Construction of a promethium-147 atomic battery

The feasibility of constructing an "atomic battery" by combining the β-emitting radioisotope Pm
¹⁴⁷
and a semiconductor containing a p-n junction has been studied both theoretically and experimentally. The properties of cells made by diffusing a p-type impurity into n-type GaAs, p-impurity into n-type silicon (p/n) and n-impurity into p-type silicon (n/p) are compared. The problems associated with the presence of an alpha emitting impurity (Am
¹⁴⁷
) in the Pm
¹⁴⁷
and with the fabrication of a suitable Pm
¹⁴⁷
source are considered. Experiments with prototype batteries composed of Pm
¹⁴⁷
and n/p silicon cells have led to the conclusion that such batteries would have a half life (1.6 years) somewhat shorter than that of Pm
¹⁴⁷
(2.6 years). Such a battery could generate a few milliwatts of power from a volume of about 2 cubic inches including shielding.