Enhanced red luminescence, Judd–Ofelt intensity parameters and supercapacitor properties of Europium doped zinc chromite nanoparticles synthesized via green mediated combustion route

Abstract

In the current communication, for the first time, Europium doped (1–9 mol%) Zinc chromite nanopar- ticles (NPs) were synthesized by solution combustion method using AloeV era gel extract as a reduc- ing agent followed by calcination at 500 °C for 3 h. The Bragg reflections confirms the formation of cubic spinel structure and also the absence of other impurities. The crystallite size estimated from Scherrer’s method found to decrease from 14.11 to 5.37 nm with increase in dopant concentration. The surface morphology consists irregular shaped agglomerated Nps. The energy band gap found to decrease from 2.95 to 2.89 eV. Further, photoluminescence spectra was recorded under 400 nm exci- tation wavelength consists characteristics peaks of Eu³⁺. The concentration quenching is observed at 7 mol% which might be due to dipole–dipole transition. The CIE and CCT coordinates clearly confirms the red emission of Eu³⁺ within the host lattice with warmer appearance and finds an application in residential, hospital etc. The Judd–Ofelt intensity parameters and their derivatives like radiative transition probability, radiative lifetime, branching ratio, and the asymmetry ratio are calculated. The cyclic voltametry analysis were also carried out to know the redox reactions, electrode kinetics, and electrochemical behavior. Ion transport kinetics were elucidated through Electrochemical Impedance Spectroscopy (EIS), while the determination of super capacitance val- ues was accomplished via Galvanostatic Charge–Discharge (GCD) analysis. The super capacitance value was found to be in the range 81.84 to 119.82 F/g with increase in dopant concentration. Hence, the material synthesized in this study holds promise for applications in both energy storage materials and the field of display technology.