First-principles studies of phase transition and structural stability of SrC2 under pressure

2014 ◽  
Vol 28 (24) ◽  
pp. 1450190 ◽  
Author(s):  
Yi-Lin Lu ◽  
Hui Zhao
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
First Principles ◽  
Phonon Dispersion ◽  
Covalent Bond ◽  
Text Structure ◽  
High Pressure Phase ◽  
Space Group ◽  
Type Space ◽  
Pressure Phase

Pressure-induced phase transitions in SrC 2 are investigated using the first-principles plane wave pseudopotential method within the generalized gradient approximation. The phase transition from monoclinic phase ( CaC 2-II-type, space group C2/c) to trigonal ( CaC 2-VII-type, space group [Formula: see text]) 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.

Pressure Driven Structural Phase Transition in EuTaO4: Experimental and First Principles Investigations

2022 ◽  
Author(s):  
Saheli Banerjee ◽  
Alka B Garg ◽  
H. K. Poswal
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
First Principles ◽  
Density Functional ◽  
Structural Phase ◽  
Polycrystalline Sample ◽  
High Pressure Phase ◽  
Spectroscopic Techniques ◽  
Volume Data ◽  
Pressure Phase

Abstract In this article we report the synthesis, characterization and high pressure investigation on technologically important, rare earth orthotantalate, EuTaO4. Single phase polycrystalline sample of EuTaO4 has been synthesized by solid state reaction method adopting monoclinic M'-type fergusonite phase with space group P2/c. Structural and vibrational properties of synthesized compound are investigated using synchrotron based x-ray powder diffraction, and Raman spectroscopic techniques respectively. Both the techniques show presence of an isostructural, first order, reversible phase transition near 17 GPa. Bulk modulus obtained by fitting the experimental pressure volume data for low pressure and high pressure phase is 136.0(3) and 162.8(21) GPa. High pressure phase is accompanied by an increase in coordination number around Ta atom from 6 to 8. First principles calculations under the frame work of density functional theory (DFT) also predicts the isostructural phase transition and change in coordination around Ta atom, corroborating the experimental findings.

scholarly journals Pressure-driven electronic phase transition in the high-pressure phase of nitrogen-rich 1H-tetrazoles

RSC Advances ◽  
2021 ◽  
Vol 11 (35) ◽  
pp. 21507-21513
Author(s):  
Ying Liu ◽  
Huifang Du ◽  
Leiming Fang ◽  
Fei Sun ◽  
Haipeng Su ◽  
...  
Keyword(s):  
Phase Transition ◽  
Hydrogen Bond ◽  
High Pressure ◽  
First Principles ◽  
High Pressure Phase ◽  
First Principles Calculations ◽  
Electronic Phase ◽  
Pressure Phase ◽  
Pressure Driven

Combined high pressure in situ spectra with first-principles calculations, a possible hydrogen-bond assisted phase transition was proposed in tetrazole.

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