Hierarchical magnetic core-shell nanostructures for microwave absorption:Synthesis,microstructure and property studies

Core-shell nanostructures have attracted considerable attention in the past decades because of their fundamental scientific significance and many technological applications.Recently,it has been reported that the core-shell nanostructures with advanced compositions and complicated morphologies show great potential as high-performance microwave absorbers due to their unique properties,such as large surface areas,multi-functionalities and synergistic effects between the interior core and outer shell.This review article focuses on the recent progress in synthesis and characterization of hierarchical magnetic core-shell nanostructures for microwave absorption applications based on our own work.In addition,several future trends in this field for next-generation microwave absorbers are discussed.

Uniform wurtzite MnSe nanocrystals with surface-dependent magnetic behavior

锰硒化物(MnSe ) 作为一个重要磁性的半导体拥有唯一的磁性，但是 MnSe nanocrystals 的合成和性质是因为无能，与另外的半导体 nanocrystals 相比开发获得高质量的 MnSe 的更少，特别在亚稳的 wurtzite 结构。这里，我们成功地经由负担得起一致水晶尺寸的一条胶体的途径制作了 wurtzite MnSe nanocrystals 并且定制形状。胺表面活化剂的选择有约束力的力量是在形状控制和形状进化的决定因素。如果在反应解决方案的 oleylamine 的部分被 trioctylamine 代替，子弹形状能被转变成梭形状，并且四足动物形状的 nanocrystals 能在 trioctylamine 系统被形成。三维(3D ) 塑造子弹的 nanorods 的结构被先进传播电子显微镜(TEM ) 表明了 3D 断层摄影术技术。高分辨率的 TEM (HRTEM ) 和电子精力损失光谱学(鳗) 显示出那平面缺点的结构象叠差错和 twinning 沿着那样[001 ] 方向在子弹形状的生长期间产生。根据小心的 HRTEM 观察，我们为 wurtzite MnSe nanotetrapods 的形成建议 quadra 双胞胎核心生长机制。而且，由于他们的 noncompensated，表面旋转的 wurtzite MnSe nanocrystals 表演 lowtemperature 表面纺纱眼镜行为和堵住的温度与增加 nanocrystals 的表面区域 / 卷比率从 8.4 K 增加到 18.5 K。我们的结果提供 wurtzite MnSe nanocrystals 的系统的研究。