双羟基复合金属氧化物的晶面生长选择性及晶粒尺寸控制

采用成核／晶化隔离法合成镁铝双羟基复合金属氧化物（LDH），考察了晶化温度及晶化时间对晶体结构，晶面生长选择性及晶粒尺寸的影响规律。结果发现晶化温度相同时，随晶化时间延长，LDH的晶体结构趋于完整，晶粒尺寸增大；晶化时间相同时，随晶化温度升高，晶体结构趋于完整，晶粒尺寸显著增大，实验条件下得到的LDH，其沿a轴方向的尺寸均大于沿c轴方向的尺寸，即共沿a轴方向的生长速率比沿c轴方向的生长速度快，亦即110]晶面的生长速率比003]晶面的生长速率快。根据LDH晶粒尺寸随晶化时间及晶化温度的变化规律，选择合适的晶化条件，制备得到了粒径分布窄的纳米LDH。

Selectivity of Crystal Growth Direction and Control of Particle Size in Layered Double Hydroxides

Mg Al layered double hydroxides(LDH) have been synthesized at high supersaturation using a new method developed in our laboratory. The influence of aging temperature and aging time on the crystal structure, selectivity of crystal growth in different directions and the particle size of LDH has been investigated. It has been shown that with increasing aging time at the same temperature, the crystallinity of the LDH increased and the particle size became larger. The same effect was observed when samples were aged at increasing temperature for a fixed period, but the particle size of the LDH increased dramatically with increasing aging temperature. The size of the crystallites in the a direction was larger than that in the c direction under all experimental conditions. This is the result of the greater rate of crystal growth in the a direction than that in the c direction. On the basis of the variation in particle size of LDH with aging time and aging temperature, an optimum aging condition was determined and LDH nanomaterials with a narrow particle size distribution were obtained.