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A single‐step hydrolytic decomposition of a mixed‐metal precursor (see Figure) results in the size‐controlled synthesis of nanocrystalline GdFeO3 particles with high compositional and morphological homogeneity. Owing to the molecular level mixing of the cations and the preformed Gd–O–Fe linkage, the temperature required for the formation of this crystalline orthoferrite phase is much lower than that for a solid‐state synthesis.

Electronic structure and band characteristics for zinc monochalcogenides with zinc-blende-and wurtzite-type structures are studied by first-principles density-functional-theory calculations with different approximations. It is shown that the local-density approximation underestimates the band gap and energy splitting between the states at the top of the valence band, misplaces the energy levels of the Zn-3d states, and overestimates the crystal-field-splitting energy. The spin-orbit-coupling energy is found to be overestimated for both variants of ZnO, underestimated for ZnS with wurtzitetype structure, and more or less correct for ZnSe and ZnTe with zinc-blende-type structure. The order of the states at the top of the valence band is found to be anomalous for both variants of ZnO, but is normal for the other zinc monochalcogenides considered. It is shown that the Zn-3d electrons and their interference with the O-2p electrons are responsible for the anomalous order. The effective masses of the electrons at the conduction-band minimum and of the holes at the valence-band maximum have been calculated and show that the holes are much heavier than the conduction-band electrons in agreement with experimental findings. The calculations, moreover, indicate that the effective masses of the holes are much more anisotropic than the electrons. The typical errors in the calculated band gaps and related parameters for ZnO originate from strong Coulomb correlations, which are found to be highly significant for this compound. The local-density-approximation with multiorbital mean-field Hubbard potential approach is found to correct the strong correlation of the Zn-3d electrons, and thus to improve the agreement between the experimentally established location of the Zn-3d levels and that derived from pure LDA calculations.

We have synthesized samples of the misfit-layered [CoCa 2 O 3 ] q CoO 2 compound with three different oxygen contents and characterized them by both wet-chemical and thermogravimetric analyses for the determination of precise oxygen content, and by synchrotron X-ray diffraction for the precise determination of the magnitude of q. Combining the results from the structural and oxygen-content analyses it is concluded that for samples synthesized in air or a more reducing atmosphere there occur considerable amounts of oxygen vacancies in at least one of the three types of layers, CoO, CaO, and CoO 2 . Bulk character of the oxygen vacancies was confirmed from transport-property measurements.