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: g_z= 2.385, g_x= 2.097, g_y= 2.072, A_z= 91 × 10^–4 cm^–1, A_x≤ 20 × 10^–4 cm^–1 and A_y= 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^–.