Published in Chemistry World, 1 Jul 2011
Concrete is heavy, tough and – you might think – a reliable insulator. But researchers in Japan have shown that, by doping it with free electrons, liquid cement can transform into a substance with metal-like electrical conductivity. According to the researchers, the surprising transition could lead to new types of semiconductor.
It has been known since the beginning of the nineteenth century that free electrons can be trapped in polar solvents such as water and ammonia. When an alkali metal is dissolved in ammonia, for example, the valence electrons are released into the solution, giving a deep blue colour when dilute and a bronze colour when more concentrated. These ‘solvated’ electrons are relatively stable, because each one is surrounded by an envelope of ammonia molecules. […]
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