A -Site Solid Solution Effects on Electrical Resistivity, Oxidation Resistance, and Hardness of MAX Phases V ₂ (As 1– x P x )C and V ₂ (As 1– x Ge x )C

MAX phases are a class of compounds known for having both metallic and ceramic properties, such as good electrical conductivity, oxidation resistance, and high hardness. The bulk of the research on their properties focuses on those with titanium at the M-site and metals from groups 13 to 15, e.g., aluminum, at the A-site. Here, we expand the properties repertoire with new arsenic-containing A-site solid solutions, V₂(As1-xPx)C and V₂(As1-xGex)C. The structure and elemental composition of the solid solutions were resolved with powder X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and hard X-ray photoelectron spectroscopy. The electrical resistivity measurements show that both full series are metallic with the parent phases being the most conductive. Thermal analyses show V₂GeC is the most oxidation resistant and V₂AsC is the least, while substitutions decrease thermal stability, as oxidation resistance of the intermediate compositions shifts toward that of V₂AsC. The V₂(As1-xGex)C series shows little variation in hardness across compositions, while the incorporation of phosphorus noticeably increases hardness.