An Efficient Strategy for Searching High Lattice Thermal Conductivity Materials

Searching for high thermal conductivity materials to efficiently conduct heat for various applications is a long-term endeavor. In 1973, Slack gave four rules for a material with high thermal conductivity, including low atomic mass, strong interatomic bonds, simple crystal structure, and low lattice anharmonicity. Comparing the thermal conductivities of 5 carbon allotropes carefully selected from the Carbon Allotrope Database, we found that a high symmetry operation number SO or a small atom number n in the primitive unit cell can significantly reduce the phonon-phonon scattering phase space. Based on SO and n, we comprehensively searched the Database of 803 carbon allotropes and found that the bcc-C6 allotrope has a high thermal conductivity owing to its high SO of 96 and small n of 6. The calculated lattice thermal conductivity of bcc-C6 can reach 2198 W/m K at room temperature if its atomic packing fraction equals that of diamond. Our findings indicate that high crystal symmetry can be employed as an efficient strategy to search for materials with high thermal conductivity.

Automated summary

Searching for high thermal conductivity materials is a long-term endeavor. Comparing the thermal conductivities of selected carbon allotropes, we found that a high symmetry operation number and a small atom number in the primitive unit cell can reduce the phonon-phonon scattering phase space. Through comprehensive searching of a carbon allotrope database, we found that the bcc-C6 allotrope has a high thermal conductivity due to its high symmetry operation number and small atom number. The calculated lattice thermal conductivity of bcc-C6 can reach 2198 W/m K at room temperature if its atomic packing fraction equals that of diamond.