Thermodynamic stability and superconductivity of tantalum carbides from first-principles cluster expansion and isotropic Eliashberg theory

2022 ◽  
Vol 202 ◽  
pp. 111004
Author(s):  
P. Tsuppayakorn-aek ◽  
A. Ektarawong ◽  
W. Sukmas ◽  
B. Alling ◽  
T. Bovornratanaraks
2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.


Author(s):  
Javaria Batool ◽  
Syed Muhammad Alay-e-Abbas ◽  
Gustav Johansson ◽  
Waqas Zulfiqar ◽  
Muhammad Arsam Danish ◽  
...  

The thermodynamic, structural, magnetic and electronic properties of pristine and intrinsic vacancy defect containing topological Dirac semimetal Ba3SnO are studied using first-principles density functional theory calculations. The thermodynamic stability of...


RSC Advances ◽  
2019 ◽  
Vol 9 (59) ◽  
pp. 34158-34165 ◽  
Author(s):  
N. Raja ◽  
D. Murali ◽  
S. V. M. Satyanarayana ◽  
M. Posselt

The temperature dependence of the free formation energy of Ba, Zr and O vacancies in BaZrO3 is investigated for all possible charge states and atomic reservoir conditions.


2011 ◽  
Vol 83 (7) ◽  
Author(s):  
Wei Chen ◽  
David Schmidt ◽  
William F. Schneider ◽  
C. Wolverton

2004 ◽  
Vol 848 ◽  
Author(s):  
Shuping Zhuo ◽  
Karl Sohlberg

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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