Defects and the optical band gap of ZnO nanoparticles prepared by a grinding method

Defects and the optical band gap of ZnO nanoparticles prepared by a grinding method

Zinc oxide (ZnO) nanoparticles with different sizes and shapes were prepared by a grinding method. Phase identification was carried out by XRD, the results showed that all samples exhibited a wurtzite structure. The particle shapes were determined by SEM. A spherical structure changed to a flower shape when the OH- concentration increased. The optical band gap was evaluated by measurements of the optical absorption with a UV-Vis spectrophotometer. The optical band gap was dependent strongly on the defect concentration in the ZnO. In this study, the presence of the flower-like structure gave rise to a reduction of the optical band gap due to the increase of oxygen vacancies that could be confirmed by the EPR measurements.

Zinc oxide (ZnO) nanoparticles with different sizes and shapes were prepared by a grinding method. Phase identification was carried out by XRD, the results showed that all samples exhibited a wurtzite structure. The particle shapes were determined by SEM. A spherical structure changed to a flower shape when the OH- concentration increased. The optical band gap was evaluated by measurements of the optical absorption with a UV-Vis spectrophotometer. The optical band gap was dependent strongly on the defect concentration in the ZnO. In this study, the presence of the flower-like structure gave rise to a reduction of the optical band gap due to the increase of oxygen vacancies that could be confirmed by the EPR measurements.