|Alternative Title||fabrication and study of quasi-one-dimensional iron oxides ordered arrays
|Place of Conferral||兰州
|Other Abstract||"In recent years, quasi-one-dimensional nanomaterials have been attracted much attention due to their superior electrical, optical, magnetic, mechanical and thermal properties, as well as their potential applications in nanodevices, sensors, and lasers. Quasi-one-dimensional magnetic ordered arrays have been considered promising candidates for high-density perpendicular magnetic recording, and the electrodeposition based on anodic aluminum oxide (AAO) template is a main method to prepare these nanoarrays. So far, a lot of metal and alloy nanowire arrays have been successfully prepared. However, as a very important class of magnetic recording material, there is little report on quasi-one-dimensional ferrite nanomaterials. This paper is aim to fabricate iron oxides nanowire arrays by electrodepositing b-FeOOH nanowires in AAO templates, followed by a heat-treating process. The properties of these nanowire arrays have also been studied. Some main contents and innovations in this paper are listed in the following:
I. Different diameters of b-FeOOH nanowires have been fabricated for the first time. Their thermal stability and magnetic properties have been studied. The Neel temperatures of these nanowire arrays are much lower than that of bulk materials. At low temperature a “spin-freezing” has been observed in ZFC curves, and the temperature corresponding to the maximum value of ZFC curves increases (decreases) with increasing diameter (increasing applied fields). These abnormal magnetic properties are associated with their amorphous structures.
II. Different diameters of a-Fe2O3 nanowires have been fabricated. Low temperature Mössbauer spectra were firstly used to investigate the Morin transition. The Blocking temperature, Debye temperature and the magnetic anisotropy constant were also evaluated. In addition, size effect on Mössbauer effect was also investigated.
III. For the first time, different diameters and lengths of Fe3O4 nanowires have been fabricated. The perpendicular magnetic anisotropy which is suitable for high-density magnetic recording has been found. The Verwey transition and its size effect of these nanowire arrays were also studied. At low temperature, the “spin-freezing” was observed, and the temperature corresponding to the maximum value of ZFC curves varies with diameter and the applied field. In addition, the orientation of the magnetic moments was also studied and the static distribution of the magnetic moment was s...|
张丽英. 准一维铁的氧化物有序阵列的制备与性质[D]. 兰州. 兰州大学,2005.
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