Kinetics of the thermal decomposition in CsH 2 PO 4 superprotonic crystal

Thermal stability of CsH 2 PO 4 was investigated in an extended temperature range below and above the superprotonic transition. Single and polycrystalline samples were studied by optical microscopy and measurements of ac conductivity using different electrodes. The kinetics of CsH 2 PO 4 thermal decomposition and the influence of different factors such as quality of the sample and especially its surface, heating rate, type of electrodes and atmosphere were studied in detail. Different stages of this process were identified such as induction time, surface nucleation, intensive growth of the nuclei until decomposition products completely cover the surface of the sample and growth of this layer into bulk of the crystal. Two clearly different high‐conductive states with the conductivities 0.04 S cm –1 and 0.003 S cm –1 , which appear during the decomposition process, were found for the first time. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)