关键词: Mg-Al水滑石, 液相共沉淀, 晶粒尺寸, 晶面生长选择性

Abstract: Mg-Al layered double hydroxides were synthesized by liquid-phase coprecipitation, using brucite and Al(NO₃)₃·9H₂O as Mg and Al sources. The influence rule of Mg²⁺ concentrition, crystallizing time and crystallizing temperature on the crystal structure, particle size and crystal selective growth direction was investigated, and the characteristics of the synthesis were described by XRD and SEM. The results showed that with the increase of Mg²⁺ concentration, the crystallinity of Mg-Al layered double hydroxides decreased and particle size became smaller, which is harmful for the development and growth of Mg-Al layered double hydroxides；With the constant of Mg²⁺ concentration, increasing crystallizing time at the same crystallizing temperature or increasing crystallizing temperature at the same crystallizing time, the crystallinity of Mg-Al layered double hydroxides tends to be integrated and its particle size becomes larger. The size of crystallites in a direction grows faster than that in c direction, that is, the crystal growth rate of ［110］ is greater than that of ［003］. The nanoscale Mg-Al layered double hydroxides are obtained on the condition that the Mg²⁺ concentration, crystallizing time and temperature are 0.12 mol/L, 80 ℃ and 8 h, respectively.

Key words: Mg-Al layered double hydroxides, Liquid-phase coprecipitation, Particle size, Crystal selective growth direction