Effects of nanostructuring on luminescence properties of SrS:Ce,Sm phosphor: An experimental and phenomenological study

Abstract In this work, we employ various experimental techniques to illustrate the effects of nanostructuring on improvement of the luminescence properties of the polycrystalline SrS co-activated by cerium and samarium dopants ( S r S : C e , S m ). The nano and microstructure S r S : C e , S m powders were synthesized by the co-precipitation and solid state diffusion methods, respectively, followed by the spark plasma sintering (SPS) process to densify powders into pellet shape. It is observed that the photo-luminescence (PL), radio-luminescence (RL), and optically stimulated luminescence (OSL) emission intensity of the nanostructure samples are significantly improved with respect to the microstructure samples. Moreover, by using an accurate photomultiplier tube, we measured the CW-OSL decay curves of the samples to demonstrate much higher and faster sensitivity of the nanostructure S r S : C e , S m for in-flight and online OSL radiation dosimetry. The obtained absorption and emission spectra are used for phenomenology of the electronic band structure of the S r S : C e , S m micro and nano-phosphors inside the band gap. The proposed phenomenological electronic structures are then used to clarify the role of C e 3 + and S m 3 + localized energy levels in the luminescence properties of the nano and microstructure samples. It is argued that electronic transitions from the T 2 2 g state of C e 3 + and the G 4 5 / 2 state of S m 3 + have strong contribution to the PL and RL emission spectra, while in the OSL mechanism, the S m 3 + G 4 5 / 2 state is mainly responsible for electrons trapping.