Lin Qing, He Yun, Xu Jianmei, Lin Jinpei, Guo Zeping, Yang Fang
College of Medical Informatics, Hainan Medical University, Haikou 571199, China.
Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology, Guangxi Normal University, Guilin 541004, China.
Nanomaterials (Basel). 2018 Sep 21;8(10):750. doi: 10.3390/nano8100750.
A sol-gel autocombustion method was used to synthesize Al ion-substituted cobalt ferrite CoAlFeO₄ ( = 0⁻1.5). According to X-ray diffraction analysis (XRD), cobalt ferrite was in a single cubic phase after being calcined at 1000 °C for 3 h. Moreover, the lattice constant decreased with increase in aluminum substituents. When the sample was analyzed by Scanning Electron Microscopy (SEM), we found that uniformly sized, well-crystallized grains were distributed in the sample. Furthermore, we confirmed that Al ion-substituted cobalt ferrite underwent a transition from ferrimagnetic to superparamagnetic behavior; the superparamagnetic behavior was completely correlated with the increase in Al ion concentration at room temperature. All these findings were observed in Mössbauer spectra. For the cobalt ferrite CoAlFeO₄, the coercivity and saturation magnetization decrease with an increase in aluminum content. When the annealing temperature of CoAlFeO₄ was steadily increased, the coercivity and saturation magnetization initially increased and then decreased.
采用溶胶-凝胶自燃烧法合成了铝离子取代的钴铁氧体CoAlFeO₄（= 0⁻1.5）。根据X射线衍射分析（XRD），钴铁氧体在1000℃下煅烧3小时后为单一立方相。此外，晶格常数随铝取代基的增加而减小。当用扫描电子显微镜（SEM）对样品进行分析时，我们发现样品中分布着尺寸均匀、结晶良好的晶粒。此外，我们证实铝离子取代的钴铁氧体经历了从亚铁磁性到超顺磁性的转变；在室温下，超顺磁性行为与铝离子浓度的增加完全相关。所有这些发现都在穆斯堡尔谱中观察到。对于钴铁氧体CoAlFeO₄，矫顽力和饱和磁化强度随铝含量的增加而降低。当CoAlFeO₄的退火温度稳步升高时，矫顽力和饱和磁化强度最初增加，然后降低。
