Luminescence and energy transfer in CsLaSiS4 single crystals doped with Tb3+ and Ce3+ ions

CsLaSiS4 single crystals doped with Tb3+ and co-doped with Ce3+, Tb3+ ions were obtained by a high-temperature flux synthesis. XRD data demonstrate that the samples crystallize in the orthorhombic Pnma space group without additional reflections belonging to the impurity phases. Low-temperature luminescent spectroscopy methods have been used to study the efficiency of radiative transitions and energy transfer between Ce3+ and Tb3+ ions. Additionally, the effect of irradiation with protons with an energy of 18 MeV from a cyclotron was studied. Spectral-kinetic measurements of pulsed cathodo- and photoluminescence of samples co-doped with Ce3⁺ and Tb3⁺ revealed bidirectional energy transfer processes between these ions, the parameters of nonradiative energy transfer Ce3+ → Tb3+ were determined. The effect of concentration quenching is observed in undoped CsTbSiS4. The method of low-temperature thermally stimulated luminescence and the kinetics of pulsed cathodoluminescence indicate a high concentration of "shallow" carrier trapping centers in doped samples. When irradiating CsLaSiS4:0.5%Ce sample with protons, both the low-temperature emission of self-trapped excitons (STE) and the energy transfer STE → Ce3+ decrease, the luminescence yield of defect-bound excitons (DBE) also decreases compared to the emission of Ce3+ ions, and defects are mainly formed, which are the centers of nonradiative recombination of band charge carriers. [Display omitted] •Monophasic single crystals of CsLaSiS4 doped and co-doped with Tb and Ce were obtained by high-temperature flux synthesis.•Spectral-kinetic studies upon UV, X-ray and e-beam excitations were carried out.•Bidirectional energy transfer processes between Ce3+ and Tb3+ ions were observed.•Postradiation optical effects of 18 MeV proton irradiation were studied.