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The effect of A-site size and disorder on metamagnetic transformation in polycrystalline [Pr.sub.0.5-x][La.sub.x][Ca.sub.0.5]Mn[O.sub.3] and [Pr.sub.0.5][Ca.sub.0.5-x][Ba.sub.x]Mn[O.sub.3] at low temperature is examined. The critical field corresponding to the metamagnetic step has increased and the field-induced magnetization has decreased, while the evolution of resistivity at low temperature with A-site ionic radii variance has displayed strong correlation with that of magnetic properties.

The optical and electrical properties of N-doped ZnO thin films, grown by plasma-assisted molecular beam epitaxy, with different doping concentrations are examined. The results have shown that highly doped samples are heavily compensated and the donor-acceptor pair (DAP) emission band has displayed a strong redshift and broadening with increasing nitrogen doping concentration.

ZnO nanostructures, including nanotowers, nanovolcanoes, nanorods, nanotubes, and nanoflowers is grown by using the hydrothermal technique. Most of the ZnO nanostructures reveal the perfect hexagonal cross section and well-faceted top and side surfaces.

A simple chemical route for ZnS-coated ZnO nanowires with preferential (002) orientation is described, where sodium sulfide and zinc nitrate are used to supply S and Zn atoms at 60 degree Celsius to form ZnS-coated ZnO nanowires structures. In the photoluminescence (PL) spectra an enhanced ultraviolet emission is observed for the ZnS-modified sample, and the visible emission is quenched after S and ZnS coating on ZnO.