Precursorchemistry with Metalalkoxides and their Use for Nano-Scaled Materials

The synthesis of nano-scaled materials using several variations of the single source precursor concept in sol–gel and chemical vapour deposition techniques is demonstrated. Mono- and biphasic ceramics and cermets (metallic phases incorporated in a metal oxide phase) are addressed. The materials prepared are all nanocrystalline in a range from 5 to 50nm. The ceramics belong inter alia to the spinel and perowskite-type. In the biphasic ceramic systems, especially NdAlO3 in Al2O3 is highlighted. In the cermet family Ge, Sn and Pb in either their oxide matrices or in perowskite matrices (M´MO3, M´ = Ca, Sr, Ba; M = Ge, Sn, Pb) and Al and Ga in Al2O3 or Ga2O3 matrices are discussed. Two general concepts are presented in more detail: 1) the arrangement of mutually dependent ligands in the precursor molecule, to facilitate intra-molecular cascade or domino reactions, and 2) the role of metastable phases for physical patterning. The temperature and pressure dependent formation of aluminum/aluminum oxide composites and their structural consequences leading to zero-dimensional ball-shape spheres or to one-dimensional nano-wires is shown as well as the core shell structures of such composites.