Influence of thermal treatment of Ti-45Nb alloy in ultrafine-grained states on its structural parameters and heat capacity

2021 ◽  
pp. 84-91
Author(s):  
E.V. Legostaeva ◽  
◽  
M.A. Khimich ◽  
Yu.P. Sharkeev ◽  
A.Yu. Eroshenko ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Capacity ◽  
Phase Transitions ◽  
Structural Parameters ◽  
Structural Phase ◽  
Coherent Scattering ◽  
Normal Stresses ◽  
Two Phase ◽  
Ω Phase ◽  
Ultrafine Grained

The effect of heat treatment of the Ti-45Nb alloy in the UFG state on its structural parameters (lattice parameters, volumetric phase ratio, sizes of coherent scattering regions, residual normal stresses) and their relationship with heat capacity have been studied. It has been established that the different character of the temperature dependence of the heat capacity for the Ti-45Nb alloy in the UFG and CC states is associated with the structural-phase features of the alloy in the UFG state: the two-phase structure of a-grains and b-grains, dispersion-hardened by the ω-phase, and phase transitions in the temperature range 400-600 °С.

scholarly journals Study on the structural phase transitions in NaSICON-type compounds using Ag3Sc2(PO4)3 as a model system

2020 ◽  
Vol 77 (1) ◽  
Author(s):  
Günther J. Redhammer ◽  
Gerold Tippelt ◽  
Quirin Stahl ◽  
Artur Benisek ◽  
Daniel Rettenwander
Keyword(s):  
Phase Transitions ◽  
Structural Phase ◽  
Ionic Conductivities ◽  
Phase Behaviour ◽  
Li Ion Batteries ◽  
Two Phase ◽  
Structured Materials ◽  
Β Phase ◽  
Nasicon Type ◽  
Li Ion

NaSICON (Na Super-Ionic CONducting) structured materials are among the most promising solid electrolytes for Li-ion batteries and `beyond Li-ion' batteries (e.g. Na and K) due to their superior ionic conductivities. Although this material has been well known for decades, its exact phase behaviour is still poorly understood. Herein, a starting material of Na3Sc2(PO4)3 single crystals is used, grown by flux methodology, where Na is subsequently chemically replaced by Ag, in order to take advantage of the higher scattering contrast of Ag. It is found that the NaSICON-type compound shows two phase transitions from a low-temperature monoclinic α-phase to a monoclinic β-phase at about 180 K and to a rhombohedral γ-phase at about 290 K. The framework of [Sc2(PO4)3]3− is rigid and does not change significantly with temperature and change of symmetry. The main driving force for the phase transitions is related to order–disorder phenomena of the conducting cations. The sensitivity of the phase behaviour on the ordering of these ions suggests that small compositional changes can have a great impact on the phase behaviour and, hence, on the ionic conductivity of NaSICON-structured materials.

Structural phase transitions coupled with prominent dielectric anomalies and dielectric relaxation in a one-dimensional organic–inorganic hybrid compound [C3H4NS][CdCl3]

2015 ◽  
Vol 3 (33) ◽  
pp. 8535-8541 ◽  
Author(s):  
Guang-Quan Mei ◽  
Wei-Qiang Liao
Keyword(s):  
Phase Transitions ◽  
Dielectric Relaxation ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Two Phase ◽  
Hybrid Compound ◽  
Inorganic Hybrid ◽  
One Dimensional

A one-dimensional organic–inorganic hybrid exhibits two phase transitions at 288 and 215 K, coupled with remarkable dielectric performances.

Heat capacity and thermodynamic functions of CsCrCl3 and RbCrCl3. Structural phase transitions

1983 ◽  
Vol 15 (12) ◽  
pp. 1109-1126 ◽  
Author(s):  
Joaquín García ◽  
Juan Bartolomé ◽  
Domingo González ◽  
Rafael Navarro ◽  
Willem Jacobus Crama
Keyword(s):  
Heat Capacity ◽  
Phase Transitions ◽  
Thermodynamic Functions ◽  
Structural Phase ◽  
Structural Phase Transitions

scholarly journals Проявление структурных фазовых переходов в кристалле Rb-=SUB=-2-=/SUB=-KLuF-=SUB=-6-=/SUB=- в спектрах комбинационного рассеяния света

2019 ◽  
Vol 126 (4) ◽  
pp. 423
Author(s):  
А.С. Крылов ◽  
А.Н. Втюрин ◽  
В.Н. Воронов ◽  
С.Н. Крылова
Keyword(s):  
Phase Transitions ◽  
Monoclinic Phase ◽  
Tricritical Point ◽  
Structural Phase ◽  
Double Perovskite ◽  
Spectral Lines ◽  
The Other ◽  
Structural Phase Transitions ◽  
Two Phase ◽  
Temperature Dependences

AbstractThe Raman spectra of an Rb_2KLuF_6 crystal are studied in the temperature range from 8 to 375 K, which includes two phase transitions: one of which proceeds from a cubic to a tetragonal phase, while the other transition takes place from a tetragonal to a monoclinic phase. An analysis of the temperature dependences of parameters of spectral lines shows that the former transition is of the second kind, while the latter transition is of the first kind, close to the tricritical point. It is shown that the structural phase transitions in the Rb_2KLuF_6 double perovskite are not associated with disordering. The former transition is associated with rotations of LuF_6 octahedra around the fourth-order axis, while the latter transition is related with rotations of octahedra and displacements of rubidium ions.

Influence of Thermal Treatment of Ti–45Nb Alloy in Ultrafine-Grained State on Its Structural Parameters and Heat Capacity

2022 ◽  
Author(s):  
E. V. Legostaeva ◽  
M. A. Khimich ◽  
Yu. P. Sharkeev ◽  
A. Yu. Eroshenko ◽  
O. A. Belyavskaya ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Thermal Treatment ◽  
Structural Parameters ◽  
Ultrafine Grained

X-ray diffraction study of the phase transitions of (CH3)4NCdCl3 between 293 and 80 K: a quantitative analysis of the ferroelastic domains distribution below 118 K

2000 ◽  
Vol 56 (2) ◽  
pp. 215-225 ◽  
Author(s):  
I. Peral ◽  
G. Madariaga ◽  
A. Pérez-Etxebarria ◽  
T. Breczewski
Keyword(s):  
Phase Transitions ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Threefold Axis ◽  
X Ray ◽  
Organic Part ◽  
Small Distortion ◽  
Diffraction Patterns ◽  
Ferroelastic Domains

X-ray diffraction patterns of [N(CH_{3})_{4}][CdCl_{3}], tetramethylammonium trichlorocadmate(II), have been investigated in the temperature range 80–293 K, which includes two phase transitions at 118 and 104 K, respectively. The main interest in this compound is to establish the mechanism of the structural phase transitions common to other members of the isostructural family [(CH_{3})_{4}N][MX_{3}]. It is supposed to be related to the ordering of the organic part together with some small distortion of the inorganic chains. The origin of the order–disorder mechanism would be the orientationally disordered distribution of the tetramethylammonium tetrahedra at room temperature. Maximum Entropy Methods suggest that the most probable distribution of the organic groups can be described through the so-called two-well model, in which one threefold axis of the tetramethylammonium tetrahedron coincides with the crystallographic threefold axis of the structure. Below 118 K the reflections are split. However, the splitting cannot be fully explained by the ferroelastic domains expected to appear after the phase transitions. Recent NMR results [Mulla-Osman et al. (1998). J. Phys. Condensed Matter, 10, 2465–2476] corroborate the existence of more domains than expected from symmetry considerations. A model of ferroelastic domains which is in agreement with both X-ray diffraction diagram and NMR measurements is proposed.

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