M相六角铁氧体的固相法与溶胶凝胶法制备及磁电性能

Preparation and magnetoelectric properties of M-type hexagonal ferrite by solid state reaction and sol-gel

为探究BaFe_(10.2)Sc_(1.8)O_(19)样品在室温下的磁电耦合性能,使用固相法和溶胶-凝胶法制备BaFe_(10.2)Sc_(1.8)O_(19)样品。使用X射线衍射仪确定物相结构,样品均为单相多晶体,其空间群是P63/mmc。使用场发射扫描电镜观察表面形貌,固相法制备的样品成分分布不均匀,存在“富钪相”;溶胶凝胶法制备的样品的成分分布均匀,晶粒呈六角形貌,晶粒尺寸约3~5μm。分别对溶胶凝胶法和固相法制备的样品的磁性进行研究,结果表明,固相法在250 K左右发生相转变,室温下的磁滞迴线并未表现出磁电耦合的行为;而溶胶凝胶法制备的样品在330 K附近发生磁相变,结合此相变点上下温度的磁滞迴线的研究,表明该相变对应亚铁磁到锥形磁结构的变化。磁电容和磁化强度随磁场类似的变化关系表明,该锥形磁结构能够诱导铁电极化,这可以根据反DM相互作用来理解。

In order to investigate the magnetoelectric coupling performance of BaFe_(10.2)Sc_(1.8)O_(19) samples at room temperature,BaFe_(10.2)Sc_(1.8)O_(19) samples were prepared by solid phase method and sol-gel method.The phase structure was determined by X-ray diffraction,the prepared samples are all single-phase polycrystals with a space group of P63/mmc.The surface morphology was observed by field emission scanning electron microscopy,the samples prepared by solid phase method show that there is not uniform in composition and a "scandium-rich phase".The morphology analysis of the sample prepared by sol-gel method shows that the grains of BaFe_(10.2)Sc_(1.8)O_(19) exhibit uniform distribution with hexagonal platelet-shaped structure,and the grain size is about 3-5 μm.The magnetic results of the samples prepared by the sol-gel method and the solid state reaction show that the solid state reaction sample undergoes phase transition at about 250 K,and the hysteresis line does not exhibit magnetoelectric coupling behavior at room temperature;Temperature and magnetic field dependence of magnetization for the sample prepared by sol-gel method show that BaFe_(10.2)Sc_(1.8)O_(19) exhibits ferrimagnetic to conical spin structures phase transition near 330 K.Magnetic field dependence of magnetocapacitance is similar to the behavior in magnetization,which indicate that the systems exist ferroelectric polarization induced by the conical spin structures.It can be understood by the inverse Dzyaloshinskii-Moriya model.