熔盐电解法制备多晶硅的研究
发布时间：2018-11-04 15:55
【摘要】：随着经济的发展，石油等传统能源日益枯竭而且人们对环境问题的日益重视，使得世界各国都极力开展新能源的开发和利用。太阳能由于具有清洁安全、无污染、相对持续、稳定以及能源取之不尽等优点被认为是最理想的可再生资源。 本文是以二氧化硅粉末为原料，以熔盐电解法为技术核心结合传统冶金法进行技术集成，直接制备多晶硅，然后对其进行了工艺研究。通过热力学计算，得出二氧化硅的理论分解电压为1.10 V(vs.Ca~(2+)/Ca)。在熔融CaCl_2体系中，进行直接电解还原SiO_2制取Si的实验，对电解产物进行了XRD、SEM、EDS分析，结果表明：在电解温度850℃，，槽电压2.6 V下电解12个小时可以得到晶体化程度高和纯度高的硅，纯度达到了96.95%。通过对不同电解电压下产物的分析，表明在2.6 V下发生离子化反应，在2.8 V下发生钙热还原反应。研究了电解工艺条件的影响，表明电解电流随着试样的质量的增加而增大；烧结温度和电解温度会对电流效率产生影响，在600℃的烧结温度和850℃电解温度时，电流效率最高；对电解产物表面分析结果表明：造成后期电流变大的主要原因是石墨脱落和副反应的发生；在不同温度下的CaCl_2 (50 mol%) NaCl混合熔盐中，成功电解出硅，证明了低温熔盐电解的可行性。对熔盐电解硅的反应机理进行了分析，其可能的还原过程为：首先二氧化硅发生电化学还原，脱离出氧原子而形成具有闲置键的硅反应中间态，中间态硅原子与邻近的硅原子以Si-Si键的形式结合，迅速生成非晶态硅，在850℃的温度下，非晶硅将发生晶型的转变，重排而生成晶体硅。
[Abstract]:With the development of economy, oil and other traditional energy are increasingly exhausted and people pay more and more attention to environmental problems, which makes the countries all over the world try their best to develop and utilize new energy. Solar energy is considered to be the most ideal renewable resource because of its advantages of clean, safe, pollution-free, relative sustainability, stability and inexhaustible energy. In this paper, polysilicon is synthesized directly from silicon dioxide powder with molten salt electrolysis as the core technology and traditional metallurgical process. By thermodynamic calculation, the theoretical decomposition voltage of silica is 1.10V (vs.Ca~ (2) / Ca). In the molten CaCl_2 system, the direct electrolytic reduction of SiO_2 to produce Si was carried out. The results of XRD,SEM,EDS analysis showed that the electrolysis temperature was 850 鈩
本文编号：2310342
[Abstract]:With the development of economy, oil and other traditional energy are increasingly exhausted and people pay more and more attention to environmental problems, which makes the countries all over the world try their best to develop and utilize new energy. Solar energy is considered to be the most ideal renewable resource because of its advantages of clean, safe, pollution-free, relative sustainability, stability and inexhaustible energy. In this paper, polysilicon is synthesized directly from silicon dioxide powder with molten salt electrolysis as the core technology and traditional metallurgical process. By thermodynamic calculation, the theoretical decomposition voltage of silica is 1.10V (vs.Ca~ (2) / Ca). In the molten CaCl_2 system, the direct electrolytic reduction of SiO_2 to produce Si was carried out. The results of XRD,SEM,EDS analysis showed that the electrolysis temperature was 850 鈩
本文编号：2310342
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