MORPHOLOGY OF POLYCRYSTALLINE ZNO AND ITS PHYSICAL-PROPERTIES

Five commercial polycrystalline ZnO samples with different morphologie s (nodular and needle-like) have been studied. Nodular ZnO crystallite s reveal lower polydispersity, higher ultraviolet luminescence (380 nm ), low green luminescence (500 nm), a small ESR signal with g=1.96 and a density close to the theoretical value for ZnO with the wurtzite st ructure. Needle-like ZnO crystallites have a higher polydispersity, hi gher green luminescence, higher ESR signal with g=1.96 and lower value s of density. The observed differences in the physical properties are associated with the presence of oxygen vacancies in needle-like partic les and probably also interstitial zinc atoms in nodular particles.