Effects of pH and annealing on microstructure and magnetic properties of fabricated Co100-xWx nanowire arrays by AC electrodeposition

Abstract

Co100-XWX (0 ≤ Χ ≤ 8) nanowire arrays with mean diameters of ~33 nm were synthesized by alternating current electrodeposition of Cobalt and Tungsten into template of anodic aluminum oxide. Effects of W concentration, pH and annealing process on magnetic properties and crystal structure of the fabricated nanowires were studied using Scanning electron microscopy, Energy dispersive X-ray spectroscopy, X-ray diffraction, and alternating gradient force magnetometer. The obtained results demonstrated that the crystal structure of prepared nanowires was hcp and fcc and a mixture of both, and the magnetic parameters such as coercivity and squareness (Sq = Mr/Ms) of nanowire arrays decreased with increasing the tungsten content and pH. For the study the effect of annealing temperature on the nanowire magnetic properties, the fabricated nanowires were annealed at different temperature (300 °C–600 °C). It is observed that the coercivity for all nanowire arrays with the different value of W content and pH increases with annealing temperature and the maximum variation is related to Co97W3 nanowire at pH = 3, which is explained by shape and magnetocrystelline anisotropy that is discussed in detail.