The structure and thermodynamics of defects which involved In3+ ions and charge-compensating Ag vacancies were studied by means of perturbed angular correlation spectroscopy. Two main defect configurations were detected, both of which were attributed to two Ag vacancies that were bound to the In3+ ion at next-nearest Ag-neighbor positions. A reversible transition occurred between the 2 configurations at about 80K. The so-called zz-axis of the electric field gradient tensor for this complex pointed along a <100> crystal axis. This complex was attributed to a co-linear configuration with two Ag vacancies at next-nearest neighbor sites on opposite sides of the In ion. The other complex, which predominated at temperatures between 80K, and the onset of diffusion-induced damping near to 200K, had its zz-axis of the electric field gradient tensor again aligned with a <100> crystal axis. This complex was attributed to a configuration with two Ag vacancies, at next-nearest sites, which formed a right triangle; with the In probe atom at the vertex. A third complex occurred near to the transition, but its parameters could not be properly determined. The transition between the complexes which predominated above and below 80K was analyzed in terms of equilibrium thermodynamics. This indicated that the differences in formation enthalpy and entropy for the 2 complexes were equal to 0.04eV and 6k, respectively.

J.C.Austin, K.Price, B.K.Patnaik, M.L.Swanson: Journal of Physics - Condensed Matter, 1996, 8[15], 2679-94