The glassy behaviour of poorly crystalline Fe2O3 nanorods obtained by thermal decomposition of ferrous oxalate
The glassy behaviour of poorly crystalline Fe2O3 nanorods obtained by thermal decomposition of ferrous oxalate
复制标题
草酸亚铁热分解得到的不良结晶 Fe2O3 纳米棒的玻璃态行为
DOI：
10.1088/0957-4484/26/11/115705
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发表时间：
2015
期刊：
影响因子：
3.5
通讯作者：
N. Pizúrová
中科院分区：
文献类型：
--
作者：
M. Perović;V. Kusigerski;A. Mraković;V. Spasojević;J. Blanuša;V. Nikolić;O. Schneeweiss;B. David;N. Pizúrová
以微乳液法合成的纳米棒二水合草酸亚铁(FeC2O4×2H2O)为前驱体，在空气气氛中进行热分解。作为最终产物的纳米赤铁矿的形成是在中间产物出现之前进行的。包括几种互补技术(X射线衍射、透射电子显微镜、选区电子衍射、热重/差热分析和SQUID磁测量)的综合研究证实，中间产物对应于结晶较差的Fe2O。由于特殊的纳米棒形状和较差的结晶结构，所研究的Fe_2O_3在5K时显示出较高的∼0.5T？？>；在这项研究中，特别关注了结晶不良的Fe2O3的特殊磁性，通过复杂的实验方法对其进行了深入的研究，如不同冷却场下的热剩余磁化松弛，零场和场冷却记忆效应以及不同等待时间的老化实验。在低温和弱外加磁场下，所研究的系统的行为类似于自旋玻璃，通过记忆、年轻化和老化效应表现出缓慢的集体磁矩弛豫动力学。
Nanorod ferrous oxalate dihydrate (FeC2O4 × 2H2O) which had been synthesized by the microemulsion method, was used as a precursor in the thermal decomposition process performed in air atmosphere. The formation of nanocrystalline hematite as the final product was preceded by the appearence of an intermediate product. Comprehensive study comprising several complementary techniques (x-ray diffraction, transmission electron microscopy, selected area electron diffraction, thermogravimetric/differential thermal analyses and SQUID magnetometry) confirmed that the intermediate product corresponds to the poorly crystalline Fe2O3. Due to the specific nanorod shape and poorly crystalline structure, the investigated Fe2O3 showed high coercive field value of ∼ 0.5 T ?> at 5 K . ?> Special attention in this study was devoted to the peculiar magnetic properties of poorly crystalline Fe2O3, which were thoroughly investigated by employing sophisticated experimental procedures such as relaxation of thermoremanent magnetization for different cooling fields, zero field and field cooled memory effects as well as aging experiments for different waiting times. At low temperatures and weak applied magnetic fields, the investigated system behaves similarly to spin glasses, manifesting slow, collective relaxation dynamics of magnetic moments through memory, rejuvenation and aging effects.