Abstract
The finite size effect of CuO nanoparticles and their effect on the magnetic behavior of a CuO-Al2O3 nanocomposite synthesized via a solution combustion method are discussed here. It is observed that the introduction of CuO nanoparticles of similar to 20 nm in size on the surfaces of Al2O3 nanosheets strongly influences the magnetic moment of the nanocomposite. The X-ray diffraction pattern reveals the presence of a CuO phase in the CuO-Al2O3 nanocomposite. Electron microscopy imaging shows the presence of CuO nanoparticles distributed over the surfaces of Al2O3 nanosheets. Magnetic measurements performed at 5 and 300 K revealed a strong enhancement in the saturation magnetization of the CuO-Al2O3 nanocomposite at both temperatures. This increase is due to the formation of CuO nanoparticles on the surfaces of the Al2O3 nanosheets. These CuO nanoparticles show a ferromagnetic nature due to the uncompensated surface Cu2+ spins of the copper ions. The presence of the Cu2+ state in the CuO nanoparticles in the CuO-Al2O3 nanocomposite was confirmed by X-ray photoelectron spectroscopy (XPS) measurements.