Sanida A, Stavropoulos S G, Speliotis Th, Psarras G C
Smart Materials & Nanodielectrics Laboratory, Department of Materials Science, School of Natural Sciences, University of Patras, 26504 Patras, Greece.
Institute of Nanoscience and Nanotechnology, NCSR "Demokritos", Aghia Paraskevi, 15310 Athens, Greece.
Materials (Basel). 2018 Dec 14;11(12):2551. doi: 10.3390/ma11122551.
In the present study two sets of nanocomposites consisting of an epoxy resin and BaFeO or SrFeO nanoparticles were successfully developed and characterized morphologically and structurally via scanning electron microscopy and X-ray diffraction spectra. The dielectric response of the nanocomposites was investigated by means of broadband dielectric spectroscopy and their magnetic properties were derived from magnetization tests. Experimental data imply that the incorporation of the ceramic nanoparticles enhances significantly the dielectric properties of the examined systems and their ability to store electrical energy. Dielectric spectra of all systems revealed the presence of three distinct relaxation mechanisms, which are attributed both to the polymer matrix and the nanoinclusions: Interfacial polarization, glass to rubber transition of the polymer matrix and the re-orientation of small polar side groups of the polymer chain. The magnetic measurements confirmed the ferromagnetic nature of the nanocomposites. The induced magnetic properties increase with the inclusion of hexaferrite nanoparticles. The nanocomposites with SrFeO nanoparticles exhibit higher values of coercive field, magnetization, magnetic saturation and remanence magnetization. A magnetic transition was detected in the ZFC/FC curves in the case of the BaFeO/epoxy nanocomposites.
在本研究中，成功制备了两组由环氧树脂与BaFeO或SrFeO纳米颗粒组成的纳米复合材料，并通过扫描电子显微镜和X射线衍射光谱对其形态和结构进行了表征。借助宽带介电谱研究了纳米复合材料的介电响应，并通过磁化测试得出其磁性能。实验数据表明，陶瓷纳米颗粒的加入显著提高了所研究体系的介电性能及其储能能力。所有体系的介电谱均显示存在三种不同的弛豫机制，这既归因于聚合物基体，也归因于纳米夹杂物：界面极化、聚合物基体的玻璃态到橡胶态转变以及聚合物链中小极性侧基的重新取向。磁性测量证实了纳米复合材料的铁磁性质。随着六方铁氧体纳米颗粒的加入，诱导磁性能增强。含SrFeO纳米颗粒的纳米复合材料表现出更高的矫顽场、磁化强度、磁饱和和剩磁磁化强度值。在BaFeO/环氧树脂纳米复合材料的零场冷却/场冷（ZFC/FC）曲线中检测到了磁转变。
