Polarization at the compositional interface in Nb-doped metastable TiO2-SnO2 solid solutions

Abstract Polarization architecture was incorporated into metastable Nb-doped TiO 2 -SnO 2 to deliver electron accumulation at the localized TiO 2 -SnO 2 compositionally fluctuating interface. Specimens were quenched from various holding temperatures to ambient temperatures in air to avoid bimodal decomposition into TiO 2 and SnO 2 endmembers. At the lowest sintering temperature of 1,400 °C, the mixed phase containing TiO 2 - and SnO 2 -rich compositions existed as an intermediate state to the single-phase solid solution. The phase boundary became more ambiguous with increasing sintering temperatures, and the compositional fluctuation size reduced to single nanometers at 1,500 °C. The permittivity due to the interfacial polarization, ε interface , increased steadily with increasing sintering temperature. The larger ε interface values at higher temperatures are attributed to the greater density of the compositionally fluctuating phase interface, which leads to greater electron accumulation at the energy barrier between the two semiconducting layers.