Thermal and dielectric studies on ferroelectric (CH₃NHCH₂COOH)₃CACL₂(TSCC)

Abstract Dielectric constants, birefringences, spontaneous polarization in TSCC were measured in a wide temperature range from 4.2 to 300 K. Dielectric constant along the b -axis exhibits an anomaly corresponding to a new phase transition at 65 K. D-E hysteresis loops were detected below 65 K: this indicates that the low-temperature phase is also ferroelectric. Changes in spontaneous polarization and birefringences were observed at 65 K. Anomalously large quadratic electro-optical coefficients were obtained. Rhodes-Wohlfarth ratio is estimated to be 1.5, which is not any typical value of order-disorder or displacive phase transition. Thermal behaviour around the ferroelectric phase transition at 130 K is in good agreement with the short-range behaviour in the temperature range of 3 K <|T − 130 K|<16 K.