I made a mistake earlier using standard electrode potentials to look
at metal-meatl junction barriers. The numbers to use are work
functions. Here are some selected candidate numbers:
Some acceptor candidates:
El. Wk.F. Elec.AFF.
Pt 5.65 205
Au 5.1 223
Cu 4.65 119
Ag 4.26 126
Sb 4.55 101
Some donor candidates
El. Wk.F. Elec.AFF.
Zn 4.33 0
Pb 4.25 35
Ti 4.33 8
Al 4.28 42
Fe 4.5 15
Mo 4.6 72
Mn 4.1 0
Co 5.0 64
From this it is immediately clear why silver, with its low work
function, plus high conductivity, was useful in the Dry Pile. Our
objective then is to find a donor with a work function higher than
the acceptor. Obvious candidates for donors are Zn, Ti, Fe, Mo, and
Co. Looks like various kinds of stainless steel might make feasible
donor candidates. Interestingly, the Zn-Ag combination just makes
the cut, though the fact zinc is a hole conductor should still make
for a boundary problem. Pb is just barely out of the running. It
may be possible to find alloys of either Pb or Zn that would make for
a viable combination. Ti, Al, and Fe, all adsorb hydrogen and form
oxides, so some work is required to find compatible transporters.
Horace Heffner
http://www.mtaonline.net/~hheffner/
