Ferrielectricity in Copper Formate Tetrahydrate

Abstract

An additional phase transition in Cu(HCOO)₂·4H₂O has been found at −46°C below the well-known antiferroelectric transition at −38°C. A distinct anomaly in pyroelectric current was observed at the new transition. Ferrielectric triple loop was obtained along b axis in the low temperature phase. Respective temperatures are shifted to higher temperature by 10°C for Cu(HCOO)₂·4D₂O. Though the net polarization is small and the phase is approximately antiferroelectric, the phase below −46°C is ferrielectric.