Ni-doped ZnO nanostructures were synthesized in situ through a pulsed-electrodeposition-assisted chemical bath deposition method, and the optical and magnetic properties of the nanostructures were studied. It was found that the morphology of the nanostructures evolved from a rodlike to a sheetlike structure because of the different growth modes, and a growth mechanism is proposed to explain these findings. A relatively strong UV emission was observed for the nanorods, whereas a relatively strong visible emission was seen for the nanosheets. Ni was successfully doped into the ZnO wurtzite lattice structure as revealed by X-ray diffraction and X-ray photoelectron spectroscopy and also verified by the cathodoluminescence characterization. Roomtemperature ferromagnetism was also observed in the Ni-doped ZnO nanostrucures. The results are helpful to tailor the physical properties of ZnO by changing its morphology and composition.

The effect of grain size on electrical and magnetic properties of La0.67Sr0.33MnO3 nanoparticles with average grain size 32–85 nm has been investigated. The metal-insulator transition temperature TP gradually decreases with decreasing grain size, while the ferromagnetic-paramagnetic transition temperature TC remains almost constant. For the 32 nm sample, the larger effective magnetic moments and the deviation of the inverse susceptibility from the Curie–Weiss law are observed, indicating the possible existence of a Griffiths-like cluster phase. The ferromagnetic transition of the samples is further investigated by measuring magnetocaloric effect (MCE). The presence of short-range magnetic order greatly depresses the magnetic entropy of the paramagnetic phase. Moreover, the analysis of the MCE using Landau theory of phase transition confirms the importance of magnetoelastic coupling and electron interaction in magnetocaloric properties of manganites.