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

Novel red phosphor materials Gd 2 −x−y GaTaO 7 : x Eu 3+ , y Bi 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 ~612 nm was observed with Bi 3+ codoping. Energy transfer from Bi 3+ to Eu 3+ was found to be the major mechanism towards the enhancement of the emission intensity. Optimal doping level of Eu 3+ and Bi 3+ in Gd 2 GaTaO 7 host was determined from the photoluminescence studies. The prepared samples exhibited higher emission intensities than the standard Y 2 O 3 :Eu 3+ red phosphors.