Structural, optical and antibacterial properties of nanocrystalline Zn1–xLaxO compound semiconductor

The Zn1–xLaxO powders were synthesized by the planetary ball milling method. An accumulated milling time of 15 h with a milling speed of 400 rpm were found to be the optimum milling conditions. The crystal structure, morphology, selected area electron diffraction, and elemental analysis were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy. The solubility limit of La that could substitute at the Zn sites was only 5 mol% or x=0.05. The dependence of the crystallite size on the La doping content can be explained by the Zener pinning effect. The particle size of the milled ZnO powder was about 34.03 nm and the particle size was reduced to 30.90 nm when doped with 10 mol% La. The particles of all milled samples could agglomerate as a cluster. The largest Eg value of 3.14 eV was obtained from the Zn0.97La0.03O powder due to this sample having the smallest crystallite size. The Zn1–xLaxO powders can inhibit Staphylococcus aureus better than Escherichia coli due to the presence of an extra lipopolysaccharide layer on the outer surface of the latter.