Effect of Ba²⁺ substitution on the stability of the antiferroelectric and ferroelectric phases in (Pb_1-xBa_x)ZrO₃: phenomenological theory considerations

Abstract

The relative stability of the ferroelectric rhombohedral (FR) and antiferroelectric orthorhombic (AO) phases of (Pb_1-xBa_x)ZrO₃ has been investigated as a function of Ba²⁺ concentration (x) using phenomenological theory considerations. It is shown that all the unknown parameters in the free-energy expressions for the F_R and A_O phases can be evaluated using the dielectric and x-ray-diffraction data as a function of temperature. We show that the differences in the energies of antiferroelectric and ferroelectric phases decrease with increasing Ba²⁺ concentration, indicating the gradual destabilization of the antiferroelectric phase. The theoretically predicted critical composition x=0.17±0.0025, above which no antiferroelectric phase can exist, is found to be in excellent agreement with the experimental observations.