Electron paramagnetic resonance spectroscopy of Cu+/Cu2+β″-alumina
Abstract
Cu+/Cu2+β″-alumina single crystals have been studied by electron paramagnetic resonance (EPR) spectroscopy. The results indicate that Cu2+ ions are essentially found in an off-centre position in the conduction planes. The co-ordination polyhedron is a distorted square pyramid of C2 symmetry. The magnetic parameters are found to be: gz= 2.385, gx= 2.097, gy= 2.072, Az= 91 × 10–4 cm–1, Ax≤ 20 × 10–4 cm–1 and Ay= 32 × 10–4 cm–1. Low concentrations of Cu2+ ions are also found in two other non-identified sites. Heat treatments in air at temperatures above 500 °C indicate that Cu2+ is reduced to Cu–.