【作者】 莫敏；

【导师】 姚素薇；

【作者基本信息】 天津大学 ， 应用化学， 2006， 硕士

【摘要】 本文以铝阳极氧化膜（AAO）为模板,通过电化学法制备一维磁性NiFe、NiAg纳米线及NiFe/Cu多层纳米线。利用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射（XRD）和振动样品磁强计（VSM）等对纳米线进行了表征和性能研究。通过二次铝阳极氧化制备了多孔铝阳极氧化膜,膜孔密度高、排布高度有序。利用逆电剥离技术将氧化膜从铝基体上剥离,并用磷酸去除阻挡层,得到贯通的纳米孔。将通孔后的AAO模板直接放入腐蚀液中进行溶解,可获得大量Al₂O₃纳米线。文中对Al₂O₃纳米线的形成机理进行了初步探讨。在AAO模板的纳米孔内交流电沉积镍铁磁性合金,获得Ni₇₉Fe₂₁合金纳米线阵列,纳米线长9.7μm,直径约60nm,长径比达160。XRD测试及选区电子衍射表明,Ni₇₉Fe₂₁纳米线为面心立方（fcc）、单晶结构。磁性能测量结果表明,Ni₇₉Fe₂₁纳米线易磁化轴沿纳米线的长轴方向,其矩形比（Mr/Ms）高达0.86,矫顽力约1203Oe;当外磁场垂直于纳米线的长轴方向时,矩形比减小为0.18,矫顽力降至620Oe,Ni₇₉Fe₂₁纳米线具有很好的垂直方向磁各向异性。随着退火温度的升高,沿纳米线轴向的矫顽力迅速增大,在500℃时出现最大值,水平方向的矫顽力没有类似的变化规律。采用直流电沉积在AAO模板内制备了高度有序的Ni₇₉Ag₂₁合金纳米线阵列,纳米线长约30μm,直径约为90nm,长径比高达300。电子衍射表明,Ni₇₉Ag₂₁纳米线具有单晶、面心立方（fcc）结构,磁滞回线显示Ni₇₉Ag₂₁纳米线具有超顺磁性。以AAO为模板,通过双槽法直流电沉积NiFe/Cu多层纳米线阵列。SEM和TEM测试结果表明:NiFe/Cu多层纳米线的直径约为90nm,与模板孔径一致;纳米线的多层结构中各子层厚度均匀,层与层之间的界限分明;周期为60层的NiFe（130nm）/Cu（30nm）多层纳米线阵列的易磁化轴垂直于AAO模板表面。当外加磁场垂直于膜面时,磁滞回线的矩形比（Mr/Ms）为0.90,远大于外加磁场平行于AAO膜面时测得的矩形比（0.25）,表明NiFe/Cu多层纳米线阵列具有明显的垂直磁各向异性。当外加磁场垂直或平行于AAO膜面时,测得矫顽力分别为1320Oe和700Oe。更多还原

【Abstract】 The magnetic NiFe and NiAg alloy nanowire arrays and NiFe/Cu multilayered nanowire arrays were prepared by electrochemical deposition into the nanoporous anodic alumina oxide （AAO） templates. The morphology, structure and magnetic properties of the nanowires were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and vibrating sample magnetometer （VSM）, respectively.The anodic aluminum oxide membranes were prepared by two-step oxidation in the solution of oxalic acid, and stripped from the aluminum substrate adopting strip against electricity technique. The oxide barrier layer was chemically dissolved from bottom side of the film in phosphoric acid, and the free-standing AAO menbrane was obtained. The alumina nanowires were obtained by etching anodic aluminum oxide films in an aqueous sodium hydroxide solution and a mixed solution of 6wt% H2CrO4 and 1.8wt% H3PO4. A discussion of the possible mechanism for the formation of nanowires was given.Ordered Fe21Ni79 alloy nanowire arrays were prepared by AC electrochemical deposition into the nanoporous anodic alumina oxide （AAO） templates. The nanowires were about 60nm in diameter and 9.7μm in length. The results indicated that the nanowires in an array were very regular, with an aspect ration controllably. Such nanowire arrays were in fcc structure. The hysteresis loops showed that the nanowire arrays had excellent perpendicular magnetic anisotropy with their easy magnetization axis parallel to nanowire arrays, the as-deposited samples had high squareness（Mr/Ms） （about 0.86） and large coercivity （as high as 1203Oe） when the magnetic field was perpendicular to the membranes. which is larger than squareness（Mr/Ms） （about 0.18） and coercivity （as high as 620Oe） when the magnetic field was parallel to the membranes. Annealing can improve the coercivity and the squareness of nanowire arrays. Coercivity as high as 1315Oe was obtained in the samples annealing at 500℃, above 500℃, the coercivity and squareness decrease sharply.Highly ordered Ni₇₉Ag₂₁ alloy nanowire arrays was fabricated successfully by electrodeposition into the pores of a porous anodic aluminum oxide（AAO）. the nanowire arrays were regularly arranged, the length of nanowires was 30μm and thediameter of the nanowires was about 90nm,L/D was up to 300. Such nanowire arrays were in fcc structure. The hysteresis loops show that the nanowire arrays were superparamagnetic. Ordered NiFe/Cu multilayered nanowire arrays were prepared by DC electrochemical deposition into the nanoporous anodic alumina oxide （AAO） templates. The nanowires were about 90nm in diameter. and there was evident boundary between every sublayer. The hysteresis loops showed that the nanowire arrays which had 60 ciecles of NiFe（130nm）/Cu（30nm） had excellent perpendicular magnetic anisotropy with their easy magnetization axis parallel to nanowire arrays, the as-deposited samples had high squareness（Mr/Ms） （about 0.90） and large coercivity （as high as 1320Oe） when the magnetic field was perpendicular to the membranes. which was larger than squareness （Mr/Ms） （about 0.25） and coercivity （as high as 700Oe） when the magnetic field was parallel to the membranes.更多还原