Pressure-induced ferroelectricity in {N(CH3)4}2FeCl4

The hydrostatic pressure effect on the stability of phases I, II, III and IV in {N(CH3)4}2FeCl4 was studied by dielectric and DTA measurements in the temperature and pressure region of -40-30°C and 0–2 kbar. The pressure-induced new phase V found at applied pressures between 0.3 and 1.0 kbar was confirmed to be ferroelectric by the observation of D-E hysteresis loop. These results are compared with those of {N(CH3)4}2XCl4 (X: Co, Zn and Mn) in this paper.