Phononic metamaterials adapted for reduced thermal transport

Abstract

Phononic metamaterials and methods for reducing the group velocities and the thermal conductivity in at least partially crystalline base material are provided, such as for thermoelectric energy conversion. In one implementation, a method for reducing thermal conductivity through an at least partially crystalline base material is provided. In another implementation, a phononic metamaterial structure is provided. The phononic metamaterial structure in this implementation includes: an at least partially crystalline base material configured to allow a plurality of phonons to move to provide thermal conduction through the base material; and at least one material coupled (e.g., as an inclusion, extending substructure, outer matrix, a coating to heavy inner inclusion, etc.) to the at least partially crystalline base material via at least one relatively compliant or soft material (e.g., graphite, rubber or polymer). The inclusion, extending substructure matrix or coating material is configured to generate at least one vibration mode by the oscillation of at least one atom within the resonating material to interact with the plurality of phonons moving within the base material and slow group velocities of at least a portion of the interacting phonons and reduce thermal conductivity through the base material.