Figure 3

(a) Intrinsic lattice thermal conductivity of γ-Si₃N₄ and γ-Ge₃N₄, and contribution of longitudinal acoustic (LA) phonon (dash dot line) and transverse acoustic (TA) phonon (dash line) to the thermal conductivity of (b) γ-Si₃N₄ and (c) γ-Ge₃N₄.