First-principles studies of phase transition and structural stability of SrC2 under pressure
Abstract
Pressure-induced phase transitions in SrC2 are investigated using the first-principles plane wave pseudopotential method within the generalized gradient approximation. The phase transition from monoclinic phase (CaC2-II-type, space group C2/c) to trigonal (CaC2-VII-type, space group R\bar {3}m) structure is predicted to occur at 10.4 GPa. The high-pressure phase is thermodynamic, mechanically and dynamically stable, as verified by the calculations of its formation energy, elastic stiffness constants and phonon dispersion. Further the electronic analysis predicates this high-pressure phase to be an insulator. When increasing pressure, the ionic bond between C and Sr is strengthened, as well is the covalent bond between C and C, however, the increase of the ionic interaction between Sr and C preponderates over that of the covalent bond interaction, so the gap is narrowed.
- Publication:
-
Modern Physics Letters B
- Pub Date:
- September 2014
- DOI:
- 10.1142/S0217984914501905
- Bibcode:
- 2014MPLB...2850190L
- Keywords:
-
- SrC <SUB>2</SUB>;
- first-principles;
- phase transition;
- structural stability;
- pressure