M型稀土铁氧体永磁的穆斯堡尔谱及微观结构与磁性研究

Mossbauer Spectrum,Microstructures and Magnetic Properties of M-Type Rare-Earth Permanent Magnets

采用陶瓷工艺,制备了M型稀土铁氧体永磁,采用热磁曲线测定样品的居里温度,用X射线衍射仪、穆斯堡尔谱仪及永磁铁氧体测量仪等分析样品的物相、晶格常数、磁学性能,实验表明:对稀土铁氧体永磁Ca_(0.45)La_xSr_(0.55-x)Fe_(10.3)Co_xO_(19-δ),当X≤0.3时,可获得单一的M相;伴随X的增加,样品的居里温度逐渐下降,12k和2b位的超交换作用加强,2b位、4f_2位的同质异能位移δ明显减少,4f_2、2a位四极矩分裂2ε逐渐增加,当x=0.2~0.4时,所获磁参数较理想,尤其是当x=0.3时,可获得Br为453 mT,H_(CJ)为404 kA/m的M型高性能稀土永磁铁氧体。

M-type rare-earth permanent magnets were prepared by ceramic technology. Then the Curie temperature was measured by the thermomagnetic curves. Finally, the sample phases, lattice constants and magnetic properties were respectively analyzed by X-ray diffraction, Mossbauer spectrometer and the measuring instrument of permanent magnet. The experiment shows that the rare-earth permanent magnet （Ca0.45LaxSr0.55-xFe10.3COxO19-8） obtains a single M-phase at x ≤ 0.3. When x increases, the Curie temperature of the sample will decrease and the role of superexchange will be strengthened for 12 k and 2 b. In the mean time, isomer shifts （5） will be significantly reduced for 2b and 4f2. The splitting of quadrupole （2 e ） will gradually increase for 4f2 and 2a. At x=0.2- 0.4 the resultant magnetic parameters are desirable. Particularly, at x=0.3, the high-performance rare-earth permanent magnets are obtained with Br of 453 mT and HCJ of 404 kA/m.