Grain growth in weak electric fields in strontium titanate: Graingrowth acceleration by defect redistribution

The impact of DC electric fields on grain growth in strontium titanate is investigated between 1350◦C and1550◦C for fields of up to 50 V/mm. To prevent joule heating by electrical currents, insulating Al2O3platesseparate electrodes from samples. The seeded polycrystal technique is used, which allows evaluatinggradients induced by electric fields. The growth direction of the single crystalline seeds is perpendicularto the electric field; hence electrostatic forces do not influence its growth. Below 1425◦C, the influence ofelectric fields is very weak. Above 1425◦C the field results in an increase of the grain boundary mobilityat the negative electrode.The enhancement of the boundary mobility at the negative electrode is attributed to electric fieldinduced defect redistribution. Oxygen vacancies migrate towards the negative electrode, while stron-tium vacancies accumulate at the positive electrode. This defect redistribution is connected to the defectchemistry dependent grain growth in strontium titanate.