Sol-gel synthesis of nanocrystalline LaAlO₃-M₂O₃ (M = La, Al) and Nd:LaAlO₃-M₂O₃ composite materials via "phase metathesis" route

A sol-gel method based on in-situ generation of mixed-metal chelates by complexing metal ions with 1,2-ethanediol in aqueous media has been developed to prepare pure and neodymium-doped nanocrystalline perovskite lanthanum aluminate (LaAlO₃, LAP and Nd: LaAlO₃, Nd:LAP) dispersed within alumina and lanthanum oxide matrix. The X-ray diffraction (XRD) patterns of the powders sintered at 1000°C showed the formation of highly crystalline composite materials. This temperature is the lowest temperature reported for the synthesis of such type composite ceramics. A homogeneous distribution of neodymium in the LAP lattice of LAP-M₂O₃ (M = Al, La) composite was achieved in all dopant concentrations investigated. The phase transformations, composition and micro-structural features in the polycrystalline samples were studied by XRD analysis, IR spectroscopy, and scanning electron microscopy (SEM). The quality of the resulting products (homogeneity, crystallization temperature, grain size, grain size distribution, etc.) is discussed.