Vanadium-doped photorefractive titanosillenite crystal

Holographic recording in a vanadium-doped B₁₂TiO₂₀ (BTO) photorefractive crystal puts into evidence a large hole–electron competition showing a fast and a slow hologram components. From the fast component evolution, some material parameters for the electron-donor photoactive centers are computed. The wavelength-resolved photoconductivity is shown to be strongly modified by V-doping compared to undoped and doped BTO with other elements. The increase of photoconductivity by green light preexposure is almost negligible here if compared with undoped BTO. Activation energy for dark conductivity measured for BTO:V is similar to that for undoped BTO, as measured close to room temperature, but sensibly lower than the value reported in the literature for a much higher temperature range. Optical absorption and EPR spectra do confirm already published results and suggestions about the possible role of vanadium in the sillenite structure.