Abstract Nano-sized CoFe2O4 (CFO), BiFeO3 (BFO) and their core-shell composites BFO@CFO and CFO@BFO were synthesized by chemical co-precipitation method. X-ray diffraction pattern confirmed the crystallinity and phase formation of bare CFO, BFO and their core-shell composites. Morphology and core-shell nature of these nanoparticles is justified by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Magnetization curve showed the weak ferromagnetic behaviour of BFO. Typical ferrimagnetic behaviour is shown by bare CFO and core-shell nanocomposites. The value of maximum magnetization, remanence magnetization and coercivity of CFO@ BFO were found to be greater than the BFO@ CFO. Also, CFO@ BFO showed the highest value of dielectric constant in the frequency range of 104–106 Hz. Dielectric constant versus temperature curve of BFO and core-shell composites exhibit incongruity close to the antiferromagnetic transition temperature (370 °C) of BFO indicating presence of magnetoelectric (ME) coupling.

中文翻译：

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CoFe2O4@BiFeO3和BiFeO3@CoFe2O4核壳纳米复合材料的结构、磁性和介电性能对比研究

摘要 采用化学共沉淀法合成了纳米尺寸的CoFe2O4（CFO）、BiFeO3（BFO）及其核壳复合材料BFO@CFO和CFO@BFO。X 射线衍射图证实了裸 CFO、BFO 及其核壳复合材料的结晶度和相形成。场发射扫描电子显微镜 (FESEM) 和高分辨率透射电子显微镜 (HRTEM) 证明了这些纳米颗粒的形态和核壳性质是合理的。磁化曲线显示了 BFO 的弱铁磁行为。典型的亚铁磁行为由裸 CFO 和核壳纳米复合材料显示。发现 CFO@BFO 的最大磁化强度、剩磁和矫顽力值大于 BFO@CFO。此外，CFO@BFO 在 104-106 Hz 的频率范围内显示出最高的介电常数值。