Equivalence of physical pressure and chemical pressure in the phase transformation of BiR<i>x</i>Sc(1−<i>x</i>)O3 (R = Y and La) compounds

In the framework of density functional theory, a new computational route combined with thermodynamics was proposed to reveal the quantitative relationship between physical and chemical pressures. The transformation pressure (physical pressure) of pure BiScO3 in doped BiScO3-based perovskites was obtained by first-principles calculations combined with the Birch–Murnaghan equation of state. The virtual crystal approximation method was employed to construct BiRxSc(1−x)O3 (R = Y and La, x = 0–1) compounds, and their chemical pressures were evaluated by the doping concentration (x). The relationship between physical and chemical pressures was formulated using a Clausius-Clapeyron-like equation to find the appropriate doping concentration of BiScO3-based compounds under normal experimental conditions. This proposed computational route is also expected to be generalized for other material systems, such as multiferroic materials, structural ceramics, superconducting materials, and permanent magnets.