Screening of 3d metals as A-elements in MAX phase Nb2SnC and their effects on the magnetic properties of the solid solutions Nb2(Sn1-xAx)C

The chemical versatility of MAX phases has increased almost exponentially over the last two decades, especially because of the synthesis/discovery of new solid solution phases. Many elements challenge the traditional ternary MAX phase compositions because they can be incorporated into the structure by alloying with another element despite not forming MAX phases by themselves. Examples are (mid-to-late) transition metals that can adopt the A-site in MAX phases, some even as the sole A-element (Fe through Zn). For solid solutions, Sn has proven to be a willing A-site partner for many transition metals (Mn, Fe, Co, Ni), even for more than one at a time. Where is the limit of transition metals that form A-site solid solutions? In this work, we demonstrate a screening of all 3d metals, except for Sc, partially substituting Sn in MAX phase Nb2SnC. We show the successful incorporation of up to 40% of V to Zn 3d metals (except for Ti), where V and Cr occupying the A-site of a MAX phase is demonstrated for the first time. The full series of solid solutions Nb2(Sn1-xAx)C with A = V,.., Zn is studied in detail by diffraction, microscopy, and spectroscopy techniques, as well as DFT calculations and the influence of the A-elements on the magnetic properties are discussed.