Bridgman growth and temperature dependent photoluminescence properties of ZnMoO4 crystals by modification with Zn2+, Mo6+, Ca2+ and W6+ ions

Abstract Zinc molybdate (ZnMoO 4 ) crystal is considered as a promising scintillator for neutrinoless double beta decay. In this paper, ZnMoO 4 crystals by modification with, such as Zn 2+ ions or Mo 6+ ions in excess of 0.2 mol% and doped by 0.5 mol% Ca 2+ ions or W 6+ ions, were grown by the vertical Bridgman method using spontaneous crystallization. All the as-grown slightly adjusted ZnMoO 4 crystals appeared light orange and the transmittance of crystals with the thickness of 2 mm were about 85% from 600 to 800 nm, which is higher than that with stoichiometry (75%). ZnMoO 4 crystals were indirect crystals with optical energy band gap of 3.69 eV and luminesced from 77 K to room temperature, while the intensities were very weak at room temperature. With the temperature increasing, the luminescence light yield of ZnMoO 4 crystals decreased. ZnMoO 4 crystal doped by 0.5 mol% W 6+ ions had the highest light yield at 77 K ZnMoO 4 crystal doped by 0.5 mol% Ca 2+ ions had the shortest decay time (τ = 9.1 μs at 300 K and τ = 72.7 μs at 77 K).