Structural, Dielectric, and Energy Storage Properties of Citric Acid and Ethylene Glycol Assisted Hydrothermally Synthesized Y₂FeCoO₆

Abstract

Citric acid and ethylene glycol assisted hydrothermal synthesis of pure-phase double perovskite oxide Y 2 FeCoO 6 is reported. The Rietveld refinement confirm the orthorhombic phase formation with Pnma space group symmetry and lattice parameters as, a ¼ 5.5039 Å, b ¼ 7.4734 Å, and c ¼ 5.2094 Å. 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 3þ and Co as Co 2þ /Co 3þ are observed by X-ray photoelectron spectroscopy. The room temperature relative permittivity, 6.8 Â 10 4 , is found to increase to 1.3 Â 10 7 at 473 K and frequency 500 Hz. The specific capacitance of %31.32 F g À1 is obtained at the current density of 1 A g À1. The effective charge storage involve the redox reactions of Fe 2þ /Fe 3þ , Co 2þ /Co 3þ , and Co 3þ /Co 4þ , and excellent capacitance retention of %99% is achieved after 5000 charging/ discharging cycles at current density of 6 A g À1 .

B-site disorder driven Griffiths-like phase and electrochemical behavior in Y2NiCrO6 double perovskite

“…A notable feature in the CV curves of YNCO electrode material is the presence of weak redox peak. This redox peak, unlike the sharp redox peaks observed in CV curves of previously reported Y-based double perovskite-type electrode materials inserted in table 2 [33,35,36,47,48], signifies a distinct characteristic of the YNCO electrode material. Specifically, this weak redox peak suggests the dominance of EDL capacitance characteristic of pseudocapacitancetype electrode materials [82].…”

“…The data presented in the table clearly demonstrates that our YNCO electrode material exhibits a higher specific capacitance at the same current density when compared to other Y-based electrode materials. Specifically, at a current density of 0.5 A g −1 , the YNCO electrode material indicates an impressive capacitance of 270 F g −1 , a value significantly superior to that of the materials listed in table 2 [33,35,36,47,48]. It is necessary to mention that while certain prior investigations, such as Dy 2 NiMnO 6 [34], Gd 2 NiMnO 6 [32], La 2 FeCoO 6 [88], have reported even higher specific capacitance values than our synthesized YNCO material, they achieved these results by employing very high-concentration (up to 6 M) alkaline solutions (KOH) as electrolytes.…”

“…Previously, the electrochemical properties of Y-based double perovskites such as Y 2 NiFeO 6 , Y 2 NiMnO 6 , Y 2 FeCoO 6 , etc were reported [36,47,48]. In a few separate investigations, both magnetic and electrochemical properties of Y-based double perovskites Y 2 NiMnO 6 and Y 2 CoNiO 6 were investigated [25,49].…”