Thermal Conductivity Reduction in Heterostructure Multilayer Composites by Phonon Density of State Mismatch

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Interfacial phonon transport is crucial for thermal conductivity, often tuned using phonon density of states (PDOS) mismatch.
• Previous tuning methods primarily focused on nanoscale superlattices.

Purpose of the Study:

• To demonstrate thermal conductivity modulation in bulk-scale multilayer composites.
• To explore the effect of PDOS mismatch in bulk materials for thermal insulation.

Main Methods:

• Fabrication of multilayer composites using silicone rubber embedded with PDOS-mismatched particles (AlN, BN, SiC).
• Molecular dynamics simulations to analyze interfacial thermal resistance and PDOS mismatch.
• Experimental characterization of acoustic impedance transmittance and thermal conductivity reduction.

Main Results:

• The SiC-BN combination showed the highest PDOS mismatch and interfacial thermal resistance.
• Experimental results confirmed the SiC-BN combination achieved a 14.9% thermal conductivity reduction in 8-layer composites.
• A significant 37.3% thermal conductivity reduction was achieved in glass wool composites with vermiculite and silica aerogel particles, reaching 2.87 mW m⁻¹ K⁻¹.

Conclusions:

• Phonon density of states (PDOS) mismatch is a critical design factor for tuning thermal conductivity in bulk-scale multilayer composites.
• This approach offers potential applications in thermal management for refrigerators, appliances, and building insulation.