Abnormal electronic transition variations of lanthanum-modified lead zironate stannate titanate ceramics near morphotropic phase boundary: A spectroscopic evidence

摘要

The structure-related optical response of (Pb_(1-1.5x_La_x)(Zr_(0.42)Sn_(0.40)Ti_(0.18))O_3 (100x/42/40/18) ceramics with different compositions has been investigated. Based on x-ray diffraction, the phase transition from rhombohedral to tetragonal structure is revealed between compositions of x = 2.6% and 2.8% near morphotropic phase boundary (MPB). Correspondingly, abnormal spectral response in the photon energy from 1.4 to 6.1 eV is observed near MPB. Furthermore, the blue shift of the two critical points related parameters, which is obtained from fitting the reflectance spectra, indicates that the variation of electronic band structure near MPB is responsible for the anomalous behavior.