Nd2Fe14B hard magnetic powders: Chemical synthesis and mechanism of coercivity

Chemical synthesis of Nd₂Fe₁₄B hard magnetic powders are still hindered due to the complicated methods. Herein, we put forward a modified sol–gel strategy to prepare Nd₂Fe₁₄B magnetic powders with excellent magnetic properties. In this synthesis procedure, acetone and boric acid are simultaneously used as the coordination reagents. The formation mechanisms of the oxide precursors as well as the effect of the reduction-diffusion temperature on the composition and magnetic properties of the products have been investigated. Magnetic properties measurement shows that the sample prepared at 950 °C possess the highest coercivity value of ~4.8 kOe. The Henkel plots and recoil loops suggest that the existence of α-Fe is responsible for the stronger exchange-coupling behavior and better magnetic performance.