Figure 2. Phonon dispersions and thermal conductivities along the armchair (ΓΜ) and zigzag (ΓΚ) directions.

(a) The phonon dispersion of Hf₂CO₂ along the armchair direction. The out-of-plane acoustic (ZA), longitudinal acoustic (LA) and transversal acoustic (TA) modes are denoted with black squares, red circles and blue triangles, respectively. (b) The phonon dispersion of Hf₂CO₂ along the zigzag direction. (c) The temperature dependence of the Hf₂CO₂ thermal conductivity along the armchair direction. The ZA, LA and LA mode contributions to the thermal conductivity are denoted with grey dashed, red dotted and blue dash-dotted lines, respectively. (d) The temperature dependence of the Hf₂CO₂ thermal conductivity along the zigzag direction.