OPTICAL-ABSORPTION SPECTRA OF ACCEPTOR-DOPED SRZRO3 AND SRTIO3 PEROVSKITE-TYPE PROTON CONDUCTORS

The optical absorption spectra were investigated to study the electron ic structures of perovskite-type proton conductors. The fundamental ab sorption edge shifts to higher energy side when an acceptor ion was do ped to the perovskite-type oxides. In SrZrO3, an absorption band was o bserved in the lower energy side of the fundamental absorption edge wh en an acceptor was doped. It is suggested that this band corresponds t o the acceptor level of the proton conductors. The absorption of this band was enhanced when the proton was removed from the crystal. This s uggests that the number of electrons in the acceptor level decreases w hen a proton is introduced to the crystal.