Search

The effect of the milling of virgin ZnO and MgO powders on structural, optical, and electrical properties of Mg0.2Zn0.8O ceramics is studied. In all Mg0.2Zn0.8O ceramics, both cubic and hexagonal phases of solid solution are formed simultaneously. The hexagonal phase is represented by densely sintered grains that are doped with magnesium homogeneously. The crystallites of cubic phase of solid solution turn out to appear in large pores. The infrared reflection spectra show that the milling of intial powders does not affect free carrier concentration in hexagonal grains. It is found to be close to that of ZnO being determined by Zn interstials. For ceramics sintered from virgin powders, a decrease of direct current conductivity of Mg0.2Zn0.8O in comparison with that of pure ZnO occurres, which is being caused by the appearance of barriers, the nature of which may be ascribed to the fluctuations in the bandgap and/or electron concentration. For ceramics sintered from milled powders, an increase in DC conductivity of all samples is found and attributed to the formation of conductive channels along the grain boundaries via their enrichment in Zn and Mg due to mechanical stress. A chemical mapping of the ceramics supports this effect. [ABSTRACT FROM AUTHOR]