Optical properties of Co/Al2O3 nano-array composite structure

Co/Al2O3 nano-array composite structure assemblies with Co grown in the pores of an anodic alumina membrane (AAM) were obtained by alternating current electrodeposition. X-ray diffraction pattern results show that a mixture of face-centred cubic and hexagonal-close-packed structures, with a preferred (100) direction, co-exists in the Co nanowires. The transmission electron microscopy image reveals that the nanowires are both very regular and uniform, with an average diameter of about 20 nm. The transmission ratio of Co/Al2O3 composite in the near-IR and mid-IR wavebands decreases with the increasing of the electrodeposition time, while it rises with the increasing of the pore-widening time. The Co/Al2O3 composite has good polarization in the near-IR waveband, and its extinction ratio increases significantly when extending the electrodeposition time. With the expanding of pores in the AAM, the extinction ratio first decreases and then rises.