Growth of lead iodide single crystals used for nuclear radiation detection of Gamma-rays

PbI2 single crystals have been fabricated by vertical Bridgeman (VB) method and vertical gradient freezing (VGF) method. The crystal grown by the VGF method exhibited high quality with no stress cracks and high infrared transmission rate compared with the one grown by VB method. A transparent orange PbI2 single crystal with size of Phi 20 mm x 80 mm was obtained by the improved parameters. Electrical resistivity of the crystal was as large as 1.4x10(11)Omega cm, and the infrared transmission rate was as high as 53% in the wave-numbers from 4000 to 400 cm(-1). The wafer was deposited with graphite explode, and the photopeak was very sharp with the shaping time of 2.7 mu s to detect Am-241@ 59.5 keV gamma-rays.