scholarly journals Structural position and oxidation state of nickel in SrTiO3

2013 ◽  
Vol 03 (04) ◽  
pp. 1350031 ◽  
Author(s):  
Irina A. Sluchinskaya ◽  
Alexander I. Lebedev ◽  
Alexei Erko
Keyword(s):  
Solid Solution ◽  
Oxidation State ◽  
Single Phase ◽  
Photovoltaic Effect ◽  
X Ray Diffraction ◽  
Spectra Analysis ◽  
Single Phase Sample ◽  
X Ray ◽  
Xafs Spectroscopy ◽  
Preparation Conditions

The properties of Ni -doped strontium titanate are studied using X-ray diffraction and XAFS spectroscopy. It is shown that regardless of the preparation conditions, the SrTi 1-x Ni x O 3 solid solution and the NiTiO 3 phase are the most stable phases which can coexist. According to the EXAFS data, in the single-phase sample of SrTi 0.97 Ni 0.03 O 3, the Ni atoms substitute for the Ti ones and are on-center. The distortion of the oxygen octahedra is not observed. The XANES spectra analysis shows that the oxidation state of nickel in NiTiO 3 is 2+, and in the SrTi 1-x Ni x O 3 solid solution it is close to 4+. It is shown that the strongest light absorption in doped samples is associated with the presence of tetravalent nickel in the SrTi 1-x Ni x O 3 solid solution. This doping seems the most promising one for solar energy converters that exploit the bulk photovoltaic effect.

Influence of Annealing Time on Microstructure of Ni-W Alloys

2013 ◽  
Vol 747-748 ◽  
pp. 613-618
Author(s):  
Qiao Zhang ◽  
Shu Hua Liang ◽  
Chen Zhang ◽  
Jun Tao Zou
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Grain Size ◽  
Grain Boundaries ◽  
Annealing Time ◽  
Single Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size ◽  
Scanning Electron

The as-cast Ni-W alloys with 15wt%W, 25wt%W and 30wt%W were annealed in hydrogen at 1100. The effect of the annealing time on the microstructure of Ni-W alloys was studied, and the phase constituents and microstructure of annealed Ni-W alloys were characterized by the X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that no any phase changed for Ni-15%W, Ni-25%W and Ni-30%W alloys annealed for 60 min, 90 min and 150 min, which were still consisted of single-phase Ni (W) solid solution. However, microstructure had a significant change after annealing. With increase of annealing time, the microstructure of Ni-15%W alloy became more uniform after annealing for 90 min, and the average grain size was 95μm, whereas the grain size of Ni-15%W alloy increased significantly after annealing for 150 min. For Ni-25%W and Ni-30%W, there was no obvious change on the grain size with increase of annealing time, and the amount of oxides at grain boundaries gradually reduced. After annealing for 150 min, the impurities at grain boundaries almost disappeared. Subsequently, the annealing at 1100 for 150 min was beneficial for the desired microstructure of Ni-25%W and Ni-30%W alloys.

Synthesis of Ti3Si0.4Al0.8C1.8 Solid Solution

2008 ◽  
Vol 368-372 ◽  
pp. 995-997
Author(s):  
Cui Wei Li ◽  
Hong Xiang Zhai ◽  
Yang Zhou ◽  
Shi Bo Li ◽  
Zhi Li Zhang
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Scanning Electron Microscopy ◽  
Single Phase ◽  
Lattice Parameters ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Scanning Electron

In this study, free Ti/Si/Al/C powder mixtures with molar ratio of 3:0.4:0.8:1.8 were heated in Argon with various schedules, in order to reveal the possibility for the synthesis of Ti3Si0.4Al0.8C1.8 solid solution powder. X-ray diffraction (XRD) was used for the evaluation of phase identities of the powder after different treatments. Scanning electron microscopy (SEM) was used to observe the morphology of the Ti3Si0.4Al0.8C1.8 solid solution. XRD results showed that predominantly single phase samples of Ti3Si0.4Al0.8C1.8 was prepared after heating at 1400oC for 5 min in Argon and the lattice parameters of Ti3Si0.4Al0.8C1.8 lay between those of Ti3SiC2 and Ti3AlC2.

Effects of V2O5 on the synthesis of Ba2Ti9O20 powders

2005 ◽  
Vol 20 (10) ◽  
pp. 2741-2744 ◽  
Author(s):  
Huixing Lin ◽  
Wei Chen ◽  
Lan Luo
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Scanning Electron Microscopy ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Eutectic Liquid ◽  
X Ray ◽  
Intermediate Phases ◽  
Phase Pure ◽  
Scanning Electron

Phase-pure Ba2Ti9O20 powders were made by doping 3 wt% of V2O5 to a Ba:Ti = 2:9 molar composition, and the effects of the dopant on the phase formation were investigated. The study shows that BaTiO3, BaTi2O5, and BaTi4O9 were the intermediate phases before the formation of Ba2Ti9O20 for samples with or without V2O5. However, with V2O5 doping, the temperature at which Ba2Ti9O20 occurred were lowered from 1150 to 1050 °C and single phase Ba2Ti9O20 powders was easily obtained at 1150 °C for 2 h. Microstructure of the powders was examined by field emission scanning electron microscopy. No evidence of V2O5–Ba2Ti9O20 solid-solution was found by x-ray diffraction and energy-dispersive spectroscopy. The benefit of V2O5 to facilitate the Ba2Ti9O20 synthesis is most probably due to a vanadium-containing eutectic liquid phase which accelerates the migration of reactant species.

scholarly journals Lattice Strain Evolutions in Ni-W Alloys during a Tensile Test Combined with Synchrotron X-ray Diffraction

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4027
Author(s):  
Tarik Sadat ◽  
Damien Faurie ◽  
Dominique Thiaudière ◽  
Cristian Mocuta ◽  
David Tingaud ◽  
...  
Keyword(s):  
Solid Solution ◽  
Tensile Test ◽  
Single Phase ◽  
Lattice Strain ◽  
Tensile Tests ◽  
X Ray Diffraction ◽  
X Ray ◽  
Significant Difference ◽  
Diffraction Peaks

Ni and Ni(W) solid solution of bulk Ni and Ni-W alloys (Ni-10W, Ni-30W, and Ni-50W) (wt%) were mechanically compared through the evolution of their {111} X-ray diffraction peaks during in situ tensile tests on the DiffAbs beamline at the Synchrotron SOLEIL. A significant difference in terms of strain heterogeneities and lattice strain evolution occurred as the plastic activity increased. Such differences are attributed to the number of brittle W clusters and the hardening due to the solid solution compared to the single-phase bulk Ni sample.

Preparation and Magnetic Properties of Nanocrystalline (Fe,Cr)-N

2012 ◽  
Vol 625 ◽  
pp. 222-225
Author(s):  
Wen Jiang Feng ◽  
Chuan Yin Wang ◽  
Hao Hua Zhang
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Magnetic Properties ◽  
Magnetic Moment ◽  
Single Phase ◽  
Nitrogen Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nano Crystalline ◽  
Intrinsic Magnetic Moment

The nano-crystalline (Fe,Cr)N was prepared as a single phase by milling Fe80Cr20 in a nitrogen atmosphere. Its crystal structure is determined to be the cubic rock salt-type CrN by X-ray diffraction measurements. The nano-crystalline is stable up to above 773 K and decomposes into (Fe,Cr)N and Fe-Cr solid solution. Due to the combination of Fe atoms and N ones, the intrinsic magnetic moment of Fe atoms is reduced, which is confirmed by our measurements.

Tetragonal to orthorhombic transformation during mullite formation

1991 ◽  
Vol 6 (4) ◽  
pp. 819-824 ◽  
Author(s):  
Dong X. Li ◽  
William J. Thomson
Keyword(s):  
Solid Solution ◽  
Single Phase ◽  
Sol Gel ◽  
The Other ◽  
Processing Conditions ◽  
Mullite Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mullite Phase ◽  
Increasing Temperature

The mullite formation process in both single phase and diphasic sol-gel precursors to mullite was studied using dynamic x-ray diffraction (DXRD). A metastable, tetragonal-like mullite phase was observed in all the single gels at temperatures from 980 °C to 1200 °C, but not in any of the other precursors. The tetragonal to orthorhombic mullite transformation was very slow as the lattice parameters, a and b, split and moved gradually away from each other as a result of a gradual decrease of alumina content in the mullite solid solution with increasing temperature from 1100 °C to 1200 °C. The formation of tetragonal mullite coincides with that of the Al–Si spinel. The occurrence of tetragonal mullite or the spinel (or both) is determined mainly by the processing conditions of the sol-gel precursors.

A Study of Natural Metamict Yttrium Niobate as Analogue of Actinide Ceramic Waste Form

2014 ◽  
Vol 1665 ◽  
pp. 313-318 ◽  
Author(s):  
Cao Qiuxiang ◽  
Anton I. Isakov ◽  
Liu Xiaodong ◽  
Sergey V. Krivovichev ◽  
Boris E. Burakov
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Single Phase ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Original Sample ◽  
X Ray Diffraction ◽  
Average Chemical Composition ◽  
X Ray ◽  
Scanning Electron

ABSTRACTNatural metamict mineral found as large (1-3 cm in size) homogeneous grains (as assumed, former single crystals), was investigated by X-ray powder diffraction (pXRD), high-temperature pXRD, scanning electron microscopy (SEM) and electron microprobe analysis (EMPA). The average chemical composition obtained by EMPA is (wt. %): Nb2O5 – 42.6; Ta2O5 – 4.4; TiO2 – 9.2; UO3 – 4.4; ThO2 – 1.0; MnO – 1.3; FeO – 19.4; Y2O3 – 16.6.The untreated (original) sample is X-ray amorphous. The sample remained amorphous after annealing at 400 °C for 1 hour. The sample became almost fully crystalline after annealing at 700 °C for 1 hour with an X-ray diffraction pattern similar to that of Fe-columbite (ICCD: 01-074-7356). Further annealing at 1000 °C and higher temperatures caused changes in the phase composition of the sample. It was proposed that under self-irradiation a single-phase U-Th-bearing solid solution, based on monocrystalline Y-niobate, became metamict but remained homogeneous without evidence of solid solution destruction. However, this metamict solid solution is unstable under thermal treatment and recrystallization.

Preparation and Characterization of Lead-Free (Ba0.4Sr0.4Ca0.2)(Zr0.05Ti0.95)O3 Ceramics Using BST Seed Induced Method

2018 ◽  
Vol 766 ◽  
pp. 180-185
Author(s):  
Jiraporn Dangsak ◽  
Sukum Eitssayeam ◽  
Tawee Tunkasiri ◽  
Uraiwan Intatha
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Single Phase ◽  
Seed Crystal ◽  
Lead Free ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Seed Crystals

The solid solution of lead-free (Ba0.4Sr0.4Ca0.2) (Zr0.05Ti0.95) O3 (BSCZT) ceramics were prepared from the seed induced method. The Ba0.6Sr0.4TiO3 (BST) were used as the seed crystals, they were prepared using the molten salt technique. The phase formation was examined using the X-ray diffraction technique (XRD). It was found that the single phase perovskite structure of BST was obtained at a temperature of 800°C. The ceramics were prepared using the conventional solid state reaction by adding of BST seed crystals at 2.5, 5, 7.5 and 10 mol%. The structure showed that a single phase perovskite was obtained after sintered at 1400 °C. This work confirmed that BST seed crystal successfully diffused into BSCZT ceramic and the BSCZT ceramic with a seed crystal showed higher dielectric than the BSCZT ceramic without seed crystals.

Raman And Fluorescence Spectra Observed in Laser Microprobe Measurements of Several Compositions in the Ln-Ba-Cu-O System

1990 ◽  
Vol 48 (2) ◽  
pp. 278-279
Author(s):  
Edgar S. Etz ◽  
Thomas D. Schroeder ◽  
Winnie Wong-Ng
Keyword(s):  
Fluorescence Spectra ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Raman Microprobe ◽  
Methods Of Synthesis ◽  
Compositional Homogeneity ◽  
Processing Techniques

We are investigating by Raman microprobe measurements the superconducting and related phases in the LnBa2Cu3O7-x (for x=0 to 1) system where yttrium has been replaced by several of the lanthanide (Ln = Nd,Sm,Eu,Ho,Er) elements. The aim is to relate the observed optical spectra (Raman and fluorescence) to the compositional and structural properties of these solids as part of comprehensive materials characterization. The results are correlated with the methods of synthesis, the processing techniques of these materials, and their superconducting properties. Of relevance is the substitutional chemistry of these isostructural systems, the differences in the spectra, and their microanalytical usefulness for the detection of impurity phases, and the assessment of compositional homogeneity. The Raman spectra of most of these compounds are well understood from accounts in the literature.The materials examined here are mostly ceramic powders prepared by conventional solid state reaction techniques. The bulk samples are of nominally single-phase composition as determined by x-ray diffraction.

Observation of pseudo 10-fold symmetry in the ordered iron-zinc delta phase

1992 ◽  
Vol 50 (1) ◽  
pp. 36-37
Author(s):  
L. A. Giannuzzi ◽  
A. S. Ramani ◽  
P. R. Howell ◽  
H. W. Pickering ◽  
W. R. Bitler
Keyword(s):  
Single Phase ◽  
X Ray Diffraction ◽  
Rich Region ◽  
Average Cell ◽  
X Ray ◽  
Delta Phase ◽  
Cell Dimensions ◽  
Δ Phase ◽  
Morphological Differences ◽  
Concentration Discontinuity

The δ phase is a Zn-rich intermetallic, having a composition range of ∼ 86.5 - 92.0 atomic percent Zn, and is stable up to 665°C. The stoichiometry of the δ phase has been reported as FeZn7 and FeZn10 The deviation in stoichiometry can be attributed to variations in alloy composition used by each investigator. The structure of the δ phase, as determined by powder x-ray diffraction, is hexagonal (P63mc or P63/mmc) with cell dimensions a = 1.28 nm, c = 5.76 nm, and 555±8 atoms per unit cell. Later work suggested that the layer produced by hot-dip galvanizing should be considered as two distinct phases which are characterized by their morphological differences, namely: the iron-rich region with a compact appearance (δk) and the zinc-rich region with a columnar or palisade microstructure (δp). The sub-division of the δ phase was also based on differences in diffusion behavior, and a concentration discontinuity across the δp/δk boundary. However, work utilizing Weisenberg photographs on δ single crystals reported that the variation in lattice parameters with composition was small and hence, structurally, the δk phase and the δp phase were the same and should be thought of as a single phase, δ. Bastin et al. determined the average cell dimensions to be a = 1.28 nm and c = 5.71 nm, and suggested that perhaps some kind of ordering process, which would not be observed by x-ray diffraction, may be responsible for the morphological differences within the δ phase.

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