Temperature sensing materials based on the fluorescence intensity ratio in Li2Ba5W3O15 :Dy3+ phosphors

One of the interesting uses of phosphors is the development of non-contact thermometers apart from their usage as visible photonic devices. A series of Dy3+-doped Li2Ba5W3O15 (LBW) phosphors were successfully synthesized using high temperature solid-state reaction process. The crystal structure and morphology of LBW:xDy(3+) phosphors were studied using X-ray diffraction (XRD), Rietveld refinements and field effect scanning electron microscopy (FE-SEM) with energy dispersive x-ray (EDX) analysis. The XRD and photoluminescence (PL) analyses validated the effective substitution of Ba2+ ions with Dy3+ ions. Two prominent emission peaks were found at 493 and 583 nm corresponding to F-4(9/2)-> H-6(15/2) and F-4(9/2)-> H-6(13/2) transitions respectively under 368 nm excitation wavelength. A comprehensive analysis has been carried out on the usage of the Dy3+ doped LBW phosphors in fluorescence intensity ratio (FIR) thermometry. The optical temperature measurement performance of the LBW:xDy(3+) phosphor was achieved by utilizing distinct thermal quenching transitions, specifically on F-4(9/2)-> H-6(15/2,13/2), at temperatures ranging from 293 to 443 K. The as-prepared phosphors demonstrate excellent performance as optical thermometers, with a maximum relative sensitivity (S-r) of 0.7% K-1 at 293 K, an absolute sensitivity (S-a) of 4.68 K-1 at 443 K and a temperature resolution of similar to 0.51 at 443 K. These values indicate that the phosphors are highly responsive to changes in temperature, making them suitable for non-contact thermometry applications.