Bridgman growth of CdWO4 single crystals

The growth of large size CdWO4 single crystals by vertical Bridgman process is reported in this letter. CdWO4 polycrystalline material with stoichiometric composition was synthesized from CdO and WO3 as the initial materials by solid-state reaction. In the Bridgman growth, the platinum crucibles charged with material were sealed so as to avoid the harmful volatilization of the melt. By means of the growing parameters such as a crucible lowering rate of 0.5–1.5 mm/h and a temperature gradient around 30–40 °C/cm across the solid–liquid interface under a furnace temperature of 1350–1400 °C, a transparent CdWO4 crystal as large as ∅40×70 mm has been grown by the vertical Bridgman process successfully. The crystal was characterized by X-ray diffraction (XRD), optical transmittance, X-ray stimulated luminescence spectrum. The desirable crystalline quality of the grown crystals is verified by XRD rocking curve. The crystal shows a high optical transmittance in the visible wavelength range and a strong emission peaked at 470 nm under X-ray excitation.