B_4C与NH_4Cl生成BN反应的研究

RESEARCH ON SYNTHESIZING BN WITH B_4C AND NH_4Cl

研究了Ｂ４Ｃ、ＮＨ４Ｃｌ和Ｌｉ３Ｎ在不同条件下的反应，分析了Ｌｉ３Ｎ及Ｈ２、Ｎ２、ＮＨ３等气体在上述反应中的作用．结果表明，在Ｎ２气氛及１２２３Ｋ温度下，Ｂ４Ｃ与Ｌｉ３Ｎ反应不生成ｈＢＮ；Ｂ４Ｃ与ＮＨ４Ｃｌ反应只生成少量ｈＢＮ；而Ｂ４Ｃ、ＮＨ４Ｃｌ、Ｌｉ３Ｎ共同反应有大量ｈＢＮ生成．说明在高温高压下合成ｃＢＮ的常用催化剂Ｌｉ３Ｎ，在常压高温下Ｂ４Ｃ与ＮＨ４Ｃｌ生成ｈＢＮ的反应中也起催化作用．

The reactions among B4C, NH4Cl and Li3N under different conditions has been studied. The X-ray diffraction (XRD) analysis of the products showed that no hBN was found in the reaction of B4C+Li3N at the temperature of 1223K and in N2, and little hBN was synthesized from the reaction of B4C+NH4Cl, but large amount hBN was synthesized from the reaction of B4C+NH4Cl+Li3N. The analysis of the functions of H2, N2, NH3 and Li3N has indicated that Li3N, a conventional catalyst of synthesizing cBN under high temperature and high pressure, also acts as catalyst in the synthesis of hBN by B4C+NH4Cl under high temperature and ambient pressure.