热处理温度对M-Ba铁氧体微米纤维结构和磁性能的影响

以柠檬酸和金属盐为原料,采用有机凝胶先驱体转化法成功制备了直径为500～600nm的钡铁氧体(BaFe12O19)微米纤维。通过XRD、SEM和VSM等技术对所制备的目标纤维进行了表征。结果表明,经750℃焙烧2h后,可获得M-Ba铁氧体纯相。随着焙烧温度的升高,晶粒逐渐长大,经850℃焙烧2h后,纤维主要由比较规则的片状晶粒组成。钡铁氧体纤维的磁性能主要受晶粒尺寸和测试温度的影响。经950℃焙烧2h后,组成纤维的晶粒尺寸约为62nm,室温下测得的饱和磁化强度和矫顽力均取得最大值,分别约为67A.m2/kg和328kA/m。在液氮(77K)条件下,纤维的饱和磁化强度有显著提高,最大值约为87A.m2/kg,这主要是由于纳米晶的表面自旋有序程度提高造成的。

Effects of Heat-treatment Temperature on Structure and Magnetic Properties of M-Ba Ferrite Microfibers

The barium ferrite(BaFe12O19) microfibers with diameters 500～600nm were prepared by the gel-precursor transformation process.The BaFe12O19 microfibers were characterized with X-ray diffraction,scanning electron microscopy and vibrating sample magnetometer.The pure barium ferrite microfibers with a high aspect ratio were formed after calcined at 750℃ for 2 hours.These barium ferrite microfibers were fabricated of nanosized hexa-particles.The magnetic properties of barium ferrite fibers are mainly influenced by the grain size and measurement tempe-rature.After calcined at 950℃ for 2 hours the barium ferrite microfibers were characterized with single-domain grains around 62nm and exhibited the specific saturation magnetization of 67A·m2/kg and coercivity of 328kA/m respectively.The magnetic characteristic difference measured at 297K and 77K can be attributed to the surface spin order of the nanocrystalline barium ferrite.