Pyroelectric and Dielectric Properties of Rb2Cd2(SO4)3

Pyroelectric and dielectric measurements have been made on Rb 2 Cd 2 (SO 4 ) 3 crystals with the simultaneous optical examination of the domain texture of the specimens. An unusual temperature dependence of the spontaneous polarization was found in the ferroelectric phases, which is similar to that found in (NH 4 ) 2 SO 4 . As the temperature is lowered, the spontaneous polarization appears at the Curie point (-144^° C ), gradually decreases and changes its sign below -160^° C without an appreciable change at the second transition temperature of -170^° C . The reversal in polarization was confirmed to take place by both pyroelectric measurement and optical observation. An abrupt change of dielectric constant ε b at the Curie point was revealed by using single domain specimens.