High-pressure synthesis, characterization, and equation of state of double perovskite Sr₂CoFeO₆

Double perovskite oxide Sr₂CoFeO₆ (SCFO) has been obtained using a high-pressure and high-temperature (HPHT) synthesis method. Valence states of Fe and Co and their distributions in SCFO were examined with X-ray photoelectron spectroscopy. The electric transport behavior of SCFO showed a semiconductor behavior that can be well described by Mott's law for variable-range hopping conduction. The structural stability of SCFO was investigated at pressures up to 31 GPa with no pressure-induced phase transition found. Bulk modulus B₀ was determined to be 163(2) GPa by fitting the pressure-volume data to the Birch-Murnaghan equation of state.