A facile in situ reduction route for preparation of spinel CoCr<sub>2</sub>O<sub>4</sub>polycrystalline nanosheets and their magnetic properties
作者:Shuijin Lei、Lei Liu、Chunying Wang、Xiaolian Shen、Chuanning Wang、Donghai Guo、Suyuan Zeng、Baochang Cheng、Yanhe Xiao、Lang Zhou
DOI:10.1039/c3ce41663a
日期:——
Considerable efforts have been exerted on the controllable synthesis of nanomagnetic materials due to their size- and morphology-dependent properties. Herein, a facile ethylene glycol in situ reduction strategy has been successfully employed in the preparation of CoCr2O4 nanosheets. X-ray diffraction patterns showed that the products have the cubic spinel structure. The electron microscopy analysis revealed that the obtained CoCr2O4 nanosheets consisted of nanoparticles with the diameters of 20–30 nm. Experiments proved that the volume ratio of ethylene glycol to water was crucial for the final morphology. The magnetization studies demonstrated that besides the long-range ferrimagnetic order below the Curie temperature (TC = 86 K), the sample exhibited two low-symmetry ordered states including the spiral magnetic order at TS = 20 K and the magnetic lock-in transition at TL = 13 K. The crystallinity- and size-dependent magnetic properties were also investigated. The temperature dependence of the specific heat revealed both phase transition at TC = 90 K and TS = 20 K, in line with the magnetic results.
由于纳米磁性材料具有尺寸和形态依赖性,因此人们对其可控合成进行了大量研究。在此,一种简单的乙二醇原位还原策略已成功用于制备CoCr2O4纳米片。X射线衍射图显示,产品具有立方尖晶石结构。电子显微镜分析显示,所获得的CoCr2O4纳米片由直径为20-30纳米的纳米颗粒组成。实验证明,乙二醇与水的体积比对于最终形态至关重要。磁化研究显示,除了居里温度(TC = 86 K)以下的远距铁磁有序外,样品还表现出两种低对称有序状态,包括TS = 20 K处的螺旋磁有序和TL = 13 K处的磁锁定转变。此外,研究人员还研究了结晶度和尺寸依赖性磁性能。比热对温度的依赖性揭示了TC = 90 K和TS = 20 K处的相变,这与磁学结果一致。