A series of high-temperature molecular ferroelectric crystals: chlorine doped diisopropylammonium bromide

Abstract

A series of chlorine doped diisopropylammonium bromide (DIPAB-C) single crystals were grown successfully. The DIPAB-C crystals have two phase transitions (from P2₁2₁2₁ to P2₁ at T₁, and from P2₁ to P2₁/m at T₂) in the warming process but only one (P2₁/m to P2₁) in the cooling process. The ferroelectric-to-paraelectric transition temperature can be modulated from 423 K to 429 K by chlorine concentration. The spontaneous polarization decreased from 23 μC cm⁻² for undoped DIPAB crystals to 13 μC cm⁻² for a chlorine concentration of x = 0.08, then it had a stable value of 14 μC cm⁻² for x > 0.1. This indicates that the ferroelectric properties, including spontaneous polarization, the phase transition temperatures, the lattice parameters, etc., can be modulated by doping with congeners.