制备方法对钴铁氧体的微观结构和磁性能的影响

Effects of Preparation Methods on Microstructure and Magnetic Properties of Cobalt Ferrite

钴铁氧体由于其独特的磁特性,如较大的饱和磁致伸缩应变、较高的电阻率、较高的应变和压力敏感度等,被广泛应用于换能器、传感器等领域,是一类重要的磁性功能材料,其中,饱和磁致伸缩系数λ_(s)和压磁系数(dλ/dH)_(max)是决定磁致伸缩材料在实际应用中器件性能的关键参数,其与化学成分和合成方法等多种因素密切相关。综述了钴铁氧体的几种制备方法,如球磨法、溶胶凝胶法、水热法、自蔓延燃烧法和化学共沉淀法等,并对不同方法进行比较,分析了它们对显微组织、结构以及磁性能的影响,即不同的制备方法主要通过得到不同尺寸的粉末颗粒和烧结块的晶粒,以及改变金属阳离子的分布和晶粒择优取向度,从而实现钴铁氧体的微观结构和磁性能的有效调控,为进一步提高钴铁氧体磁致伸缩性能提供了实验设计思路。

Cobalt ferrites are extensively applied as a kind of important magnetic functional materials in transducers, sensors and other fields because of the unique magnetic properties, such as large saturation magnetostrictive strain(λ_(s)), high resistivity,high strain and pressure sensitivity. Among these properties, the saturation magnetostrictive coefficient λS and the piezomagnetic coefficient(dλ/dH)_(max) are the pivotal parameters to determine the performance of magnetostrictive materials in the actual application, and are closely related to many factors such as chemical composition and synthesis method. Several kinds of preparation methods of cobalt ferrite were reviewed, such as ball mill method, sol-gel method, hydrothermal method, auto-combustion method and chemical co-precipitation method. Then, these different methods were compared and their influence on the microstructure, structure and magnetic properties were analyzed. Different preparation methods can effectively control the microstructure and magnetic properties of cobalt ferrite by obtaining different sizes of powder particles and sintered block grains, as well as changing the distribution of metal cation and the preferred orientation of grain, and provide experimental design ideas for further improving magnetostrictive properties of cobalt ferrite.