Formation of Ti₂AuN from Au-Covered Ti₂AlN Thin Films: A General Strategy to Thermally Induce Intercalation of Noble Metals into MAX Phases

Abstract

Thermally-induced intercalation of noble metals into non-van der Waals ceramic compounds presents a method to produce a new class of layered materials. We recently demonstrated an exchange reaction of Au with A layers of MAX phase carbides with plentiful combinations of A and M elements. Here, we report the first substitution of Al with Au in a Ti2AlN MAX phase nitride at an elevated temperature without destroying the original layered structure.These results bolster the generalization of the Au intercalation for the A elements in MAX phases with diverse combinations of M, A, and X elements. Furthermore, we propose crucial factors to achieve the exchange reaction: there should be a chemical potential for the A element to dissolve in or react with noble metals to intercalate; the noble metals should be inert to the initial metal

Processing of MAX phases: From synthesis to applications

“…In fact, the huge demand and interest in MXenes during the last years have relaunched the synthesis of new phases, such as containing double A-layer (ie Mo 2 Ga 2 C) and compositions with noble metals as "A" element (ie Ti 2 AuN). 298,299 These MAX phases with novel layer-structure/element might exhibit new properties or applications, such as superconductivity or unusual magnetic response. Another aspect is the development of phase diagrams for systems that are difficult to synthesize such as Zr-Al-C.…”

“…However, investigating new solid solutions and/or doping with catalyst elements such as Pd, Pt, Ni, Mo, Ru, etc would be of interest. In fact, the huge demand and interest in MXenes during the last years have relaunched the synthesis of new phases, such as containing double A‐layer (ie Mo 2 Ga 2 C) and compositions with noble metals as “A” element (ie Ti 2 AuN) 298,299 . These MAX phases with novel layer‐structure/element might exhibit new properties or applications, such as superconductivity or unusual magnetic response.…”