Laser-Calorimetric Study of Fundamental Absorption Edge in Pb,La(ZrTi)O_3 (PLZT) Perovskite Ceramics

摘要

The values of the light absorption coefficient of PLZT 10/65/35 ceramics at selected wavelengths have been obtained by laser calorimetric emasurements. The absorption coefficient of the PLZT ceramics is an exponential function of the photon energy. Two values of characteristic Urbach energy have been found #DELTA#E_1=106 meV and #DELTA#E_2=238 meV. The first one is a characteristic of the potential of electron-phonon interaction of the optically excited transitions from the valence band to the conduction band and does not depend on lattice defects or admixtures. The other characterises the electron-phonon interaction at optical transitions between two localized electron state in the energy gap separated by 2.8 eV from each other. A hypothesis is proposed identifying the absorption band at 2.8 eV from each other. A hypothesis is proposed identifying the absorption band at 2.8 eV as the band of electron transitions in lead atoms perturbed by the presence of oxygen vacancies.