Comment on “High-temperature soft magnetic properties of antiperovskite nitrides ZnNFe3 and AlNFe3” by Yankun Fu, Shuai Lin, and Bosen Wang, J. Magn. Magn. Mater. 378 (2015) 54–58

Abstract

The authors of the aforementioned manuscript have recently claimed the synthesis of the ternary nitrides ZnNFe3 (=ZnFe3N) and AlNFe3 (=AlFe3N), ordered substituted variants of the binary phase γ‘-Fe4N [1]. 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‘-Fe4N has already been mentioned in 1961 [2], and the existence of AlFe3N has also been claimed in 2009 [3] from a two-step ammonolysis reaction combining a high-temperature sintering step and a low-temperature nitriding reaction [4]. 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 “AlFe3N” consisted of an intimate solid mixture of γ‘-Fe4N and amorphous Al2O3[5]. From what follows, we have strong reasons to believe that the authors of Ref. [1] overlooked our findings [5] and also did not synthesize ZnFe3N and AlFe3N.