Zhang Jin, Post Michael, Veres Teodor, Jakubek Zygmunt J, Guan Jingwen, Wang Dashan, Normandin Francois, Deslandes Yves, Simard Benoit
Institute for Chemical Process and Environmental Technology, National Research Council of Canada, Ottawa, Ontario, Canada.
J Phys Chem B. 2006 Apr 13;110(14):7122-8. doi: 10.1021/jp0560967.
A novel method combining wet chemistry for synthesis of an Fe core, 532 nm laser irradiation of Fe nanoparticles and Au powder in liquid medium for deposition of an Au shell, and sequential magnetic extraction/acid washing for purification has been developed to fabricate oxidation-resistant Fe@Au magnetic core-shell nanoparticles. The nanoparticles have been extensively characterized at various stages during and up to several months after completion of the synthesis by a suite of electron microscopy techniques (HRTEM, HAADF STEM, EDX), X-ray diffraction (XRD), UV-vis spectroscopy, inductively coupled plasma atomic emission spectroscopy, and magnetometry. The surface plasmon resonance of the Fe@Au nanoparticles is red shifted and much broadened as compared with that of pure colloidal nano-gold, which is explained to be predominantly a shell-thickness effect. The Au shell consists of partially fused approximately 3-nm-diameter fcc Au nanoparticles (lattice interplanar distance, d = 2.36 A). The 18-nm-diameter magnetic core is bcc Fe single domain (d = 2.03 A). The nanoparticles are superparamagnetic at room temperature (300 K) with a blocking temperature, T(b), of approximately 170 K. After 4 months of shelf storage in normal laboratory conditions, their mass magnetization per Fe content was measured to be 210 emu/g, approximately 96% of the Fe bulk value.
一种新颖的方法已被开发出来用于制备抗氧化的Fe@Au磁性核壳纳米颗粒，该方法结合了用于合成铁核的湿化学法、在液体介质中对铁纳米颗粒和金粉进行532 nm激光辐照以沉积金壳，以及用于纯化的顺序磁萃取/酸洗。通过一系列电子显微镜技术（高分辨率透射电子显微镜、高角度环形暗场扫描透射电子显微镜、能量散射X射线光谱）、X射线衍射、紫外可见光谱、电感耦合等离子体原子发射光谱和磁测量，在合成过程中及合成完成后的几个月内的各个阶段对纳米颗粒进行了广泛表征。与纯胶体纳米金相比，Fe@Au纳米颗粒的表面等离子体共振发生红移且显著变宽，这主要被解释为壳层厚度效应。金壳由部分融合的直径约为3 nm的面心立方金纳米颗粒组成（晶格面间距，d = 2.36 Å）。直径为18 nm的磁性核是体心立方铁单畴（d = 2.03 Å）。这些纳米颗粒在室温（300 K）下具有超顺磁性，阻塞温度T(b)约为170 K。在正常实验室条件下储存4个月后，测得其每铁含量的质量磁化强度为210 emu/g，约为铁块体值的96%。
