Two reversible ferroelectric phase transitions in diisopropylammonium perchlorate

Abstract

Two reversible first-order phase transitions were found in an improper ferroelectric, diisopropylammonium perchlorate (DIPAP), due to the crystal symmetry transforming from P2₁/c to P1 at 296 K, and subsequently to P2₁/c at 338 K in the heating process, similar to the structural transitions of the first discovered ferroelectric, Rochelle salt. The dielectric behavior shows two remarkable dielectric step-like increases at 296 K and 338 K, characteristic of improper ferroelectrics. The mechanism of the two improper ferroelectric phase transitions involves the transformation of diisopropylammonium cations and perchlorate anions, as confirmed by X-ray diffraction and Raman spectroscopy.