Synthesis of Polyceriborosilazane via Substitution and Polymerization and Pyrolysis to SiBCN(Ce) Ceramics

摘要

The introduction of metal atoms into the molecular network of polymer precursors allows the formation of polymer-derived ceramics with multi-element network which is attractive to the development of high temperature ceramics and functional materials. In this work, rare-earth metal -cerium (Ce) is introduced into polyborosilazane (PBSZ) through the substitution and polymerization reactions and a novel molecular precursor of polyceriborosilazane (PCeBSZ) is synthesized. The synthesis of PCeBSZ starts from PBSZ through lithium substitution with BuLi followed by Ce replacement using CeCl_3 as the precursor. The chemical structure of the PBSZ and the Li containing PBSZ intermediate are characterized and analyzed by Fourier transform infrared spectroscopy. SiBCN ceramics containing Ce (SiBCNCe) are formed by pyrolysis of the PCeBSZ precursor in argon flow at 1100 °C for 2 h. X-ray photoelectron spectroscopic analysis of the ceramics reveals the ceramic has multi-components consisting of Ce , Si, B , C and N. Scanning electron microscope observation shows the presence of dense phase in the ceramics and micro pores on the surface.