Luminescence characteristics of Ca1−xSrxS:Ce nanophosphors

Luminescence characteristics of Ca1−xSrxS:Ce (x = 0, 0.25, 0.50, 1) nanophosphors have been investigated. XRD of all the samples show a single cubic phase of Ca1−xSrxS:Ce. TEM micrographs exhibit the rod like structure of the samples with a decrease in diameter with decreasing amount of Ca. The results of TEM were found to be in good agreement with the XRD results. The photoluminescence spectrum comprises of a main peak in the range 480-510 nm with a shoulder in the range 530-565 nm, which may be ascribed to transitions from 5d-4f levels of cerium in the mixed host lattice. The red shift in the emission wavelength with increasing Ca content may be correlated with the change in crystal field of mixed host lattice for different Ca and Sr concentrations. We have also investigated TL response of Ca1−xSrx:Ce to 60Co-γ rays. All the samples with different Sr and Ca contents show different TL response. TL response for the sample with x = 0.75 shows the simplest TL glow curve with the maximum TL intensity, for which we have calculated the activation energy using glow curve deconvolution functions.