Percolative BaTiO 3–Ni composite nanopowders from alkoxide-mediated synthesis

Abstract

BaTiO 3–Ni nanopowders have been synthesized via an alkoxide-mediated synthesis route through the hydrolysis and condensation of barium hydroxide octahydrate and titanium (IV) isopropoxide in the presence of submicron sized, spherical Ni particles originating from a commercial Ni paste, that was introduced during the preparation procedure. X-ray diffraction (XRD) patterns indicate that nanocomposite powders of the phases BaTiO 3 and Ni could be successfully prepared and tailor-made composition control was confirmed. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the synthesized BaTiO 3 nanoparticles were aggregates of nanosized primary particles as small as 40 nm in diameter. The average Ni particle size was estimated to be about 200 nm. Dilatometric measurements on green compacts of these powders revealed that the shrinkage of BaTiO 3–Ni composites is retarded compared to both, pure BaTiO 3 and Ni. Thermogravimetric analysis (TGA) shows weight losses due to the decomposition of organic binder from Ni paste, the release of water from the surface and of hydroxyl ions from inside the lattice of the BaTiO 3 nanoparticles. With the addition of nickel, the dielectric constant increased slightly due to the percolation effect.