Effect Of Ba2+ Substitution On The Stability Of The Antiferroelectric And Ferroelectric Phases In (Pb1-Xbax)Zro3: Phenomenological Theory Considerations

The relative stability of the ferroelectric rhombohedral (F-R) and antiferroelectric orthorhombic (A(O)) phases of (Pb1-xBax)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.