(755c) Passively Controlled Thermal Material Deposited by Atomic Layer Deposition

Atomic Layer Deposition (ALD) is a cost effective nano-manufacturing technique that allows for the conformal coating of substrates with atomic control in a benign temperature and pressure environment.  Through the introduction of paired precursor gases thin films can be deposited on a myriad of substrates ranging from glass, polymers, aerogels, and metals to high aspect ratio geometries.  Methods for passive thermal control of radiators have been in development for several decades where emissivity as a function of wavelength can be switched using radiator temperature.  These smart radiators are typically aluminum that has been coated with thermochromic materials such as tungsten-doped vanadium using a sputtering technique.  The percentage of the dopant determines the emissivity range and temperature switch point.  This technique is typically a high temperature manufacturing process limited to flat radiator planes where control and conformality of the doped thermochromic material is difficult to accomplish.    In contrast, the work in this paper utilizes a lamination property of ALD where individual layers of different materials are deposited.  For this work we have deposited individual stacks of dopant material and vanadium where the ratio of dopant and vanadium layers determines the switch point temperature.  Additionally a novel method for testing the switching point is discussed.