摘要：低温水溶液法是合成低维材料的方法之一，这种合成方法耗时较小，所需设备简单，反应温度低，在敞开环境中操作，便于观察合成过程。在本文中我将采用低温水溶液法制备碲化铋纳米晶，并研究PH值和络合剂对产物的物相、形貌和热电性能的影响。主要研究内容如下：

1.以氯化铋、碲粉为原料，硼氢化钾为还原剂，EDTA为络合剂，氢氧化钾为碱性调节剂，采用低温水溶液法制备碲化铋纳米晶，并改变氢氧化钾的含量，研究PH值对产物的成分、形貌和热电性能的影响；

2. 以氯化铋、碲粉为原料，硼氢化钾为还原剂，氢氧化钾为碱性调节剂，EDTA为络合剂，采用低温水溶液法制备碲化铋纳米晶，并改变EDTA的含量，研究EDTA含量对产物的成分、形貌和热电性能的影响。

最后运用XRD衍射等方式对生成的产物粉末进行了物相分析，获得结果如下：

通过低温水溶液发，以Te粉，BiCl3为合成原材料，以EDTA，氢氧化钾以及硼氢化钾为反应添加剂，进行碲化铋晶体粉末的反应合成。其反应温度始终控制在65摄氏度左右的范围内，连续反应5小时，最终能够得到相对较纯的碲化铋晶体。并且，EDTA不是必须的添加剂，对产物纯度没有影响，但是，氢氧化钾必须添加，而且要足量。

另外，络合剂EDTA可以抑制碲化铋纳米晶的相互吸附作用，使之不能成团，保证了晶粒的细化，从而提高其的散射系数。

关键词：热电材料；碲化铋；低温水溶液法

Preparation of bismuth telluride nanocrystals and their thermoelectric properties by low temperature aqueous solution method

Abstract:Low-temperature aqueous solution method is one of the synthesis of low-dimensional materials, the synthetic method takes less, the required equipment is simple, low reaction temperature, operation in the open environment, convenient for observation synthesis process.In this paper, I will prepare bismuth telluride nanocrystals by low temperature aqueous solution method, and study the effect of PH value and complexing agent on the phase, morphology and thermoelectric properties of the products.The main research contents are as follows:

1. With chlorinated bismuth and tellurium powder as raw materials, potassium borohydride as reducing agent and EDTA as complexing agent and potassium hydroxide alkaline regulator, low-temperature aqueous solution prepared bismuth telluride nanocrystals, and change the content of potassium hydroxide, the PH value to the product of the influence of the composition, morphology and thermal properties;

2. With chlorinated bismuth and tellurium powder as raw materials, potassium borohydride as reducing agent, potassium hydroxide alkaline regulator, EDTA as complexing agent, low-temperature aqueous solution prepared bismuth telluride nanocrystals, and change the content of EDTA, the EDTA content on the product of the influence of the composition, morphology and thermal properties.

Finally, XRD diffraction and other methods were used to conduct physical phase analysis of the product powder, and the results were as follows:

The synthesis of bismuth telluride crystal powder was carried out by using Te powder and BiCl3 as synthetic raw materials and EDTA, potassium hydroxide and potassium borohydride as reaction additives.The reaction temperature is always within a range of about 65 degrees Celsius, and the reaction lasts for 5 hours. Finally, relatively pure bismuth telluride crystals can be obtained.Moreover, EDTA is not a necessary additive and has no effect on the purity of the product. However, potassium hydroxide must be added in sufficient quantity.

In addition, complexant EDTA can inhibit the mutual adsorption of bismuth telluride nanocrystals and prevent them from forming into clumps, which ensures the refinement of the grains and improves their scattering coefficient.

Keywords:  Bismuth telluride; Thermoelectric materials; Solvent heating.