Erbium substituted baddeleyites (ErxZr(1-x)O2): Structural, ferroelectric, magnetic and electrochemical analysis for supercapacitors electrodes using walnut shells charcoal

The fabrication of ErxZr(1-x)O2 (x = 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) is carried out with solid-state method at 1200 °C temperature for 4-hrs to get the desired monoclinic structure. The structural, ferroelectric magnetic and electrochemical properties are investigated with X-ray diffractometer, ferroelectric, magnetic, cyclic voltametric, charging/discharging and electrochemical impedance respectively. The XRD and refinement parameters shows the formation of monoclinic symmetry. The low value of R-factors ensures the structural stability. The vista and diamond software are used to determine the different physical properties. The characteristic band at 665 and 721 cm−1 confirms the monoclinic identity of ZrO2 with ATR-FTIR. The SEM graphs show that the average particle size is present in 127-122 nm range. The decreased particle size is associated with the enhanced Csp due to the incease of surface-to-volume ratio. The ferroelectric analysis revealed the centrosymmetric alignment of tetrahedron sites having the 4-faces, 6 edges and 4-vertices. The magnetic analysis exposed the soft-diamagnetic feature. The high value of coercivity (Hc < Mr/2) gives the direction towards energy storage application. The CV graphs gives the good 389.8 F/g Csp which correlated with the GCD and EIS data. The highest 396.1 F/g Csp is measured using the charge/discharge curve and 309.75 F/g is calculated using the frequency-dependent EIS spectra. These high aggregates of specific capacitance values make them eligible for supercapacitors application.