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 (1G4 → 3H6), 653 nm (1G4 → 3F4), 702 nm (3F2 → 3H6) and 795 nm (1G4 → 3H5). 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.