Simultaneous influence of Zn2+/Mg2+ on the luminescent behaviour of La2O3:Tm3+-Yb3+ phosphors

The structural characterizations of La2O3 phosphors doped/codoped with Tm3+ and Yb3+ ions synthesized by the urea assisted solution combustion technique were performed using X- ray diffraction analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. Codoping with Zn2+/ Mg2+ ions causes an increase in the particle size and aggregation for the La2O3:Tm3+-Yb3+ phosphor. The upconversion (UC) study under 980 nm excitation shows four UC emission bands centred around 476 nm ((1)G(4) -> H-3(6)), 653 nm ((1)G(4) -> F-3(4)), 702 nm (F-3(2) -> H-3(6)) and 795 nm ((1)G(4) -> H-3(5)). The effect of codoping with Zn2+ and Mg2+ ions in the Tm3+- Yb3+ codoped La2O3 phosphor was investigated. Decay curve analysis of the prepared phosphors was done to understand the mechanism of the upconversion emission intensity variation due to codoping with Zn2+/Mg2+ ions. The purity of colour emitted from the sample does not show any change with variations in pump power density.