In-situ fabrication of ceramic/Metal nanocomposites by reduction reaction in barium titanate-Metal oxide systems

Novel ceramic/metal nanocomposites were prepared by in-situ reduction method in BaTiO₃/NiO, BaTiO₃/WO₃ and BaTiO₃/MoO₃ systems. The fabrication processes and the phase stability of these metal and metal oxides were studied using X-ray diffraction analysis and thermodynamic consideration. For BaTiO₃/NiO system, NiO was entirely reduced at 500°C for several hours and dense BaTiO₃/Ni nanocomposites were obtained without additional reaction phases. However, it was confirmed that a small amount of Ni²⁺ was dissolved in the BaTiO₃ lattice. In the BaTiO₃/WO₃ system, in parallel with the reduction of WO₃, BaTiO₃ reacted with WO₃ or WO₂ to produce BaWO₄. BaTiO₃/W composite powder having no reaction products was difficult to fabricate by in-situ reduction process. On the other hand, BaTiO₃/W composite could be obtained from BaTiO₃ and W powder mixture when sintering below 1200°C. In contrast, the fabrication of BaTiO₃/Mo composite was successfully achieved after reducing BaTiO₃/MoO₃ powder mixture at 800°C.