Electrons are the charge carriers in most electronic transactions.
Sometimes, in semiconductors, holes, the moving voids recently vacated
by an electron, constitute a usable current flow.
But positive ions can also act as an important current. Lead-acid batteries
in cars are a prominent application of this principle.
A particularly interesting phenomenon in this regard is the “superprotonic”
transition, an effect discovered in the 1980s by Russian scientists,
in which the proton conductivity jumps by several orders of magnitude
at a certain temperature, when a structural rearrangement of some of
the molecular oxyamion groups (such as SO4) occurs.
Sossina M. Haile and her colleagues at Caltech (email@example.com,
626-395-2958) have performed new experiments which have expanded the
roster of superprotonic materials, or cleared up past mysteries. For
example, they have cleared up any doubt that the solid-form acid CsH2PO4,
whose chemistry and conducting properties are especially promising as
a candidate for the electrolyte in fuel cells, can undergo the superprotonic
The new results were reported at last month’s meeting of the American
Crystallographic Association in Chicago (also see Caltech