Atomic structure of co-dopant complex in thallium bromide that binds charged vacancies and reduces their mobility, allowing selective control over ionic conductivity without affecting electronic conductivity. |
Lawrence
Livermore National Laboratory researchers have discovered a new method to
control the conductivity of materials that could eventually apply to fuel
cells, batteries, and gas sensors.
Postdoctoral
researcher Cedric Rocha-Leão, working with Codensed Matter and Materials
Division’s Vince Lordi, has found a new method to independently control ionic
and electronic conductivities in certain solids.
The
method, which uses tailored acceptor-donor co-doping to bind charged native
vacancies and selectively modulate ionic but not electronic
conductivity, was developed by using first-principles materials simulations.
The
computational materials design approach allowed quantitative screening of
dopants to find those most effective for a particular application. Their recent
work focused on optimizing conduction in thallium bromide for
high-resolution, room-temperature gamma radiation detectors, for which high
electronic conductivity and low ionic conductivity are required.
Achieving
simultaneous control of ionic and electronic conductivity in materials is one
of the great challenges in solid state ionics. Since these properties are
intertwined, optimizing one often results in degrading the other.
But
the new method limits ionic current without impacting the electronic properties
for a general class of materials, based on co-doping with oppositely charged
ions.
The
research appears in Physical Review Letters.
