Next-generation materials: Comprehensive physical insights into transition metal diborides XB2 (X = Ti, Zr, Hf) via first-principles study for applications in extreme conditions
{"title":"Next-generation materials: Comprehensive physical insights into transition metal diborides XB2 (X = Ti, Zr, Hf) via first-principles study for applications in extreme conditions","authors":"Minhajul Islam, Md Murshidul Islam","doi":"10.1016/j.chemphys.2025.112917","DOIUrl":null,"url":null,"abstract":"<div><div>Transition metal diborides XB<sub>2</sub> (X = Ti, Zr, Hf) have emerged as promising candidates for next-generation ultra-high temperature ceramics (UHTCs) due to their exceptional thermal stability, mechanical hardness, electrical conductivity, and oxidation resistance. In this study, a comprehensive first-principles investigation based on density functional theory (DFT) is conducted to explore the fundamental physical properties of TiB<sub>2</sub>, ZrB<sub>2</sub>, and HfB<sub>2</sub>, targeting their potential application under extreme environments. Most of the properties investigated in this comprehensive study are novel, aiming to provide a comparative understanding among the XB<sub>2</sub> materials. The structural, mechanical, electronic, thermodynamic, elastic, thermophysical, and vibrational properties of these compounds are systematically analyzed. The computed lattice parameters of hexagonal XB<sub>2</sub> exhibit strong consistency with previously reported experimental and theoretical results. All compounds exhibit mechanical and dynamical stability with strong covalent-metallic bonding characteristics. The phonon dispersion and density of states confirm vibrational stability and provide insight into lattice dynamics. Electronic band structures and density of states reveal metallic conductivity (E<sub>g</sub> = 0 eV) and non-magnetic ground states. The thermodynamic properties, including Debye temperature, heat capacity, free energy, and melting temperature, suggest robust high-temperature performance. The XB<sub>2</sub> metal diborides exhibit elastic anisotropy and mechanical brittleness, with their hardness following the order: TiB<sub>2</sub> > ZrB<sub>2</sub> > HfB<sub>2</sub>. Among them, TiB<sub>2</sub> demonstrates the highest melting point at 3025 K, while ZrB<sub>2</sub> and HfB<sub>2</sub> show slightly lower melting temperatures of 2669 K and 2759 K, respectively. The essential thermodynamic and thermophysical properties of hexagonal XB<sub>2</sub> compounds have been thoroughly investigated for the first time. Remarkably, all three materials demonstrate exceptionally high lattice thermal conductivities at 300 K, measured as 453 Wm<sup>−1</sup> K<sup>−1</sup> for TiB<sub>2</sub>, 302 Wm<sup>−1</sup> K<sup>−1</sup> for ZrB<sub>2</sub>, and 189 Wm<sup>−1</sup> K<sup>−1</sup> for HfB<sub>2</sub>, indicating their strong potential for high-temperature heat management applications. This study highlights the intrinsic superiority of these diborides and their tunable physical responses, affirming their applicability in aerospace, nuclear reactors, and thermal protection systems. Overall, this comprehensive investigation predicts the suitability of XB<sub>2</sub> (X = Ti, Zr, Hf) compounds in high-temperature environments and inspires further experimental validation for practical utilizations.</div></div>","PeriodicalId":272,"journal":{"name":"Chemical Physics","volume":"600 ","pages":"Article 112917"},"PeriodicalIF":2.4000,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemical Physics","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0301010425003180","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Transition metal diborides XB2 (X = Ti, Zr, Hf) have emerged as promising candidates for next-generation ultra-high temperature ceramics (UHTCs) due to their exceptional thermal stability, mechanical hardness, electrical conductivity, and oxidation resistance. In this study, a comprehensive first-principles investigation based on density functional theory (DFT) is conducted to explore the fundamental physical properties of TiB2, ZrB2, and HfB2, targeting their potential application under extreme environments. Most of the properties investigated in this comprehensive study are novel, aiming to provide a comparative understanding among the XB2 materials. The structural, mechanical, electronic, thermodynamic, elastic, thermophysical, and vibrational properties of these compounds are systematically analyzed. The computed lattice parameters of hexagonal XB2 exhibit strong consistency with previously reported experimental and theoretical results. All compounds exhibit mechanical and dynamical stability with strong covalent-metallic bonding characteristics. The phonon dispersion and density of states confirm vibrational stability and provide insight into lattice dynamics. Electronic band structures and density of states reveal metallic conductivity (Eg = 0 eV) and non-magnetic ground states. The thermodynamic properties, including Debye temperature, heat capacity, free energy, and melting temperature, suggest robust high-temperature performance. The XB2 metal diborides exhibit elastic anisotropy and mechanical brittleness, with their hardness following the order: TiB2 > ZrB2 > HfB2. Among them, TiB2 demonstrates the highest melting point at 3025 K, while ZrB2 and HfB2 show slightly lower melting temperatures of 2669 K and 2759 K, respectively. The essential thermodynamic and thermophysical properties of hexagonal XB2 compounds have been thoroughly investigated for the first time. Remarkably, all three materials demonstrate exceptionally high lattice thermal conductivities at 300 K, measured as 453 Wm−1 K−1 for TiB2, 302 Wm−1 K−1 for ZrB2, and 189 Wm−1 K−1 for HfB2, indicating their strong potential for high-temperature heat management applications. This study highlights the intrinsic superiority of these diborides and their tunable physical responses, affirming their applicability in aerospace, nuclear reactors, and thermal protection systems. Overall, this comprehensive investigation predicts the suitability of XB2 (X = Ti, Zr, Hf) compounds in high-temperature environments and inspires further experimental validation for practical utilizations.
期刊介绍:
Chemical Physics publishes experimental and theoretical papers on all aspects of chemical physics. In this journal, experiments are related to theory, and in turn theoretical papers are related to present or future experiments. Subjects covered include: spectroscopy and molecular structure, interacting systems, relaxation phenomena, biological systems, materials, fundamental problems in molecular reactivity, molecular quantum theory and statistical mechanics. Computational chemistry studies of routine character are not appropriate for this journal.