莫来石复相晶体生长习性

Growth habit of mullite composites

常压水热条件下,以天然高岭土为原料,制备莫来石复相晶体实验观察到莫来石晶体呈柱状生长习性.用Materials Studio 4.4 CASTEP(Cambridge serial total energy package)程序,对莫来石晶体的特征显露面族(001),(210),(110)和(120)晶面表面能进行理论计算,进而分析各晶面生长速度与习性关系.计算得出其表面能大小依次为0.337,0.022,0.217和0.039keVnm–2,根据居里-吴尔夫原理,则各晶面生长速度为V(001)>V(110)>V(120)>V(210),表明莫来石晶体能够沿c轴生长成柱状形态.莫来石晶体模型表面能计算结果合理解释了实际莫来石的柱状生长习性.

Under open-system hydrothermal conditions, the observed growth habit for mullite composites is columnar. Based on theoretic calculations, performed with the Cambridge serial total energy package, of mullite crystal surface energies for facets （001）, （210）, （110）, and （120）, we analyze and discuss the relationship between growth rate and growth habit. Following the above facet order, these surface energies are 0.337, 0.022, 0.217, and 0.039 keV nm–2. According to the Curie-Woolf principle, growth rates would follow the sequence （001）（110）（120）（210）. Thus mullite crystals would favor theoretically a c-axis columnar growth habit. This result supports in this instance growth rate determinations based on theoretic calculations of surface energies.