Intense Photoluminescence Emission in Eu~(3+)- and Dy~(3+)-Doped Low-Band Gap Perovskite Titanate, Na_(0.5)Gd_(0.5)TiO3

摘要

Na_(0.5)Gd_(0.5-x)RExTiO3 (RE = Eu and Dy) phases with orthorhombic perovskite structure were synthesized by high temperature solid state reaction and the photoluminescence properties were investigated. The phase purity was confirmed by Rietveld refinement of the powder XRD patterns in Pnma space group. The band gap of the host was found to be 3.41 eV from UV/Vis diffuse reflectance spectrum. In the Eu~(3+) doped phases, the ~5D_0→~7F_2 electric dipole (ED) transition is predominant in the emission spectrum of Eu~(3+), under 397 nm excitation, and is in agreement with the non-centrosymmetric Cs point group of the EuO8 polyhedron. The critical concentration of the Eu~(3+) was found to be x=0.075 above which, concentration quenching occurs. Dy~(3+) doping resulted in intense white light emission under 389 nm excitation.