Determination of the Width of the Single Phase Stability Field of Nickel Titanate Spinel

1991 ◽  
Vol 237 ◽  
Author(s):  
Ian M. Anderson ◽  
C. Barry Carter
Keyword(s):  
Phase Stability ◽  
Single Phase ◽  
Narrow Range ◽  
Spinel Phase ◽  
Stability Field ◽  
Diffusion Couples ◽  
Temperature Dependent ◽  
X Ray ◽  
Nickel Titanate

ABSTRACTThe width of the single-phase stability field of nickel titanate spinel (Ni2(1+x)Ti1−xO4) has been determined in order to resolve an ambiguity in the analysis of the microstructure of equilibrated and quenched spinel-containing specimens. Bulk polycrystalline diffusion couples of the constituent oxides, NiO and NiTiO3, have been prepared at several reaction temperatures between 1400°C and 1550°C. The microstructure of the reaction layers of slow-cooled specimens has been examined by SEM and the composition has been mapped using x-ray microanalysis. It is concluded that the nickel titanate spinel phase has a narrow range of stability, and that the stoichiometry of the spinel is temperature dependent. The microstructure of equilibrated and quenched specimens is discussed in light of these findings.

scholarly journals Microstructure and chemistry of MgO- and CoO-doped nickel-titanate spinels

1994 ◽  
Vol 52 ◽  
pp. 1002-1003
Author(s):  
I. M. Anderson ◽  
C. B. Carter ◽  
J. Bentley
Keyword(s):  
Single Phase ◽  
Spinel Phase ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
Powder Mixtures ◽  
X Ray ◽  
Nickel Titanate ◽  
Diffraction Patterns ◽  
Faceted Particles ◽  
Single Set

When NiO-rich powder mixtures of NiO and TiO2 are equilibrated in air above ∼1425°C and subsequently quenched, X-ray diffraction patterns of the resulting specimens can be indexed with a single set of reflections in the Fd3m space group. Originally this result was cited as evidence of a highly nonstoichiometric single phase. However, subsequent TEM investigations showed that these specimens are composed of periclase- and spinelstructured phases with small domains and coherent phase boundaries. Periclase-structured domains are distributed throughout the spinel with two distinct morphologies: cuboidal particles, faceted on {100}, of uniform size that increases from 30 to 150 run with increasing NiO-mole-fraction; and an isotropic interconnected twophase microstructure, also of uniform size, varying from 2 to 5 ran seemingly independent of composition. The finer-scale features strongly resemble those arising from spinodal decomposition in an isotropic medium and can be ascribed to decomposition of a nonstoichiometric spinel phase during quenching. It has recently been suggested that the faceted particles coexist with the nonstoichiometric spinel at the equilibration temperature.

Synthesis, Structure, and Characterization of La1−xBax (0 ≤ x ≤ 1)

1992 ◽  
Vol 271 ◽  
Author(s):  
Joseph E. Sunstrom ◽  
Susan M. Kauzlarich
Keyword(s):  
Magnetic Susceptibility ◽  
Powder Diffraction ◽  
Single Phase ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Temperature Dependent ◽  
X Ray ◽  
Early Transition Metal ◽  
Arc Melting

ABSTRACTThe compounds La1−xBaxTiO3 (0 ≤ × ≤ 1) have been prepared by arc melting stoichiometric amounts of LaTiO3 and BaTiO3. Single phase samples can be made for the entire stoichiometry range. The polycrystalline samples have been characterized by thermal gravimetric analysis, X-ray powder diffraction, and temperature dependent magnetic susceptibility. This series of compounds has been studied as a possible candidate for an early transition metal superconductor.

Synthesis of the Sr3Zn2Fe24O41 Z-Type Ferrite by Polymerizable Complex Method

2013 ◽  
Vol 566 ◽  
pp. 231-234 ◽  
Author(s):  
Takuya Tainaka ◽  
Takeyuki Kikuchi ◽  
Tatsuya Nakamura ◽  
Tohru Yamasaki ◽  
Makoto Nakanishi ◽  
...  
Keyword(s):  
Saturation Magnetization ◽  
Single Phase ◽  
Lattice Parameters ◽  
Complex Method ◽  
Vibrating Sample Magnetometer ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Characteristic Two

Synthesis of Sr3Zn2Fe24O41 Z-type ferrite was investigated. Precursors of ferrite were prepared by polymerizable complex method. Identification of formed phases in the obtained samples and determination of lattice parameters of Z-type ferrite were performed by powder X-ray diffraction (XRD). Single-phase of Sr3Zn2Fe24O41 Z-type ferrite was synthesized by heating at 1463 K for 5hours in air. M-H curve of prepared single-phase Sr3Zn2Fe24O41 Z-type ferrite was measured by using vibrating sample magnetometer (VSM). It was revealed that Sr3Zn2Fe24O41 Z-type ferrite has larger saturation magnetization (23.5 μB/formula unit) than that of Sr3Co2Fe24O41 (22.7 μB/formula unit) and shows characteristic two-step saturation of magnetization as well as Sr3Co2Fe24O41 Z-type ferrite.

Calibration of a heating/cooling chamber for X-ray diffraction measurements of mechanical stress and crystallographic texture

2006 ◽  
Vol 39 (2) ◽  
pp. 194-201 ◽  
Author(s):  
M. Wohlschlögel ◽  
U. Welzel ◽  
G. Maier ◽  
E. J. Mittemeijer
Keyword(s):  
Thermal Expansion ◽  
The Other ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Specimen Holder ◽  
Lattice Strains ◽  
Cooling Chamber ◽  
Line Positions

Methods have been developed for the calibration of specimen temperature and of specimen displacement caused by the thermal expansion of the specimen holder in a heating/cooling chamber equipped with a strip or plate heater mounted on an X-ray diffractometer. For the temperature calibration two methods were proposed. One method relies on X-ray diffraction measurements of thermal lattice strains, whereas the other method is based on resistance thermometry. The method proposed for the determination of the temperature-dependent specimen displacement is based on the measurement of diffraction-line positions of the specimen employing two diffraction geometries, one being sensitive to the specimen displacement and the other being insensitive to the specimen displacement. The thermal displacement of the specimen due to thermal expansion of the specimen holder is significant and was determined as about 38 µm per 100 K.

Diffusion Measurements by Analytical Electron Microscopy

1985 ◽  
Vol 62 ◽  
Author(s):  
A. D. Romig
Keyword(s):  
Electron Microprobe ◽  
Analytical Electron Microscopy ◽  
Thin Foil ◽  
Diffusion Couples ◽  
Concentration Gradients ◽  
X Ray ◽  
Analytical Electron ◽  
Multiphase Diffusion ◽  
Better Than

ABSTRACTThe analytical electron microscope (AEM) has been used to measure the concentration gradients which form in single and multiphase diffusion couples. The procedures used to collect x-ray microanalytical data and reduce that data to elemental compositions are typical of those used to quantify x-ray data generated in thin films. The primary difficulty in analyzing diffusion couples with the AEM is sample preparation. The principle advantage of the AEM as a tool to measure diffusion induced concentration gradients is its high spatial resolution, approximately 20 to 100 times better than that of the electron microprobe which has been traditionally used to measure these concentration profiles. As a consequence, the AEM data can yield diffusivities as much as 5 orders of magnitude smaller than those obtained from electron microprobe data. This paper will review the fundamental principles of the determination of diffusion coefficients from the concentration gradients measured in single and multiphase diffusion couples and the basic considerations of thin foil x-ray microanalysis. With this understanding of the basic concepts, recent studies of diffusion in Ta-W and U-Nb will be discussed.

Determination Of Temperature Dependent Unstressed Lattice Spacings In Crystalline Thin Films On Substrates

1997 ◽  
Vol 505 ◽  
Author(s):  
G. Cornella ◽  
S. Lee ◽  
O. Kraft ◽  
W. D. Nix ◽  
J. C. Bravman
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Strain Analysis ◽  
Lattice Parameter ◽  
Gold Films ◽  
Sample Material ◽  
Temperature Dependent ◽  
X Ray

ABSTRACTX-ray strain analysis via Generalized Focusing Diffractometry (GFD) [1], and the concurrent need for accurate values of the unstrained lattice parameter, are discussed. A new method for determining the unstrained lattice parameter without knowledge of the elastic constants of the sample material is described. Stress measurements at varying temperatures, and extraction of the coefficient of thermal expansion from these measurements, are demonstrated for aluminum and gold films.

Bestimmung der Röntgen-Debye-Temperatur aus dem Borrmann-Effekt in Germanium / Determination of the X-ray Debye Temperature in Germanium by Means of the Borrmann Effect

1973 ◽  
Vol 28 (7) ◽  
pp. 1204-1213 ◽  
Author(s):  
J. Ludewig
Keyword(s):  
Temperature Dependence ◽  
Compton Scattering ◽  
Debye Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Perfect Crystal ◽  
Photoelectric Absorption ◽  
Temperature Dependent ◽  
X Ray

The anomal transmission of CuK radiation through "thick"' perfect crystal slices of Germanium is strongly temperature dependent. This temperature dependence was measured between 293 and 6 K in the (220) symmetric Laue case and used to evaluate the Debye temperature θM . The wellknown uncorrected value θ′M = 290K was obtained near room temperature. Taking into account TDS and Compton scattering in addition to the photoelectric absorption the corrected value θM = 294 or 296 K was found, depending on the source of data. With decreasing temperature the corrected θM increases slightly up to a maximum at very low temperatures, as predicted by Batterman and Chipman and by Salter.

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