To investigate this further, researchers conducted a detailed theoretical study of four-phonon scattering in graphene. They developed a theoretical framework based on the Boltzmann transport equation and incorporated various scattering mechanisms, including four-phonon scattering, Umklapp scattering, and boundary scattering.
Their results revealed that four-phonon scattering becomes the dominant heat transport mechanism in graphene at temperatures above 100 Kelvin. This scattering process involves the interaction of four phonons, where two phonons merge to form a higher-energy phonon, while the other two phonons carry away the excess energy.
The researchers found that the four-phonon scattering rate increases rapidly with temperature, leading to a significant reduction in graphene's thermal conductivity. This explains why graphene's thermal conductivity decreases at higher temperatures, in contrast to the behavior of most other materials.
The study also highlighted the importance of considering the full range of scattering mechanisms to accurately predict graphene's thermal conductivity. By incorporating four-phonon scattering along with other scattering processes, the researchers obtained excellent agreement with experimental measurements.
Their findings contribute to a deeper understanding of the heat conduction mechanisms in graphene and provide valuable insights for optimizing graphene-based materials for thermal management applications.
While graphene may not be the absolute best heat conductor, its exceptional thermal conductivity, along with its other remarkable properties, make it a highly desirable material for numerous technological applications, such as electronics, energy storage, and thermal management systems.
