Preparation of Fine Silicon Particles from Amorphous Silicon Monoxide by the Disproportionation Reaction

本工作实现了一种新的制备固态硅微粒的简单方法。该方法是基于非晶氧化硅（SiO）对Si和SiO_2的固态氧化还原反应。该反应传统上称为“歧化反应”，其化学式如下：2SiO→Si+SiO_2，其中Si[II]在加热时氧化为Si[IV]，同时还原为Si[0]。结果表明，在非晶SiO_2介质中，在900℃以上析出结晶Si。电镜分析表明，Si以细小的单晶颗粒形式出现，其平均尺寸仅受反应温度控制在几~几十nm之间，通过氧化硅（SiO）的歧化反应，即2SiO→Si+SiO_2，制备了细小的Si颗粒。在900 ~ 1400℃的氩气中加热SiO非晶粉末，用x射线粉末衍射和高分辨透射电镜对样品进行了分析。在1000 ~ 1300℃处理0.5小时以上，形成分散在非晶态氧化介质中的Si颗粒。根据加热温度的不同，颗粒大小从1-3 nm到20-40 nm不等。动力学分析表明，该反应的活化能为1.1 eV （82.1 kJ mol^<-1>）。在1350℃以上退火后，样品变成了硅和方石英的混合物，表明其周围的氧化物由非晶态转变为晶态。

The present work has achieved a new simple method for preparation of fine Si particles in a solid state. This method is based on a solid state oxidation-reduction reaction of amorphous silicon monoxide (SiO) to Si and SiO_2. The reaction, traditionally called "disproportionation reaction", proceeds with the following chemical formula ; 2SiO→Si+SiO_2, where both the oxidation of Si[II] to Si[IV] and the reduction to Si[0] simultaneously occur on heating. As a result, crystalline Si was precipitated above 900℃ in amorphous SiO_2 media. Electron microscope analyses revealed that Si appeared in a form of fine single-crystal particles whose mean size was controlled only by the reaction temperature from several to several ten nm. Fine Si particles have been prepared by the disproportionation reaction of silicon monoxide (SiO), that is : 2SiO→Si+SiO_2. Amorphous powders of SiO are heated between 900 and 1400℃ in a flow of Ar and the obtained specimens are analyzed by X-ray powder diffraction and high resolution transmission electron microscopy. The treatments between 1000 and 1300℃ for more than 0.5 hour result in origination of Si particles dispersed in amorphous oxide media. The particle size varies from 1-3 to 20-40 nm, depending on the heating temperature. Kinetic analyses of the reaction reveal that the activation energy is 1.1 eV (82.1 kJ mol^<-1>). The specimens annealed above 1350℃ changes into a mixture of Si and cristobalite, suggesting a transformation in the surrounding oxides from the amorphous to crystalline states.