钴铂纳米线阵列的制备与性能研究

Study on preparation and magnetic properties of CoPt_3 nanowire arrays

在具有纳米级孔洞的多孔氧化铝模板上,用电化学方法成功地制备了CoPt3纳米线有序阵列复合膜。分别用透射电子显微镜(TEM)、选区电子衍射(SAED)、X射线衍射(XRD)、振动样品磁强计(VSM)和超导量子干涉仪(SQUID)对样品进行测试与表征。形貌观察和物相分析表明,模板中的CoPt3纳米线构成的阵列,排列均匀有序,相互平行;而纳米线中的CoPt3为L12无序结构。磁性研究表明,纳米线的无序晶体结构决定了纳米线阵列弱的磁晶各向异性;同时纳米线中部分小晶粒在400 K左右表现出顺磁性,导致纳米线阵列居里温度的下降。比较低温和室温下的磁滞回线,低温下有大的矫顽力,从另一方面证明纳米线中的小晶粒确实存在相转变。

Arrays of CoPt3 nanowires have been prepared by co-depositing Pt and Co on the porous anodic alumina template. The samples were measured and characterized by transmission electron microscope （TEM）, selected area electron diffraction （SAED）, X-ray diffraction （XRD）, vibrating sample magnetometer （VSM） and superconducting quantum interference device magnetometer （SQUID）, respectively. TEM results showed that the nanowires were regular and uniform, about 1.5 μm in length and 35 nm in diameter. Structural determination by XRD indicated that L12 CoPt3 phase appeared with disorder fcc structure in each nanowire. Magnetic measurement by VSM and SQUID showed that the arrays of nanowires exhibited weak magnetic anisotropy which depended on the degree of crystallite order/disorder in each nanowire. Magnetic hysteresis loops measured at temperatures from 1.9 K to 400 K demonstrated that the nanowire arrays existed super-paramagnetic phase which reduced the Curie temperature of nanowire.