Growth and Luminescence Properties of Large-Size Na2Mo2O7 Single Crystal by the Vertical Bridgman Method

This study investigates the growth and luminescence properties of Na₂Mo₂O₇ crystal for the application in the low-temperature radiation detectors, specifically for neutrinoless double β decay research. φ25 and φ40 mm Na₂Mo₂O₇ transparent crystals are grown by the vertical Bridgman method. The crystal phase is characterized using X-ray diffraction (XRD), Raman spectrometer, thermogravimetric-differential thermal analysis (TG-DTA), and energy dispersive spectroscopy (EDS). UV–vis spectrophotometry reveals that the crystal exhibits high transmittance, reaching up to 84%. Fluorescence spectrometry indicated that the emission spectrum of Na₂Mo₂O₇ reaches its maximum intensity at 80 K. The luminescence decay time increases with decreasing temperature, and the decay time at 10 K is 697.5 µs. The activation energy (E_a) of the crystal is fitted to be 193.3 meV. The result shows that the Na₂Mo₂O₇ crystal has excellent luminescence properties at low temperatures.