Thermal expansion, luminescence, and scintillation properties of CaMoO4 crystals grown by the vertical Bridgman method

CaMoO4 crystal is a promising scintillator for investigating the neutrinoless double beta decay process and is commonly grown by the Czochralski method. In this study, CaMoO4 single crystals were grown by the vertical Bridgman method using both spontaneous crystallization and seed crystal approaches. The CaMoO4 crystal grown using the spontaneous crystallization approach exhibited yellow, light blue, and deep blue colours (from top to middle part of the ingot). The thermal expansion coefficients, αa and αc, were calculated to be 6.11 × 10−5/°C, and 23.58 × 10−5/°C, respectively. The optical transmission spectra and photo- and thermally stimulated luminescence spectra of the crystals before and after thermal annealing were also investigated. The yellow cubic CaMoO4 crystal showed the highest x-ray-stimulated luminescence intensity and the best light output under the excitation of a 137Cs radioactive source.