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<p>The possible structures of scandium diboride (ScB<sub>2</sub>) under ambient conditions were investigated by combining the structure prediction algorithm CALYPSO with first-principles calculations. The results indicate that <i>P</i>6/<i>mmm</i> (<i>hP</i>3-ScB<sub>2</sub>), <i>I</i>41/<i>amd</i> (<i>tI</i>12-ScB<sub>2</sub>), <i>Cm</i> (<i>mP</i>18-ScB<sub>2</sub>), and <i>P</i>63/<i>mmc</i> (<i>hP</i>6-ScB<sub>2</sub>) are all dynamically and mechanically stable under ambient pressure. Based on the calculated formation enthalpies, the energy stability of ScB<sub>2</sub> follows the order: <i>hP</i>3 &gt; <i>tI</i>12 &gt; <i>mP</i>18 &gt; <i>hP</i>6. Moreover, the Vickers hardness of <i>hP</i>3-ScB<sub>2</sub> exceeds 40 GPa, suggesting its potential as a super-hard material. In contrast, <i>tI</i>12-ScB<sub>2</sub> is a potential hard material, whereas <i>mP</i>18-ScB<sub>2</sub> and <i>hP</i>6-ScB<sub>2</sub> are unsuitable for use as hard materials. Analysis of the elastic anisotropy reveals that the bulk modulus anisotropy follows the sequence <i>mP</i>18 &gt; <i>hP</i>6 &gt; <i>hP</i>3 &gt; <i>tI</i>12, while the Young’s modulus anisotropy follows <i>hP</i>6 &gt; <i>mP</i>18 &gt; <i>tI</i>12 &gt; <i>hP</i>3. Finally, the calculated minimum thermal conductivity of ScB<sub>2</sub> decreases in the order: <i>hP</i>3 &gt; <i>tI</i>12 &gt; <i>mP</i>18 &gt; <i>hP</i>6. As the minimum thermal conductivity values of all these phases exceed 1.25 W·m<sup>−1</sup>·K<sup>−1</sup>, none of them are suitable for application as thermal barrier coating materials.</p>

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Structure stability, mechanical properties and minimum thermal conductivity of different ScB2 phases: a first-principles study

  • 期刊论文

  • 发表日期：

    2026年2月13日

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  • Yi-Xian Wang,
  • Zhuo Wang,
  • Wu-Na Xie,
  • Zhao-Qi Wang,
  • Jian-Bing Gu

摘要

The possible structures of scandium diboride (ScB2) under ambient conditions were investigated by combining the structure prediction algorithm CALYPSO with first-principles calculations. The results indicate that P6/mmm (hP3-ScB2), I41/amd (tI12-ScB2), Cm (mP18-ScB2), and P63/mmc (hP6-ScB2) are all dynamically and mechanically stable under ambient pressure. Based on the calculated formation enthalpies, the energy stability of ScB2 follows the order: hP3 > tI12 > mP18 > hP6. Moreover, the Vickers hardness of hP3-ScB2 exceeds 40 GPa, suggesting its potential as a super-hard material. In contrast, tI12-ScB2 is a potential hard material, whereas mP18-ScB2 and hP6-ScB2 are unsuitable for use as hard materials. Analysis of the elastic anisotropy reveals that the bulk modulus anisotropy follows the sequence mP18 > hP6 > hP3 > tI12, while the Young’s modulus anisotropy follows hP6 > mP18 > tI12 > hP3. Finally, the calculated minimum thermal conductivity of ScB2 decreases in the order: hP3 > tI12 > mP18 > hP6. As the minimum thermal conductivity values of all these phases exceed 1.25 W·m−1·K−1, none of them are suitable for application as thermal barrier coating materials.