An ultrathin coating engineered from samarium nickel oxide (SmNiO3) has been found to emit the same amount of thermal radiation irrespective of temperature, within a range of about 30 °C. The coating, which was developed by engineers at the University of Wisconsin-Madison and exhibits temperature-independent thermal radiation, could someday be used to control the visibility of objects to infrared (IR) cameras.
The thermally emitted power of most solids increases monotonically with temperature in a one-to-one relationship. However, the researchers found that the use of SmNiO3, a quantum material that undergoes a reversible, temperature-driven solid-state phase transition as an ultrathin thermal emitter, alters this one-to-one relationship. This insulator-to-metal phase transition enabled the researchers to engineer the temperature dependence of emissivity to cancel out the intrinsic blackbody profile described by the Stefan-Boltzmann law, for both heating and cooling.