An introduction to computational crystallography:the relationship between aluminum-based spinel structures and their morphologies

Computing technology is developing very fast and has permeated among many fields of sci-ence and technology, giving rise to many interdisciplinary subjects. Crystallography, originating from the activity of mining and smelting, has now become a comprehensive subject concerning crystal growth mechanism, chemical composition, structural morphology and physical properties and its research scope is widened by introducing many new achievements from basic sciences such as physics, chemistry, and math…     

Coalescence of the crystallites under hydrothermal conditions (II) —— The morphology and stability energy calculation of cuprite

The coalescence of crystallite under hydrothermal conditions was discussed in our previous paper[1]. When the solute concentration exceeds the supersaturation, the nucleation and growth process take place. The initial crystallites are only several nanometers. They have high surface-to-volume ratio, high index surfaces, and therefore have high surface energy. As the hydrothermal reactions proceed in the alkaline medium, the crystallite surfaces are apt to absorb polar solvate ions such as OH-,…     

Solvothermal preparations of α-alumina and boehmite crystallites and investigations on the formation of their morphologies

Ｃｏｒｕｎｄｕｍ(αＡｌ2Ｏ3)ｉｓａｎｉｍｐｏｒｔａｎｔｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｓｔｒｕｃｔｕｒａｌｃｅｒａｍｉｃｍａｔｅｒｉａｌ.Ｉｎｏｒｄｅｒｔｏｉｍｐｒｏｖｅｔｈｅｃｅｒａｍｉｃｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅｍａｔｅｒｉａｌｓ,ｉｔｉｓｅｓｓｅｎｔｉａｌｆｏｒｕｓｔｏｐｒｅｐａｒｅｈｉｇｈｑｕａｌｉｔｙｓｕｐｅｒｆｉｎｅｐｏｗｄｅｒｓ(ｃｒｙｓｔａｌｌｉｔｅｓ).Ｈｙｄｒｏｔｈｅｒｍａｌｍｅｔｈｏｄｍａｙｂｅｕｓｅｄｔｏｐｒｅｐａｒｅｍａｎｙｋｉｎｄｓｏｆｓｕｐｅｒｆｉｎｅｐｏｗｄｅｒｓ(ｃ…     

The growth units and hydrothermal preparation of lead tungstate (PbWO4) crystallites

The crystal structure of lead tungstate (PbWO4) can be regarded as ordered combination of the tungsten oxide tetrahedrons (WO4) and lead ions (Pb2 ). According to the growth unit model, the growth units of lead tungstate are the aggregations of the tungsten oxide tetrahedrons and lead cations with various geometry configurations. It is suggested that the favorable growth units of lead tungstate crystal are pyramidal, tetragonal prism and quadrangular units corresponding to geometric orientations of the simple forms of the crystal. Under low restricted growth conditions, the growth form of lead tungstate crystallites is the aggregation of the geometric configurations of these favorable growth units. The above conclusions are completely confirmed by the experiment on hydrothermal preparation of lead tungstate crystallites.     

Hydrothermal preparation and formation mechanism of titanium dioxide microcrystallites

Hydrothermal preparation experiments of TiO_2 microcrystallites were carried out. The formation of TiO_2 microcrystallites of polymorpbic forms was related to the precursor types and the basicity or acidity of reaction mediums under hydrothermal conditions. Based on the "growth unit" model, the space lattice graphs of growth units responding to different polymorphs were established. The stable energy of growth unit was calculated for different basicity or acidity of reaction mediums. The formation of polymorphic TiO_2 microcrystallites under hydrothermal conditions was discussed based on the experimental results.