High-Temperature Oxidation-Resistance of Rare-Earth Transition Metal Silicides: Crystal Chemistry Insights from the Sc–Os–Si System

Amid growing interest in space exploration and the development of next-generation nuclear reactors, the demand for multifunctional materials capable of enduring extreme environments is growing. In this context, intermetallic compounds have re-emerged as an area of interest due to their notable structural properties including the ability to withstand high temperatures. The potential for forming ternary and higher-order intermetallics makes them particularly attractive to tune the properties and satisfy the stringent requirements of these applications. The research herein focuses on identifying materials suitable for high-temperature structural applications by synthesizing and characterizing rare-earth transition metal silicides within the Sc–Os–Si system. This system is particularly intriguing because seven unique compounds are uncovered displaying diverse but related crystal chemistries. These include identifying a new, previously unreported structure type and demystifying a previously reported, yet unclear structure type. Each compound’s potential was assessed through Vickers microhardness indentation and thermogravimetric analysis up to 1000 °C. The best-performing material, Sc3Os2Si6, further exhibited outstanding oxidation resistance for over 10 days at 1000 °C, a result attributed to the formation of a passivation layer composed of complex oxides. This study connects the crystal structures across the Sc–Os–Si system while underscoring the potential of identifying resilient materials through fundamental studies of underexplored phase spaces.