Six-principal-component high-entropy carbonitride aerogel thermal insulator: Theoretical and experimental studies

A combined theoretical and experimental approach was used to investigate high-entropy carbonitride. Density functional theory (DFT) calculations suggest that the [N]/([C]+[N]) ratio in (Ti 1/6 Cr 1/6 V 1/6 Mo 1/6 Nb 1/6 Ta 1/6 )(C 1− x N x ) affects its lattice thermal conductivity which could be decreased by 89% by increasing the ratio from 0 to 1/2. Moreover, a robust, flame-retardant and high-temperature resistant (Ti 1/6 Cr 1/6 V 1/6 Mo 1/6 Nb 1/6 Ta 1/6 )(C 0.64 N 0.36 ) high-entropy carbonitride aerogel (6-HECNA) was synthesized. It exhibited a porosity of 94.3%, a compressive strength of 0.9 MPa, and a good high-temperature stability up to 1673 K. These properties, along with its outstanding fire-retardancy, and low thermal conductivity (0.122 W·m −1 ·K −1 at 298 K), make it a promising candidate material for thermal insulation applications under harsh conditions.