Determination of ferroelectric compositional phase transition using a novel virtual crystal approach

We employ a new method for studying compositionally disordered ferroelectric oxides. This method is based on the virtual crystal approximation (VCA): in which two or more component potentials are averaged : Into a composite atomic potential. In our method, we construct a virtual atom with the correctly averaged atomic size and atomic eigenvalues, We have used our new method to study the composition dependent phase transition in Pb(Zr1-xTix)O-3 lying between x: = 0.5 and x = 0.4. We correctly predict the experimentally determined phase transition from the tetragonal phase to a low-temperature rhombohedral phase between these tao compositions.