Lattice vibrations and thermal properties of carbon nitride with defect ZnS structure from first-principles calculations

The phonon spectrum of C3N4 with defect zincblende-type structure (δ-C3N4) was calculated by density functional theory (DFT) techniques. The results permit an assessment of important mechanical and thermodynamical properties such as the bulk modulus, lattice specific heat, vibration energy, thermal expansion coefficient, and thermal Grueneisen parameter. The thermal Grueneisen parameter of δ-C3N4 is calculated to be about 1.19 at 300 K, comparable to that of diamond. The coefficient of linear thermal expansion of this structure is calculated to be about 2.2 x 10-6 K-1 at room temperature. The thermal conductivity coefficient of δ-C3N4 is also estimated using Slack's theory to be as high as about 216 W m-1 K-1