DENSITY OF VALENCE STATES OF THE SUPERIONIC CONDUCTOR AGI

Temperature dependent photoelectron spectra of AgI are measured between room temperature and 251°C for photon energies hω = 21.2 and 40.8 eV. The spectra are decomposed into approximate partial p and d densities of valence states by using atomic cross sections for the corresponding partial photoexcitation probabilities. Significant abrupt reversible changes are observed in the partial p density of states at Tc = 147°C, where the crystal structure changes from the wurtzite (β) phase to the superionic “disordered” α‐phase. In contrast, the partial d density of states, except for a slow continuous broadening with temperature, shows no sudden change at Tc. The results strongly support the model, that in the α‐phase the Ag+ ions occupy lattice sites with tetrahedral symmetry for a large fraction of the time. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA