Synthesis of CeFe$_{10.5}$Mo$_{1.5}$ with ThMn$_{12}$-Type Structure by Melt Spinning

Rare earth compounds RFe$_{12-x}$M$_{x}$ with tetragonal ThMn$_{12}$-type structure are of great interest for potential applications as permanent magnets. These materials serve as precursors for nitriding and hydriding, processes which can dramatically increase the Curie temperature, spontaneous magnetization, and affect the magnetic anisotropy. We report the phase study of CeFe$_{10.5}$Mo$_{1.5}$ samples melt spun at various surface wheel speeds v$_{s}$ between 5 and 60 m/s. The results from quantitative Rietveld analysis indicate that the as-spun ribbons are a mixture of primary CeFe$_{10.5}$Mo$_{1.5\, }$phase with impurity phases such as Ce$_{2}$Fe$_{17}$, Fe-Mo compound and CeFe$_{2}$. At wheel speeds v$_{s}$ below 25 m/s, CeFe$_{10.5}$Mo$_{1.5\, }$phase accounts for greater than 85 wt{\%}, while the Fe-Mo compound is the only detectable impurity phase. Above v$_{s\, }=$ 25 m/s, as the wheel speed increases, CeFe$_{10.5}$Mo$_{1.5\, }$phase decreases monotonically to about 60 wt{\%} at v$_{s\, }=$ 60 m/s while the amounts of impurity phases increase. Thermogravimetric measurement indicates that the Curie temperature T$_{c}$ of the CeFe$_{10.5}$Mo$_{1.5\, }$phase is 340 K. As a result, the best performing sample melt spun at v$_{s}=$15m/s only exhibits an energy product BH$_{max}=$0.121 MGOe at room temperature. Although such a number is modest for a permanent magnet, nitriding is expected to greatly enhance the Curie temperature, and hence the magnetic performance.