Jing Panpan, Pan Lining, Du Jinlu, Wang Jianbo, Liu Qingfang
Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education, Lanzhou University, Lanzhou, 730000, People's Republic of China.
Phys Chem Chem Phys. 2015 May 21;17(19):12841-8. doi: 10.1039/c5cp01228g.
A range of robust SiO2-modified CoFe2O4 hollow nanofibers with high uniformity and productivity were successfully prepared via polyvinylpyrrolidone-sol assisted electrospinning followed by annealing at a high temperature of 1000 °C, and they were characterized using scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction and X-ray photoelectron spectroscopy in detail. It was demonstrated that amorphous SiO2 has a significant influence on not only the surface morphology, microstructure and crystalline size but also the room temperature magnetic performance of the inverse spinel CoFe2O4 nanofibers. The pure CoFe2O4 sample shows a particle chain rod-shape appearance but the SiO2-modified CoFe2O4 sample shows a robust hollow fibrous structure. With increasing SiO2 content, an increase at first and then a decrease in coercivity (Hc) and monotonously a decrease in saturation magnetization (Ms) have been determined in the obtained modified CoFe2O4 hollow nanofibers. A maximum Ms of about 80 emu g(-1) and a maximum Hc of about 1477 Oe could be, respectively, acquired from the pure CoFe2O4 nanorods and the modified CoFe2O4 hollow nanofibers with about 14.9% SiO2. The changes in Ms, Hc and the structure evolution mechanism of these SiO2-modified CoFe2O4 hollow nanofibers have been elaborated systematically. Furthermore, it is suggested that amorphous SiO2 enables effectively improving the structure endurance of 1D electrospun inorganic oxide hollow nanostructures being subjected to high temperatures.
通过聚乙烯吡咯烷酮 - 溶胶辅助静电纺丝，随后在1000℃的高温下退火，成功制备了一系列具有高均匀性和高产量的坚固的SiO₂修饰的CoFe₂O₄中空纳米纤维，并使用扫描电子显微镜、透射电子显微镜、振动样品磁强计、X射线衍射和X射线光电子能谱对其进行了详细表征。结果表明，非晶态SiO₂不仅对反尖晶石CoFe₂O₄纳米纤维的表面形貌、微观结构和晶体尺寸有显著影响，而且对其室温磁性能也有显著影响。纯CoFe₂O₄样品呈现颗粒链棒状外观，而SiO₂修饰的CoFe₂O₄样品呈现坚固的中空纤维结构。在所制备的修饰CoFe₂O₄中空纳米纤维中，随着SiO₂含量的增加，矫顽力（Hc）先增大后减小，饱和磁化强度（Ms）单调减小。从纯CoFe₂O₄纳米棒和约14.9% SiO₂的修饰CoFe₂O₄中空纳米纤维中分别可获得约80 emu g⁻¹的最大Ms和约1477 Oe的最大Hc。系统阐述了这些SiO₂修饰的CoFe₂O₄中空纳米纤维的Ms、Hc变化及结构演变机制。此外，研究表明非晶态SiO₂能够有效提高一维静电纺无机氧化物中空纳米结构在高温下的结构耐久性。
