异型纳米AlOOH在水热条件下的界面模型及生长机制

The interface model and growth mechanism of heterogenic nano AlOOH under hydrothermal condition

根据古典和现代结晶理论,结合AlOOH晶体结构特点,构建了晶体生长界面模型,预测了晶体生长速率,揭示了异型纳米AlOOH在水热过程中的生长机制.采用高分辩透射电镜、X射线等检测手段,分析了不同水热条件下的实验样品.结果表明;AlOOH在(010)、(001)面上显露的氧基和羟基多于(100)、(101)面,酸性环境促进了垂直于晶面方向的氢键结合,导致一维晶须生长;纳米片的成长机理由其附着能和棱边能的相对大小决定,碱性环境下具有较大的附着能,符合片状生长条件;纳米颗粒的成长机理由最低能量原则决定,中性环境体系下各种添加剂吸附在生长台阶处造成了晶面棱边能的降低,加速了生长层的宽展,导致了各个晶面的同步生长,从而形成三维块体.

On the basis of classical and modern crystallization theory and combining the structural features of AlOOH crystal,we establish an AlOOH crystal growth interface model and predict the rate of crystal growth,and reveal the growth mechanism of heterogenic nano AlOOH under hydrothermal condition.By adopting various detection methods including high-resolution transmission electron microscope,X-ray etc.,we analyze the samples under different hydrothermal conditions.The results show that the number of oxy-radical and hydroxide radical shown by the ALOOH on（010） and（001） surface is more than that on（100） and（101） surfaces,the acidic condition promotes hydrogen bonding perpendicular to the crystal surface,leading to the growth of one-dimensional crystal whiskers.However,the growth mechanism of nano-sheet is depended upon the relative value of attachment energy and the energy of edge.Under alkaline condition,the attachment energy is relative higher,which can meet the requirements for the growth of nano-sheets.The growth mechanism of nano-particle relies on the minimum energy principle.Under neutral condition,the various additives added in the system are absorbed against the growth step,causing the reduction to the energy of edge of crystal plane,which accelerates the spreading of growth layer and leads to the concurrent growth of each crystal plane,which can finally form 3-dimensional bulk crystal.