Study On Influencing Factors Of Silicon Material Prepared Via Molten Salt Electrolysis

Pure Si is not present in nature.Preparation of elemental silicon is particularly important.Since 2000,the global$7.5 billion silicon materials industry has driven the250 billion semiconductor integrated circuit industry?More than 95%of semiconductor devices are used,and more than 99%of integrated circuits are silicon materials?.This has led to the rapid development of modern information industries such as optical fibers,computers and communications.Therefore,the preparation of high-quality silicon resources and preparation techniques have become an immediate priority.The current methods for preparing silicon include metallurgical methods,modified Siemens method,silane thermal decomposition method,and carbothermal reduction method.However,these preparation methods have disadvantages.The molten salt electro-deoxidation method is widely concerned at home and abroad as a new method for preparing silicon materials.In this paper,silicon material was prepared on the FFC process.The thermodynamic data was used to determine the range of the electrolytic voltage in the experiment.The different cathodic conductive materials,cathode and anode spacing,corresponding surface of cathode and anode are analyzed to determine the most suitable experimental conditions.The main reasons for the difference in morphology of Si products at different electrolysis voltages are the differences in their electrolytic reduction mechanisms.The reduction mechanism of high voltage?3.2 V?and low voltage?2.2 V?is further proposed according to the core-shell reaction model.The effect of electrolysis time and temperature on the morphology of the product was described.Explore the different post-treatment methods,the effects of natural cooling and sudden drop temperatures,water washing and dilute hydrochloric acid cleaning on the electrolytic products.The main research work and result are as follows:In order to find the best experimental conditions,the optimal cathodic conductive material,cathode spacing and cathode-anode mapping surface were selected by current efficiency.The cathode uses molybdenum wire,titanium sheet and foamed nickel as cathode conductive materials.The results show that the molybdenum wire wound cathode has the best current efficiency.The optimal anode and cathode spacing is determined by the amount of electron transport path and the amount of attached cathode graphite carbon powder.Experimental data show that the optimal spacing between the anode and cathode is 3 cm.The electrolysis efficiency of the front surface of the anode graphite rod and the side surface of the cathode quartz wafer is far less than the current efficiency of the front and front surfaces.Therefore,the experiment selected molybdenum wire as the cathode conductive material,the anode and cathode spacing is3 cm,the anode and cathode front and the front of the corresponding.The microscopic morphology of electrolytic samples under different voltages was analyzed,and it was found that the morphology was different under different voltages.With the decrease of voltage,the microcosmic morphology of silicon material presents a nanometer law.Based on the test results and the core-shell reaction model,a more specific electrolytic reduction mechanism with large voltage?3.2 V?and small voltage?2.2 V?was proposed.According to the change of morphology of the product at different electrolysis times,the electrolysis process of a SiO₂ particle is divided into four stages.When the electrolysis time is 1 h,it is in the second stage of electrolysis;when it is 2 h,it is in the mixing of the third stage and the fourth stage.When the electrolysis time is 3 h,the SiO₂ particles are completely reduced and are in the fourth stage of electrolysis.The shape of the hollow capsular silicon is successfully controlled by controlling the temperature.Under the condition of constant temperature of 1173 K,the hollow-sac-like nano-silicon particles were prepared by fused-salt electrolytic quartz crystals,and the hollow-capsular micro-silicon particles and nano-silicon particles were prepared at a temperature ranging from 1178 to 1208 K.Experiments have found that different cooling methods have a great influence on the electrolytic products.The product of electrolysis,which is naturally cooled,is mainly silicon.After the acid washing,Si with better crystallinity is obtained;Dipping temperature to obtain electrolytic product Ca-Si compound;Therefore,the post-treatment methods that should be selected for the preparation of silicon in this experiment are natural cooling and dilute hydrochloric acid cleaning.