不同晶粒尺寸的(La_(0.47)Gd_(0.2))Sr_(0.33)MnO_3纳米颗粒磁性能

Magnetic Properties of (La_(0.47)Gd_(0.2))Sr_(0.33)MnO_3 Nanoparticles with Different Grain Sizes

采用非晶态多核配合的方法制备了(La0.47Gd0.2)Sr0.33MnO3纳米颗粒,用XRD、HRTEM和MPMS等手段对纳米颗粒的微观结构和磁性能进行研究。XRD和SAD分析表明,所有的样品都具有单相钙钛矿结构;TEM分析表明,经过600,800和1000℃烧结10h后的样品颗粒尺寸分别为40～50nm,90～100nm和140～150nm。样品的磁学性能结果表明:(La0.47Gd0.2)Sr0.33MnO3纳米颗粒的居里温度TC(298K)基本上不随颗粒尺寸的变化而变化,而相对磁制冷能力取决于颗粒尺寸;颗粒尺寸为90～100nm的(La0.47Gd0.2)Sr0.33MnO3纳米颗粒的相对磁制冷能力最大,可以作为室温下使用的磁制冷工质侯选材料。

(La0.47Gd0.2)Sr0.33MnO3 nanoparticles were synthesized by an amorphous heteronuclear complexing method. The microstructure and magnetic properties of the synthesized nanoparticles were characterized by XRD, HRTEM and MPMS. XRD and selected area electron diffraction (SAD) analyses reveal that the products are of pure single-phase rhombohedral structure. TEM observation shows that the particle sizes of the products calcined at 600, 800 and 1000 degrees C for 10 h are about 40-50 nm, 90-100 nm and 140-150 nm, respectively. The Curie temperature T-C (298 K) of the nanoparticles does not depend on the particle size, while the relative cooling power (RCP) is determined by the particle size. (La0.47Gd0.2)Sr0.33MnO3 with particle sizes ranging from 90 nm to 100 nm has the largest RCP, which may be a suitable candidate as working substance in magnetic refrigeration at room temperature.