Solvent-deficient synthesis of nanocrystalline Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3- δ powder

Nanocrystalline Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3-δ powders were prepared by a cost-effective solvent-deficient method using metal nitrates and ammonium bicarbonate as precursors. X-ray diffraction (XRD), specific surface determination (BET), thermal analyses (TG-DTA-DSC), dynamic light scattering (DLS) and scanning electron microscopy (SEM) were used to examine the effects of the calcination temperature on the Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3- δ (BSCF) formation. XRD analysis showed that a cubic Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3-δ was obtained after heating for 1 h at 1000 °C. BSCF nanocrystals with a diameter of about 25 nm were obtained. On the other hand, the sample mass was stabilized at 915 °C as recorded by thermogravimetric analysis (TG), indicating a formation of the complex BSCF oxide already at this temperature. The phase transformations during the synthesis of BSCF oxide are defined and confirmed with the note on the instability of the cubic phase. Using the four-point DC measurements between −73 °C and 127 °C, the band gap of 0.84 eV was determined. The solvent-deficient method used in this study to synthesize Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3-δ showed distinct advantages in comparison with other synthesis techniques considering simplicity, rapid synthesis, and quality of the produced nanocrystals.