Characterization and photoluminescence properties of some MLn2(1−x)O4:2xEu3+ or 2xTb3+ systems (M=Ba or Sr, Ln=Gd or La)

BaGd2O4, BaLa2O4 and SrLa2O4 powders doped with different concentrations of Eu3+ or Tb3+ are prepared by combustion synthesis method and the samples were further heated to 500, 700 and 900 °C to improve the crystallinity of the materials. The structure and morphology of materials have been examined by X-ray diffraction and scanning electron microscopy. It is remarkable that all the samples of BaGd2O4, BaLa2O4 and SrLa2O4 have similar morphology. The SEM images show homogeneous aggregates of varying shapes and sizes, which are composed of a large number of small elliptical shaped crystallites with an average diameter of about 0.5-3.0 μm. Photoluminescence for all materials increases with increase of temperature and shows a maximum for the samples heated to 900 °C with 4 mole% doping of Eu3+ or Tb3+ ions. The luminescence is almost same for all powders when doped with same concentration of Eu3+.