Electric permittivity E(D . pyroelectric current ~( D and photoresponse of Cd 2 Nbl0, single crystals under illumination were investigated in the temperature region of 100-300 K. Light-induced change in E(7), ~(7), P,(D. T" and Tc related to optical recharge of traps and to an anomalous photovoltaic effect was observed. At room temperature , photosensitivity of Cd~Nb~O, is observed in the spectral region of extrinsic (between X. = 400 ~ 500 nm) and intrinsic (X. :S 380 nm) absorption. At T <

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... the spectra shift as a whole towards a short light wavelength side . A photoinduced Curie point shift of 6 Tc = -2 ~ 3 K occurs on transition from para· to ferroelectric phase . An internal macroscopic electric field generated along P, during the Maxwell relaxation time due to the photovoltaic effect is equal to ~ = 1 x 1()3 V/cm (for light intensity of about 2 x 10 -z W lcm 2 and X. = 632.8 nm) . Photorefractive effect in Cd:::Nb 2 0 7 in such an electric field is estimated to be of (6n)w-lQ-l ~ I0-6 .