Ferroelectricity in Potassium Ferrocyanide Trihydrate and its Isomorphous Substances

Abstract

Several A₄[M(CN)₆]·3H₂O type cyano-complexes belonging to the crystal class C_2h were studied to examine ferroelectricity. Isomorphous substances obtained through replacing the Fe⁺⁺ ion by Ru⁺⁺, Os⁺⁺ and Mn⁺⁺ ions show ferroelectric behavior below −14°C, −2.4°C and −40°C respectively. Ferroelectric behavior of these compounds are vary similar to that of the potassium ferrocyanide trihydrate, reported before. The potassium ferrocyanide group ferroelectrics has ferroelectric axis parallel to [10\bar1] direction. Ferroelectric transition of these substances is probably of the second order.