Computational Screening and Stabilization of Boron-Substituted Type-I and Type-II Carbon Clathrates

Area of Science:

• Materials Science
• Computational Chemistry
• Solid-State Physics

Background:

• Carbon clathrates are promising materials but lack stable substitution schemes beyond type-VII.
• Stabilizing clathrate structures is crucial for exploring their potential applications.

Purpose of the Study:

• To computationally investigate boron substitution in type-I and type-II carbon clathrates.
• To identify thermodynamically stable boron-substituted carbon clathrate structures.

Main Methods:

• Performed over 5000 computational boron decoration schemes for type-I and type-II clathrates.
• Utilized density functional theory (DFT) calculations at 10 and 50 GPa.
• Evaluated structural stability and energetic favorability based on formation enthalpies.

Main Results:

• Boron substitution significantly stabilizes carbon clathrates under high pressure.
• Optimal stability achieved with boron in hexagonal rings of large cages and full occupancy by intermediate guests (Na, Ca, Sr).
• Identified several stable structures, including type-I Ca8B16C30, which is on the convex hull at 50 GPa.

Conclusions:

• The first thermodynamically stable type-I clathrate (Ca8B16C30) was computationally identified.
• Boron-substituted carbon clathrates represent a potentially large family of diamond-like materials.
• This discovery expands the possibilities for designing novel clathrate structures with tailored properties.