SILVER-DOPED ALKALINE-EARTH FLUORIDES - CRYSTAL-GROWTH AND PHYSICOCHEMICAL PROCESSES STUDIED BY OPTICAL SPECTROSCOPY AND EPR

Single crystals of the alkaline earth fluorides doped with silver were grown successfully. This paper presents details of the methodology. T he as-grown crystals consist of colorless transparent and yellowish re gions. The former were show, to contain the Ag+ ion and the latter als o silver pairs, small clusters and probably colloidal aggregates. Comp lex optical absorption bands were observed in the samples of the forme r parts after they had been X-irradiated. The samples were subsequentl y exposed to extended series of physico-chemical treatments with the a im to obtain information regarding the electronic structures involved. The evolution was monitored with the aid of optical absorption experi ments. Factor analysis technique is presented and was applied to uncov er mutually independent contributions to these absorption spectra. We identified the Jahn-Teller Ag2+ [Bill H. et al., Solid State Commun. 7 0, 511 (1989)] and several centers which formally involve an Ag- ion.