Electrostriction, Piezoelectricity and Elasticity in Ferroelectric SbSI

By the use of the resonance method, the electrostrictive coefficient Q 33 and the elastic compliance coefficients s 33 D , s 33 E have been determined from -70°C to 50°C. In the ferroelectric phase, Q 33 was obtained from the piezoelectric coefficient and spontaneous polarization, while in the paraelectric phase it was obtained from the field-induced piezoelectricity. An a c bias was used to avoid the errors arising from a space charge polarization. The coefficient Q 33 (1.8×10 -12 CGSesu) was found to be nearly temperature independent throughout the para- and ferroelectric phases. Further it agreed with the value estimated from the spontaneous strain. These facts indicate that the strain is proportional to the square of polarization over the temperature range investigated. While s 33 E , exhibits a pronounced anomaly below T c , s 33 D (3.0×10 -12 cm 2 /dyn) is almost temperature independent. Thermodynamic discussion is made of stress dependence of the transition point.