scholarly journals Equilibrium and metastable phase transitions in silicon nitride at high pressure: A first-principles and experimental study

2011 ◽  
Vol 84 (1) ◽  
Author(s):  
Bin Xu ◽  
Jianjun Dong ◽  
Paul F. McMillan ◽  
Olga Shebanova ◽  
Ashkan Salamat
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Phase Transitions ◽  
Silicon Nitride ◽  
First Principles ◽  
Metastable Phase

Phase transitions of BaCO3 at high pressures

2008 ◽  
Vol 72 (2) ◽  
pp. 659-665 ◽  
Author(s):  
S. Ono ◽  
J. P. Brodholt ◽  
G. D. Price
Keyword(s):  
Phase Transition ◽  
Experimental Study ◽  
High Pressure ◽  
Phase Transitions ◽  
Bulk Modulus ◽  
First Principles ◽  
High Pressures ◽  
Ambient Conditions ◽  
The Stability ◽  
Previous Experimental Study

AbstractFirst-principles simulations and high-pressure experiments were used to study the stability of BaCO3 carbonates at high pressures. Witherite, which is orthorhombic and isotypic with CaCO3 aragonite, is stable at ambient conditions. As pressure increases, BaCO3 transforms from witherite to an orthorhombic post-aragonite structure at 8 GPa. The calculated bulk modulus of the post-aragonite structure is 60.7 GPa, which is slightly less than that from experiments. This structure shows an axial anisotropicc ompressibility and the a axis intersects with the c axis at 70 GPa, which implies that the pressure-induced phase transition reported in previous experimental study is misidentified. Although a pyroxene-like structure is stable in Mg- and Ca-carbonates at pressures >100 GPa, our simulations showed that this structure does not appear in BaCO3.

Crystal structure, compressibility and possible phase transitions in \boldvarepsilon-FeSi studied by first-principles pseudopotential calculations

1999 ◽  
Vol 55 (4) ◽  
pp. 484-493 ◽  
Author(s):  
Lidunka Vočadlo ◽  
Geoffrey D. Price ◽  
I. G. Wood
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Phase Transitions ◽  
First Principles ◽  
Stable Phase ◽  
Third Order ◽  
First Derivative ◽  
Pseudopotential Calculations ◽  
Cscl Type ◽  
Murnaghan Equation

An investigation of the relative stability of the FeSi structure and of some hypothetical polymorphs of FeSi has been made by first-principles pseudopotential calculations. It has been shown that the observed distortion from ideal sevenfold coordination is essential in stabilizing the FeSi structure relative to one of the CsCl type. Application of high pressure to FeSi is predicted to produce a structure having nearly perfect sevenfold coordination. However, it appears that FeSi having a CsCl-type structure will be the thermodynamically most stable phase for pressures greater than 13 GPa. Fitting of the calculated internal energy vs volume for the FeSi structure to a third-order Birch–Murnaghan equation of state led to values, at T = 0 K, for the bulk modulus, K 0, and for its first derivative with respect to pressure, K 0′, of 227 GPa and 3.9, respectively.

scholarly journals High-pressure phase transitions in rubidium and caesium hydroxides

2016 ◽  
Vol 18 (24) ◽  
pp. 16527-16534 ◽  
Author(s):  
Andreas Hermann
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
First Principles ◽  
Phase Evolution ◽  
High Pressure Phase ◽  
First Principles Calculations ◽  
Pressure Phase

First-principles calculations on the phase evolution of RbOH and CsOH under compression suggest new high-pressure phases in both compounds.

First Principles Study of High Pressure Phase Transitions in ThN and UN

2011 ◽  
Author(s):  
P. Modak ◽  
Ashok K. Verma ◽  
Alka B. Garg ◽  
R. Mittal ◽  
R. Mukhopadhyay
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
First Principles ◽  
High Pressure Phase ◽  
First Principles Study ◽  
Pressure Phase

Structural and Physical Properties of ZrSi2 under High Pressure: Experimental Study and First-Principles Calculations

2018 ◽  
Vol 58 (1) ◽  
pp. 405-410 ◽  
Author(s):  
Haihua Chen ◽  
Hao Liang ◽  
Fang Peng ◽  
Huishan Li ◽  
Bin Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Physical Properties ◽  
First Principles ◽  
First Principles Calculations

Metastable phase transitions and structural transformations in solid-state materials at high pressure

2007 ◽  
Vol 80 (10-12) ◽  
pp. 1003-1032 ◽  
Author(s):  
Paul F. McMillan ◽  
Olga Shebanova ◽  
Dominik Daisenberger ◽  
Raul Quesada Cabrera ◽  
Edward Bailey ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Solid State ◽  
Metastable Phase ◽  
Structural Transformations ◽  
Solid State Materials
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