Stability and photoluminescence of Bi doped (La,Y)2O3 phosphor powders

La2-yYyO3 phosphor powders were prepared via the citric acid sol-gel combustion method and their stability was checked after four months of storage in the atmosphere using X-ray diffraction. The material, like La2O3, was prone to hydroxylation unless a high proportion of Y was added, which also caused changes in the phases present. Based on its stability, the composition La0.5Y1.5O3 was selected for further study with Bi doping. The luminescence from this material was not as intense as that from Y2-xO3:Bix=0.005, but there was a significant shift in colour as a result of the added La which meant that emission from the Bi3+ ions at the S6 sites of the alloy was close to that of unstable La2O3 on the colour chart.