A Flame‐Reaction Method for the Large‐Scale Synthesis of High‐Performance Sm x Co y Nanomagnets

We report a flame‐reaction method to synthesize high‐performance Sm x Co y ( x =1, y =5; x =2, y =17) particles on a multigram scale. This flame reaction allows the controlled decomposition of Sm(NO 3 ) 3 and Co(NO 3 ) 2 to 320 nm SmCo‐O (SmCoO 3 + Co 3 O 4 ) particles. A 5.8 g sample of SmCo 3.8 ‐O particles was coated with CaO and then reduced at 900 °C by Ca to give 4.2 g of 260 nm SmCo 5 particles. The SmCo 5 particles are strongly ferromagnetic and the aligned particles in epoxy resin exhibit a large room‐temperature coercivity (H c ) of 41.8 kOe and giant (BH) max (maximum magnetic energy product) of 19.6 MGOe, the highest value ever reported for SmCo 5 made by chemical methods. This synthesis can be extended to synthesize Sm 2 Co 17 particles, providing a general approach to scaling up the synthesis of high‐performance Sm x Co y nanomagnets for permanent magnet applications.