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An ethylenediaminetetraacetic acid (EDTA)-mediated hydrothermal route to cerium orthovanadate (CeVO 4 ) microcrystals has been developed. The EDTA/Ce 3+ ratio, solution pH, and temperature of the reaction systems are found to play important roles in determining the morphologies and growth process of the CeVO 4 products. During the process of synthesis, EDTA plays important roles such as chelating ligand and capping reagent. These products have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Moreover, the results of X-ray photoelectron spectra (XPS) and magnetic measurements reveal the existence of Ce 4+ induced by surface oxidation of air. The existence of Ce 4+ ions may be helpful for oxidative dehydrogenation of propane of CeVO 4 . On the basis of the experimental results, we suppose this method may have wide applications in exploring the crystal growth process and may provide guidance for the morphology controllable synthesis.

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A ferromagnet-metal-type composite, La0.7Ca0.3MnO3 (LCMO)–Ag, was fabricated by a two-step chemical route which can avoid the doping of Ag into the lattice of LCMO. The grain size of Ag can be reduced by increasing calcination temperature, which favors the penetration of Ag into LCMO matrices. A large enhancement in magnetoresistance (MR) near room temperature and a dramatic decrease in resistivity are observed for the samples calcined at above the melting temperature of Ag. We suggest that the shift of metal–insulator transition up to Curie temperature in melted-Ag-added LCMO and magnetic inhomogeneity are responsible for the enhanced MR.