III-Nitride Polymorphs: XN (X=Al, Ga, In) in the Pnma Phase

2018 ◽  
Vol 24 (65) ◽  
pp. 17280-17287 ◽  
Author(s):  
Qingyang Fan ◽  
Wenzhu Zhang ◽  
Sining Yun ◽  
Jie Xu ◽  
Yanxing Song
Keyword(s):  
Pnma Phase

STRUCTURAL TRANSITIONS OF BiI3 UNDER PRESSURE

2012 ◽  
Vol 26 (32) ◽  
pp. 1250217
Author(s):  
XIAO-XIAO SUN ◽  
ZHI-RU REN ◽  
DAO-GUANG WANG
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Structural Transition ◽  
High Pressures ◽  
Functional Theory ◽  
High Pressure Studies ◽  
Volume Collapse ◽  
Pseudopotential Calculations ◽  
Structural And Electronic Properties ◽  
Pnma Phase

High pressure studies of BiI 3 at 0 K are performed using first-principles pseudopotential calculations within the framework of density functional theory. The calculations indicate that BiI 3 undergoes a structural transition from rhombohedral R-3 phase to monoclinic P2 1/c phase at 7 GPa which is accompanied by a 5.8% volume collapse. In addition, we find that P2 1/c phase prevails about 60 GPa range and transforms to cubic Fm-3m phase at 68 GPa, and finally takes the orthorhombic Pnma phase at high pressures up to 133 GPa. The structural and electronic properties of four competitive structures are also calculated. The analysis of density of states reveals that BiI 3 has semiconductor-metal transition at about 61 GPa, which also demonstrates the metallic nature of both Fm-3m and Pnma phases.

Excellent thermal stability and thermoelectric properties of Pnma -phase SnSe in middle temperature aerobic environment

2018 ◽  
Vol 27 (11) ◽  
pp. 118105 ◽  
Author(s):  
Yu Tang ◽  
Decong Li ◽  
Zhong Chen ◽  
Shuping Deng ◽  
Luqi Sun ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermoelectric Properties ◽  
Excellent Thermal Stability ◽  
Middle Temperature ◽  
Pnma Phase

scholarly journals Characterization of the high-pressure superconductivity in the Pnma phase of calcium

2012 ◽  
Vol 249 (11) ◽  
pp. 2194-2201 ◽  
Author(s):  
R. Szczęśniak ◽  
D. Szczęśniak
Keyword(s):  
High Pressure ◽  
Pnma Phase

scholarly journals Rhombohedral R3c to orthorhombic Pnma phase transition induced by Y-doping in BiFeO3

2018 ◽  
Vol 30 (28) ◽  
pp. 285701 ◽  
Author(s):  
M E Graf ◽  
S Di Napoli ◽  
M A Barral ◽  
L M Saleh Medina ◽  
R M Negri ◽  
...  
Keyword(s):  
Phase Transition ◽  
Pnma Phase

FIRST-PRINCIPLES STUDY OF THE STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF MgSiO3 AT HIGH PRESSURE

2009 ◽  
Vol 20 (07) ◽  
pp. 1093-1101 ◽  
Author(s):  
YANLING LI ◽  
ZHI ZENG
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Optical Properties ◽  
First Principles ◽  
Density Functional ◽  
Plane Waves ◽  
Generalized Gradient ◽  
Equation Of States ◽  
Phase Transition Pressure ◽  
Pnma Phase

The high-pressure behavior of perovskite ( MgSiO 3) is studied based on density functional simulations within generalized gradient approximation (GGA). All calculations are performed by using the linear augmented plane waves plus local orbital (LAPW+lo) method to solve the scalar-relativistic Kohn-Sham equations. The static calculations predict a perovskite (pnma phase) — post-perovskite (Cmcm phase) transition occurring at 86 gigapascals (GPa). The similar bulk modulus values, differing only 3 GPa, are given by using three kinds of equation of states. The electronic structure and optical properties of MgSiO 3 at phase transition pressure are also discussed.

The Imma ↔ Pnma phase transition of NH3(CH2)5NH3CdCl4 studied by X-ray diffraction

1987 ◽  
Vol 100 (2) ◽  
pp. 473-483 ◽  
Author(s):  
P. Négrier ◽  
N. B. Chanh ◽  
C. Cotjrseille ◽  
C. Hauw ◽  
A. Méuresse ◽  
...  
Keyword(s):  
Phase Transition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pnma Phase

Theoretical study of the R3c-to-Pnma phase transition in BiAlO3

2018 ◽  
Vol 152 ◽  
pp. 211-216 ◽  
Author(s):  
Qiang Li ◽  
Zelong He ◽  
Qilong Cao
Keyword(s):  
Phase Transition ◽  
Theoretical Study ◽  
Pnma Phase

scholarly journals Evolution of the Structural, Mechanical, and Phonon Properties of GeSe Polymorphs in a Pressure-Induced Second-Order Phase Transition

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3612 ◽  
Author(s):  
Jianhui Yang ◽  
Qiang Fan ◽  
Bing Xiao ◽  
Yingchun Ding
Keyword(s):  
Phase Transition ◽  
Structural Transition ◽  
Transition Process ◽  
First Principle ◽  
First Principle Calculations ◽  
Phase Transition Process ◽  
Raman Modes ◽  
Pnma Phase ◽  
Phonon Properties ◽  
Second Order Phase Transition

A pressure-induced structural transition from the layered-like phase (Pnma) to another bilayer structure (Cmcm) in GeSe was investigated with first principle calculations. The variations of the structural, electronic, elastic, and vibrational properties of GeSe with the application of pressure were obtained. The transformation from the Pnma to Cmcm phase occurred at 34 GPa. The Cmcm phase structure showed dynamical stability above 37 GPa. The lattice parameters and the equation of state varied continuously at the transition pressure. Obvious stiffening in the C33 and C23 elastic constants associated with the compressive and shear components was observed to occur within the phase transition process. Two characteristic Raman modes (Ag and B3g) of the Pnma phase showed significant softening by increasing the pressure.

Sign in / Sign up

Export Citation Format

Share Document