Polycrystal Synthesis and Single Crystal Growth of PbI<sub>2</sub>

Abstract

High-pure and single-phase PbI2 polycrystal was synthesized by Pb and I elements (99.9999%) according to the stoichiometry of PbI2 with excess of 0.3% Pb through modified two-zone vapor-transporting method (MTVM). The synthesis reaction was carried in a special quartz ampoule to prevent the ampoule exploding by controlling the temperature. With presynthesized polycrystal, an integral PbI2 single crystal with 15 mm in diameter and 25 mm in length was grown by vertical Bridgman method (VBM). The as-grown crystal was characterized by X-ray diffraction (XRD), ZC36 megger and Infrared (IR) spectrophotometers. XRD analysis indicated the structure of PbI2 crystal is 2H with hexagonal space group of , the lattice constants of a and c are 0.4560 nm and 0.6979 nm, respectively. The IR transmittance of a sample of 2.5 mm thickness is about 40% in the range from 4000 to 400 cm-1. Resistivity of the crystal is about 1013 Ωcm magnitude. These results demonstrate that the quality of the as-grown crystal is high enough for applications of room temperature nuclear radiation detectors.