采用红外漫反射光谱研究纳米Si_3N_4的表面结构

Study of Surfacial Structure of Nano Si_3N_4 by Fourier Infrared Diffusion Reflection Spectra

采用付利叶红外漫散反射光谱对激光法制取的具有不同化学组成的纳米Si3N4粉（15-30nm）的表面结构，室温表面氧化及热稳定性进行了研究.结果表明新鲜的富氮粉体表面主要为硅胺基（Si3-xNHx，x=1-3）结构，粉体暴露空气后硅胺基会与空气中的水分子反应形成硅醇基（SiOH）结构.具有不同组成的粉体随粉中氮含量的增大粒子表面硅胺基量也增加；富硅粉体表面硅胺基较少，其氧化主要为表面硅原子与空气中氧原子形成Si－O键．

The surface structure, ambient okidation and thermal stability of the lasersynthesized Si3N4 nano powders (15-30nm) with different compositions have been studied by Difusion Reflectin Infrared Fourier Transform (DRIFT) spectra. Results show that the nitrogen rich powders with a freshed surface have silazane structure (Si3-xNHx, x=1-3)and this silazane group reacts with water in the air to form silanol group (Si-OH). The amount of the silazane groups increases with the increase of the nitrogen content in the powders. The silicon rich powders have little silazane on powder surface and the oxidation of the powders occurs by the formation of Si-O bonds from the reaction between the surface Si atoms and the oxygen in the air. The silazane groups and the silanol groups are edrinated from the particle surface upon a vaccum annealing at temperature higher than 600 and 1500℃, respectively.