Spectrally tunable temperature sensitive fluorescence of (Sr x Ca(1−x))S:Cu phosphors

Abstract

The present work aims at investigating spectrally tunable temperature sensitive fluorescence of (SrxCa(1−x))S:Cu; (0 ≤ x ≤ 1) phosphors. Accordingly, these phosphors have been synthesized and their X-ray diffraction (XRD), the excitation and PL emission spectra at room temperature (RT=27°C) and the variation of fluorescence intensity at λmax, the wavelength of maximum intensity, with temperature have been studied. The XRD measurements confirm the formation of mixed lattice of (SrxCa(1−x))S. The lattice constant increases linearly with increase in x (within the lattice constants of end members, i.e. CaS and SrS). With appropriate excitation (λexc varying from 314 nm to 361 nm) at RT, the peak wavelength (λmax) of PL emission can be tuned from 428 nm to 523 nm by varying x from 0 to 1. Further the fluorescence intensity at λmax varies almost linearly with temperature in the range from 40° C to about 140° C. These properties appear to be suitable for thermographic application of these phosphors.