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A precursor-engineered route to high-entropy diborides: Unraveling solid-solution formation and bonding character via DFT.

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Title: A precursor-engineered route to high-entropy diborides: Unraveling solid-solution formation and bonding character via DFT.
Authors: Guo, Linwei1 (AUTHOR), Wang, Saidi1 (AUTHOR), Ouyang, Yimin1 (AUTHOR), Zhang, Tao1 (AUTHOR), Ma, Mengdong1,2,3 (AUTHOR) mamengdong@ysu.edu.cn, Du, Bin1 (AUTHOR) dubin@gzhu.edu.cn
Source: Journal of Alloys & Compounds. Sep2025, Vol. 1040, pN.PAG-N.PAG. 1p.
Subjects: Melting points, Density functional theory, Electronic structure, Extreme environments, Covalent bonds
Abstract: High-entropy diboride ceramics have attracted considerable attention due to their exceptional properties, including ultra-high melting points, high hardness, and excellent thermal stability. Herein, high-entropy diboride (Hf 0.25 Zr 0.25 Nb 0.25 Ta 0.25)B 2 ceramic powders were successfully synthesized via a polymer-derived ceramics route at 2100°C. The as-prepared powders exhibit a single-phase hexagonal AlB₂-type structure with excellent compositional homogeneity from nanoscale to microscale and low oxygen impurity content of 0.65 %. The phase composition, microstructure, and solid-solution formation mechanism were systematically investigated. First-principles calculations based on Density Functional Theory reveal that the powders possess metallic conductivity, strong B–B covalent bonding, and mixed ionic/covalent metal–boron interactions. These findings provide valuable insights into the bonding nature and electronic structure of high-entropy diborides. This study not only offers an effective strategy for synthesizing high-entropy diboride powders with controlled composition and high purity, but also advances the fundamental understanding of their structure–property relationships, facilitating future applications in extreme environments. • The (Hf 0.25 Zr 0.25 Nb 0.25 Ta 0.25)B 2 high-entropy diboride ceramic powders were synthesized via the polymer-derived-ceramic route. • The phase composition, microstructure, and solid-solution formation mechanism of the powders were systematically analyzed. • The first-principles calculations based on Density Function Theory (DFT) were performed to investigate the electronic structure. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:High-entropy diboride ceramics have attracted considerable attention due to their exceptional properties, including ultra-high melting points, high hardness, and excellent thermal stability. Herein, high-entropy diboride (Hf 0.25 Zr 0.25 Nb 0.25 Ta 0.25)B 2 ceramic powders were successfully synthesized via a polymer-derived ceramics route at 2100°C. The as-prepared powders exhibit a single-phase hexagonal AlB₂-type structure with excellent compositional homogeneity from nanoscale to microscale and low oxygen impurity content of 0.65 %. The phase composition, microstructure, and solid-solution formation mechanism were systematically investigated. First-principles calculations based on Density Functional Theory reveal that the powders possess metallic conductivity, strong B–B covalent bonding, and mixed ionic/covalent metal–boron interactions. These findings provide valuable insights into the bonding nature and electronic structure of high-entropy diborides. This study not only offers an effective strategy for synthesizing high-entropy diboride powders with controlled composition and high purity, but also advances the fundamental understanding of their structure–property relationships, facilitating future applications in extreme environments. • The (Hf 0.25 Zr 0.25 Nb 0.25 Ta 0.25)B 2 high-entropy diboride ceramic powders were synthesized via the polymer-derived-ceramic route. • The phase composition, microstructure, and solid-solution formation mechanism of the powders were systematically analyzed. • The first-principles calculations based on Density Function Theory (DFT) were performed to investigate the electronic structure. [ABSTRACT FROM AUTHOR]
ISSN:09258388
DOI:10.1016/j.jallcom.2025.183592