Ethylene glycol/citric acid stabilized wet chemically synthesized Y_2CoNiO_6, and its structural, dielectric, magnetic and electrochemical behavior

摘要

We report the synthesis of the novel double perovskite Y_2CoNiO_6 by an ethylene glycol and citric acid stabilized facile wet sol-gel chemical process. The material is iso-structural to the yttrium oxide cubic phase of Ia3 symmetry (a= 10.5957 A). The Raman vibrational modes at the wave numbers of 247, 489, 518, 566, 604, 649, 741 and 824 cm~(-1) further confirmed the formation of Y_2CoNiO_6. The Y_2CoNiO_6 shows the room temperature dielectric constant of 5660 at the frequency of 500 Hz which increases further with the increase of temperature. It exhibits a predominant paramagnetic behavior with a second-order phase transition from antiferromagnetic to paramagnetic at the Neel temperature being T_(FC) = 51.65 K. The energy density of 19.97 W h kg~(-1) at 1 A g~(-1) and power density of 1324 W kg~(-1) at 6 A g~(-1) have been obtained. The effective charge storage is due to redox reaction of Co~(2+)/Co~(3+) and Co~(3+)/Co~(4+) as supported by X-ray photoelectron spectroscopy. The capacitance retainability of ～98.5% was achieved after 1200 charging/discharging cycles at 6 A g~(-1).