scholarly journals Структурные, магнитные и тепловые свойства соединения Tb-=SUB=-0.8-=/SUB=-Sm-=SUB=-0.2-=/SUB=-Fe-=SUB=-2-=/SUB=- cо структурой фаз Лавеса

2019 ◽  
Vol 61 (12) ◽  
pp. 2471
Author(s):  
Т.А. Алероева ◽  
И.С. Терешина ◽  
Т.П. Каминская ◽  
З.С. Умхаева ◽  
А.В. Филимонов ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Wide Temperature Range ◽  
Room Temperature ◽  
Structural Features ◽  
Surface Topology ◽  
Magnetic Domains ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Range ◽  
Comprehensive Study

A comprehensive study of the structure, phase composition, features of the surface topology, the magnetostrictive and thermal properties of the Tb0.8Sm0.2Fe2 compound are performed. The structural features were established at micro- and nanoscale levels, and information on the magnetic domains structure at room temperature was obtained. The results of x-ray diffraction studies in a wide temperature range of 90–760 K, including Curie temperature, are represented. Experimental data on thermal expansion and magnetostriction in magnetic fields up to 12 kOe were obtained and analyzed. Anomalies were found in the thermal expansion curves dl/l (T) and magnetostriction λ (T) at low temperatures. It is established that in compound under study the value of the magnetostrictive effect remains almost unchanged in a wide temperature range 100–300 K in fields up to 3.5 kOe.

Nonlinear thermal expansion in Li2NiMn3O8

2008 ◽  
Vol 23 (3) ◽  
pp. 224-227
Author(s):  
Lingmin Zeng ◽  
Yeqing Chen ◽  
Wei He ◽  
Liangqin Nong
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Room Temperature ◽  
Linear Thermal Expansion ◽  
Lithium Ion ◽  
Entire Temperature Range ◽  
X Ray Diffraction ◽  
Spinel Type ◽  
X Ray ◽  
Temperature Range

A lattice thermal expansion study on Li2NiMn3O8, a high-voltage cathode material for lithium-ion batteries, was carried out by high-temperature X-ray diffraction from room temperature to 973 K. Rietveld refinement of a high-quality room-temperature diffraction pattern confirmed that Li2NiMn3O8 has the cubic Al2MgO4 spinel type of crystal structure. The analysis of the high-temperature X-ray diffraction patterns showed that the Li2NiMn3O8 structure remained stable and no phase transition was detected over the temperature range from 298 to 973 K. As expected, the value of lattice parameter a or unit cell volume V increases with increasing temperature. The increase in a or V is linear only in the low-temperature region and nonlinear over the entire temperature range from 298 to 973 K. Least-squares analysis of the data for a or V showed the thermal expansion of a or V for Li2NiMn3O8 can best be fitted by a 3-degree polynomial function of temperature. The linear thermal expansion coefficients for a and V averaged over the entire temperature range from 298 to 973 K were also calculated, and αTa=1.10×10−5 K−1; αTV=3.29×10−5 K−1.

Effects of Vacancies on the Thermal Expansion of Mercury Indium Telluride Crystals

2010 ◽  
Vol 663-665 ◽  
pp. 1008-1011
Author(s):  
Ling Hang Wang
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Linear Expansion ◽  
Semiconductor Material ◽  
X Ray ◽  
Temperature Range ◽  
Vertical Bridgman ◽  
Indium Telluride

The thermal expansion of a novel semiconductor material, mercury indium telluride (MIT) grown by vertical Bridgman (VB) method, was measured from room temperature till 573K by two methods, i.e. Macroscopic dilatometric and X-ray measurements. It is found that the macroscopic expansion is quite different from the expansion of the lattice (micro-expansion). The macroscopic expansion is lower than micro-expansion in the temperature range of 303-425.5K and has a minimum of -0.14% linear expansion, while the macro-expansion becomes larger than micro-expansion in the temperature higher than 425.5K. The former may be due to the effects of the existing neutral vacancies. The latter may result from the influence of thermal-activated vacancies on the lattice.

scholarly journals Study of multiferroic properties of Bi2Fe2WO9 ceramic for device application

2016 ◽  
Vol 06 (03) ◽  
pp. 1650023 ◽  
Author(s):  
Jyoshna Rout ◽  
R. N. P. Choudhary
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Electrical Parameters ◽  
Orthorhombic Crystal ◽  
Solid State Reaction Technique ◽  
X Ray ◽  
Universal Power Law ◽  
Phase Compound ◽  
Comprehensive Study

The Bi2Fe2WO9 ceramic was prepared using a standard solid-state reaction technique. Preliminary analysis of X-ray diffraction pattern revealed the formation of single-phase compound with orthorhombic crystal symmetry. The surface morphology of the material captured using scanning electron microscope (SEM) exhibits formation of a densely packed microstructure. Comprehensive study of dielectric properties showed two anomalies at 200[Formula: see text]C and 450[Formula: see text]C: first one may be related to magnetic whereas second one may be related to ferroelectric phase transition. The field dependent magnetic study of the material shows the existence of small remnant magnetization ([Formula: see text]) of 0.052[Formula: see text]em[Formula: see text]/g at room temperature. The existence of magneto-electric (ME) coupling coefficient along with above properties confirms multi-ferroic characteristics of the compound. Selected range temperature and frequency dependent electrical parameters (impedance, modulus, conductivity) of the compound shows that electric properties are correlated to its microstructure. Detailed studies of frequency dependence of ac conductivity suggest that the material obeys Jonscher’s universal power law.

Crystal structure and thermal expansion of hexakis(phenylthio)benzene and its CBr4 clathrate

1995 ◽  
Vol 73 (4) ◽  
pp. 513-521 ◽  
Author(s):  
Darek Michalski ◽  
Mary Anne White ◽  
Pradip K. Bakshi ◽  
T. Stanley Cameron ◽  
Ian Swainson
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Neutron Powder Diffraction ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

The crystal structures of hexakis(phenylthio)benzene (HPTB) and its CBr4 clathrate have been determined by single crystal X-ray diffraction data collected at T = 18 °C and refined to final Rw of 0.036 and 0.047, respectively. Pure HPTB is triclinic, space group [Formula: see text] (No. 2), with a = 9.589(2) Å, b = 10.256(1) Å, c = 10.645(2) Å, α = 68.42(1)°, β = 76.92(2)°, γ = 65.52(1)°, and Z = 1. The CBr4 clathrate of HPTB is rhombohedral, space group [Formula: see text] (No. 148), with a = 14.327(4) Å, b = 20.666(8) Å, and Z = 3. The host–guest mole ratio of HPTB–CBr4 is 1:2. Neutron powder diffraction was carried out on powders of both compounds in the temperature range 25 K < T < 295 K. Thermal expansion coefficients were determined for HPTB and HPTB–CBr4 over this temperature range. Keywords: thermal expansion, crystal structure, clathrate.

scholarly journals Polar and non-polar structures of NH4TiOF3

2019 ◽  
Vol 52 (1) ◽  
pp. 23-26
Author(s):  
O. Boytsova ◽  
I. Dovgaliuk ◽  
D. Chernyshov ◽  
A. Eliseev ◽  
P. O'Brien ◽  
...  
Keyword(s):  
Room Temperature ◽  
Phase 1 ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase ◽  
Starting Compound ◽  
Different Temperatures ◽  
Fourfold Axis

Ammonium oxofluorotitanate, NH4TiOF3, is probably the best known precursor for the synthesis of anatase mesocrystals. Transformation of NH4TiOF3 into TiO2 through thermal decomposition, accompanied by hydrolysis, preserves some structural features of the precursor. Currently, any discussion of the mechanism of this transformation is difficult, as the exact crystal structure of the starting compound is not available and no intermediate structures are known. This article describes the outcome of single-crystal and powder X-ray diffraction studies, revealing the existence of two polymorphs of the parent NH4TiOF3 at different temperatures. A second-order phase transition from the polar Pca21 α phase (1), stable at room temperature, to the Pma2 β phase (2) above ∼433 K has been demonstrated. The direction of the pseudo-fourfold axis in NH4TiOF3 coincides with the orientation of the fourfold axis of anatase mesocrystals, consistent with a topotactical transformation.

Behaviors of the Zr–1.0Sn–0.39Nb–0.31Fe–0.05Cr Alloy at High Temperature

2011 ◽  
Vol 399-401 ◽  
pp. 80-84
Author(s):  
Yi Yuan Tang ◽  
Jie Li Meng ◽  
Kai Lian Huang ◽  
Jian Lie Liang
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
High Temperature ◽  
Oxide Film ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thin Oxide Film ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Phase transformation of the Zr-1.0Sn-0.39Nb-0.31Fe-0.05Cr alloy was investigated by high temperature X-ray diffraction (XRD). The XRD results revealed that the alloy contained two precipitates at room temperature, namely β-Nb and hexagonal Zr(Nb,Fe,Cr,)2. β-Nb was suggested to dissolve into the α-Zr matrix at the 580oC. Thin oxide film formed at the alloy’s surface was identified as mixture of the monoclinic Zr0.93O2and tetragonal ZrO2, when the temperature reached to 750oC and 850 oC. The thermal expansion coefficients of αZr in this alloy was of αa = 8.39×10-6/°C, αc = 2.48×10-6/°C.

Electrical Resistivity Improvement by Precipitation and Strain in Al-Cu Thin Films

2010 ◽  
Vol 305-306 ◽  
pp. 33-37 ◽  
Author(s):  
S. Lallouche ◽  
M.Y. Debili
Keyword(s):  
Thin Films ◽  
Copper Content ◽  
Room Temperature ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Glass Substrates ◽  
Transmission Electron ◽  
Hall Method

This work deals with Al-Cu thin films, deposited onto glass substrates by RF (13.56MHz) magnetron sputtering, and annealed at 773K. The film thickness was approximately the same 3-4µm. They are characterized with respect to microstructure, grain size, microstrain, dislocation density and resistivity versus copper content. Al (Cu) deposits containing 1.8, 7.21, 86.17 and 92.5at%Cu have been investigated. The use of X-ray diffraction analysis and transmission electron microscopy lead to the characterization of different structural features of films deposited at room temperature (< 400K) and after annealing (773K). The resistivity of the films was measured using the four-point probe method. The microstrain profile obtained from XRD thanks to the Williamson-Hall method shows an increase with increasing copper content.

The tunable negative thermal expansion covering a wide temperature range around room temperature in Sn, Mn co-substituted Mn3ZnN

2020 ◽  
Vol 49 (30) ◽  
pp. 10407-10412
Author(s):  
Shugang Tan ◽  
Chenhao Gao ◽  
Cao Wang ◽  
Tong Zhou ◽  
Guangchao Yin ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Wide Temperature Range ◽  
Room Temperature ◽  
Negative Thermal Expansion ◽  
Temperature Range

Based on anti-perovskite Mn3ZnN, the negative thermal expansion (NTE) temperature can be effectively broadened via co-substituting Sn, Mn.

Thermal analysis of the phases of HMX using X-ray diffraction

1993 ◽  
Vol 204 (1) ◽  
Author(s):  
M. Herrmann ◽  
W. Engel ◽  
N. Eisenreich
Keyword(s):  
Thermal Analysis ◽  
Thermal Expansion ◽  
Phase Transitions ◽  
Diffraction Pattern ◽  
X Ray Diffraction ◽  
Volume Changes ◽  
X Ray ◽  
Temperature Range

AbstractThe 4 phases of HMX and its transitions were investigated using X-ray diffraction. The phases were heated stepwise in a temperature range from 170 K to 510 K, measuring a diffraction pattern after each step.The thermal expansion of the different phases and the volume changes during the phase transitions were obtained. Anomalies and strongly anisotropic expansions were observed withThe highest thermal expansion was found with

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