Russo Johnny, Litz Marc, Ray William, Rosen Gerald M, Bigio David I, Fazio Robert
Sensors and Electron Devices Directorate, US Army Research Laboratory, Adelphi, MD 20783, USA; Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA.
Sensors and Electron Devices Directorate, US Army Research Laboratory, Adelphi, MD 20783, USA.
Appl Radiat Isot. 2017 Jul;125:66-73. doi: 10.1016/j.apradiso.2017.04.013. Epub 2017 Apr 7.
Beta radioisotope energy sources, such as tritium (H), have shown significant potential in satisfying the needs of a sensor-driven world. The limitations of current beta sources include: (i) low beta-flux power, (ii) intrinsic isotope leakage and (iii) beta self-absorption. The figure of merit is the beta-flux power (dP/dS in μW/cm), where an optimal portion of incident beta particles penetrates the semiconductor depletion region. Thus, the goal of this research was to identify a compound to contain a beta emitter that can permit beta-flux power of at least 0.73 μW/cm from one side, where it can be used for both planar and textured semiconductor structures. Nitroxides were chosen because of previous demonstrated deuteration, ease of synthesis, diversity of structure, and pliability. As a proof-of-principle, nitroxide [1] was prepared and tritiated with a specific activity of 103Ci/g. The corresponding tritiated nitroxide in toluene was found to have no measurable H outgassing after 27 days, thus it was considered stable. After 256 days in solution, analysis of the compound showed only 2% tritium loss, whereas in solid form, there was approximately 50% of tritium loss after 21 days. To compare with the performance of a typical metal tritide carrier, the standard MCNPX Monte Carlo code was used to calculate the beta-flux power of tritiated nitroxide and titanium tritide (0.2 μW/cm and 0.70 μW/cm), respectively. The difference between numerical and empirical results of titanium tritide was 4%, showing the model validity. For the tritiated nitroxide to be comparable to titanium tritide in a planar configuration (2-D), the gravimetric density (H weighted percentage) would need to be at least 9%.
β放射性同位素能源，如氚（H），在满足传感器驱动的世界需求方面已显示出巨大潜力。当前β源的局限性包括：（i）β通量功率低，（ii）固有同位素泄漏，以及（iii）β自吸收。品质因数是β通量功率（以μW/cm为单位的dP/dS），其中入射β粒子的最佳部分穿透半导体耗尽区。因此，本研究的目标是确定一种含有β发射体的化合物，该化合物能够从一侧提供至少0.73μW/cm的β通量功率，可用于平面和纹理化半导体结构。选择氮氧化物是因为其先前已证明的氘化、易于合成、结构多样性和柔韧性。作为原理验证，制备了氮氧化物[1]并以103Ci/g的比活度进行了氚化。发现甲苯中的相应氚化氮氧化物在27天后没有可测量的H脱气，因此被认为是稳定的。在溶液中放置256天后，对该化合物的分析表明氚损失仅2%，而以固体形式存在时，21天后氚损失约50%。为了与典型金属氚载体的性能进行比较，使用标准的MCNPX蒙特卡罗代码分别计算了氚化氮氧化物和氢化钛的β通量功率（分别为0.2μW/cm和0.70μW/cm）。氢化钛的数值结果与实验结果之间的差异为4%，表明该模型有效。为了使氚化氮氧化物在平面配置（二维）中与氢化钛具有可比性，重量密度（H加权百分比）至少需要达到9%。
