Structural property-induced different phonon-twin-boundary scattering in diamond

Thermal transport in crystalline materials is influenced by phonon scattering at crystal defects. Twin boundaries (TBs) are common structural imperfections that can affect heat flow. Prior research has shown that the (111)/[110] TB in diamond exhibits weak phonon scattering. However, uncertainty remains about whether other TB configurations in diamond behave similarly. This gap motivated a deeper investigation into the thermal properties of various TBs. No prior work had resolved the relationship between TB structure and phonon scattering strength. Understanding how TB geometry influences thermal resistance is essential for optimizing materials for thermoelectric and thermal management applications. This paper's contribution lies in systematically analyzing multiple TB types in diamond. It provides new insights into how structural properties impact phonon-TB interactions. This study addresses a key knowledge gap in phonon transport across crystal defects.

The aim of this study is to investigate how different twin boundaries in diamond influence phonon scattering and thermal transport. The specific problem is the lack of understanding about whether various TB configurations in diamond exhibit similar thermal properties to the (111)/[110] TB. The motivation stems from the need to design materials with controlled thermal properties. The researchers propose to examine six distinct TB types in diamond. This approach allows for a comprehensive comparison of thermal boundary resistance. The study's goal is to identify structural factors that influence phonon-TB interactions. By linking TB geometry to thermal resistance, the work aims to inform material design strategies. This research fills a critical gap in phonon scattering at crystal defects.

The researchers employed molecular dynamics simulations and first-principles calculations to study phonon transport across six TB types in diamond. These methods allowed for the calculation of thermal boundary resistance for each TB configuration. The TBs included (111)/[110], (221)/[110], (331)/[110], (113)/[110], (112)/[110], and (310)/[001]. The simulations captured phonon transmission coefficients and thermal resistance values. First-principles calculations provided structural and energetic data for each TB. The study also analyzed group velocity and phonon mean free path effects. Structural properties such as TB energy and bond difference parameter were evaluated. These tools enabled a detailed comparison of phonon-TB scattering behavior.

The thermal boundary resistance of the six TBs ranged from 1.01 × 10-11 to 6.35 × 10-10 m2 K W-1. The (111)/[110] TB exhibited the weakest phonon scattering among the studied configurations. Other TBs showed significantly higher thermal resistance values. The (111)/[110] TB had a thermal resistance of 1.01 × 10-11 m2 K W-1. The (310)/[001] TB had the highest resistance at 6.35 × 10-10 m2 K W-1. Transmission coefficients across TBs with similar symmetry played a key role in phonon scattering. The combined effect of group velocity and phonon mean free path also influenced resistance. Structural properties like TB energy and bond difference parameter correlated strongly with thermal resistance.

The findings suggest that TB thermal resistance varies significantly with structural configuration. The (111)/[110] TB shows much weaker phonon scattering than other TB types in diamond. This difference is attributed to transmission coefficients and structural properties like TB energy. The researchers propose that TB geometry strongly influences phonon-TB interactions. The study confirms that TB energy and bond difference parameter are key factors in thermal resistance. These results provide a basis for designing materials with controlled phonon scattering. The authors suggest that these findings may guide thermoelectric and thermal management material design. The study highlights the importance of structural properties in determining phonon-TB scattering.