Computational Screening of Dopants for Gas Suppression and Thermoelastic Response in PCS-Derived SiC

H₂/CH₄ evolution during polycarbosilane (PCS) pyrolysis generates microdefects that impair densification, while dopant-induced changes in the derived SiC further affect its thermoelastic compatibility. Here, we develop a descriptor-based computational screening framework to evaluate dopants for simultaneous gas-suppression tendency in PCS and thermoelastic regulation of PCS-derived SiC ceramics. Both substitutional and non-substitutional doping scenarios were considered, and the latter was selected for systematic screening because it is considered more representative of practical precursor modification within the present descriptor-based screening framework. The screening identifies 13 promising dopants, among which B, Hf, Zr, Re, and Os exhibit strong radical-trapping capability and positive thermodynamic suppression of H₂/CH₄ formation. Molecular dynamics simulations further suggest dopant- and concentration-dependent changes in free volume, Young's modulus, Poisson's ratio, thermal expansion, and thermal-mismatch risk. Within the present computational framework, Ta-10% and Os-10% are predicted as priority candidates that offer favorable trade-offs between gas-suppression descriptors and thermoelastic compatibility, with Hf-10%, Zr-5%, and Re-3% emerging as secondary candidates for further validation.