Effect of zinc substitution on the growth morphology of ZnO-CuO tenorite solid solutions

ZnxCu1_xO nanoparticles were synthesized by microwave heating of hydroxide mixtures to form single-phase tenorite crystallites with compositions of up to x ?0.12 zinc concentration, after which formation of wurtzite ZnO was also observed. The lattice parameters, determined by Reitveld refinement of the x-ray diffraction data, showed a linear relationship in zinc concentration, a phenomenon known as Vegard?s Law which is generally taken as an indication of homogeneous cation distribution. Substitution of zinc for copper in the tenorite structure affects the particle growth kinetics, which results in a morphological change from plate-like in pure CuO to smaller, needle-like crystallites for compositions emerging at approximately Zn0.025Cu0.975O. The needlelike particles form as a result of imperfect oriented attachment in two dimensions, with the third dimension controlled by the initial hydroxide condensation step. When the concentration of zinc is increased to x = 0.075, imperfect oriented attachment occurs in three dimensions, which yields particles with flower morphologies.