UV light-induced IR absorption and photoconductivity in KTa1-xNbxO3

Observation and first studies of the UV light-induced optical absorption for KTa1-xNbxO3 single crystals (x = 0.004, 0.007, 0.012, 0.07) are reported. Under illumination (300-400 nm, 3.10-4.13 eV) at low temperatures a broad light-induced absorption band was found in NIR region, peaking at 5600 cm(-1) (1.79 mu, 0.69 eV T = 1.3 K)for x = 0.007. No light-induced absorption was found at room temperature in all Nb containing samples as well as in nominally pure KTaO3. Results of detailed studies, including photoconductivity and photoluminescence experiments, are associated with the localization of the charge carriers in the form of electronic polarons at low temperatures.