Cation Substitution In ZnO Obtained By Mechanical Milling

L.C.DAMONTE; M.HERNÁNDEZ FENOLLOSA; B.MARÍ

Paris, Francia

Simposio; International Symposium on Metastable, Mechanically Alloyed and Nanocrystalline Materials (ISMANAM); 2005

Due to its unique optical and electronic properties and thus for its potential use in many demanding technological applications, such as blue and ultraviolet light emitter and detector, ZnO is been extensively studied. The direct bandgap of this semiconductor (Eg=3.2eV) can be changed by substitution on the cation site, decreasing (increasing) in the case of Cd (Mg). [1]. Mechanical milling is an effective, useful  and simple processing technique widely applied to produce the synthesis of a variety of alloy phases including solid solutions, quasicrystalline, nanocrystalline and crystalline materials. In this work we present a structural and optical characterization of M-doped ZnO (M: Cd, Mg) powders obtained by mechanical milling. The starting materials were commercially ZnO, MgO and CdO powders. The samples were prepared by mechanical milling in a Restch PM 400 rotating ball mill. The milling was performed in a steel cylinder (12 cm3) with two steel ball (diameter 10mm), at different  times and frecuencies. The milled powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), positron annihilation spectroscopy (PALS) and photoluminescence spectroscopy (PL). The mixing of the oxides is followed by means of XRD and SEM. As milling proceeds a clearly reduction of grain size and homogenization are observed. The evolution of annihilation parameters and PL spectra with milling time were analyzed and related with the kind of mechanical induced defect involved. References [1]   S.J.Pearton, D.P.Norton, K.Ip, Y.W.Heo, T.Steiner; Progress in Mat.Sc. 50.(2005) 293-340.