Cool white light emission on Ca3−(l+n)MgSi2O8: $\mathrm{Ce}_{\mathrm{l}}^{3+}$ , $\mathrm{Eu}_{n}^{2+}$ phosphors and analysis of energy transfer mechanism

Abstract

Rare earth ions (Ce3+, Eu2+) activated Ca3MgSi2O8 (CMSO) phosphors have been synthesized using solid-state reaction method in 95%N2+5%H2 reduction atmosphere at elevated temperatures by varying Eu2+ concentration from 0.0075 to 0.0300 at the fixed Ce0.03 concentration to study their photoluminescence (PL) properties. An energy transfer occurs from Ce3+ to Eu2+ through a significant overlap of Eu2+ excitation spectrum with Ce3+ emission spectrum in CMSO, together with the systematic relative decrease and increase in emission bands of Ce3+ and Eu2+, respectively, have been observed. To support the phenomenon, diffuse reflectance spectra show various absorption levels corresponding to Ce3+, Eu2+, and/or mixture of both rare earth ions. An optimum emission was realized at 0.0150 of Eu2+ via. energy transfer from Ce3+ ion. By utilizing the principle of energy transfer, the critical distance (Rc) between activator ions was found to be 18.64 A. The CIE chromaticity coordinates measured on the Ca3MgSi2O8:Ce3+, Eu2+ phosphors excited under ultraviolet (365 nm) source shows the values lie in cool white light region could be applied to solid state lighting.