ITODYS, Université Paris Diderot, CNRS UMR-7086, F-75205, Paris, France.
J Phys Condens Matter. 2011 Dec 21;23(50):506001. doi: 10.1088/0953-8984/23/50/506001. Epub 2011 Nov 28.
Highly crystalline CoFe(2)O(4) nanoparticles with different diameters ranging from 2.4 to 6.1 nm have been synthesized by forced hydrolysis in polyol. The size can be controlled through adjusting the nominal water/metal molar ratio. X-ray diffraction, transmission electron microscopy, x-ray absorption spectroscopy and (57)Fe Mössbauer spectrometry were employed to investigate the structure and the microstructure of the particles produced. Magnetic measurements performed on these particles show that they are superparamagnetic with a size-dependent blocking temperature. At 5 K, high saturation magnetization (~85 emu g(-1)) approaching that of the bulk was found for the larger particles, whereas a very large coercivity (14.5 kOe) is observed for the 3.5 nm sized particles.
通过多元醇中的强制水解，成功合成了具有不同直径（2.4-6.1nm）的高结晶 CoFe(2)O(4)纳米粒子。通过调节名义水/金属摩尔比可以控制尺寸。X 射线衍射、透射电子显微镜、X 射线吸收光谱和（57）Fe Mössbauer 谱研究了所制备的颗粒的结构和微观结构。对这些颗粒进行的磁测量表明，它们是具有尺寸依赖性的超顺磁体，具有尺寸依赖性的阻塞温度。在 5 K 下，较大的颗粒具有接近块体的高饱和磁化强度（~85 emu g(-1))，而 3.5nm 大小的颗粒表现出非常大的矫顽力（14.5 kOe）。
