The structural phase transition process of free-standing monoclinic vanadium dioxide micron-sized rods: temperature-dependent Raman study

RSC Advances ◽  
2015 ◽  
Vol 5 (101) ◽  
pp. 83139-83143 ◽  
Author(s):  
Huafang Zhang ◽  
Quanjun Li ◽  
Pengfei Shen ◽  
Qing Dong ◽  
Bo Liu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Vanadium Dioxide ◽  
Structural Phase ◽  
Transition Process ◽  
Temperature Dependent ◽  
Free Standing ◽  
Lower Phase ◽  
Phase Transition Process ◽  
Raman Study

Micro-sized rods show a lower phase transition temperature than nano-sized rods, and this is interpreted on the basis of nucleating defects.

STRUCTURAL, TRANSPORT AND MAGNETOTRANSPORT IN NONMAGNETIC Al3+ DOPED MIXED VALENT La0.7Ca0.3Mn1-XAlXO3 MANGANITES

2012 ◽  
Vol 26 (24) ◽  
pp. 1250136 ◽  
Author(s):  
JALSHIKHABA S. RATHOD ◽  
UMA KHACHAR ◽  
R. R. DOSHI ◽  
P. S. SOLANKI ◽  
D. G. KUBERKAR
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Structural Phase ◽  
Concentration Field ◽  
Structural Disorder ◽  
Orthorhombic Structure ◽  
Temperature Dependent ◽  
Metal Insulator ◽  
Ceramic Method ◽  
Xrd Studies

We report the modifications in the transport and magnetotransport in La 0.7 Ca 0.3 Mn 1-x Al x O 3 (LCMAO); x = 0.0, 0.02, 0.04, 0.06, 0.08 and 0.1 polycrystalline manganites synthesized by conventional ceramic method. XRD studies reveal the single phasic orthorhombic structure for all the Al -doped LCMO samples without any detectable impurities and structural phase transition. SEM micrographs show island-like grain growth in all the samples studied. Transport measurements indicate an increase in resistivity and decrease in metal-insulator (M-I) transition temperature (TP) with the increase in Al -concentration. Field and temperature dependent variation in MR for all the Al (x) doped LCMO samples has been discussed in detail in the light of substitution induced structural disorder.

Structural Phase Transition of Tungsten-Doped Vanadium Dioxide Nanopowders Prepared by Thermolysis

2008 ◽  
Vol 8 (3) ◽  
pp. 1417-1421 ◽  
Author(s):  
Zifei Peng ◽  
Wei Jiang ◽  
Heng Liu
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Vanadium Dioxide ◽  
Structural Phase ◽  
Hysteresis Loops ◽  
Tungstic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron

Tungsten-doped vanadium dioxide (VO2) nanopowders were prepared by thermolysis of (NH4)5[(VO)6(CO3)4(OH)9] · 10H2O at low temperature, with active white powdery tungstic acid used as a substitutional dopant. The composition and microstructure of the powders were examined by X-ray diffraction, transmission electron microscope, and differential scanning calorimetry. The change in electrical resistance due to the S–M transition was measured from 0 to 150 °C by the four-probe method. Hysteresis loops and differential scanning calorimetry analysis of the samples indicated that the phase-transition temperature of VO2 nanopowders was 67.15 °C. For tungstendoped VO2 nanopowders, the temperature was reduced to 26.46 °C. After sintering the nanopowders, Tc rose from 26.46 °C to 34.85 °C with the sizes increasing to the bulk. A significant direct correlation between particle size and Tc was confirmed. The results indicated that white powdery tungstic acid is exceptionally effective as a dopant for reducing transition temperature.

scholarly journals First-principles study of the structural phase transition process of solid nitrogen under pressure

2021 ◽  
Vol 27 (10) ◽  
Author(s):  
Zhi-Xin Bai ◽  
Cheng-Lu Jiang ◽  
Sheng-Hai Zhu ◽  
Mi Zhong ◽  
Ming-Jian Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
First Principles ◽  
Structural Phase ◽  
Transition Process ◽  
First Principles Study ◽  
Solid Nitrogen ◽  
Phase Transition Process

scholarly journals To the Methodology of Phase Transition Temperature Determination in Aqueous Solutions of Thermo-Sensitive Polymers

2020 ◽  
Vol 22 (2) ◽  
pp. 129
Author(s):  
G.A. Mun ◽  
I. Moldakhan ◽  
S.B. Kabdushev ◽  
B.B. Yermukhambetova ◽  
R. Shaikhutdinov ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Aqueous Solutions ◽  
Temperature Interval ◽  
Phase State ◽  
Transition Process ◽  
Phase Portraits ◽  
Quantitative Parameter ◽  
Phase Transition Process

An advanced methodology of phase transition determination in aqueous solutions of thermo-sensitive polymers by using of the phase portraits method has been suggested. The methodology allows highly accurate determining the temperature when exactly a half of molecules loses solubility (from the maximum number that can go to another phase state under given conditions). It is shown that since phase transition passes usually in a wide enough temperature interval this indicator should be used as a quantitative parameter that characterizes phase transition process. Additionally the suggested methodology allows introducing one more quantitative parameter that reflects a sharpness of phase transition. The methodology is verified by an example of phase transitions study in aqueous solutions of thermo-sensitive copolymers based on N-vinylpyrrolidone and vinyl propyl ether.

Symmetry-Controlled Structural Phase Transition Temperature in Chromium-Doped Vanadium Dioxide

2016 ◽  
Vol 120 (49) ◽  
pp. 28163-28168 ◽  
Author(s):  
Xiaogang Tan ◽  
Wei Liu ◽  
Ran Long ◽  
Xiaodong Zhang ◽  
Tao Yao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Structural Phase Transition ◽  
Vanadium Dioxide ◽  
Structural Phase

scholarly journals First-Principles Study of The Structural Phase Transition Process of Solid Nitrogen Under Pressure

2021 ◽  
Author(s):  
Zhi-Xin Bai ◽  
Cheng-Lu Jiang ◽  
Sheng-Hai Zhu ◽  
Mi Zhong ◽  
Ming-Jian Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
First Principles ◽  
Structural Phase ◽  
Transition Process ◽  
Whole Process ◽  
Solid Nitrogen ◽  
Phase Transition Process ◽  
The Stability ◽  
New Criterion

Abstract Due to the diversity of solid nitrogen structure, its phase transition has been a hot topic for many scientists. Herein, we first studied the structural softening of rhombohedral solid nitrogen under pressure using first-principles calculations. Then, a new criterion, Egret criterion, was proposed to predicting the whole process from beginning to end of structural phase transition of solid nitrogen. Based on the discussion of acoustic phonons, we concluded that the phase transition of rhombohedral solid nitrogen starts from k-point F along the [-1, -1, 0] direction in a-axis, and the structural phase transition velocity is slow. Also, we use the Egret criterion proposed by us to predict the emergence of ξ-N2 and the stability of ξ-N2 at 17 GPa and 22 GPa, respectively, and this result is in good agreement with the phase diagram of nitrogen.

Enhanced Néel temperature in EuSnP under pressure

2019 ◽  
Vol 48 (16) ◽  
pp. 5327-5334 ◽  
Author(s):  
Xin Gui ◽  
Gregory J. Finkelstein ◽  
David E. Graf ◽  
Kaya Wei ◽  
Dongzhou Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Transition Temperature ◽  
Structural Phase ◽  
Antiferromagnetic Transition ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Resistivity Measurements ◽  
Temperature Dependent Resistivity

The high-pressure single crystal X-ray diffraction results for EuSnP are reported with no structural phase transition below ∼6.2 GPa. Temperature-dependent resistivity measurements up to 2.15 GPa indicate that the antiferromagnetic transition temperature (TN) is significantly enhanced under pressure.

Thermodynamics of solution of gypsum and anhydrite in water over a wide temperature range

1984 ◽  
Vol 62 (3) ◽  
pp. 484-488 ◽  
Author(s):  
Horacio R. Corti ◽  
Roberto Fernandez-Prini
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Thermodynamic Properties ◽  
Transition Process ◽  
Calcium Sulphate ◽  
Phase Transition Process ◽  
Different Temperatures ◽  
Pure Phases ◽  
Constant Charge

The solubility of calcium sulphate in water at different temperatures is important for the description of chemical processes occurring in heat exchangers as well as in geothermal processes. Great discrepancies have been reported between experimental and predicted solubilities at high temperature and the transition temperature for the phase transition process (gypsum → anhydrite) is ill-defined.We have analyzed the available data for the solubility of calcium sulphate in water with no added electrolyte. Ion-pairing has been taken into account to calculate the standard thermodynamic properties of the solution process.It is found that the solubility data for gypsum and anhydrite are thermodynamically very consistent. It is possible to obtain the thermodynamic properties of the phase transition from solution data and, at 298.15 K and 101.325 kPa, they are in very good agreement with reported values from measurements with the pure phases. The transition temperature is calculated to be 315.7 ± 0.4 K.It is also shown that the experimental data agree with values predicted for high temperature by employing well-established methods of calculation of solution thermodynamic properties (e.g., principles of correspondence and of constant charge).

Optical Switching of Coherent VO2 Precipitates Embedded in Sapphire

1995 ◽  
Vol 396 ◽  
Author(s):  
L. A. Gea ◽  
L. A. Boatner ◽  
J. D. Budai ◽  
R. A. Zuhr
Keyword(s):  
Phase Transition ◽  
Vanadium Dioxide ◽  
Thermal Processing ◽  
Optical Switching ◽  
Optical Transmission ◽  
Structural Phase ◽  
Switching Behavior ◽  
New Type ◽  
Single Crystal Sapphire ◽  
Smart Surface

AbstractIn this work, we report the formation of a new type of active or “smart” surface that is produced by ion implantation and thermal processing. By co-implanting vanadium and oxygen into a single-crystal sapphire substrate and annealing the system under appropriate conditions, it was possible to form buried precipitates of vanadium dioxide that were crystallographically oriented with respect to the host AI2O3 lattice. The implanted VO2 precipitate system undergoes a structural phase transition that is accompanied by large variations in the optical transmission which are comparable to those observed for thin films of VO2 deposited on sapphire. Co-implantation with oxygen was found to be necessary to ensure good optical switching behavior.

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