Octahedral-Shaped Zn2SnO4 and Hexagonal Cylinder-like ZnO Crystals Grown via Thermal Evaporation of Mixtures of ZnS and SnO Powders

Octahedron-shaped zinc stannate (Zn2SnO4) crystals and hexagonal cylinder-like ZnO crystals were synthesized through a simple thermal evaporation method under uncomplicated conditions of air atmosphere. The Zn2SnO4 octahedrons were grown by heating a mixture of ZnS and SnO powders, and the ZnO hexagonal cylinder-like crystals were fabricated by heating mixtures of ZnS, SnO and graphite powders. X-ray diffraction analysis confirmed that the Zn2SnO4 crystals had a cubic inverse spinel crystal structure, and the ZnO crystals had a hexagonal wurtzite crystal structure. Scanning electron microscopy analysis revealed that the Zn2SnO4 octahedrons had six vertices and eight equilateral triangular faces with very smooth surfaces, and the ZnO crystals had two parallel hexagonal bases and six side faces. Judging from the crystal structure of Zn2SnO4, the octahedral crystals were covered with eight {111} planes. Considering the crystal structure of ZnO, the hexagonal cylinder-like crystals were enclosed by two {001} basal planes and six {100} side planes, which indicated that the ZnO crystals were grown along the [001] direction. When the amount of graphite in the source powder was increased, the aspect ratio of the hexagonal cylinder-like ZnO crystals increased. Energy dispersive x-ray spectroscopy analysis also showed that the octahedral crystals were Zn2SnO4, and the hexagonal cylinder-like crystals were ZnO.