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06:53
Fabrication and Optimization of Type II Silicon Clathrate Films
Published on: October 14, 2025
Novel refractory phase, Ta7Si2(Si(x)B(1-x))2.
V Romaka1, V Fosodeder, P F Rogl
1Institute of Physical Chemistry, University of Vienna , Währingerstrasse 42, A-1090 Wien, Austria.
Inorganic Chemistry
|September 21, 2013
Summary
This study reveals the crystal structure of a new silicon boride, Ta7Si2(Si(x)B(1-x))2, using X-ray diffraction. DFT calculations confirm its covalent-ionic nature and high hardness, indicating metallic behavior.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Crystallography
Background:
- Refractory borides are crucial for high-temperature applications.
- Understanding the structure-property relationships in novel silicides and borides is essential for developing advanced materials.
Purpose of the Study:
- To elucidate the crystal structure of the new refractory silicon boride Ta7Si2(Si(x)B(1-x))2.
- To investigate the bonding characteristics and physical properties of this compound.
Main Methods:
- X-ray single crystal (XSC) and powder diffraction (XPD) were employed for structural determination.
- Density Functional Theory (DFT) calculations were performed to analyze electronic structure and bonding.
- Vickers hardness (HV) and Sommerfeld constant (γ) were measured/calculated to assess material properties.
Main Results:
- The crystal structure of tetragonal Ta7Si2(Si(x)B(1-x))2 (space group P4/mbm) was determined, showing a unique arrangement of metal prisms and antiprisms.
- DFT calculations revealed strong B(Si)-B(Si) and Si-Si bonding, classifying the compound as covalent-ionic.
- A high hardness value of 1750 HV and a Sommerfeld constant of 7.58 mJ/mol K(2) were reported, suggesting a combination of hardness and metallic behavior.
Conclusions:
- Ta7Si2(Si(x)B(1-x))2 exhibits a complex crystal structure with distinct coordination polyhedra around nonmetal atoms.
- The compound possesses a blend of covalent-ionic bonding and metallic characteristics, contributing to its high hardness and electrical properties.
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