“The thermodynamic punishment must fit the structural crime.”

Materials for Ultra-High Temperature Photonics

Source of Support: Defense Advanced Research Projects Agency (DARPA)
Duration: 10/01/2020 to 3/31/2022 
PI: Jeremy Munday (UCD)
Co-PI: Marina Leite (UCD)
Co-PI: Scott J. McCormack (UCD)

Aim/Abstract: In this project, we will lay the groundwork for a new field: ultra-high temperature photonics, where we will control the wavelength and directionality of thermal radiation throughout the visible and near-infrared (NIR), while operating at extreme temperatures, >1800 °C. The past two decades have given rise to tremendous advances in room temperature photonics where metallic and dielectric structures have allowed for nearly complete control of optical radiation using concepts from plasmonics and metamaterials. However, at extreme temperatures and/or the harsh environments relevant to many real-world DoD applications, these techniques cannot be fully utilized because there is a lack of knowledge about how materials (and specifically their optical properties) respond under these conditions. Further, many of the design concepts involving metamaterials encompass nano-structuring materials in 2D or 3D arrays, which is difficult for materials where etching procedures are non-existent and is impossible for many structures due to thermal and chemical stresses and expansions that occur under extreme conditions. In this project, we will circumvent many of these challenges through the use of single- layer ultra-thin films, which are more tolerant to stresses and cracking and do not require complex and time-consuming nano-fabrication processes. Further, we will develop new materials for both substrate and optical coating. For the former we will investigate the effects of alloying on the permittivity of refractory metals (W, Mo, Ta, Cr). The novel alloys for the latter will include thermochemically and thermodynamically stable quaternary metal nitrides using elements from groups II through V of the periodic table and combinations of metal oxides from groups IIIb and IVb that will enable us to finely tune their optical properties depending on chemical composition. While these concepts are broadly applicable to many ultra-high temperature systems, we have chosen Si thermophotovoltaics (TPV) as our focus application and propose to produce an emitter structure that outperforms the current state-of-the art in terms of heat-to- electricity efficiency by >4x, greatly exceeding the minimum 10% improvement required for this proposal call.     

Articles that inspire our work

1. Materials Research for Fusion (2016)

2. Space Nuclear Propulsion for Human Mars Exploration (2021)

3. US hypersonic initiatives require accelerated efforts of the materials research community (2021)