Investigations on spectroscopic and optothermal ability of bright red-emitting Cr doped LiAlSi3O8 nanophosphor

The present article reports the synthesis of LiAlSi3O8 nanophosphor doped with the trivalent Cr ion, synthesized by the conventional high-temperature coprecipitation method. The structural, morphology, photoluminescence and optothermal studies were carried out in detail. The analysis revealed the precipitation of the tetragonal structure of LiAlSi3O8 nanophosphor with an average crystalline size of ∼ 23 nm. The laser (450 nm) excitation was carried out for which samples yielded an intense, broad and asymmetrical emission band centered at 717 nm (orange-red region), corresponds to 2Eg→4A2 g transition of Cr3+ ion. The concentration-dependent, laser power-dependent and thin film analysis of the samples were carried out. The optimum Cr dopant concentration was found to be 0.06 mol%. The optothermal analysis based on the ‘luminescence intensity ratio’ method reveals that the emission intensity variation of states (2Eg and 4T2) may use for temperature estimation and serve as temperature sensor. The calculated value of activation energy ΔE was found to be 1917 cm−1, having maximum relative sensitivity of 3.06 % K−1 at 300 K. The detailed color analysis was also carried out by estimating CIE coordinates for different temperatures and laser powers. A significant variation in the coordinates was observed and discussed.