Spectroscopic and temperature sensing properties of Sm3+ in self-activated CsLu(WO4)2 phosphors

Abstract

In this research, a series of Sm3+ doped CsLu(WO4)2 phosphors was prepared via high temperature solid phase technique to design new red phosphors and optical thermometric materials. Their structures, morphology, band gap and luminescence properties were characterized by X-ray diffraction, scanning electron microscopy, diffuse reflection and luminescence spectra, respectively. Under UV excitation, CsLu(WO4)2 gives rise to a blue broad emission band between 350 and 700 nm, which stems from the 3T1u → 1A1g transition of WO66− groups. When Sm3+ is introduced into CsLu(WO4)2, energy transfer between WO66− groups and Sm3+ ions takes place in CsLu(WO4)2:Sm3+ phosphors, and color-tunable luminescence from blue to red is realized by controlling the Sm3+ doping concentration. The energy transfer efficiency between WO66− groups and Sm3+ ions was analyzed, and the energy transfer mechanism was determined to be dipole–dipole interactions. According to the temperature-dependent luminescence spectra, WO66− groups and Sm3+ ions exhibit large discrepancy in thermal quenching rates, and thus the temperature sensing properties of CsLu(WO4)2:Sm3+ in the temperature range of 283–403 K were analyzed. Based on the framework of fluorescence intensity ratio theory, the basic optical thermometry parameters including absolute and relative sensitivity of CsLu(WO4)2:Sm3+ were calculated and the results show that it has great potential for application in optical thermometry.