The Electronic Structure Of The Sm-co-based Ternary Permanent Magnet Alloy And Magnetic Studies

The rare-earth permanent magnetic materials have been widely used in the fields of the computer technology, communction, aviation & space technology, and nuclear energy with the development of modern industry and defence science technology. However, some magnetic properties of the classical rare-earth permanent magnets, such as coercivity, Curie temperature and temperature coefficient aren't suited for the new demands. Therefore, the investigating and developing to permanent magnets with excellent magnetic properties is an important subject for the magnetism researchers.Heretofore, the investigating work was concentrated in some permanent magnets with a higher Curie temperature and a higher magnetic anisotropy, which can be used above 450℃. Take Sm₂Co₁₇-series magnet for example, it has the higher Curie temperature(T_C=920℃) and higher energy product [(BH)_max=297KJ/m³] at room temperatue. Since its temperature coefficient of coercivity (β=-0.3%) is rather larger, its remanence decreases down to 1T at about 300°C that is far below the required operating temperature(450-500℃). The interest has been focused recently on the TbCu₇-type Sm-Co intermetallic alloys with a stronger uniaxial megnetocrytalline anisotropy(H_A=10～18T) and a lower temperature coefficient(β =-0.11%) due to their potential applications as high-temperature permanent magnets. The pure binary alloy SmCo₇ with TbCu₇-type structure does not exist stably at room temperature and it is easy to decompose to SmCo₅ and Sm₂Co₁₇ phases. One found that a third metal element M(M=Cu, Ti, Si, et al) is necessary to replace a part of Co atoms in order to stabilize the Sm-Co 1:7 phase with TbCu7-type structure, because this substituting atoms help to decrease the total energy of systems. Therefore, the current works are searching for the stable structure of Sm(Co, M)₇(M=Cu, Ti, Si, et at) alloys by experiments. Although many samples with excellent magnetic properties have been obtained, the batch production can't be gone due to the bad repeatness. Up to...