High Throughput Study on the Phase Evolution and Water Vapor Corrosion of Compositionally Complex Yb‐Ho‐Er‐Gd Silicates

ABSTRACT The development of non‐equimolar, compositionally complex rare‐earth (RE) silicates is crucial for enhancing their properties to meet the demands of applications in SiC‐based composites. In the present work, a high‐throughput combinatorial material chip approach is employed to rapidly explore the Yb‐Ho‐Er‐Gd silicate system. It is demonstrated that the precise design of RE combinations facilitates the formation of targeted crystal polymorphs. Specifically, for compositionally complex Yb‐Ho‐Er‐Gd disilicates, limiting the content of large‐radius cations (e.g., Gd < 12 at.% in RE) promotes the stabilization of low‐thermal‐expansion β/γ structures. The as‐deposited combinatorial material chip reveals that water vapor corrosion induces preferential RE volatilization, leading to surface silicon enrichment and phase transformation. Notably, Yb exhibits superior stability in the multi‐cation systems, which has been confirmed across the combinatorial material chip. This work establishes a fundamental design principle, demonstrating that strategic non‐equimolar RE combinations simultaneously optimize phase stability, corrosion resistance, and mechanical properties, providing an accelerated pathway for designing next‐generation RE silicates.