Synthesis of Ti 3 AuC 2 , Ti 3 Au 2 C 2 and Ti 3 IrC 2 by noble metal substitution reaction in Ti 3 SiC 2 for high-temperature-stable Ohmic contacts to SiC.

The large class of layered ceramics encompasses both van der Waals (vdW) and non-vdW solids. While intercalation of noble metals in vdW solids is known, formation of compounds by incorporation of noble-metal layers in non-vdW layered solids is largely unexplored. Here, we show formation of Ti ₃ AuC ₂ and Ti ₃ Au ₂ C ₂ phases with up to 31% lattice swelling by a substitutional solid-state reaction of Au into Ti ₃ SiC ₂ single-crystal thin films with simultaneous out-diffusion of Si. Ti ₃ IrC ₂ is subsequently produced by a substitution reaction of Ir for Au in Ti ₃ Au ₂ C ₂ . These phases form Ohmic electrical contacts to SiC and remain stable after 1,000 h of ageing at 600 °C in air. The present results, by combined analytical electron microscopy and ab initio calculations, open avenues for processing of noble-metal-containing layered ceramics that have not been synthesized from elemental sources, along with tunable properties such as stable electrical contacts for high-temperature power electronics or gas sensors.