Abstract Nickel nanoparticles were synthesized by the reduction of nickel chloride with hydrazine hydrate in a polyol medium in the presence of sodium polyacrylates (Na-PA) having molecular weights (Mw) of 1200, 5100 and 8000. The size and morphology of the resulting nickel nanoparticles were characterized by X-ray diffraction, scanning and transmission electron microscopy. Polymers having lower Mw values were found to be more efficient in reducing the nickel particle size. A decrease in the polymer concentrations yielded the smaller particles. Magnetic measurements showed that the as-prepared powders are ferromagnetic and their saturation magnetization and coercivity are size-dependent. Compared with bulk nickel, the nanoparticles exhibit an enhanced coercivity which is due to their small size and a decreased saturation magnetization resulted from the surface oxidation of the powder. The synthesis procedure offers a simple approach to preparing nickel nanopowders on a large scale which could be used as magnetic recording materials, including high-density memory storage devices.

中文翻译：

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聚丙烯酸钠分子量对改性多元醇法合成镍纳米粒子尺寸、形貌及磁性能的影响

摘要 通过在多元醇介质中，在分子量 (Mw) 为 1200、5100 和 8000 的聚丙烯酸钠 (Na-PA) 存在下，氯化镍与水合肼还原合成镍纳米粒子。所得镍的尺寸和形态通过 X 射线衍射、扫描和透射电子显微镜对纳米颗粒进行表征。发现具有较低 Mw 值的聚合物在减小镍颗粒尺寸方面更有效。聚合物浓度的降低产生更小的颗粒。磁性测量表明，所制备的粉末是铁磁性的，其饱和磁化强度和矫顽力与尺寸有关。与散装镍相比，纳米颗粒表现出增强的矫顽力，这是由于它们的小尺寸和由粉末表面氧化导致的饱和磁化强度降低。该合成过程提供了一种大规模制备镍纳米粉末的简单方法，可用作磁记录材料，包括高密度存储设备。