Molecular ways to nanoscale particles and films

Abstract
Chemical routes for the synthesis of nanoparticles and films are proving to be highly efficient and versatile in tailoring the elemental combination and intrinsic properties of the target materials. The use of molecular compounds allows a controlled interaction of atoms or molecules, when compared to the solid-state methods, resulting in the formation of compositionally homogeneous deposits or uniform solid particles. Assembling all the elements forming the material in a single molecular compound, the so-called single-source approach augments the formation of nanocrystalline phases at low temperatures with atomically precise structures. To this end, we have shown that predefined reaction (decomposition) chemistry of precursors enforces a molecular level homogeneity in the obtained materials. Following the single-step conversions of appropriate molecular sources, we have obtained films and nanoparticles of oxides (Fe ₃O ₄, BaTiO ₃, ZnAl ₂O ₄, CoAl ₂O ₄), metal/oxide composites (Ge/GeO ₂) and ceramic-ceramic composites (LnAIO ₃/AI ₂O ₃; Ln = Pr, Nd). For a comparative evaluation, CoAl ₂O ₄ nanoparticles were prepared by both single- and multi-component routes; whereas the single-source approach yielded monophasic high purity spinels, phase contamination, due to monometal phases, was observed in the ceramic obtained from multicomponent mixture. An account of the size-controlled synthesis and characterisation of the new ceramics and composites is presented.