The effect of the host lattice on the optical properties of Bi3+in Ca1-xO:Bi and Ca1-x(OH)2:Bi phosphors

The present work refers to the structural and luminescence changes in Ca1-xO:Bi (x = 0.5%) phosphor due to the reaction of the Ca1-xO: Bi (x = 0.5%) phosphor with atmospheric air. The X-ray diffraction (XRD) patterns of the as-annealed sample (at 1200 °C) showed the characteristic peaks of CaO, while high-intensity peaks of Ca(OH)2 were also observed for the same samples that were kept in the air after annealing. Indicating that mixed phases of Ca1-xO:Bi (x = 0.5%) and Ca(OH)2:Bi were present in the exposed samples. It was clear that the observed optical properties (excitation and emission) of the Bi3+ depended strongly on the reaction of the CaO with the environment due to the host lattice structure changes and therefore a big challenge for practical applications.