Av. Egorysheva et al., SPECTROSCOPIC AND CHIROPTICAL PROPERTIES OF DOPED SILLENITE CRYSTALS - VII - PHOTOCHROMIC EFFECT IN CU-DOPED BI12TIO20, Inorganic materials, 34(10), 1998, pp. 1005-1009
The effect of doping with CuO on the spectroscopic and chiroptical pro
perties of bismuth titanate, Bi12TiO20, crystals was studied. Doping w
ith copper produces no additional photosensitive states in the band ga
p but increases the concentration of the centers already present in un
doped BTO. The photochromic effect in sillenite crystals is due to a f
ew types of low-symmetry deep centers.