无容器气动悬浮技术制备SmFeO3橘子晶体及其微结构与磁性能

Microstructure and Magnetic Properties of SmFeO_3 Orange Crystal Prepared by Containerless Aerodynamic Levitation

采用无容器气动悬浮技术制备了单相SmFeO_3陶瓷球体,并研究其微结构与磁性能。结果表明:SmFeO_3陶瓷球体表面为树枝晶和析出物共混的独特结构,球体内部各元素分布均匀,其凝固过程是从表面向内部推移,最终形成"橘子晶体"。在室温下,SmFeO_3呈现出类似单晶的矩形磁滞回线,有利于提高磁光开关的响应速度。在159×10~3 A/m外磁场下,SmFeO_3的磁化强度随温度变化的关系表明其自旋重取向温度和Neel温度在室温以上,当温度降低到140 K时,SmFeO_3陶瓷球的磁矩开始逐渐降低,同时自40 K开始伴随着温度的降低而急速下降,其原因归结于反向平行的Sm^(3+)离子自旋的活化作用。

SmFeO3 ceramic balls were prepared via containerless aerodynamic levitation, their microstructure and magnetic properties were investigated. The spherical surface of SmFeO3 is a unique structure of the blend of dendritic and precipitates. The solidification process of the sphere is from the surface to the inside, finally forming the ＂orange crystal＂. Similar to the single crystal, SmFeO3 ceramic balls show nearly rectangular hysteresis loops at room temperature, which favors the improvement of the response speed of magneto-optical switch. The spin orientation temperature and the Neel temperature both are above the room temperature at an external magnetic field of 159× 10^3 A/m. The magnetic torque of SmFeO3 begins to gradually reduce at 140 K, and decreases sharply as the temperature reduces to 40 K, which is attributed to the spin activation of the reverse parallel Sm3＋ ions.