Low temperature synthesis of SrS:Ce phosphor by carbothermal reduction method: Influence of sulfur and charge compensator on the luminescent properties

We report here on an ecologically friendly carbothermal reduction method to realize SrS:Ce phosphor. The method effectively reduces the preparation temperature by 100 °C. The effect of sulfur and charge compensator were studied separately and in combination, on the luminescent properties of SrS:Ce phosphor prepared from SrSO4:Ce(SO4)2·4H2O using this method without inert gas or hazardous gas (H2S) environment. To analyze the role of charge compensator on the luminescent emission property of SrS:Ce, various fluxes, viz., NH4Cl, NaCl were used. The synthesized products were characterized by XRD, photoluminescence emission and excitation spectroscopy (PLE). SrS:Ce showed a bright blue–green emission at 480 and 540 nm corresponding to energy bands originating from 2T2g (5d) to 2F7/2, 2F5/2 (4f) of Ce3+ transitions. The characterization results showed the formation of SrS calcined at 900 °C for 5 h with an increase in blue–green luminescence intensity after the addition of sulfur and charge compensator, separately. When the sulfur and NH4Cl were jointly added, the intensity of blue emission was enhanced, whereas, that of green emission was suppressed. The excitation spectrum showed a fundamental absorption of SrS host crystal lattice at 283 nm and Ce3+ absorption at 430 nm respectively. The CIE (Commission International de’Eclairge) chromaticity coordinates of the phosphor are also reported.