| As the astronomy and nuclear physics are improving,γ-ray detectors are applied in increasing areas of human society. The core part ofγ-ray detector is the detecting material. Compared with the current detecting materials such as cadmium telluride (CdTe), thallium bromide (TlBr) is a semiconductor with a relatively high Z (Tl:81,Br:35), high density(7.56g/cm3) and wide band gap(2.68eV). Besides, TlBr melts at relatively low temperature (560℃), and shows no destructive phase transition below the melting point. Hence, the crystal growth can be performed simply from the melt. All the above make TlBr a promising material forγ-ray detection.The working principle ofγ-ray detector determines that the raw materials for growing thallium bromide single crystals should possess high purity. In this paper, hydrothermal method for TlBr purification is studied. Re-crystallized thallium nitride (TlNO3) and distilled (HBr) are applied to synthesize thallium bromide which has been characterized by X-ray diffraction (XRD) and X-ray fluorescent testing (XRF). It has been proved that the synthesized product is single-phased, ultra-pure and stoichiometric ratio of the product is almost 1:1. After the confirmation of the fact that the structure of the hydrothermal bomb will cause fast fluid convection which leads to the unsuitability of the double-temperature purification, therefore, cooling method is applied to purify TlBr. With the guide of cooling model, the temperature of TlBr solution falls under control from 170℃to ambient temperature. The purified product is characterized by Inductive Coupled Plasma- Atom Emission Spectroscope (ICP-AES), which indicates that the total impurities are lowered to 100 ppm. Besides, the recycling of the poisoning TlBr has been studied in the paper. The steps of oxidation by nitric acid and reduction by ammonium sulfide make the regeneration of TlBr.
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