Thermal Radiation Coatings
Paints and thin films
Engineered coatings are crucial under extreme temperature surroundings. For example, the Sun (T = 5800 K or 10,000oF) can make an untreated car exterior exceedingly hot. Conversely, deep space (T = 3 K or -450oF) can help cool spacecraft electronics and living systems. Our interest is in developing coatings using nano- or microscopic features to mitigate or control thermal radiation in various environments.
Metamaterials consist of engineered features typically smaller than the wavelength of light. In that sense, electromagnetic waves interact with metamaterials in an unusual manner. Applications where metamaterials are found include thin flat lenses, thermal cloaking, and molecular sensing. The group is designing metamaterials consisting of 2D materials and topological insulators.
Bridging the gap
What is "near-field" thermal radiation? When two surfaces are separated by a nanoscale-size gap (order of 1 billionth of a meter), energy transport between the gap exceeds that between two perfect emitters. This is because photons and electrons can tunnel through the gap. The group is investigating how nanomaterials can improve and control energy transport in this near-field domain.
Bottom-Up Transport Quantification
Partially funded by the US AFOSR - AFRL
In nanomaterials, such as 2D materials, nanowires, nanoparticles, etc., movement of energetic particles have nowhere to go. In this segment, the group is uncovering the theoretical link between mechanical and electrical properties in confined atomic geometries. We employ numerical methods of coupled non-linear and non-thermodynamic equilibrium phonon transport equations to understand why certain materials can induce thermoelectricity and extraordinary thermal conductivity.
Thermoelectric devices convert a temperature gradient to usable electrical power, by means of the Peltier effect. The primary challenge of making efficient thermoelectric materials is low thermal conductivity while maintaining high electrical conductivity. The group is researching the thermal and electric properties of nanopatterned topological insulators, materials that behave as an insulator in volume but conductor on the surface.
Thermal Properties Testing
Under sunlight or in space, how does a material or coating absorb and transfer heat with the environment? The group can help perform measurements on novel materials, for thermal conductivity, optical response, electronic properties, and more. Characterization techniques at the nanoscale level are being developed, including probe microscopy and near-field tunneling sensors.