Department of Materials Science and Engineering , Clemson University , Clemson , South Carolina 29634 , United States.
Institute of Optoelectronic and Nanomaterials College of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China.
ACS Appl Mater Interfaces. 2018 Apr 11;10(14):11907-11919. doi: 10.1021/acsami.7b16572. Epub 2018 Mar 29.
Addressing the challenge of making ceramic thin films with the in-plane-oriented nanorods, we propose to decorate the nanorods with magnetic nanoparticles and orient them using the external magnetic field. As an illustration, the mullite thin films with embedded and oriented SiC nanorods were synthesized. The SiC nanorods were decorated with the FeO nanoparticles. A two-step processing route was developed when the nanorods are first oriented in a sacrificial polymer layer. Then, the polymer film with the aligned nanorods was removed by heat-treatment. In the second step, a sol-gel/dip-coating method was applied to produce the mullite composite film. The main challenge was to guarantee that all of the nanorods that were initially randomly distributed in the polymer would have time to rotate toward the field direction before complete solidification of the sacrificial layer. Theoretical and experimental analyses of the orientational distribution of the nanorod axes were conducted to identify a relationship between the polymer viscosity and processing parameters of the system. In contrast to the ferromagnetic nanorods, the rate of rotation of paramagnetic nanorods and their time of alignment are more sensitive to the magnetic field. This methodology allows manufacturing of different ceramic films with aligned nanorods and making nonmagnetic ceramic coating magnetic.
针对具有面内取向纳米棒的陶瓷薄膜的制造挑战，我们提出通过磁性纳米粒子对纳米棒进行修饰，并利用外部磁场对其进行定向排列。作为一个实例，合成了嵌入和定向 SiC 纳米棒的莫来石薄膜。SiC 纳米棒被 FeO 纳米粒子修饰。采用两步法工艺，首先在牺牲聚合物层中对纳米棒进行定向排列。然后，通过热处理去除具有定向纳米棒的聚合物薄膜。在第二步中，采用溶胶-凝胶/浸涂法制备莫来石复合薄膜。主要的挑战是确保在牺牲层完全凝固之前，所有最初随机分布在聚合物中的纳米棒都有时间转向磁场方向。对纳米棒轴的取向分布进行了理论和实验分析，以确定聚合物粘度与系统加工参数之间的关系。与铁磁纳米棒相比，顺磁纳米棒的旋转速度及其取向时间对磁场更为敏感。这种方法允许制造具有定向纳米棒的不同陶瓷薄膜，并使非磁性陶瓷涂层具有磁性。
