Size dependence of lattice parameters in ZnO nanocrystals

Abstract

Wurtzite-type ZnO nanocrystals are synthesized by chemical co-precipitation method. The lattice parameters ‘a’ and ‘c’, lattice volume, bond length, crystallite size and lattice strain are measured by analyzing the X-ray diffraction line profiles. The Williamson–Hall (WH) method is applied for the estimation of crystallite size and lattice strain. From the already reported values in the literature and present results, the crystallite size dependence of the lattice parameters ‘a’ and ‘c’, lattice volume, bond length and lattice strain is investigated. These parameters remain almost same for crystallite sizes above 30 nm. The lattice parameter ‘a’ and lattice strain decrease slightly, while the lattice parameter ‘c’, lattice volume and bond length increase with reducing crystallite size below 30 nm. The lattice volume expansion observed in ZnO nanocrystals with reducing crystallite size is similar to some other oxide nanocrystals such as TiO2, CeO2, Fe2O3 and MgO.