Recipe for stronger but lower-cost magnets
The demand for stronger permanent magnets is now growing more and more in both (stronger but costly) rare-earth and (decent but economic) ferrite magnets, which dominate the market of the hard magnet. In this talk, we particularly pick up the low-cost ferrite magnet. The base materials is the magnetoplumbite-type (M-type) hexagonal ferrite such as SrFe12O19. The improvement of the magnetic performance in recent commercial ferrite magnets has been achieved by adding a small amount of cobalt to the base materials. However, the physical origin of the improvement has not been well understood. In addition, the Co addition raises significantly the material cost in the production due to recent rapid increase in the Co price. Here, we explain the reason why the Co addition improve the performance microscopically and show the recipe to develop high-performance ferrite magnets for future generation with rather reducing the material cost on the basis of recent experimental results of specified 59Co-NMR for the La-Co co-substituted M-type strontium ferrites.
Hiroyuki Nakamura received the B.S. and M.S. in metal science and engineering form Kyoto University in 1985 and 1987, respectively and Ph.D in solid state physics form Osaka University in 1994. He was assistant professor of Osaka University and Kyoto University in 1988 and 1990, respectively, associate professor in the University of Hyogo in 2002, and professor in Kyoto University in 2007. His research interest includes fundamental magnetic properties of metals and compounds, search for new materials with novel quantum phenomena, effects of geometry in strongly-correlated-electron metals, and development of magnetic materials.