Luminescence and electric dipole in Eu3+ doped strontium phosphate: Effect of SiO4

Eu3+-doped strontium phosphorous silicate phosphors were synthesized at 200 degrees C using microwave assisted reaction and their crystal structure and optical properties were investigated. Cation/anion ratio and SiO4 content in strontium phosphorous silicate are sensitive to processing conditions such as pH and starting composition of reaction precursors. Stoichiometric Sr-5(PO4)(2)(SiO4):Eu3+ phosphor prepared by the microwave reaction emits more intense red light than previously reported Sr-5(PO4)(2)(SiO4):Eu3+ and Sr-5(PO4)(3)OH:Eu3+ phosphors. As the amount of SiO4 in the anion site increases and P/Si ratio gets close to stoichiometry, the intensity of red luminescence with a narrow band width increases. Strong red luminescence from Sr-5(PO4)(2)(SiO4):Eu3+ synthesized by the microwave-reaction is explained from the viewpoint of defect formation, charge compensation during co-doping process, and local structural symmetry. Large electric dipoles near Eu3+ ions enhance photoluminescence of Sr-5(PO4)(2)(SiO4):Eu3+ from (5)D0-(7)F2 transition at a peak wavelength of 614 nm. This study shows that Sr-5(PO4)2(SiO4):Eu3+ prepared by the microwave reaction is promising red phosphor for white light emitting diode. (C) 2018 Elsevier B.V. All rights reserved.