c-plane sapphire xrd
The thermal conductivity of sapphire is higher at lower temperatures and gradually decreases with increasing temperature.
This is because the internal heat conduction in sapphire mainly depends on phonon thermal conductivity, and as the temperature increases, the vibration of phonons intensifies and their free travel decreases, which leads to a decrease in thermal conductivity.
c-plane sapphire xrd
When the temperature rises to 100°C, the thermal conductivity drops to 25.12 W/(m-K).
For example, in fields such as LEDs and optoelectronic devices, understanding the variation of sapphire’s thermal conductivity with temperature is especially critical for designing efficient heat dissipation solutions.
This is because at low temperatures, the scattering of phonons is dominated by boundary scattering and defect scattering, whereas as the temperature increases, the mean free range of the phonons increases, leading to a rise in thermal conductivity .
In composites, as the volume fraction of sapphire increases, the thermal conductivity of the composite may first increase and then decrease, depending on the interfacial thermal resistance between the sapphire and the matrix material, as well as the change in the thermal conductivity of the sapphire itself.
