PHOTOINDUCED REVERSIBLE CHARGE-TRANSFER PROCESSES IN TRANSITION-METAL-DOPED SINGLE-CRYSTAL SRTIO3 AND TIO2

When SrTiO3 or TiO2 doped with certain transition elements is irradiated with light in the region 0.39 to 0.43 μ, broad visible absorption bands with peak absorption as high as 100 cm-1 are introduced. The study of optical and EPR spectra of Fe/Mo doped crystals under the influence of light and various heat treatments shows that the effect is due to a transfer of charge between Fe and Mo ions such that the nonabsorbing Fe3+ and Mo6+ ions become Fe4+ and Mo5+ with absorption bands in the visible. © 1968 The American Physical Society.