Estimation of Phase Stability in Pb(Mg _1/3 Nb _2/3 )O ₃ and Pb(Zn _1/3 Nb _2/3 )O ₃ Using the Bond Valence Approach

Abstract

The structure stability of perovskite‐type compounds has been quantitatively estimated by applying bond valence calculations to Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) and Pb(Zn 1/3 Nb 2/3 )O 3 (PZN). The bond valence calculations revealed that the bond strength between oxygen and cations in the pyrochlore‐type compounds is greater than that in the perovskite PMN. It is found that the absolute value of the bond valence sum of oxygen, | V O |, for a PZN single crystal is smallest in reported Pb‐containing perovskite‐type compounds, corresponding to the fact that it is impossible to synthesize PZN by solid‐state reaction under atmospheric pressure. The calculated amount of additives required for stabilizing PZN under atmospheric pressure agreed well with the experimental values.