Study on neutron diffraction and correlated magnetic properties of (R1−xZrx)Fe12−yMoy with low Mo concentration

In order to determine the Zr occupancy site, neutron diffraction study on (R1−xZrx)Fe12−yMoy (R = rare earth) were performed at 300 K and 573 K respectively. It is found that Zr occupies the 2a site, like the R atoms behavior. Zr is the first neighbor of Y in the periodic table, and has a similar chemic property as Y, but with a smaller atomic radius. Due to the suitable chemic property and atomic dimension, the addition of Zr at 2a site facilitates forming of the 1–12 phase, allowing more Fe atoms to enter the 8i site and decreasing Mo content from 1.5 to 0.8. As a result, Sm0.9Zr0.1(Fe0.75Co0.25)11.2Mo0.8 shows a large saturation magnetization σs of 137.6 emu/g, a high Curie temperature TC of 775 K and a strong anisotropy field Ha of 87.5 kOe, and its estimated value of maximum magnetic energy product (BH)max is up to 50.4 MGOe, favorable for permanent magnet applications. At present, almost rare-earth sintered magnets are made of Nd2Fe14B, causing the price of the raw material Nd to soar. Therefore, the development of low-cost Sm-Fe based hard magnetic materials is of particular significance.