Optical characteristics of Er3+-doped PMN–PT transparent ceramics

The pure and Er3+-doped (0.5, 1.0, 2.0 and 5.0 mol.%) PMN–0.25PT transparent ceramics were fabricated. The phase formations were investigated by X-ray diffraction patterns. The optical transmittance and absorption spectra were measured. The Er3+-doping in the region of 0.5–2.0 mol.% can enhance the optical transmittance of Er3+-doped PMN–0.25PT transparent ceramics. The Er3+ doping can modify the optical absorption near the band gap energy of PMN–0.25PT. The shift of the absorption edge to higher energy was observed in the case of the low doping concentration (<2.0 mol.%) and the red-shift was found for the higher doping concentration (5.0 mol.%). This has been explained by the combined effects of ion polarization and localized defect energy level. The direct energy gaps, the indirect energy gaps and phonon energy contributing in the indirect transition were determined based on the theory of band to band transitions.