Acceptor and donor codoping of SrTiO3: Impact on grain growth behavior, space charge and electrical properties

SrTiO 3 is a model electro-ceramic representing the very significant group of perovskite ceramics which display versatile electric properties (ferroelectricity, ionic conductivity, semi-conductivity). The impact of dopants on the properties of SrTiO 3 is comparably well investigated. This study explores the correlation between dopant type, grain growth and electrical properties of acceptor-donor codoped SrTiO 3 . The electric properties of undoped and doped (Fe, Nb, Fe/Nb) SrTiO 3 were investigated using electrochemical impedance spectroscopy (EIS). Space charge potentials Δ Φ and thickness λ MS were evaluated. Cationic segregation profiles at grain boundaries (GBs) were characterized using Scanning Transmission Electron Microscopy (STEM) combined with Energy Dispersive X-ray Spectroscopy (EDS). Grain growth coefficients were evaluated for each sample. Fe segregation reduces grain growth rates (solute drag) and increases GB conductivity. Under certain annealing conditions solute drag transitions to abnormal grain growth. Codoping does not alter bulk conductivity. Nb doping drastically changes electric properties and grain growth kinetics.