The Electrical Conductivity of Strontium-Barium Niobate
We propose an explanation for the high electrical conductivity of the ferroelectric strontium-barium niobate. As the temperature T approaches the ferroelectric transition Tc, the static dielectric constant $$\varepsilon(0)$$ diverges when a soft mode occurs. This divergence of $$\varepsilon(0)$$ reduces the donor binding energy, and increases the effective Bohr radius of the donor. The electrons bound to the donors become unbound, and the material becomes conductive.