STUDY OF POLYCRYSTALLINE CUBR AND THE INTERFACE CU CUBR BY IMPEDANCE SPECTROSCOPY/

The electrical properties of polycrystalline copper(I) bromide were in vestigated between 20 and 430 degrees C by impedance spectroscopy with copper electrodes. Extrinsic and intrinsic regions in gamma-CuBr and a domain of fast ionic conduction in beta-CuBr are separated. Enthalpi es of migration of copper interstitials (25 kJ/mol) and copper vacanci es (50 kJ/mol) and the enthalpy of formation of Frenkel defects (160 k J/mol) are deduced. The phase boundary copper/copper(I) bromide can be represented by a parallel circuit of an interfacial resistance and a constant phase-angle (CPA) element. The interfacial resistance depends exponentially on temperature and is practically negligible above 350 degrees C. Contributions of charge transfer resistance and space charg e resistance are discussed. Prefactors of CPA elements depend also exp onentially on temperature; they are compared with interfacial capacita nces.