METASTABLE BEHAVIOR IN UNIAXIAL FERROELECTRICS TGS AND TGSE NEAR T-C

High resolution hysteresis loops measurements in triglycine sulfate (o rdinary critical point) and in triglycine selenate (tricritical point) allow the approximate characterization of the behavior in the metasta ble region (E < 0, P > 0, or vice versa) at T less than or equal to T- C. The coercive field may be assumed to reflect three different regime s corresponding with three switching regimes. The observed coercive fi eld seems to approach E-C approximate to Const(1 -T/T-C)(3/2) for TGS and E-C approximate to Const(1 -T/T-C)(3/4) for TGSe in the intervals 10(-4) < (1 -T/T-C) < 10(-3) and 10(-4) < (1 - T/T-C) < 10(-2), respec tively.