纳米级垂直磁记录材料BaFe_（12）O_（19）和Ba（CoTi）_xFe_（

Preparation and Magnetic Properties of Nanometerscale BaFe_(12)O_(19) and Ba(CoTi)_xFe_(12-2x)O_(19) Ultrafine Particles

采用有机树脂法合成了超细ＢａＦｅ１２Ｏ１９及其离子取代物Ｂａ（ＣｏＴｉ）ｘＦｅ１２－２ｘＯ１９利用ＴＥＭ和ＸＲＤ对所制样品进行了结构、形貌和晶相分析。其颗粒大小为２０～１００ｎｍ。ＶＳＭ静态磁性测试结果表明，在６５０°处所制样品显示极低的矫顽力Ｈｃ和比饱和磁化强度，随着退火温度的提高，Ｈｃ和δｓ迅速增大，探讨了磁性能随退火温度和保温时间的变化关系。

Nanometer barium hexaferrtie ultrafine particles with the grain diameter between 20￣100nm have been prepared by the citrate-precursor method. These particles show relatively low saturation magnetisation. When raised the annealing temperature,the coercive forces increase rapidly. If both raised the annealing temperature and prolonged the time of keeping temperature,both the coericivities and saturation magnetisations increase rapidly.Finally some discussions about the present results are given.