碱式硫酸镁晶须的一步法水热合成及生长机理

Hydrothermal Synthesis and Growth Mechanism of Magnesium Hydroxide Sulfate Hydrate Whiskers by the One-Step Procedure

以MgCl2、MgSO4和氨水为原料,采用一步法水热合成碱式硫酸镁晶须[MgSO4.5Mg(OH)2.2H2O,magnesium hydroxide sulfate hydrate,MHSH]。用扫描电镜、透射电镜、X射线能谱仪和X射线衍射仪等对产物的形貌和组成进行表征,结果表明:采用一步法190℃水热反应5 h合成的MHSH晶须呈纤维状,且一端聚集成扇形,晶须直径为0.5～2μm,长径比为50～200;MHSH晶须的生长机理实质上是生长基元Mg–O6从周围环境中通过界面不断进入晶格位点的过程;晶须生长是晶体内部缺陷——螺型位错延伸的结果。

Magnesium hydroxide sulfate hydrate（MHSH） whiskers were prepared with magnesium chloride,ammonia and magne-sium sulfate as starting raw materials by an one-step hydrothermal method.The stoichiometric composition of the whiskers is MgSO4·5Mg（OH）2·2H2O.The effect of reaction condition on the composition and morphology of products was investigated by scan-ning electron microscope,transmission electron microscope,X-ray powder diffraction and energy dispersive X-ray spectroscopy.The MHSH whiskers were prepared at 190 ℃ for 5 h.The products exhibited a randomly arranged,fanlike morphology with the average diameter of 0.5–2 μm and aspect ratios between 50 and 200.It is indicated that the growth of MgSO4·5Mg（OH）2·2H2O whiskers is essentially the process of Mg–O6 entering the crystal lattice through the interface.The extension of dislocations could result in the growth of the whiskers.