Advanced Materials for High‐Temperature Thermal Transport

Abstract

High temperature processes are widely used in a variety of existing and emerging industrial and aerospace applications. The thermal properties of high‐temperature materials thus play an important role in controlling the thermal energy, as highlighted by successful applications of thermal barrier coating and aerogels. While thermal transport processes at room and low temperature have witnessed tremendous progress in the past two decades, particularly on the fronts of understanding basic heat transfer properties at the micro‐ and nanoscale, the understanding at high temperature is still at the nascent stage, owing to several unique features at high temperature, such as the dominant Umklapp scattering effect that can render a crystalline material amorphous‐like thermal properties, and the important radiation contribution at high temperature. This lack of systematic understanding, coupled with the challenges in maintaining high‐temperature stability in a large number of materials, has limited the development of materials to meet the thermal transport properties pertaining to several current and emerging high‐temperature applications. This Review is aimed at providing an overview of the basic mechanisms governing thermal transport processes at high temperature, to identify their unique features and challenges, and to explore opportunities in material research for high‐temperature thermal materials.

High ZT 2D Thermoelectrics by Design: Strong Interlayer Vibration and Complete Band‐Extrema Alignment

“…Currently, the TE efficiency can be improved by two approaches: i) Tuning effective mass to improve the electronic transport and ii) increasing phonon scattering to suppress the lattice thermal transport. [ 8–11 ] For a given carrier concentration, a large carrier effective mass ( m *) contributes to a large S , and the m * is proportional to the band effective mass ( m b *) according to m * = N V 2/3 m b *, where N V refers to the band degeneracy. [ 10,12 ] A large m b *, however, will reduce the carrier mobility μ since (2D systems).…”

“…[ 8–11 ] For a given carrier concentration, a large carrier effective mass ( m *) contributes to a large S , and the m * is proportional to the band effective mass ( m b *) according to m * = N V 2/3 m b *, where N V refers to the band degeneracy. [ 10,12 ] A large m b *, however, will reduce the carrier mobility μ since (2D systems). [ 13–16 ] Hence, to optimize S 2 σ, it is important to attain high N V and moderate m b * simultaneously.…”

3D Assembly of Graphene Nanomaterials for Advanced Electronics

“…Heat sinks with brush architecture are one common strategy but require expensive and time‐consuming fabrication . Exploring composite structures using highly thermally conductive particles or ballistic modes for heat dissipation would also push forward the application scope of electronic devices …”

Energy Applications of Magnetocaloric Materials

“…Over the last 20 years, in addition to thermoelectricity, much research on solid‐state thermal energy harvesting ( Figure 2 ) has also focused on thermionics and thermophotovoltaics . Researchers have also investigated new frontiers in spin‐caloritronics, spin‐Seebeck, and anomalous Nernst effects .…”

“…[82,84] Over the last 20 years, in addition to thermoelectricity, much research on solid-state thermal energy harvesting (Figure 2) has also focused on thermionics [85][86][87] and thermophotovoltaics. [88][89][90] Researchers have also investigated new frontiers in spin-caloritronics, [91,92] spin-Seebeck, [93,94] and anomalous Nernst effects. [95,96] However, with the rapid development of caloric (ferroic) materials and technologies for refrigeration and air conditioning, caloric (ferroic) power generation [64,77] is being revisited and prototype devices are being developed.…”