New Zirconium Diboride Polymorphs-First-Principles Calculations
Marcin Maździarz1, Tomasz Mościcki1
1Institute of Fundamental Technological Research Polish Academy of Sciences, Warsaw, Poland.
Materials (Basel, Switzerland)
|July 10, 2020
Summary
Two new zirconium diboride (ZrB 2) polymorphs were identified as stable and not brittle. These hypothetical phases exhibit promising mechanical and thermodynamic properties for advanced material applications.
Area of Science:
- Materials Science
- Solid State Physics
- Computational Chemistry
Background:
- Zirconium diboride (ZrB 2) is a refractory ceramic with excellent properties.
- Exploring new polymorphs can lead to materials with enhanced characteristics.
- Understanding structural, mechanical, and thermodynamic stability is crucial for material design.
Purpose of the Study:
- To investigate two novel hypothetical polymorphs of zirconium diboride (ZrB 2).
- To determine the structural, mechanical, and thermodynamic stability of these new phases.
- To compare their properties with the known ZrB 2 phase.
Main Methods:
- First-principles density functional theory (DFT) calculations were employed.
- Analysis included structural, mechanical, and thermodynamic property assessments.
- Phonon band structure and density of states (DOS) were computed to assess dynamic stability.
Main Results:
- Two new ZrB 2 polymorphs (hP6 and oP6) were identified and characterized.
- Both phases exhibit negative formation enthalpy, indicating thermodynamic stability.
- Mechanical studies revealed lower hardness compared to the known phase, with no brittleness.
- Phonon analysis confirmed dynamic stability, with positive frequencies across all modes.
- The acoustic Debye temperature (Θ D) was estimated to be approximately 760 K.
Conclusions:
- The newly proposed ZrB 2 polymorphs are both thermodynamically and dynamically stable.
- These phases present a less hard, non-brittle alternative to the existing ZrB 2 structure.
- The findings provide valuable insights for the design and application of advanced zirconium diboride materials.
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