高温熔剂法制备氧化镁晶须的研究

采用MgCl₂·6H₂O为原料、KCl为助熔剂, 分段灼烧制备出直径1～50μm、长50～2000μm的MgO晶须. 通过对水氯镁石热解的理论分析、以及对灼烧各阶段产物的化学分析, 确定生成晶须的中间产物为无水氯化镁, 然后直接从无水氯化镁制备出MgO晶须. 并探讨了MgCl₂、HCl和H₂O浓度的变化对晶须形貌的影响. 提出了MgO晶须生长的机制: 即MgO分子在容器壁上非均相成核, 晶须生长的初期是以VLS机制进行, 在合成的后期, VLS机制变成VS机制.

Magnesia Whiskers Prepared by High-Temperature Solvent Method

Magnesia whiskers with a diameter of 1--50μm and a length of 50--2000μm were synthesized via calcinations at different stages using MgCl₂·6H₂O as raw materials and KCl as flux. Through theoretical analysis of bischofite’s pyrolysis and chemical analysis of intermediate products during different sintering stages, anhydrous magnesium chloride was presumed to be the precursor, which was confirmed by the preparation of MgO whisker from anhydrous magnesium chloride. Three factors that influence the whiskers morphology were also discussed including MgCl₂, HCl and H₂O. During the whisker’s growth, heterogeneous nucleation of MgO occurs on the container-wall at initial stage, and then MgO whiskers are grown through VLS mechanism, finally dominated by VS mechanism.