A high-pressure induced stable phase of Li2MnSiO4 as an effective poly-anion cathode material from simulations

2019 ◽  
Vol 7 (27) ◽  
pp. 16406-16413 ◽  
Author(s):  
Shuo Wang ◽  
Junyi Liu ◽  
Yu Qie ◽  
Sheng Gong ◽  
Cunzhi Zhang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Cathode Material ◽  
First Principles ◽  
High Performance ◽  
First Principles Calculation ◽  
Stable Phase ◽  
Structure Search

A novel poly-anion Li2MnSiO4 material is predicted at high pressure using global crystal structure search combined with first-principles calculation, which shows great potentials as a high-performance cathode.

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 Crystal Structures of Al2Cu Revisited: Understanding Existing Phases and Exploring Other Potential Phases

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1037 ◽  
Author(s):  
Sai Wang ◽  
Changzeng Fan
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Single Crystal ◽  
First Principles ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Relationships ◽  
Al2cu Phase ◽  
High Pressure Sintering

When processing single crystal X-ray diffraction datasets for twins of Al2Cu sample synthesized by the high-pressure sintering (HPS) method, we have clarified why the crystal structure of Al2Cu was incorrectly solved about a century ago. The structural relationships between all existing Al2Cu phases, including the Owen-, θ-, θ’-, and Ω-Al2Cu phases, were investigated and established based on a proposed pseudo Al2Cu phase. Two potential phases have been built up by adjusting the packing sequences of A/B layers of Al atoms that were inherent in all existing Al2Cu phases. The mechanical, thermal, and dynamical stability of two such novel phases and their electronic properties were investigated by first-principles calculations.

The thermodynamic stability of three near-degenerate phases of platinum dioxide

2004 ◽  
Vol 848 ◽  
Author(s):  
Shuping Zhuo ◽  
Karl Sohlberg
Keyword(s):  
High Pressure ◽  
Fixed Point ◽  
Low Temperature ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Energy Surface ◽  
Stable Phase ◽  
Free Energies ◽  
Rutile Structure ◽  
Unstable Fixed Point

ABSTRACTThe thermodynamic stability of the three nearly energy degenerate crystal structures of PtO2 is studied here with first-principles-based calculations of their free energies. For P = 0 the α-(CdI2) structure is the thermodynamically stable phase at low temperature, while the β-(CaCl2) structure is stable at high pressure. The β'-(rutile) structure represents an unstable fixed point on the potential energy surface, or is possibly just barely bound. These results reconcile seemingly contradictory findings and answer longstanding questions about PtO2.

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