Growth morphology of zinc tris (Thipurea) sulphate crystals

摘要

The growth morphology of crystals of zinc tris (thiourea) sulphate (ZTS) is investigated experimentally, and computed using the Hartman-Perdok approach. Attachment energies of the observed habit faces are calculated for determining their relative morphological importance. A com- puter code is developed for carrying out these calculations. A special procedure is adopted for com putting the cohesive energy of a slice of the structure parallel to any rational crystallographic plane. For estimating the cohesive energies, formal charges on the experimentally determined atomic posi- tions in the molecules of ZTS are calculated by ab initio molecular-orbital computations, with wave Functions obtained by the Hartree-Fock procedure. Fairly good agreement with the observed crys- tal morphology is obtained for a model of growth mechanism in which ZTS is assumed to exist in Solution as zinc tristhiourea) ions and sulpharte ions.