Temperature dependence of luminescence properties in Li2WO4 single crystal grown by Bridgman method

Transparent Li2WO4 single crystal was grown by vertical Bridgman method. The phase identification, Fourier transform infrared spectra, thermal behavior, and optical transmission spectra of Li2WO4 crystal had been studied in detail. The luminescence properties as a function of temperature were investigated systematically. The transmissivity of as-polished crystal samples with the thickness of 2.0 mm, 4.0 mm, and 6.0 mm reached 85–89%, 81–85%, and 78–81% in 400–800 nm wavelength range, respectively. Li2WO4 crystal has wide luminescence peaks around 626 nm, 574 nm, and 543 nm at the ambient temperature of 30 K, 50 K, and 75 K, respectively. The luminescence peaks are ascribed to the intrinsic luminescence emission of tetrahedral [WO4]2-. The emission line width presents an obvious broadening with the increasing temperature. The maximal luminescence intensity increases with the ambient temperatures cooling down. The luminescence decay times monotonically decrease with the temperature increasing in temperature range of 30–75 K. The decay times at 30 K, 50 K, and 75 K correspond to 97.92 μs, 30.16 μs, and 1.97 μs, respectively, while maintain a constant around 1.80 μs in 75–300 K.