Structural properties and phase transitions in MgCaSrO quaternary compounds

Abstract

First-principles calculations of structural properties of MgCaSrO quaternary compounds have been carried out. All possible polymorphs of a certain size (16-atom supercells) are considered in the calculations. The structural phase transitions under pressure in these compounds have been studied, taking into account all possible polymorphs in the competing structures. The details of the phase transition in these compounds were found to be sensitive to the ratio of ionic radii of the constituent alkaline-earth metal atoms. The significant differences at phase transitions of compounds with predominance of Ca atoms from those with predominance of Mg or Sr atoms were found. The cases of predominance of Mg and Sr atoms in these compounds from the point of view of phase transition details, i.e. in the realization through certain polymorphs, coincide completely.