Phonon-engineered extreme thermal conductivity materials

Abstract

Ultrahigh or low thermal conductivity materials are desirable for many technological applications such as thermal management of electronic and photonic devices, heat exchangers, energy converters, and thermal insulations. Recent advances in simulation tools (first principles, atomistic Green's function, and molecular dynamics) and experimental techniques (pump-probe techniques and microfabricated platforms) have led to new insights on phonon transport and scattering in materials, the discovery of new thermal materials, and are enabling the engineering of phonons towards desired thermal properties. We review recent advances in discovering both inorganic and organic materials with ultrahigh and low thermal conductivity, highlighting heat conduction physics, strategies, and future directions to achieve extreme thermal conductivities in solid-state materials.

Recovery of the Irreversible Crystallinity of Nanocellulose by Crystallite Fusion: A Strategy for Achieving Efficient Energy Transfers in Sustainable Biopolymer Skeletons**

“…[1] Proper crystallite interactions at the grain boundary can allow mechanical stress or thermal phonons to directionally transfer in the aggregate; however, a grain boundary is often a structural defect that deforms under stress or scatters phonons. [2][3] This feature becomes pronounced when the crystallites have nanoscale dimensions and form a large area of the grain boundary. In the eld of nanotechnology, it is currently a challenge to exploit the potential of such nanoscale crystallites, including biopolymer brils and clay platelets, in bulk aggregates or composites by tailoring the interactions between crystallites or with other components.…”

Crystallite fusion in nanocellulose aggregates

“…Mechanical and thermal energy transfers in crystal aggregates are governed by a grain boundary or the interface where multiple crystallites meet 1 . Proper crystallite interactions at the grain boundary can allow mechanical stress or thermal phonons to directionally transfer in the aggregate; however, a grain boundary is a structural defect that deforms under stress or scatters phonons 3,4 . This feature becomes pronounced when the crystallites have nanoscale dimensions and form a large area of the grain boundary.…”

Crystallite fusion in nanocellulose aggregates

“…Mechanical and thermal energy transfers in crystal aggregates are governed by a grain boundary or the interface where multiple crystallites meet 1 . Proper crystallite interactions at the grain boundary can allow mechanical stress or thermal phonons to directionally transfer in the aggregate; however, a grain boundary is often a structural defect that deforms under stress or scatters phonons 3,4 . This feature becomes pronounced when the crystallites have nanoscale dimensions and form a large area of the grain boundary.…”