Room-Temperature Ferroelectricity in Lithium Hydrazinium Sulfate, Li (N2H5)SO4

Abstract

Li(${\mathrm{N}}_2$ ${\mathrm{H}}_5$)S${\mathrm{O}}_4$ is ferroelectric over the temperature range from below —15°C to above 80°C, and shows no dielectric peaks between —196°C and 140°C. No thermal anomalies are observed. The crystals are orthorhombic, space group $\mathrm{Pbn}{2}_1$, with $a={8.96}_9$ A, $b={9.91}_3$ A, $c={5.17}_8$ A, and the ferroelectric axis is, of course, along $c$; $\rho =1.966\mathrm{}$ g/cc, and there are 4 molecules per cell. The coercive field is about 320 volts/cm at room temperature, and the spontaneous polarization is 0.30 microcoulomb/${\mathrm{cm}}^2$. Beautiful large crystals can be grown from water by a variety of methods. After electroding, the crystal plates should be protected by silicone oil. Without such protection, reaction with normal atmosphere for prolonged time results in excessive conductivity.