Room-temperature ferroelectricity in diisopropylammonium bromide

A room-temperature ferroelectric, diisopropylammonium bromide (DPB), with dielectric constant epsilon approximate to 12 000 and a clear hysteresis loop at T-c = 425 K is reported. At 417 K DPB undergoes the irreversible phase transition from nonpolar orthorhombic P2(1)2(1)2(1) to the ferroelectric monoclinic phase (P2(1)) and subsequently, at 425 K, to the paraelectric prototype phase (P2(1)/m). The molecular mechanism of the paraelectric-ferroelectric transition is ascribed to the 'order-disorder' behaviour of the diisopropylammonium cations.