乱层石墨结构的硼碳氮化合物在高温高压下的晶化与分相

Crystallization and decomposition of turbostratic B-C-N compound under high temperature and pressure

以硼酸和三聚氰胺为原料,采用化学法制备了乱层石墨结构的B-C-N化合物。在5.5GPa、800～1500℃条件下对该化合物进行了高温高压处理。采用X射线衍射（XRD）、透射电子显微镜（TEM）以及电子能量损失谱（EELS）对所制备的样品进行了结构、形貌和成分分析。研究结果表明：在5.5GPa压力下,随着温度的升高,B-C-N化合物逐渐由乱层石墨结构转变为六方结构,在1200℃时,得到了结晶较好的六方B-C-N化合物,同时样品中含有少量的六方BN和非晶C。当温度高于1400℃,B-C-N化合物完全分解成六方BN和石墨。

A turbostratic B-C-N compound was prepared using boric acid and melamine as starting materials by a chemical process.Then,this turbostratic B-C-N compound was treated at 5.5GPa and 800-1500℃.The structural and composition analyses for the samples obtained under high temperature and pressure were performed by X-ray diffraction（XRD）,transmission electron microscope（TEM） and electronic energy loss spectroscopy（EELS）.The results indicated that at 5.5GPa,the turbostratic B-C-N compound gradually transformed into hexagonal structure with the increasing temperature.At 1200℃,the crystalline hexagonal B-C-N compounds were obtained with a little hexagonal BN and amorphous C forming simultaneously.While above 1400℃,B-C-N compounds were completely decomposed into hexagonal BN and graphite.