Ag assisted evolution of ordered L10 CoPt alloy nanoparticles
Ag assisted evolution of ordered L10 CoPt alloy nanoparticles
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DOI：
10.1016/j.jallcom.2012.01.090
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发表时间：
2012-05
影响因子：
6.2
通讯作者：
N. Sehdev;R. Medwal;Annapooni S.
中科院分区：
文献类型：
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作者：
N. Sehdev;R. Medwal;Annapooni S.
在聚N-乙烯-2-吡咯烷酮(PVP)存在下，通过多元醇同时还原相应的金属前驱体，成功地制备了CoPT-Ag纳米粒子。本研究详细研究了Ag掺杂对CoPt结构和磁性随Ag浓度变化的影响。尽管有轻微的四方形变，但X射线衍射研究表明，在700℃下热处理2小时，含银最高(即70%)的CoPT-Ag纳米粒子从面心立方向L10相转变的程度最大。可以清楚地观察到，银颗粒与退火后的CoPt表面接触，从而使这些纳米颗粒具有表面应变。热处理后观察到磁性相变，表明硬磁性材料从最初合成的软CoPT-Ag纳米粒子演化而来。磁硬度随Ag含量的增加而增大。与X射线衍射仪一致的是，磁性测量结果表明，当最大Ag含量达到1.5T时，样品的矫顽力得到了最显著的提高。化学有序性和矫顽力之间的可调性这一有趣的特征可能对数据存储设备有用。
CoPt–Ag nanoparticles were successfully prepared by the simultaneous polyol reduction of the corresponding metal precursors in the presence of poly(N-vinyl-2-pyrrolidone) (PVP). This study details the influence of Ag additive on the structural and magnetic properties of CoPt as a function of Ag concentration. Despite a slight tetragonal distortion, the XRD studies reveal the maximum degree of transformation from fcc to L10phase, for CoPt–Ag nanoparticles containing the highest Ag percent (i.e. 70%) on annealing at 700°C for 2h. The Ag particles are clearly observed to be in contact with the surface of the annealed CoPt thus imparting surface strain to these nanoparticles. A magnetic phase transformation is observed after heat treatment showing an evolution of a hard magnetic material from the initially synthesized soft CoPt–Ag nanoparticles. The measure of magnetic hardness increases with increasing Ag content. Consistent with XRD, magnetic measurements show the most remarkable increase in coercivity for the maximum Ag content attaining a value of 1.5T. The interesting feature of tunability between chemical ordering and coercivity may be useful for data storage devices.