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采用溶胶-凝胶法,通过控制烧结温度,成功制备了晶粒尺寸分别为30nm、40nm、52nm和60nm的纯相Y0.1Ca0.9MnO3纳米粒子,并研究了样品晶粒尺寸变化对其磁性能的影响.结果表明,随着晶粒尺寸的减小,Y0.1Ca0.9MnO3纳米粒子的单位有效磁化强度和饱和磁化强度均逐渐减小,而矫顽力却呈逐渐增大的趋势.对于不同晶粒尺寸Y0.1Ca0.9MnO3纳米粒子中所表现出来的这种异常的磁行为变化,主要归功于Y0.1Ca0.9MnO3纳米化以后样品中出现了磁有序和磁无序的相分离现象,即形成了一种以反铁磁母体中嵌入铁磁簇磁有序相为核、反铁磁或者顺磁的磁无序相为壳的核壳结构.
The pure Y0.1Ca0.9MnO3 nanoparticles with the grain sizes of 30nm, 40nm, 52nm and 60nm were successfully prepared by sol-gel method and the sintering temperature was controlled. The effect of grain size on the magnetic properties The results show that the unit effective magnetization and saturation magnetization of Y0.1Ca0.9MnO3 nanoparticles decrease with the decrease of the grain size, while the coercive force shows a gradually increasing trend. This abnormal magnetic behavior exhibited by the grain size Y0.1Ca0.9MnO3 nanoparticles is mainly due to the phase separation of magnetic ordering and magnetic disorder in the samples after the nanocrystallization of Y0.1Ca0.9MnO3. That is, a kind of core-shell structure with the magnetism ordered phase of ferromagnetic cluster embedded in the antiferromagnetic matrix as the core and the anti-ferromagnetic or paramagnetic magnetic disorder phase as the shell is formed.