Кинетический анализ газофазного переноса кремния сульфидом цинка

Abstract

The article gives a theoretical and experimental substantiation of the possibility of vapor transfer of silicon by a sulfide carrier—zinc sulfide. It is shown that, in terms of thermodynamics, the high-temperature interaction of Si with ZnS has all the signs of a chemical transport reaction and occurs at sublimation temperatures of zinc sulfide—above 1330 K. According to thermogravimetry (TG) data processed by the Ozawa–Flynn–Wall and ASTM methods of model-free kinetic analysis, the transfer of silicon in the form of volatile monosulfide can be considered with an acceptable approximation as a one-step reaction with average values of Eα and logA equal to 243.8 kJ/mol and 7.13 s–1, respectively. The temperature dependences calculated by the autocatalysis and solid nucleation models correlate well with experimental data of thermal analysis and do not contradict the proposed mechanism of sequential transformation Si → SiS2 → SiS (gas), where the rate of formation of silicon disulfide plays a decisive role. The HSC 6.1 Chemistry (Outotec) program and the Netzsch Thermokinetics software package were used in thermodynamic calculations and for kinetic analysis, respectively. The obtained information will find application in the development of a new halogen-free method for producing of high-purity silicon.