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<p>MAX-phase materials are promising candidates for thermal barrier coating applications, owing to their ultra-high thermal stability, high hardness, and excellent thermal shock resistance. The exploration of new MAX phases is therefore of great significance for developing advanced thermal barrier coating materials. The present work theoretically predicted three novel boron-based Nb<sub>2</sub>AB (A = Si, Ge, Sn) compounds using swarm intelligent optimization combined with first-principles calculations. Nb<sub>2</sub>GeB and Nb<sub>2</sub>SnB are confirmed to adopt the typical MAX-phase <i>P</i>6<sub>3</sub>/<i>mmc</i> structure, whereas Nb<sub>2</sub>SiB crystallizes in an orthorhombic <i>Pnma</i> structure. These structures are verified to be dynamically stable at ambient pressure and thermodynamically stable from 0 to 1500&#xa0;K, supporting their experimental feasibility. Notably, orthorhombic <i>Pnma</i>_Nb<sub>2</sub>SiB exhibits larger bulk modulus (214 GPa), shear modulus (137 GPa), Young’s modulus (338 GPa), and higher melting temperature (2919&#xa0;K) than the conventional <i>P</i>6<sub>3</sub>/<i>mmc</i> phase, with its melting point approaching that of 8YSZ (2973&#xa0;K). The minimum thermal conductivity of the presently designed Nb<sub>2</sub>AB compounds ranges from 0.52 to 0.85 W/m·K, which is significantly lower than that of 8YSZ (2.34 ~ 2.21 W/m·K). Although their thermal expansion coefficients are slightly lower than that of 8YSZ, the outstanding overall mechanical and thermodynamic properties render Nb<sub>2</sub>AB compounds promising for thermal barrier coating applications. The present results are expected to provide valuable theoretical guidance for the experimental synthesis of Nb<sub>2</sub>AB compounds and further rational design of novel MAX-phase materials.</p>

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Potential thermal barrier coating materials Nb2AB (A = Si, Ge, Sn) predicted by first-principles calculations

  • 期刊论文

  • 发表日期：

    2026年5月12日

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  • Fengyue Cheng,
  • Yu Zhao,
  • Chengyu Wang,
  • Boning Zhang,
  • Wei Li,
  • Xinxin Zhang

摘要

MAX-phase materials are promising candidates for thermal barrier coating applications, owing to their ultra-high thermal stability, high hardness, and excellent thermal shock resistance. The exploration of new MAX phases is therefore of great significance for developing advanced thermal barrier coating materials. The present work theoretically predicted three novel boron-based Nb2AB (A = Si, Ge, Sn) compounds using swarm intelligent optimization combined with first-principles calculations. Nb2GeB and Nb2SnB are confirmed to adopt the typical MAX-phase P63/mmc structure, whereas Nb2SiB crystallizes in an orthorhombic Pnma structure. These structures are verified to be dynamically stable at ambient pressure and thermodynamically stable from 0 to 1500 K, supporting their experimental feasibility. Notably, orthorhombic Pnma_Nb2SiB exhibits larger bulk modulus (214 GPa), shear modulus (137 GPa), Young’s modulus (338 GPa), and higher melting temperature (2919 K) than the conventional P63/mmc phase, with its melting point approaching that of 8YSZ (2973 K). The minimum thermal conductivity of the presently designed Nb2AB compounds ranges from 0.52 to 0.85 W/m·K, which is significantly lower than that of 8YSZ (2.34 ~ 2.21 W/m·K). Although their thermal expansion coefficients are slightly lower than that of 8YSZ, the outstanding overall mechanical and thermodynamic properties render Nb2AB compounds promising for thermal barrier coating applications. The present results are expected to provide valuable theoretical guidance for the experimental synthesis of Nb2AB compounds and further rational design of novel MAX-phase materials.