在氩气保护下,将镁粉(99 % , ≤300μm) 与氧化硼(AR) 以摩尔比3 ∶1 在玛瑙研钵中混合均匀,平铺在氧化铝瓷舟中并加盖,瓷舟两端留出通气槽。事先将5 %摩尔分数(相对氧化硼) 的氯化亚铁溶于少量水,涂覆在瓷舟盖子内侧并烘干。将装有反应物的瓷舟置于管式炉恒温区中央,通入500 mL/ min
氩气冲洗炉管数分钟,然后固定氩气流量50mL/ min ,升温至1100 ℃时,关闭氩气并通入氨气,保持氨气流量为30~50mL/ min 。待达到1500~1600 ℃时,恒温
2h 。恒温结束时同时关闭进气口和排气口,随炉冷却至室温。
以上文献称作CVD。
那这里的气化是不是指通入的气体,气体与原料反应(最终生成BN),就称为沉积?
High-quality boron nitride nanotubes were synthesized by annealing porous precursor in flowing NH3 gas at 1150◦C. The porous precursor B18Ca2(MgO)9 was produced by self-propagation high-temperature synthesis (SHS) method using Mg, B2O3, and CaB6 as the starting materials, which played an important role in synthesis of BN nanotubes in large quantities. 这篇文献中也有气体(气化?),是氨气和前驱物反应生成BN,但是却称为退火,为什么呢?