Abstract: CdSe is one of the most important Ⅱ-Ⅵ group semiconductors, it is widely used in the nuclear radiation detection, nonlinear frequency conversion and so on.As the foundation for achieving these applications, the polycrystals act as the base for the growth of high quality CdSe single crystals.However, the traditional synthesis methods have shortcomings of one kind or another, for instance the lower yield or purity.Hence, a modified synthesis method was introduced, with the aid of numerical simulation, by lowering the pressure difference on the inner and outer crucible, about 200 g CdSe polycrystals could be obtained in one run.The XRD, TG/DTA, ICP methods were used to characterize the synthetic materials, the test results show the prepared materials are high purity and suitable for single crystals growth.The effects on the purity of polycrystals probably exist in the synthesis process are also discussed in the paper.

Key words: CdSe is one of the most important Ⅱ-Ⅵ group semiconductors, it is widely used in the nuclear radiation detection, nonlinear frequency conversion and so on.As the foundation for achieving these applications, the polycrystals act as the base for the growth of high quality CdSe single crystals.However, the traditional synthesis methods have shortcomings of one kind or another, for instance the lower yield or purity.Hence, a modified synthesis method was introduced, with the aid of numerical simulation, by lowering the pressure difference on the inner and outer crucible, about 200 g CdSe polycrystals could be obtained in one run.The XRD, TG/DTA, ICP methods were used to characterize the synthetic materials, the test results show the prepared materials are high purity and suitable for single crystals growth.The effects on the purity of polycrystals probably exist in the synthesis process are also discussed in the paper.