强磁场对FePt纳米粒子液相生长速率的影响

Effect of high magnetic field on liquid-phase growth rate of FePt nanoparticles

本文使用定量金相法分析了6 T强磁场对FePt晶体<100>、<111>方向生长行为的影响机制。结果表明:FePt晶体液相生长包括<100>、<111>方向的快速生长和缓慢生长两个阶段。强磁场通过降低原子浓度、抑制原子扩散、抑制表面活性剂吸附等方式降低生长速率和生长距离,细化晶粒。强磁场通过增强磁晶各向异性、影响—NH_(2)官能团在(100)面吸附、促进Fe原子在(100)面吸附生长等方式,减小<100>方向生长速率的降低幅度,使生长过程中FePt晶体形状从截角立方体向立方体和凹立方体转变所需时间增加,使相同生长时间时晶体形状从立方体转变为截角立方体、从凹立方体转变为截角立方体和立方体。

A quantitative metallographic method has been employed to analyze the effect of the 6 T high magnetic field on growth behavior of FePt crystals along<100>and<111>directions.The results indicate that the liquidphase growth of FePt crystals includes two stages,rapid growth and slow growth along the<100>and<111>directions.The high magnetic field reduces the growth rates and distances along the<100>and<111>directions by reducing the concentration of atoms,inhibiting the diffusion of atoms,and inhibiting the adsorption of surfactants.Thus,the crystal grains are refined.The high magnetic field reduces the decreasing degree of growth rate along the<100>direction by enhancing the magnetocrystalline anisotropy,affecting the adsorption of—NH_(2) functional groups on the(100)face,and promoting the deposition of Fe atoms on the(100)face,leading to the increase of time required for FePt crystals shape transition from truncated-cubes to cubes and concave-cubes during the growth processes.Otherwise,when using the same growth time,the crystal shapes transit from cube to truncated-cube,from concave-cube to truncated-cube and cube under the high magnetic field.