钕掺杂对M型锶铁氧体结构和磁性能的影响

Effect of Nd-Doping on the Microstructure and Magnetic Properties of M-type Strontium Ferrites

采用溶胶-凝胶自蔓延燃烧合成了稀土钕掺杂的M型锶铁氧体（SrNdxFe12-xO19,x=0～1．0）纳米粉体，再将粉体压制成型在1200℃下烧结成磁体。用X射线衍射对粉体进行相结构分析，用磁特性测试仪测试了烧结体的磁性能。结果表明，焙烧温度高于850℃时可形成六方磁铅石型SrNdxFe12-xO19纳米粉体。随着稀土Nd掺杂量的增加，晶格常数α缓隧增大，c缓慢减小，晶体密度线性增大，晶粒尺寸保持在20-50nm范围，并且表现出逐渐减小的趋势。而SrNdxFe12-xO19磁体的剩磁研、磁感矫顽力Hcb以及最大磁能积（BH）m印。先增大后减小，在x=0．4时都达到最大值，内禀矫顽力Hcj却随着x的增大而不断增大。

The rare earth Nd-doped M-type strontium ferrites （SrNdxFe12-xO19, x=0-1.0）nano-powders were synthesized by sol-gel self-propagating combustion method and subsequent roasting. The roasted powders were subjected to the press compaction and sintered at 1200℃ for 2h. The powders were characterized by means of X-ray diffraction （XRD）. Measurements of magnetic performances were carried out using a magnetic properties tester. The results showed that nanosizsd single hexagonal phase SrNdxFe12-xO19 powders with the magnetoplumbite structure were prepared when roastinging temperature was above 850℃. With the increase of Nd-doping contents x, the lattice constant a of SrNdxFe12-xO19 powders increases slowly but c decreases slowly, whereas the X-ray density increases linearly. Furthermore, the grain sizes are maintained at 20nm to 50nm and showes a decreasing trend with the increase ofx. The residual magnetic induction, coercivities and the maximum energy product of SrNdxFe12-xO19 magnet increase first and then decrease, with maximum values at x=0.4, but the intrinsic coercivities increases monotonously with increasing x.