EPR of Ag2+in β-alumina

EPR measurements have been made on Ag 2+ in sodium beta -alumina single crystals. Silver is introduced into the conduction plane as Ag + by exchange with Na + in amounts varying from 5 to 26%: Ag 2+ is produced by X-ray irradiation at 300K. EPR results indicate that the Ag 2+ occupies two sites of orthorhombic symmetry in the conduction plane. The measured g-values are g x =2.0230(2), g y =2.0678(15), g z =2.2730(5) and g x =2.015(4), g y =2.0580(15), g z =2.2335(4) where x, y, z are parallel to a*, c, a axes respectively. The hyperfine interaction with the 107 Ag nuclei is unresolved and estimated to be less than 1 mT. No motional effects are observed. Models are discussed for the two sites which involve an excess of O 2- ions in the conduction plane.