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

Abstract

Novel red phosphor materials Gd2-x-y GaTaO7:xEu(3+),yBi(3+) 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 similar to 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.