Novel red phosphors Gd2GaTaO7:Eu3+,Bi3+ for white LED applications

Novel red phosphor materials Gd2−x−yGaTaO7:xEu3+,yBi3+ were prepared using a high temperature solid state reaction route. Crystalline structure, morphology, absorbance and photoluminescence properties were studied using powder X-ray diffractometer, scanning electron microscope, UV–Vis absorption spectrophotometer and fluorescence spectrophotometer respectively. Red shift in the charge transfer band coupled with an increased emission intensity in the red region ~612 nm was observed with Bi3+ codoping. Energy transfer from Bi3+ to Eu3+ was found to be the major mechanism towards the enhancement of the emission intensity. Optimal doping level of Eu3+ and Bi3+ in Gd2GaTaO7 host was determined from the photoluminescence studies. The prepared samples exhibited higher emission intensities than the standard Y2O3:Eu3+ red phosphors.