Structural evaluation of polysilane-derived products: from amorphous to thermodynamically stable phases

Abstract

A polysilane with a C-to-Si ratio of 6.0 was pyrolysed to produce an amorphous matrix (source powder), which was heated further to obtain different products. These polysilane-derived samples were studied using X-ray diffraction, Raman spectroscopy, solid-state magic-angle-spinning nuclear magnetic resonance and transmission electron microscopy. The source powder is a hydrogenated matrix composed of free carbon, random SiC₄ sites and trace SiCO species. Pyrolysis of the source powder leads to the nucleation and growth of SiC and progressive organization of free carbon. SiC forms at 1100°C and fast growth appears at 1700°C accompanied by obvious weight loss. SiC decomposition also occurs at high temperatures, which leads to the formation of relatively well-organized carbon. The structural evolution is discussed and compared with the literature.

Acknowledgements

The authors would like to thank the Andrew Carnegie Research Fund of the Institute of Materials, Minerals and Mining (UK) for providing a PhD research scholarship to X. Li. This study also benefited from The University of London Intercollegiate Research Services; Dr M. Odlyha of Birkbeck College, Dr A. E. Aliev and Mr D. A. Butler and Dr S. Firth of University College London are thanked greatly for help in thermal analysis, NMR and Raman tests, respectively, and for their valuable discussions. Dr I. Abrahams and Mr M. Motevalli are thanked for their assistance with XRD. Dr Z. B. Luklinska, Mr M. Willis and Mr R. Whitenstall are thanked for their help with electron microscopy. Dr M. R. Nangrejo is also thanked for his advice on precursor synthesis.