An effective dopant to improve the thermal stability of a Fe16N2 permanent magnet is proposed in this paper. It is demonstrated both theoretically and experimentally that manganese is a promising candidate as dopant in Fe16N2 magnet to improve the thermal stability. Firstly, the atomic moments of the Fe ions with respect to N is investigated by using first-principles DFT calculation. Two possible candidates of elements, including Co and Mn, are compared in terms of its preferred position and magnetic coupling mode. It is found that Mn prefers Fe1 position and ferromagnetic coupling in the Fe16N2 lattice. So Mn is considered as a promising dopant in Fe16N2 magnet to improve its thermal stability. Based on theoretical results, experiments are conducted by a cold-crucible method to prepare (Fe1-xMnx) N bulk samples. The samples are thermal treated at different temperatures to observe their thermal stabilities. X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) are characterized on the samples.
Bibliographical noteFunding Information:
This work was supported in part by ARPA-E (Advanced Research Projects Agency-Energy) BCT Fe<Inf>16</Inf>N<Inf>2</Inf> Magnet project under contract No.0472-1595. Parts of this work were carried out in using the Characterization Facility, which receives partial support from NSF through the NSF Minnesota MRSEC program under Award Number DMR-0819885.Dr. Jian-Ping Wang has equity and royalty interests in, and serves on the Board of Directors and the Scientific Advisory Board for, Niron Magnetics LLC, a company involved in the commercialization of FeN magnets. The University of Minnesota also has equity and royalty interests in Niron Magnetics LLC. These interests have been reviewed and managed by the University of Minnesota in accordance with its Conflict of Interest policies.