Tritiation and Stability Measurements of Nitroxide for Betavoltaic Cells
Technical Report,01 Feb 2016,01 May 2016
ARMY RESEARCH LAB ADELPHI MD ADELPHI United States
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Beta radioisotope energy sources, such as tritium 3H, have shown significant potential in satisfying the needs of an energy-driven world. The drawbacks of current beta source compounds include low beta-flux power, intrinsic isotope leakage, and beta self-absorption. The figure of merit for a tritiated compound is the input power or specific surface activity of the thin layer Cicm2 where an optimal portion of incident beta particles are penetrating the semiconductor depletion region. The goal is to synthesize a compound with an effective surface activity from one side of 30 mCicm2 where it can be used for both planar and high aspect ratio, textured structures pillared, etched, etc.. Nitroxides are chosen to meet these requirements because of physical properties solid and pliable at standard temperature and pressure and controllable deuteration and hydrogenation synthesis from previous published work. Calculations show that only 1 of the 4 compounds can possibly meet short-term goal of approximately 30 mCicm2, but its tritiation stability during and after synthesis is unknown. As a proof of concept with respect to tritiation, the nitroxide 4-methoxycarbonyl-methylene-2,2,6,6-tetramethyl-1-piperidinyloxyl TEMPO is tritiated 3H with a specific activity of 103 Cig. The stability of TEMPO containing tritium in a solution of toluene is achieved. TEMPO in toluene is found to be 100 stable at least up to 27 days, when the experiments are terminated, as no loss of tritium from a solution of this nitroxide is observed.