Thermal annealing effects on the luminescence and scintillation properties of CaMoO4 single crystal grown by Bridgman method

CaMoO4 single crystal with high quality and large size was grown by Bridgman method. The as-grown CaMoO4 crystal presents blue-black color, and the annealed CaMoO4 crystal presents optically transparent. The mechanisms of crystal fading by thermal annealing were explained in detail. The annealing effects on the optical transmission, photoluminescence spectra, X-ray luminescence spectra and luminescence decay time were investigated. The results indicate that thermal annealing not only has positive effects on reducing oxygen vacancies and alleviating the self-absorption phenomenon, but also the luminescent intensity can be enhanced greatly. The annealed CaMoO4 crystal has moderate Stokes shift (1.46 eV). The light output of annealed CaMoO4 single crystal by the excitation of 662 KeV X-ray from a 137Cs source was measured to be 57.9 p.e. per MeV. This work offers detailed and significant data of scintillation properties of CaMoO4 single crystal, which are very helpful for potential applications in searching for rare events especially in neutrinoless double beta decay area.