六方片状氢氧化镁的合成及其第一性原理分析

Preparation of hexagonal plates of magnesium hydroxide and mechanism analysis with first principles

分别以硝酸镁和氯化镁为原料,氨气为沉淀剂,采用一步水热法制备六方片状氢氧化镁,并利用扫描电镜(SEM)和X射线衍射(XRD)对产品进行表征。采用第一原理赝势平面波方法,对氢氧化镁的各个经常显露面族的能量、电子结构和布居数进行理论计算。结果表明,p轨道对氢氧化镁晶体各表面的结构稳定性起着主导作用,氢氧化镁晶体(001)面的总能量较低,O-Mg和H-Mg键的结合力较强,存在热力学稳定性,会成为顽强显露晶面,较好地解释了氢氧化镁六方片状形貌的成因。

Hexagonal plates of magnesium hydroxide were prepared by one-step hydrothermal method with magnesium nitrate or magnesium chloride as starting materials and gaseous ammonia as precipitator. Scanning electron microscope（SEM） and X-ray powder diffraction（XRD） were employed to characterize the products. The energy, electronic structures and population of exposing plane of all developing facets in the magnesium hydroxide crystals were calculated by the first principle methods based on plane wave pseudo-potential theory. The results showed that the P track played a leading role to maintain lattice structure stability of magnesium hydroxide planes. Total surface energy of（001） plane was lower than all the others, while bonding strength of O Mg bond and H Mg bond were strong. Thus,（001） plane had a higher thermodynamic stability, giving a reasonable explanation for morphology of hexagonal plates of magnesium hydroxide.