Dielectric Properties and Phase Transitions in Some Oxyfluorides with the MeO_xF_(6-x)(x = 1, 2, 3) Anion in Structure

摘要

In order to understand the role of central atom in the nature of hase transitions in two series of ammonium oxyfluorides, A_2MeO_2F_4 and A_2A'MeO_xF_(6-x), the permittivity was studied in wide temperature range. In most cases structural distortions are associated with the ferroelasticity. The ferro- and antiferroelectric properties were revealed only in molybdates.