Effects of Eu3+ concentration on the thermoluminescence properties of narrow-band red-emitting Eu3+: SrLaGaO4 phosphor

A series of Eu3+ doped SrLaGaO4 ceramic phosphors were successfully synthesized by the solid-state reaction method. The optical properties of (x at%) Eu: SrLaGaO4 samples with x = (0.1, 1, 3, 5, 10, 15, 20, 30) were investigated and analyzed. The room temperature emission spectra of xEu: SrLaGaO4 ceramic samples, under blue and UV excitation wavelengths, showed a maximum relative emission intensity at 620 nm, corresponding to the hypersensitive 5D0→7F2 transition, with a full width at half maximum (FWHM) of ∼7 nm, for a doping concentration with Eu3+ ions of 10 at% (x = 10). The asymmetry parameter (the ratio between the 5D0→7F2 and 5D0→7F1 transitions) and the critical distance between Eu3+ ions allowed to obtain a very good color purity of the red emission (88 %) for the 10Eu: SrLaGaO4 phosphor. The cross-relaxation and energy migration processes between Eu3+ ions in the 10Eu: SrLaGaO4 sample are negligible and do not contribute to the quenching of the 5D0 emitting level. From the investigation of the temperature-dependent luminescence intensity ratio (LIR) of the 5D0→7F2 and 5D0→7F1 transitions of the 10Eu: SrLaGaO4 sample in the range of 10–575 K, the relative sensitivity parameter (Sr) was found to be 0.4 % K−1 at 10 K and 0.45 % K−1 at 450 K. These results suggest that 10Eu: SLO phosphor is a versatile material that could be operated as a temperature sensor over a wide range of temperatures, as well as a narrow-band red-emitting phosphor for phosphor-converted white light-emitting diodes (pc-WLEDs).