1：Experimental Design and Method Selection:

The electrical behavior of Fe:SrTiO3 single crystals was investigated via impedance spectroscopy. Samples were annealed and quenched at various oxygen partial pressures to study their conductivity and defect chemistry.

2：Sample Selection and Data Sources:

Fe:SrTiO3 single crystals with a reported 0.01 wt % Fe doping were purchased from MTI Corporation, USA. Samples were sectioned into 2 × 2 × 0.5 mm samples, polished, and annealed at 900 °C for 12 hours with oxygen partial pressures ranging from 2 × 104 Pa to 4 × 10-18 Pa.

3：01 wt % Fe doping were purchased from MTI Corporation, USA. Samples were sectioned into 2 × 2 × 5 mm samples, polished, and annealed at 900 °C for 12 hours with oxygen partial pressures ranging from 2 × 104 Pa to 4 × 10-18 Pa. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment used includes a zirconia-electrolyte oxygen sensor from Ceramic Oxide Fabricators, an HP 4192A impedance analyzer, and a Biologic VMP3 for low frequency impedance measurements. Platinum electrodes were sputtered onto the samples.

4：Experimental Procedures and Operational Workflow:

Samples were equilibrated at high temperatures and quenched to room temperature. Impedance measurements were performed between 150 °C and 380 °C. The bulk conductivity was determined from the imaginary modulus peak fit to a simple resistor-capacitor element.

5：Data Analysis Methods:

The bulk conductivity was calculated from the relaxation frequency obtained from the fit. Activation energies were determined from Arrhenius plots of conductivity versus temperature.