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表面结构决定了晶体材料的许多重要的物理化学性质.可控制备具有特定表面结构的微纳米晶体,从而实现对晶体材料性能的改善,引起了广泛的关注.本课题组近期相关的研究表明,晶体生长体系中,生长单元的过饱和度决定了晶体的表面结构.基于已有研究结果,本文通过调节混合溶剂体系中乙二醇和水的相对体积比及Na OH的用量,改变晶体生长体系中生长单元的过饱和度,合成了亚微米尺寸的Na Ta O3立方体、削角立方体、削角削棱立方体和准球体.低过饱和度条件下,形成的Na Ta O3颗粒是低能{100}晶面裸露的立方体;随过饱和度的增加,立方体的角和棱逐渐削去,裸露表面能更高的晶面;极高过饱和度条件下,则形成准球体Na Ta O3颗粒.这种准球体的形成难以用经典的晶体生长理论加以解释.通过研究同样受过饱和度影响的二维晶核生成功(Whkl),发现在极高的过饱和度的条件下,晶体生长趋于各向同性,合理地解释了准球体的形成机制.
The surface structure determines many important physicochemical properties of crystalline materials.Continuously concerned about the improvement of the properties of crystalline materials by controlling the preparation of micro-nano-crystals with specific surface structure has attracted a great deal of attention.Recently, In the crystal growth system, the supersaturation of the growth unit determines the crystal structure of the crystal.On the basis of previous studies, by adjusting the relative volume ratio of ethylene glycol to water and the amount of Na OH in the mixed solvent system, Supersaturation of growth units, sub-micron size Na Ta O3 cubes, chamfered cubes, chamfered cubes and quasi-spheres were synthesized.The Na Ta O3 particles formed under low over-saturation were low-energy {100} With the increase of supersaturation, corners and edges of cubes are gradually shaved off, the crystal planes with higher exposed surface can be formed, and Na Ta O3 particles can be formed under very high supersaturation conditions. It is difficult to explain the formation of the sphere by the classical theory of crystal growth.By studying the two-dimensional nucleation energy (Whkl) also affected by the saturation, we find that in the very high supersaturation , The crystal growth tends to be isotropic, formed explained reasonably quasi-sphere mechanism.