Experimental Studies on Phase Transitions in Ferroelectric {N(CH3)4}2ZnCl4

Thermal, dielectric and dilatational measurements were performed to study the phase transitions in ferroelectric {N(CH 3 ) 4 } 2 ZnCl 4 . The temperature dependence of triple D - E hysteresis loop in ferroelectric Phase III (3.3∼6.0°C, C 2 v 9 - P 2 1 c n ) was observed in detail. The crystal is paraelectric along the b and c directions. A remarkable contraction of the lattice is seen in Phase V (-112∼-92°C, C 2 h 5 - P 12 1 / c 1). Calculated pressure-coefficients of transition temperatures were compared with the measured ones.