tailieunhanh - Báo cáo hóa học: " Low-Temperature Preparation of Superparamagnetic CoFe2O4 Microspheres with High Saturation Magnetization"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Low-Temperature Preparation of Superparamagnetic CoFe2O4 Microspheres with High Saturation Magnetization | Nanoscale Res Lett 2010 5 1817-1821 DOI s11671-010-9718-7 NANO EXPRESS Low-Temperature Preparation of Superparamagnetic CoFe2O4 Microspheres with High Saturation Magnetization Hong Lei Yuan Yong Qiang Wang Shao Min Zhou Li Sheng Liu Xi Liang Chen Shi Yun Lou Rui Jian Yuan Yao Ming Hao Ning Li Received 23 May 2010 Accepted 26 July 2010 Published online 11 August 2010 The Author s 2010. This article is published with open access at Abstract Based on a low-temperature route monodispersed CoFe2O4 microspheres MSs were fabricated through aggregation of primary nanoparticles. The microstructural and magnetic characteristics of the as-prepared MSs were characterized by X-ray diffraction photoelectron spectroscopy scanning transmitting electron microscopy and vibrating sample magnetometer. The results indicate that the diameters of CoFe2O4 MSs with narrow size distribution can be tuned from over 200 to 330 nm. Magnetic measurements reveal these MSs exhibit superparamagnetic behavior at room temperature with high saturation magnetization. Furthermore the mechanism of formation of the monodispersed CoFe2O4 MSs was discussed on the basis of time-dependent experiments in which hydrophilic PVP plays a crucial role. Keywords Magnetism Nanostructure Superparamagnetism Introduction Over the past decades superparamagnetic SP nanostructures of spinel ferrites MFe2O4 M Fe Co Cu Zn etc. have drawn intense scientific and technological interests because they possess a wide range of applications in magnetic fluid 1-3 magnetic resonance imaging MRI H. L. Yuan Y. Q. Wang S. M. Zhou L. S. Liu X. L. Chen S. Y. Lou R. J. Yuan Y. M. Hao N. Li Key Lab for Special Functional Materials of Ministry of Education Henan University 475004 Kaifeng People s Republic of China e-mail smzhou@ 4 5 and drug delivery technology 6-8 . Recently spinel cobalt ferrite CoFe2O4 nanostructure materials have been extensively studied because they form a magnetic system which is an .