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Nanoparticles composed of iron and carbon have been produced by chemical vapor synthesis. A detailed structural, electronic, and magnetic characterization has been performed by several methods. The atomic arrangement in the as-prepared particles is strongly affected and stabilized by excess carbon. Small clusters of different ferrous phases are the building blocks of the particles. Due to the in situ formation of a carbonaceous shell the particles are stable against oxidation at ambient conditions. The magnetic properties are influenced by the exceptionally small particle size. The particles exhibit superparamagnetic behavior with a blocking temperature of 30K and the temperature dependence of the magnetization is governed by the finite size of the system.

Metal citrate gels of samarium and magnesium were used as precursors for the generation of hollow sphere particles by spray pyrolysis under mild thermal conditions. Six mixtures with different Sm/Mg ratios as well as pure Sm and Mg samples were prepared. As a result of the low synthesis temperature the particles consist of amorphous metal carboxylate networks. The texture of the shells is governed by microporosity yielding the major part of the total surface area. A detailed investigation of thermal decomposition, crystallization, and grain growth behavior was carried out under constant heating rate conditions. The decomposition products are nanocrystalline Sm2O3 and MgO and corresponding two‐phase nanocomposites. The pure samarium carboxylate gel features considerably higher thermal stability compared with the one comprised of only magnesium. Accordingly the decomposition behavior of mixed samples is dependent on the Sm/Mg ratio. Furthermore it is shown that small amounts of MgO are able to slow down the kinetics of grain growth of Sm2O3 whereas high amounts are necessary to significantly reduce the final grain size at 1000°C.

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