Search

Among layered compounds, the transition metal hydroxynitrates M(OH)$_{2\hbox{-}{\rm x}}$(NO$_{3})_{\rm x}$.nH2O (with M= Co, Ni,Cu) are still currently investigated, since they are good precursors for the synthesis of simple or mixed metal oxides with interesting catalytic and electronic properties.From a structural point of view, the hydroxynitrates derive from the CdI2type stucture of M (OH)2. They can be described as 2D triangular arrays of metal ions with large interplanar distances, and accordingly, they are good candidates for studying bidimensional magnetic systems. Knowing that from a magnetic point view, Co(OH)2and Co2(OH)3(NO$_{3})$were shown to be a genuine examples of layered ferromagnetic systems, with the occurrence of 3d antiferromagnetic order at nearly the same temperature ; we report in this paper the preparation and magnetic properties of layered cobat mixed metal(II) hydroxynitrates CoM(OH)3(NO$_{3})$(M= Cu, Ba) hydrated or no which display, according to the metal ion, either ferro or antiferromagnetic interlayer interactions. We discuss the interest in these compounds named hybrid organic-inorganic compounds for the stabilizing ferromagnetic interactions.

The LiMVO4(M = Mn, Co, Ni) vanadates have been synthetized and characterized by X-ray diffraction, Raman and FTIR spectroscopy. Conductivity measurements by impedance spectroscopy show the correlation between structure and transport mechanism.