Anisotropic Phononic and Electronic Thermal Transport in BeN₄

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Beryllium polynitride (BeN4) was recently synthesized under high pressure.
• Its structure exhibits pressure-dependent anisotropy, suggesting unique thermal properties.

Purpose of the Study:

• To theoretically investigate the thermal transport properties of beryllium polynitride.
• To understand the influence of bonding anisotropy and anharmonicity on thermal conductivity.
• To explore pressure-driven changes in bonding and their effect on thermal transport.

Main Methods:

• Combined Boltzmann transport equation with ab initio calculations.
• Analyzed phonon and electron group velocities.
• Investigated three- and four-phonon scatterings to capture anharmonicity.

Main Results:

• Observed strong anisotropy in both phononic and electronic thermal conductivity components.
• Identified bonding anisotropy and anharmonicity as key factors influencing thermal transport.
• Found that pressure-driven evolution of Be-N bonding dictates interlayer thermal conductivity.

Conclusions:

• Beryllium polynitride exhibits highly anisotropic thermal transport.
• Material's thermal properties are tunable via pressure-induced bonding changes.
• This work suggests a strategy for directional control of thermal transport in synthetic materials.