Comment on 'High-temperature soft magnetic properties of antiperovskite nitrides ZnNFe_3 and AlNFe_3' by Yankun Fu, Shuai Lin, and Bosen Wang, J. Magn. Magn. Mater. 378 (2015) 54-58

摘要

The authors of the aforementioned manuscript have recently claimed the synthesis of the ternary nitrides ZnNFe_3 (=ZnFe_3N) and AlNFe_3 (=AlFe_3N), ordered substituted variants of the binary phase γ'-Fe_4N. While soft ferromagnets of such kind are presently attracting lots of attention, their history dates back for more than half a century. In particular, Al-substituted γ'-Fe_4N has already been mentioned in 1961, and the existence of AlFe_3N has also been claimed in 2009 from a two-step ammonolysis reaction combining a high-temperature sintering step and a low-temperature nitriding reaction. Nonetheless, one of us had to withdraw the latter claim after finding out, by means of scanning-electron microscopy and elemental mapping, that all samples of "AlFe_3N" consisted of an intimate solid mixture of γ'-Fe_4N and amorphous Al_2O_3. From what follows, we have strong reasons to believe that the authors of Ref. overlooked our findings and also did not synthesize ZnFe_3N and AlFe_3N.