Partially Disordered Structure of Ca₂Sr(C₂H₅CO₂)₆ in the Ferroelectric Phase

Abstract

The crystal structure of Ca₂Sr(C₂H₅CO₂)₆ in the ferroelectric phase was determined at −40°C by X-ray reflection data from a monodomain crystal. The least-squares calculation was converged with the R-factor of 0.044. Among the six independent propionate ions in a formula unit, four ones which are disordered perfectly in the paraelectric phase are in partially disordered states with two equilibrium atomic positions. Correlation between the positions of methyl groups in the disordered propionate ions is discussed on the basis of the van der Waals version.