Red emitting phosphors based on titanite with high thermal stability

• Na+ was doped into (Ca, Eu)TiSiO5+δ to prevent the reduction of Ti4+ to Ti3+.
• Emission intensity of (Ca0.93Eu0.07)TiSiO5+δ was enhanced by codoping of Na+.
• (Ca0.90Eu0.07Na0.03)TiSiO5+δ showed the highest emission intensity of 22%.
• (Ca0.90Eu0.07Na0.03)TiSiO5+δ had higher thermal stability than commercial phosphor.

Red emitting phosphors based on titanite, (Ca1−x−yEuxNay)TiSiO5+δ (x = 0.05, 0.07, 0.10; y = 0, 0.01, 0.03, 0.05), were synthesized by the conventional solid state reaction method, and their photoluminescence properties were investigated. Among (Ca1−xEux)TiSiO5+δ (x = 0.05, 0.07, 0.10), (Ca0.93Eu0.07)TiSiO5+δ (x = 0.07) showed the highest emission intensity of 14% in comparison with the commercial (Y0.98Eu0.02)2O2S phosphor. Introduction of monovalent Na+ into the (Ca0.93Eu0.07)TiSiO5+δ lattice also enhanced the emission intensity by preventing the reduction of Ti4+ to Ti3+. Consequently, the (Ca0.90Eu0.07Na0.03)TiSiO5+δ phosphor enhanced the emission intensity up to 22%. From the thermal analysis results, it is revealed that the thermal stability of the present (Ca0.90Eu0.07Na0.03)TiSiO5+δ phosphor was much higher than that of the commercial one.