Strong up conversion photoluminescence in Er 3+ doped Bi 4 Ti 3 O 12 ferroelectric materials prepared by sol–gel method

Bi 4 Ti 3 O 12 (BTO) doped with different concentrations of Er 3+ was prepared using sol–gel method. Their structures and surface morphology were examined by X-ray diffraction, Raman spectroscopy and scanning electron microscopy, respectively. All XRD peaks can be indexed according to orthorhombic BTO phase, which is consistent with Raman measurement results. Strong upconversion green luminescence is observed in the Er 3+ doped BTO powders pumped by 980 nm at room temperature. Three upconversion emission bands centered at about 525, 550 and 662 nm are due to the radiative relaxation of Er 3+ from 2 H 11/2 , 4 S 3/2 and 4 F 9/2 to the ground level 4 I 15/2 , respectively. The upconversion emission mechanism of the samples were identified and analyzed. In addition, the doped BTO ceramics show obvious hysteresis loops, demonstrating the ferroelectric properties of the samples. These results illustrate the potential of this class of materials for photonic applications in optoelectronics devices.