Dielectric and photovoltaic phenomena in tungsten-doped Pb(Mg1/3Nb2/3)1-xTixO3 crystal

This work investigates dielectric and photovoltaic behaviors in Pb(Mg1∕3Nb2∕3)0.64Ti0.36O3 single crystal doped with 0.5mol% WO3. Dielectric permittivities measured as functions of temperature and frequency reveal two first-order-type phase transitions upon heating and cooling. The photovoltaic response strongly depends on illumination wavelength, sample thickness, and prior electric-field poling. The relation of photovoltage and light intensity under near-ultraviolet (λ=406nm) illumination for the poled samples can be expressed by an exponential equation. Optical transmission reveals that the cutoff wavelength is near 400nm and indicates a minimum electronic energy gap of ∼3.0eV.