Nanowerk August 11, 2021
For most solids, the thermally emitted power increases monotonically with temperature in a one-to-one relationship that enables applications such as infrared imaging and noncontact thermometry. A team of researchers in the US (University of Wisconsin–Madison, Harvard University, Purdue University, Brookhaven National Laboratory) has demonstrated that ultrathin thermal emitters that violate this one-to-one relationship via the use of samarium nickel oxide (SmNiO3), a strongly correlated quantum material that undergoes a fully reversible, temperature-driven solid-state phase transition. Due to the smooth and hysteresis-free nature of this unique insulator-to-metal phase transition enabled them to engineer the temperature dependence of emissivity to precisely cancel out the intrinsic blackbody profile described by the Stefan–Boltzmann law, for both heating and cooling. Their design resulted in temperature-independent thermally emitted power within the long-wave atmospheric transparency window (wavelengths of 8 to 14 µm), across a broad temperature range of ∼30 °C, centered around ∼120 °C. The ability to decouple temperature and thermal emission opens a gateway for controlling the visibility of objects to infrared cameras and, more broadly, opportunities for quantum materials in controlling heat transfer. This could also advance applications such as infrared camouflage, privacy shielding, and heat transfer control…read more. TECHNICAL ARTICLEÂ
Comparison between a typical thermal emitter and a zero-differential thermal emitter (ZDTE)… Credit: PNAS December 26, 2019, 116 (52) 26402-26406Â