LAUSR

Abstract We report an experimental study of colloidal crystals based on SiO 2 artificial opals, infiltrated with 1.34(M1), 2.03(M2) and 24.4(M3) wt% Fe3O4 nanoparticles, using the co-assembly method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and Vibration sample magnetometer (VSM) were used to study the structural, magnetic and optical properties of the samples. At 300 K all the samples exhibit superparamagnetic behavior due to the magnetic coupling of Fe 3 O 4 nanoparticles infiltrated into opal. However, for higher concentration of nanoparticles this strong coupling distorts the opal network. The UV–vis diffuse reflectance spectroscopy and Kubelka-Munk theory were applied to determine that the energy band gap of the opal-magnetite composites can be adjusted by varying the concentration of Fe 3 O 4 nanoparticles. This values are between the energy band gap of SiO 2 and Fe 3 O 4 .