Structural, Dielectric, and Energy Storage Properties of Citric Acid and Ethylene Glycol Assisted Hydrothermally Synthesized Y_2FeCoO_6

摘要

Citric acid and ethylene glycol assisted hydrothermal synthesis of pure-phase double perovskite oxide Y_2FeCoO_6 is reported.The Rietveld refinement confirm the orthorhombic phase formation with Pnma space group symmetry and lattice parameters as, a=5.5039 A, b=7.4734 A, and c=5.2094 A.The high-resolution transmission electron micrographs exhibit formation of flakes, composed of agglomerated crystallites, oriented in [121] direction.The oxidation states of Fe as Fe~(3+) and Co as Co~(2+)/Co~(3+) are observed by X-ray photoelectron spectroscopy.The room temperature relative permittivity, 6.8 × 10~4, is found to increase to 1.3×10~7 at 473 K and frequency 500 Hz.The specific capacitance of ≈31.32 F g~(-1) is obtained at the current density of 1 A g~(-1).The effective charge storage involve the redox reactions of Fe~(2+)/Fe~(3+), Co~(2+)/Co~(3+), and Co~(3+)/Co~(4+), and excellent capacitance retention of ≈99% is achieved after 5000 charging/ discharging cycles at current density of 6 A g~(-1).