Probing of structural, surface morphological, optical, low temperature magnetic and electrochemical investigations on gadolinium selenite

Gadolinium selenite (Gd2Se3O9) has been synthesized by co-precipitation method. It exhibits spherical-shaped particles. Gd2Se3O9 is crystallized in monoclinic structure. Cyclic voltammogram of three-electrode system, manifests pseudocapacitance with a potential window of 0.65 V. Specific capacitance is 84 F/g. Chronopotentiometry analysis shows 78.84 F/g specific capacitance. Gd2Se3O9 electrode-based symmetric supercapacitor device was successfully fabricated and tested by two-electrode configuration in aqueous electrolyte of KOH. This full cell fabricated symmetric device exhibits 1.30 V potential window, 48.53 F/g specific capacitance, 5.70 Wh kg-1 energy density and 650 Wkg-1 power density at current density of 1 A/g. The improved cycling performance after 6000 cycles is 77% specific capacitance retention. This device possessed greater specific capacitance, wider potential window, good cycle stability, and high energy and power density for energy storage and conversion applications. Energy gap is 5.327 eV, Urbach energy value is 0.121 eV and refractive index is 1.953. Absorption and emission peaks are assigned by optical transitions between energy levels. X-ray photo emission spectrum confirmed that the gadolinium was present in the samples in oxide form. Magnetic susceptibility study between 300 and 20 K, shows decrease of susceptibility with temperature, then reaches saturation and aligns all gadolinium spins. This results cooperative interaction of gadolinium spins. M-H curve at 300 K confirms the paramagnetic nature of sample. It also shows a feeble ferromagnetic signal.