method for SnS using a one-step electrochemical technique was developed. The sulfide semiconductor was formed by electrodeposition using an aqueous bath at low temperatures. The sulfide semiconductor particles produced were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The highest current density at which SnS was formed was 1800 mA/cm2 at a bath temperature of 293 K, which is 36 times larger than that in a previous deposition process. Analysis of the chronoamperometric current-time transients indicated that in the potential range from -1100 to -2000 mV vs saturated calomel electrode (SCE), the electrodeposition of SnS can be explained by an instantaneous nucleation model.

On the possibility of room temperature ferromagnetism on chunk-shape BaSnO3/ZnO core/shell nanostructures

NASA Astrophysics Data System (ADS)

Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

2018-04-01

Core/shell BaSnO3/ZnO (BS-ZO) nanostructures were prepared by oxalate precipitation method and wet-chemical method. BaSnO3 (BSO) cubic perovskite structure and ZnO hexagonal wurtzite structure were confirmed by X-ray diffraction (XRD). The crystallite sizes is 23 nm, 29 nm and 27 nm for BSO, ZnO and BS-ZO, respectively. Chunk-shape and cuboids morphology observed from scanning electron microscopy (SEM) analysis. The magnetic properties were studied by VSM for bare and core-shell nano systems and the room temperature ferromagnetism observed for core-shell nanostructures. The BSO/ZnO shows enhanced coercivity and saturated magnetization as compared with BSO and ZnO nanostructures.

Synthesis and structural characterization of polyaniline/cobalt chloride composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asha, E-mail: arana5752@gmail.com; Goyal, Sneh Lata; Kishore, Nawal

2016-05-23

Polyaniline (PANI) and PANI /cobalt chloride composites were synthesized by in situ chemical oxidative polymerization of aniline with CoCl{sub 2}.6H{sub 2}O using ammonium peroxidisulphate as an oxidant. These composites were characterized by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The XRD study reveals that both PANI and composites are amorphous. The XRD and SEM results confirm the presence of cobalt chloride in the composites.

Structural, optical and magnetic investigation of Gd implanted CeO2 nanocrystals

NASA Astrophysics Data System (ADS)

Kaviyarasu, K.; Murmu, P. P.; Kennedy, J.; Thema, F. T.; Letsholathebe, Douglas; Kotsedi, L.; Maaza, M.

2017-10-01

Gadolinium implanted cerium oxide (Gd-CeO2) nanocomposites is an important candidate which have unique hexagonal structure and high K- dielectric constant. Gd-CeO2 nanoparticles were synthesized using hydrothermal method. X-ray diffraction (XRD) results showed that the peaks are consistent with pure phase cubic structure the XRD pattern also confirmed crystallinity and phase purity of the sample. Nanocrystals sizes were found to be up to 25 nm as revealed by XRD and SEM. It is suggested that Gd gives an affirmative effect on the ion influence behavior of Gd-CeO2. XRD patterns showed formation of new phases and SEM micrographs revealed hexagonal structure. Photoluminescence measurement (PL) reveals the systematic shift of the emission band towards lower wavelength thereby ascertaining the quantum confinement effect (QCE). The PL spectrum has wider broad peak ranging from 390 nm to 770 nm and a sharp one centered on at 451.30 nm which is in tune with Gd ions. In the Raman spectra showed intense band observed between 460 cm-1 and 470 cm-1 which is attributed to oxygen ions into CeO2. Room temperature ferromagnetism was observed in un-doped and Gd implanted and annealed CeO2 nanocrystals. In the recent studies, ceria based materials have been considered as one of the most promising electrolytes for reduced temperature SOFC (solid oxide fuel cell) system due to their high ionic conductivities allowing its use in stainless steel supported fuel cells. CeO2 having an optical bandgap 3.3 eV and n-type carrier density which make it a promising candidate for various technological application such as buffer layer on silicon on insulator devices.

Structural and optical properties of nanostructured CdSe thin films prepared by electrochemical deposition

NASA Astrophysics Data System (ADS)

Bai, Rekha; Chaudhary, Sujeet; Pandya, Dinesh K.

2018-05-01

Cadmium selenide (CdSe) nanostructured thin films have been grown on fluorine doped tin oxide (FTO) coated glass substrates by potentiostatic electrochemical deposition (ECD) technique for use in solar energy conversion devices. The effect of bath temperature on the structural, morphological and optical properties of prepared CdSe films has been explored. X-ray diffraction (XRD) and Raman spectroscopy clearly show that the CdSe films are polycrystalline and exhibit phase transformation from wurtzite to zincblende structure with increase in bath temperature. Optical spectra reveal that the nanostructured CdSe films have high absorbance in visible region and the films show a red shift in direct optical energy band gap from 1.90 to 1.65 eV with increase in bath temperature due to change in phase and bandgap tuning related to quantum confinement effect.

Effect of growth temperature on the epitaxial growth of ZnO on GaN by ALD

NASA Astrophysics Data System (ADS)

Särkijärvi, Suvi; Sintonen, Sakari; Tuomisto, Filip; Bosund, Markus; Suihkonen, Sami; Lipsanen, Harri

2014-07-01

We report on the epitaxial growth of ZnO on GaN template by atomic layer deposition (ALD). Diethylzinc (DEZn) and water vapour (H2O) were used as precursors. The structure and the quality of the grown ZnO layers were studied with scanning electron microscope (SEM), X-ray diffraction (XRD), photoluminescence (PL) measurements and positron annihilation spectroscopy. The ZnO films were confirmed epitaxial, and the film quality was found to improve with increasing deposition temperature in the vicinity of the threshold temperature of two dimensional growth. We conclude that high quality ZnO thin films can be grown by ALD. Interestingly only separate Zn-vacancies were observed in the films, although ZnO thin films typically contain fairly high density of surface pits and vacancy clusters.

Magnetic materials for mobile communication antennas substrate application

NASA Astrophysics Data System (ADS)

Chen, Hui; Liang, Difei; Li, Weijia; Pang, Chao

2017-11-01

In this work, 3Ba0.7Sr0.3O·2CoO·10.8Fe2O3 and Ba2Co2Fe12O22 had been fabricated successfully by conventional ceramic process. Crystallographic structure and electromagnetic properties of two kind of hexagonal ferrite with different sintering temperature were investigated. X-ray Diffraction (XRD), Agilent-N5230A Network Analyzer were used to measure ferrite samples. The mobile phone antenna performance was analysed by HFSS. The results revealed that the main phase of two ferrite samples generated at lower temperature due to additive. The optimized parameters of ferrite are sintering temperature at 1000°C. And to emulate antenna model by HFSS find that Z-type and Y-type ferrite substrate can contribute to antenna frequency shifting, radiation efficiency were affected a little.

A Sustainable and Selective Roasting and Water-Leaching Process to Simultaneously Extract Valuable Metals from Low-Grade Ni-Cu Matte

NASA Astrophysics Data System (ADS)

Cui, Fuhui; Mu, Wenning; Wang, Shuai; Xin, Haixia; Xu, Qian; Zhai, Yuchun

2018-03-01

Due to stringent environmental requirements and the complex occurrence of valuable metals, traditional pyrometallurgical methods are unsuitable for treating low-grade nickel-copper matte. A clean and sustainable two-stage sulfating roasting and water-leaching process was used to simultaneously extract valuable metals from low-grade nickel-copper matte. Ammonium and sodium sulfate were used as sulfating agents. The first roasting temperature, mass ratio of ammonium sulfate to matte, roasting time, dosage of sodium sulfate, second roasting temperature and leaching temperature were studied. Under optimal conditions, 98.89% of Ni, 97.48% of Cu and 95.82% of Co, but only 1.34% of Fe, were extracted. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to reveal the sulfating mechanism during the roasting process.

Synthesis of TiO2 Nanoparticle and its phase Transition

NASA Astrophysics Data System (ADS)

Mangrola, M. H.; Joshi, V. G.; Parmar, B. H.

2011-12-01

Here we report the synthesis of titanium dioxide (TiO2) nanoparticles and study of its phase transition from anataze to rutile. Titanium dioxide (TiO2) nanoparticles have been prepared by hydrolysis of Titanium isopropoxide an aqueous solution with constant value of pH 2 and peptizing the resultant suspension gel(white-Blue) and calcinate gel at different temperature. Structures of synthetic samples of TiO2 have been examined by X-ray diffraction (XRD) and scanning electron microscope (SEM). The anatase-rutile transition has been a popular topic due to its interest to scientific and engineering fields. . Here we have seen that the 100 °C calcinate powder consist of anatase fine crystalline phase with a particle size 14 to 15 nm. The prepared TiO2 nanoparticles have uniform size and morphology, and the phase transformation kinetics of obtained material was studied by interpretation of the X-ray diffraction patterns peaks. The phase transform occurred from anatase to rutile at calcinate temperature up to 600 °C. A very fine network texture made from uniform nanoparticles was revealed by scanning electron microscopy (SEM) analyses.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rauf, Nurlaela, E-mail: n-rauf@fmipa.unhas.ac.id; Tahir, Dahlang; Arbiansyah, Muhammad

Structural analysis has been performed on bioceramic materials for denture application by using X-ray diffraction (XRD), X-ray fluorescence (XRF), and Scanning Electron Microscopy (SEM). XRF is using for analysis chemical composition of raw materials. XRF shows the ratio 1 : 1 : 1 : 1 between feldspar, quartz, kaolin and eggshell, respectively, resulting composition CaO content of 56.78 %, which is similar with natural tooth. Sample preparation was carried out on temperature of 800 °C, 900 °C and 1000 °C. X-ray diffraction result showed that the structure is crystalline with trigonal crystal system for SiO{sub 2} (a=b=4.9134 Å and c=5.4051more » Å) and CaH{sub 2}O{sub 2} (a=b=3.5925 Å and c=4.9082 Å). Based on the Scherrer’s equation showed the crystallite size of the highest peak (SiO{sub 2}) increase with increasing the temperature preparation. The highest hardness value (87 kg/mm{sup 2}) and match with the standards of dentin hardness. The surface structure was observed by using SEM also discussed.« less