Dielectric Properties and Characterisation of the Superionic Phase of [C(NH2)3]2SbCl5*[C(NH2)3]Cl (GHCA)

Abstract

GHCA undergoes four phase transitions at Tc1 = 402 K, Tc2 = 373 K, Tc3 = 162 K, and Tc4 = 146 K. Below Tc3 it possesses pyroelectric properties with the spontaneous polarization vector (Ps) in the ac plane and the maximum along the c axis equal to 8 μC/m2. Dielectric dispersion studies of GHCA show that the main dielectric dispersion connected probably with collective motions of chlorine ions is above 1GHz. For the phase transition at Tc2 to a superionic phase the thermal dilatation and electric conductivity were measured. The anomalies of the electric conductivity at Tc2 and Tc1 were observed with large values of σ(10-3 S/m) above Tc3. The guanidinium cations above Tc2, besides reorientational motions, undergo slow self diffusion.