Cortés Andrea, Lavín Roberto, Denardin Juliano C, Marotti Ricardo E, Dalchiele Enrique A, Valdivia Patricio, Gómez Humberto
Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110-V, Valparaíso, Chile.
J Nanosci Nanotechnol. 2011 May;11(5):3899-910. doi: 10.1166/jnn.2011.3826.
The influence of electrodeposition potential, pH, composition and temperature of the electrolytic bath on the structure of cobalt nanowires arrays electrodeposited into anodic aluminum oxide (AAO) porous membranes is reported. XRD, SEM, and TEM analysis were employed to characterize structural (crystal phase, crystallographic texture, and grain size), and morphological nanowire properties. It was confirmed that at pH 2 the electrodeposition potential has not influence on the preferred crystallographic orientation of the electrochemically grown Co nanowires. At pH 4 the electrodeposition potential controls the growth of cobalt nanowires along some preferential crystallographic planes. The electrolytic pH bath modulates the fcc or hcp phase exhibited by the cobalt nanowires. Single crystalline nanowires with a hcp phase strongly oriented along the (2021) crystallographic plane were obtained at pH 4 and at -1.1 V (vs. Ag/AgCl), a result not previously reported. High electrolytic bath temperatures contributed to improve the single crystalline character of the cobalt nanowires. The presence of chloride anion in the electrolytic bath also influenced on the structural properties of the resulting cobalt nanowires, improving their crystallinity. The optical reflectance of the samples shows a structure in the UV-blue region that can be assigned to the two-dimensional morphology arising in the shape of the almost parallel nanowires. Magnetic measurements showed that different electrodeposition potentials and electrolytic bath pH lead to different magnetic anisotropies on the nanowire array samples.
报道了电解槽的电沉积电位、pH值、组成和温度对电沉积到阳极氧化铝（AAO）多孔膜中的钴纳米线阵列结构的影响。采用XRD、SEM和TEM分析来表征结构（晶相、晶体织构和晶粒尺寸）以及纳米线的形态学性质。证实了在pH值为2时，电沉积电位对电化学生长的Co纳米线的择优晶体取向没有影响。在pH值为4时，电沉积电位控制着钴纳米线沿某些择优晶面的生长。电解槽的pH值调节钴纳米线呈现的面心立方（fcc）或六方密堆积（hcp）相。在pH值为4且电位为-1.1 V（相对于Ag/AgCl）时获得了沿（2021）晶面强烈取向的具有hcp相的单晶纳米线，这一结果此前未见报道。较高的电解槽温度有助于改善钴纳米线的单晶特性。电解槽中氯离子的存在也影响了所得钴纳米线的结构性质，提高了它们的结晶度。样品的光学反射率在紫外-蓝光区域呈现出一种结构，这可归因于几乎平行的纳米线形状中产生的二维形态。磁性测量表明，不同的电沉积电位和电解槽pH值会导致纳米线阵列样品产生不同的磁各向异性。
