A six-mode optical thermometry rooted from the distinct thermal behavior of SrLaLiTeO6: Mn4+, Eu3+ double perovskites and their potential application in wavelength detection
Sariga C. Lal, I. N. Jawahar, Subodh Ganesanpotti
Abstract
Developing accurate and reliable temperature sensors with better temperature sensitivity, high spatial, temporal, and temperature resolutions via cost-effective methods is a major concern in the scientific world. Optical thermometry has gained worldwide interest owing to its unique features compared to its conventional counterparts. For the first time, a six-mode optical thermometry is implemented in Eu3+ and Mn4+ co-doped SrLaLiTeO6 (SLLT) double perovskites. X-ray diffraction analysis identified the crystal structure of the phosphor as monoclinic (P21/n). Additionally, the Raman and FTIR spectra confirmed the successful incorporation of Eu3+ and Mn4+ ions into the SLLT host. Thermometric properties of SLLT: Eu3+, Mn4+ over a wide temperature range were analyzed using fluorescence intensity ratio (FIR) of Mn4+ to Eu3+ emissions, TCL-based FIR, dual excitation single emission band (SBR) ratio, the ratio of charge transfer absorption edge of the host to 4f-4f absorption of Eu3+ ions, lifetime and line broadening methods. A maximum temperature sensitivity of 1.97% K−1 at 200 K is obtained using the intensity ratio of absorption bands in the excitation spectra, 0.33% K−1 at 340 K is obtained using the lifetime method, and 0.20% K−1 at 500 K is obtained using the line broadening method. The study envisages double perovskites as potential optical temperature sensors if a proper sensing method is identified to detect temperature. SLLT: Eu3+, Mn4+ is also examined for wavelength detection in the range 270–330 nm and proves to be a promising candidate for wavelength detection with maximum wavelength sensitivity of 8.09% nm−1 at 305 nm.