用(C_2H_5)_2O·BF_3和Li_3N苯热合成cBN机理探讨

Discussion on the Mechanism of cBN Synthesized by Benzene Thermal Method Using(C_2H_5)_2O·BF_3 and Li_3N as Reactants

以(C2H5)2O.BF3和Li3N为原料,于苯热条件下合成氮化硼并研究其相变机理。X射线粉末衍射和傅立叶变换红外吸收光谱分析证明,产物中不仅有hBN和cBN物相存在,而且还发现了正交氮化硼(oBN)和锂硼氮的常压相Li3BN2(O)及高压相Li3BN2(T)存在。分析了Li3BN2在高温高压条件下和在苯热条件下对合成cBN催化机制的差异,探讨了Li3BN2在以Li3N和(C2H5)2O.BF3为原料合成BN的催化机制,提出常压相Li3BN2(O)和高压相Li3BN2(T)分别对生成cBN和oBN起催化作用的观点。

BN is synthesized by benzene thermal method using （C2H5）2O· BF3 and Li3N as reactants and its phase transition mechanism is studied. Not only hBN and cBN are found in the products testified by XRD and FTIR, but also oBN,atmosphere form Li3BN2 （O） and high pressure form Li3BN2 （T） are discovered. The differences of cBN catalytic mechanism between high pressure and high temperature method and benzene thermal synthesis method are analyzed. Furthermore, the catalytic mechanism of Li3BN2 to synthesize BN using Li3N and （C2H5）2O·BF3 as reactants is discussed. At the same time,it stands out the atmosphere form Li3BN2 （O） and the high pressure form Li3BN2 （T）can catalyze the synthesis of cBN and oBN,respectively.