Czochralski growth, electronic structure, luminescence and scintillation properties of Cs2Mo3O10: A new scintillation crystal for 0νββ decay search

Abstract

A new molybdenum (Mo) based Cesium tri-molybdate (Cs2Mo3O10) single crystal scintillator has been grown successfully by the Czochralski technique. The crystal growth conditions such as pulling, rotation and cooling rate were optimized for crack free high-quality single crystals. The electronic band structure has been calculated with density functional theory using projector augmented wave potentials as implemented in the Vienna ab initio Simulation Package. The major contribution in the formation of valence band near the fermi level is observed from Mo and O p orbitals while the bottom of the conduction band mainly consists from Mo-d and O-p states. The grown crystal possesses good transparency above the fundamental absorption edge in the wavelength range of 400–900 nm. Optical band gap of 3 eV is estimated from the absorption spectra measured at room temperature. Luminescence and scintillation properties were measured in the temperature range of 10–300 K under the excitation of UV light at 4.42 eV, X-rays and beta rays. The emission spectrum measured at 230 K is comprising of a single band peaking at 645 nm, which intensity is enhanced with the cooling of crystal. A single exponential photoluminescent decay time of 43 μs is obtained at 220 K which further slows down upon cooling of the crystal and found to be 1.64 ms at 10 K. The scintillation light yield of Cs2Mo3O10 crystal at 10 K is found to be 185% of Li2MoO4 (LMO) crystal. The thermally stimulated luminescence (TSL) kinetic parameters such as trap depth and frequency factor from the glow curve measured after X-ray irradiation at 10 K, have been determined using general order kinetics. A possibility of crystal growth with large volume, good optical, luminescence and scintillation properties reveal that this scintillation material can be a good candidate for the neutrinoless double beta (0νββ) decay search of 100Mo.