| Abstract Scope |
Hard materials like diamond, Si3N4, and SiC are often accompanied by high thermal conductivity, due to their strong covalent bonds and high Young’s modulus, which increase sound velocity and benefit heat transportation. How to achieve concurrent high hardness and low thermal conductivity remains a challenge in thermal insulation materials. In our work, we reported (Yb+Ca) co-doped α-SiAlON (a solid solution of α-Si3N4) with a low thermal conductivity of 3.1 W/(m·K) and a hardness of 18 GPa at 25℃ by utilization of the rattling effect. We demonstrated that by utilization of the rattling effect, α-SiAlON, well-known for its excellent mechanical properties, can be tuned to exhibit low thermal conductivity comparable to that of La2Zr2O7 and 8YSZ, with higher hardness/toughness and lower density. |