Polaronic conduction and Anderson localization in reduced strontium barium niobate

Electron transport mechanisms in reduced Sr0.5Ba0.5Nb2O6 (SBN50) are investigated from ∼100 to 955 K through an analysis of the electrical conductivity (σ) and the Seebeck coefficient (S) with respect to temperature (T). Notably, experimental evidence is presented that supports a scenario of Anderson localization below 600 K and carrier excitation across a mobility edge at higher temperature. As a relaxor ferroelectric, stoichiometric SBN has intrinsic disorder associated with both the distribution of Sr/Ba vacancies and the formation of polarized nanoregions. The removal of oxygen through reduction generates conduction electrons in SBN. At the lowest temperatures measured (100–155 K), the electrical conductivity exhibits a temperature dependence characteristic of variable range hopping, followed by a transition to small polaron hopping at intermediate temperatures (250–545 K). In both the variable range and small polaron hopping regimes, a semiconductor-like temperature dependence of the electrical condu...

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