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:xDy3+ 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 583nm corresponding to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions respectively under 368nm 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:xDy3+ phosphor was achieved by utilizing distinct thermal quenching transitions, specifically on 4F9/2→6H15/2,13/2, at temperatures ranging from 293 to 443K. The as-prepared phosphors demonstrate excellent performance as optical thermometers, with a maximum relative sensitivity (Sr) of 0.7% K-1 at 293K, an absolute sensitivity (Sa) of 4.68K-1 at 443K and a temperature resolution of ~0.51 at 443K. These values indicate that the phosphors are highly responsive to changes in temperature, making them suitable for non-contact thermometry applications.