Remote optical thermometry by two-dimensional LiAl5O8:Cr3+ luminescence sensor probe

Pure-phase LiAl5O8:Cr3+ leaf-like particles were synthesized by combustion synthetic route at various concentrations. Both sharp peaks and broad emission photoluminescence are apparent even at room temperature. The most optimum doping concentration of 0.75% based on lifetime and emission intensity was chosen. Peaks of different configurations were separated by deconvolution from 120 K to 680 K, where 4T2 peak increases in temperature to the expense of the sharp 2E emissions, giving luminescence intensity ratio (LIR) relative sensitivity of 2.8% K-1 at room temperature. Large separation between Cr3+ R lines marks their LIR as perspective at low temperatures. At high temperatures luminescence lifetime provided for 0.8% K-1 sensitivity, while line-shift and bandwidth methods are not sensitive enough for thermometric applications. Deconvolution of peaks enabled for 10% more precise estimation of Debye temperature (679 K).