Effect of the synthesis route on luminescence dynamics and thermographic properties of Sm3+doped Ba2Mg(PO4)2 phosphor

The present study investigates the impact of synthesis routes on the structure, optical, and thermographic properties of Ba2Mg(PO4)2:xSm3+ (x = 2 mol.%) phosphor. The two techniques used for the synthesis were combustion synthesis (CS) and solid-state reaction synthesis (SSR). X-ray diffraction analysis confirmed a pure monoclinic phase with space group P21/n in both SSR and CS synthesized samples. The average crystallite size was 41 +/- 0.19 nm for SSR and 21 +/- 0.02 nm for CS phosphors. Using Fourier transform infrared (FTIR) analysis, the vibrational behavior of both synthesized phosphor samples was analyzed. Both samples displayed a bright orange-red photoluminescence (PL) emission, attributed to the 4G5/2 -> 6H7/2 transition when excited with 403 nm light at room temperature. However, the intensity of PL emission was higher in the CS-prepared sample. The UV-Vis absorption measurements indicated several bands in both samples. The CIE coordinates were calculated for both samples and they corresponded to the shade of orange-red emission of the Sm3+ ions. The study also included an investigation into the temperature-sensing characteristics of the synthesized phosphors, which was performed in the 323-673 K temperature range. The fluorescence intensity ratio (FIR) technique was used to study the non-contact temperature sensing for both samples, and the CS-prepared phosphors exhibited the maximum value of absolute sensitivity (0.00629 K-1) and relative sensitivity (0.26 % K-1) at temperature 673 K. Overall, the results indicate that the CS method provides better results in terms of luminescence and temperature sensing characteristics compared to the SSR method.