Growth and structural, optical, and electrical properties of zincite crystals

An X-ray diffraction study of ZnO crystals grown by the hydrothermal method has revealed reflections that give grounds to assign them to the sp. gr. P3 rather than to P6(3) mc. The distribution of Zn1, Zn2, O1, and O2 over structural positions, along with vacancies and incorporated zinc atoms, explains the dissymmetrization observed in terms of the kinetic (growth) phase transition of the order-disorder type, which is caused by ordering Zn and O atoms over structural positions. The color of crystals of refined compositions (Zn(0.975)a-(0.025))Zn (i(0.015))(O(0.990)a-(0.010)) (green) and (Zn(0.965)a-(0.035))Zn O-i(0.035) (bright green) is related to different oxygen contents, which is confirmed by the results of electron probe X-ray microanalysis and absorption spectroscopy. The degree of the structural quality of crystals, their resistivity, and activation energy are also related to oxygen vacancies.