Optical interband transitions in relaxor-based ferroelectric 0.93Pb(Zn1∕3Nb2∕3)O3–0.07PbTiO3 single crystal

摘要

The optical transmission spectrum of [111]c poled relaxor-based ferroelectric single crystal 0.93Pb(Zn1∕3Nb2∕3)O3–0.07PbTiO3 (PZN–0.07PT) was measured in the range of ultraviolet to near infrared. The optical absorption edge has been determined and the wavelength dependence of the absorption coefficient was calculated. The direct energy gap Egd=3.144 eV, indirect energy gap Egi=2.915 eV, and phonon energy Ep=0.097 eV (or 782 cm⁻¹) were determined based on the theory of band to band transitions. It was also confirmed by Raman spectra that the indirect transition for the [111]c poled PZN–0.07PT single crystal is mainly due to the contribution of 780 cm⁻¹ phonon corresponding to the Nb–O–Zn bond stretching mode.