Abstract
In this work, the mechanochemical synthesis method was used for the first time to produce powders of the nanocrystalline Nd1.1Fe10CoTi compound from Nd2O3, Fe2O3, Co and TiO2. High-energy-milled powders were heat treated at 1000 °C for 10 min to obtain the ThMn12-type structure. Volume fraction of the 1:12 phase was found to be as high as 95.7% with 4.3% of a bcc phase also present. The nitrogenation process of the sample was carried out at 350 °C during 3, 6, 9 and 12 h using a static pressure of 80 kPa of N2. The magnetic properties Mr, µ0Hc, and (BH)max were enhanced after nitrogenation, despite finding some residual nitrogen-free 1:12 phase. The magnetic values of a nitrogenated sample after 3 h were Mr = 75 Am2 kg–1, µ0Hc = 0.500 T and (BH)max = 58 kJ·m–3. Samples were aligned under an applied field of 2 T after washing and were measured in a direction parallel to the applied field. The best value of (BH)max ~ 114 kJ·m–3 was obtained for 3 h and the highest µ0Hc = 0.518 T for 6 h nitrogenation. SEM characterization revealed that the particles have a mean particle size around 360 nm and a rounded shape.
Highlights
The high demand for Nd2Fe14B permanent magnets, with maximum energy product (BH)max up to 450 kJ·m–3 [1], in applications such as electric vehicles and wind turbines, implies a high production cost owing to the considerable content of Nd
It has been found that the ferromagnetic R(Fe,M)12 compounds crystalize in the tetragonal ThMn12type structure with R= Y, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm or Lu [4], and that these compounds exhibit strong exchange interactions for the light rare earths
The nitrogenated Nd1.1Fe10CoTiNx compounds exhibited a significant improvement of their magnetic properties after being washed, and aligned, even though according to the Le Bail analysis of the X-ray diffraction (XRD) patterns about 40 vol.% of the original 1:12 phase, did not adsorb nitrogen in this experiment
Summary
The high demand for Nd2Fe14B permanent magnets, with maximum energy product (BH)max up to 450 kJ·m–3 [1], in applications such as electric vehicles and wind turbines, implies a high production cost owing to the considerable content of Nd. The mechanochemical synthesis was demonstrated to yield single-crystal submicron and nanoparticles of hard magnetic materials, including the R(Fe,M) alloys, which exhibit coercivity values typical of nanocrystalline powders [18,19]. This synthesis technique requires less-expensive oxides, rather than metals, as the raw materials, and it may be expected to reduce local demagnetization fields due to more regular shapes of the particles [20]. The aim of this work was to prepare a Nd(Fe,Co,Ti)12Nx permanent magnet material through mechanochemical synthesis and subsequent nitrogenation of the Nd(Fe,Co,Ti) compound and to study its extrinsic magnetic properties as a function of the temperature and magnetic alignment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
