Tm3+ Modifying Er3+ Red Emission and Dielectric Properties of Tm3+-Doped LaErO3 Perovskite

A series of LaEr(1-x)TmxO3 (x=0, 0.05, and 0.1) oxides were synthesized using the combustion method. X-ray diffraction analysis indicates that a single orthorhombic structure phase for all compounds was formed. The influence of thulium doping on optical and electrical properties of LaErO3 was studied. The upconversion emissions were investigated under 980 nm excitation, and the doping with Tm3+ ions was found to preferentially decrease the green emission of Er3+ (H-2(11/2), S-4(3/2)-> I-4(15/2)) and to spectrally promote its red emission (F-4(7/2)-> I-4(15/2)) by populating and depopulating red and green emission levels, respectively. The electrical and dielectric properties were investigated through impedance spectroscopy measurements. It was found that the conductivity was decreased by doping, and that the resistivity was dominated by the bulk effect rather than grain boundary resistivity for doped samples. The grain boundary resistivity is increased by doping and suggests the appearance of considerable potential barriers through the grain boundaries.