Preparation and characterization of nanocrystalline La-doped ZnO powders through a mechanical milling and their optical properties

Structural and optical properties of mechanically milled La-doped ZnO powders are presented in this paper. The Zn1−xLaxO phase formed when x varied in a range of 0.02–0.06 and milled at 400 rpm for 20 h. The secondary La2O3 phase occurred with an increase of La content. The crystallite and particle size decreased as a function of La content as x = 0–0.14 due to the effect of Zener pinning and solute drag. The absorption edge shifted to a lower wavelength when La content was increased to x = 0.14 because of the size effect. The energy band gap of Zn1−xLaxO powders varied in a range of 2.96–3.12 eV depending on the crystallite size. The broad emission bands in a visible region centered at about 640 nm are attributed to oxygen deficiency.