Temperature-dependent ultrasonic study on parity-violating phase transitions of d- and l-alanine single crystals

2003 ◽  
Vol 5 (18) ◽  
pp. 4000 ◽  
Author(s):  
Wenqing Wang ◽  
Wei Min ◽  
Changfei Zhu ◽  
Fang Yi
Keyword(s):  
Phase Transitions ◽  
Single Crystals ◽  
Temperature Dependent ◽  
Ultrasonic Study

A Thermo-Magneto-Mechanical Free Energy Model for NiMnGa Single Crystals

2007 ◽  
Vol 1050 ◽  
Author(s):  
Phillip Morrison ◽  
Stefan Seelecke ◽  
Manfred Kohl ◽  
Berthold Krevet
Keyword(s):  
Free Energy ◽  
Phase Transitions ◽  
Single Crystals ◽  
Energy Landscape ◽  
Stable States ◽  
Temperature Dependent ◽  
One Dimensional ◽  
Rate Dependent ◽  
Energy Equations ◽  
Increasing Temperature

AbstractThe paper extends the authors' recent model for one-dimensional rate-dependent magneto-mechanical behavior of NiMnGa single crystals to account for temperature-dependent effects including austenite/martensite and ferro-/paramagnetic phase transitions. The magneto-mechanical model is based on the Helmholtz free energy landscape constructed for a meso-scale lattice element with strain and magnetization as order parameters. This two-dimensional energy landscape includes three paraboloidal wells representing the two easy-axis and one hard-axis martensite variants relevant for the structurally one-dimensional case. Phase transformations resulting from applied stresses and magnetic fields follow from a system of evolution laws based on the Gibbs free energy equations and the theory of thermally activated processes, which in the low-thermal-activation limit appropriately reproduce the athermal transformation behavior observed in these materials. The phase fractions subsequently determine the macroscopic strain and magnetization of a sample of NiMnGa by means of a standard averaging procedure. To account for the first-order phase transitions to austenite, additional temperature-dependent wells representing the stable states of austenitic NiMnGa are introduced into the Helmholtz energy landscape. The transition from ferromagnetic to paramagnetic states is modeled as a second order transformation based on the gradual degeneration of the ferromagnetic wells with increasing temperature.

Ultrasonic study of vortex viscosity and phase transitions in YBa2Cu3O7 single crystals

1997 ◽  
Vol 101 (5) ◽  
pp. 3168-3168
Author(s):  
D. Dasgupta ◽  
C. Hucho ◽  
J. R. Feller ◽  
B. K. Sarma ◽  
M. Levy
Keyword(s):  
Phase Transitions ◽  
Single Crystals ◽  
Ultrasonic Study

scholarly journals Magnetic phase transitions in Eu( Co1−xNix)2−yAs2 single crystals

2020 ◽  
Vol 4 (8) ◽  
Author(s):  
N. S. Sangeetha ◽  
Santanu Pakhira ◽  
D. H. Ryan ◽  
V. Smetana ◽  
A.-V. Mudring ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Single Crystals ◽  
Magnetic Phase ◽  
Magnetic Phase Transitions

On the nature of the phase transitions of aluminosilicate perrhenate sodalite

2020 ◽  
Vol 235 (6-7) ◽  
pp. 213-223
Author(s):  
Hilke Petersen ◽  
Lars Robben ◽  
Thorsten M. Gesing
Keyword(s):  
Raman Spectroscopy ◽  
Phase Transitions ◽  
Decomposition Temperature ◽  
Second Phase ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Two Phase ◽  
Structure Property Relationships ◽  
Heat Capacity Measurements

AbstractThe temperature-dependent structure-property relationships of the aluminosilicate perrhenate sodalite |Na8(ReO4)2|[AlSiO4]6 (ReO4-SOD) were analysed via powder X-ray diffraction (PXRD), Raman spectroscopy and heat capacity measurements. ReO4-SOD shows two phase transitions in the investigated temperature range (13 K < T < 1480 K). The first one at 218.6(1) K is correlated to the transition of dynamically ordered $P\overline{4}3n$ (> 218.6(1 K) to a statically disordered (<218.6(1) K) SOD template in $P\overline{4}3n$. The loss of the dynamics of the template anion during cooling causes an increase of disorder, indicated by an unusual intensity decrease of the 011-reflection and an increase of the Re-O2 bond length with decreasing temperature. Additionally, Raman spectroscopy shows a distortion of the ReO4 anion. Upon heating the thermal expansion of the sodalite cage originated in the tilt-mechanism causes the second phase transition at 442(1) K resulting in a symmetry-increase from $P\overline{4}3n$ to $Pm\overline{3}n$, the structure with the sodalites full framework expansion. Noteworthy is the high decomposition temperature of 1320(10) K.

Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Engelbert ◽  
Rolf-Dieter Hoffmann ◽  
Jutta Kösters ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Phase Transitions ◽  
Driving Force ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

Phase transitions in PbZr0.72Sn0.28O3 single crystals studied by Raman spectroscopy

2016 ◽  
Vol 89 (7-8) ◽  
pp. 768-776 ◽  
Author(s):  
Irena Jankowska-Sumara ◽  
Min-Seok Jeong ◽  
Jae-Hyeon Ko ◽  
Andrzej Majchrowski ◽  
Józef Żmija
Keyword(s):  
Raman Spectroscopy ◽  
Phase Transitions ◽  
Single Crystals
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