Fabrication of NiO/ZrO2 nanocomposites using ball milling-pyrolysis method

Abstract

It is well known that composites of nano-ZrO2 and nano-NiO have many advantageous properties that can be harnessed in a variety of applications. However, the state-of-the-art methods for producing these nanocomposites are often cumbersome and expensive. Therefore, in the current study, we introduced a new method for the synthesis of NiO/ZrO2 nanocomposites, and tried to explore the formation mechanism using in-situ transmission electron microscopy (TEM). The NiO/ZrO2 nanocomposites, with NiO nanoparticles uniformly and densely distributed on the ZrO2 surface, were fabricated by ball milling-pyrolysis method. It was found that the attachment of NiO on ZrO2 could be regulated by controlling the ball milling time and Ni/Zr molar ratios. In-situ TEM observations indicated an initial self-assembly reaction that led to the attachment of the precursor on the ZrO2. Subsequently, during the beam irradiation, the precursor decomposed into intermediate products consisting of NiCO3/Ni(OH)2, followed by their merging and growth. Finally, with continuous irradiation, these NiCO3/Ni(OH)2 transformed into NiO. Additionally, the mismatch of ZrO2/NiO interfaces was found to be in the range 0.029–0.054, which indicated that they were either semi-coherent or coherent.