Реферат: Single-phase crystals of the solid solution CsLaxCe1–xAB4 (x = 0 – 1; A = Si,Ge; B = S,Se) were obtained by high-temperature flux synthesis and studied by absorption and low-temperature (from 5 K) luminescence spectroscopy, DFT calculations of the band structure. According to calculations and absorption spectroscopy data, the La → Ce, S → Se or Si → Ge replacements in initial CsLaSiS4 leads to a decrease in the band gap determined in the Tauc model: Eg = 3.76 (CsLaSiS4), 3.50 (CsLaGeS4), 3.18 (CsLaSiSe4), 2.75 eV (CsСеSiS4). The 4f5d excited states of Ce3+ are located in the band gap, therefore a non-elementary d → f band of Ce3+ emission is observed in the 520 – 600 nm region in the photoluminescence (PL) spectra at any value of the x parameter. The Ce3+ luminescence decay kinetics upon excitation by a pulsed electron beam or X-ray synchrotron radiation is characterized by a dominant ns-component. With an increase in the x parameter, the decay time decreases. Concentration quenching of Ce3+ emission is clearly visible at x = 1 [1]. New intense emission bands appear in the visible region and at ~ 700 – 760 nm in the PL spectra of all pure or lightly doped Ce3+ matrices at T = 5 K. They are due to the emission of self-trapped excitons (STEs) and defects, respectively. No emission of free excitons (FE) was detected. With increasing of x parameter, the STE emission band is reabsorbed due to absorption by Ce3+ ions and is quenched due to STE → Ce3+ energy transfer. STE PL is excited exclusively in the region of the long-wavelength fundamental absorption edge and interband transitions. At low temperatures, Ce3+ emission and defect emission are effectively excited both by intracenter or recombination pathways and by creating defect-bound excitons (DBE). The Stokes shift of the STE emission band, the exciton binding energy, and the region of PL temperature quenching depend on the matrix composition (La → Ce, S → Se, Si → Ge). At temperatures above ~25 K, the PL of the STE is quenched according to the Mott law due to the autoionization of excitons [2-4]. Additionally, the effects of irradiating crystals with 18 MeV protons from a cyclotron were studied using PL, absorption and thermal activation spectroscopy methods. CsLaSiB4 (B = S, Se) thiosilicates doped with Ce3+ ions are promising as effective fast radiation-resistant detectors of various types of ionizing radiation.

Библиографическая ссылка: Tavrunov D.A. , Pustovarov V.A. , Sarychev M.N. , Sapov A.A. , Tarasenko M.S.
Fast radiation converters based on solid solutions of chalcogenides: electronic structure, optical properties
10th International Congress on Energy Fluxes and Radiation Effects 14-18 Sep 2026