Determination of optical constants of tetragonal Pb(Mg1/3Nb2/3)O3-PbTiO3ferroelectric single crystals

The optical properties of 0.65Pb(Mg1/3Nb2/3)O3?0.35PbTiO3 (PMN?0.35PT) single crystals were investigated by means of the optical transmittance spectrum. The refractive indices were measured in the visible region, and the dispersion behaviours of ordinary and extraordinary lights were well described in terms of the Wemple?Didomenico single oscillator dispersion model. The optical band gap values were obtained from the Tauc model. For (1 ? x) Pb(Mg1/3Nb2/3)O3 ? xPbTiO3 single crystals, as the PbTiO3 content increases, the refractive index increases, while the optical band gap energy decreases.