Influence of Rare Earth Doping on Microstructure and Luminescence Behaviour of Sodium Sulphate

Abstract

Na 2 SO 4 , Na 2 SO 4 : Li, and Na 2 SO 4 : Li, Eu, Dy phosphors were prepared by using slow evaporation technique followed by subsequent calcination at 400°C for 4 h. Doping with Li + ion stabilized the thenardite phase of host matrix, while codoping with RE 3+ stabilized the phase transformation from stable thenardite to metastable mirabilite crystal structure. The microstructure and morphology were studied by using scanning electron microscopy and transmission electron microscopy. The thermoluminescence studies revealed that isovalent doping of Li + served as a quencher and addition of codopant introduces the additional trap sites in the host matrix. The room temperature emission spectra of Li-doped, RE 3+ -codoped, and undoped Na 2 SO 4 were studied under ultraviolet radiation. For pure Na 2 SO 4 the two peaks which appeared are at 364 and 702 nm, respectively. The emission intensities of RE 3+ -codoped samples increase with increase in dopant concentration.