Non-Arrhenius grain growth in SrTiO3: Impact on grain boundary conductivity and segregation

In this study, a correlation between the conductivity, space charge layers, solute drag and non-Arrhenius grain growth in SrTiO3 was investigated. Strontium titante is known for its non-Arrhenius grain growth where grain growth rates decrease by orders of magnitude with increasing temperatures between 1350 °C and 1425 °C. Here, undoped SrTiO3 was sintered and annealed at temperatures below and above the grain growth transition. The influence of the annealing temperature and time on the conductivity and space charge layers at grain boundaries (GBs) in SrTiO3 was investigated by electrochemical impedance spectroscopy (EIS). STEM-EDS analysis indicates the presence of GBs with qualitative different cationic segregation in SrTiO3. A distortion of the GB semi-circle in the impedance plots was found which was attributed to the presence of multiple GB types with different electric properties and space charge layers. The presence of two GB types as indicated by impedance analysis corresponds well with previous results, where solute drag and segregation was supposed to cause the non-Arrhenius grain growth behavior of SrTiO3. © 2024