Thermal transport properties and lattice vibration modes in crystalline and amorphous LaMgAl₁₁O₁₉

Thermal energy transport plays a crucial role in determining the performance of LaMgAl₁₁O₁₉-based applications. Herein, we report the inherent thermal transport in crystalline (c-LMA) and amorphous LMA (a-LMA) using atomistic simulations. It is found that c-LMA have a low κ comparable to the classical 7YSZ at 300–1500 K, while the κ of a-LMA is 8–68% lower than that of c-LMA. The mode decomposition shows that the phonon modes in c-LMA consist of local, normal and diffuse modes, while those in a-LMA consist of local and diffuse modes. The dual-channel model reveals that the thermal conduction in c-LMA is dominated by the normal modes at low temperatures (<420 K) while by the diffusive modes at high temperatures, but that in a-LMA results entirely from diffusive modes. This new insight into the thermal transport properties in c-LMA and a-LMA provides a foundation for designing LH-based thermal management applications.