Influence of RE-Gd3+ ion substitution on structure, morphology, optical, and magnetic analysis of Cu-Cd based nano ferrites synthesized by low-temperature citrate sol–gel auto combustion method

Abstract

The current study focused on the influence on physical, thermal, spectral, optical, and magnetic properties with the replacement of Fe3+ ions by large ionic radii rare-earth Gd3+ ions in CuCdFe2O4 nano-ferrites. The Gd3+ doped CuCdFe2O4 ferrite samples with chemical composition Cu0.8Cd0.2GdxFe2-xO4 (x = 0, 0.025, 0.05, 0.075 and 0.1) were produced by citrate sol–gel auto combustion route from the metal nitrates of the corresponding compounds. With the help of Thermo-gravimetric and differential thermal (TG-DTA) analysis, the temperature-dependent spinel phase formation and weight loss percentages were examined. The results of Powder X-ray diffraction patterns and FTIR spectra revealed the development of a cubic single-phase structure with α-Fe2O3 secondary phase, and stretching of metal ion bonds with the addition of Gd3+ ion in CuCdFe2O4 ferrites. From XRD data the observed lattice parameter was in the range of 8.323–8.469 Å and the average crystalline size was increased from 13 to 18 nm. “Field emission scanning electron microscopy” (FE-SEM) and “high-resolution transmission electron microscopy” (HR-TEM) analysis was used to give the particle size, shape, clear agglomeration, and dense structure of Gd3+ doped Cu-Cd nanoparticle. The semiconducting nature of the fabricated samples were confirmed from the characteristic UV–Vis spectra and the respective optical band gap values (1.70–1.74 eV). Electron spin resonance spectroscopy (ESR) analysis was provided the information about the various factors including g-value, peak to peak line width (ΔHPP), resonance field (Hr), and time relaxation (T2). The magnetic characteristic hysteresis loops of synthesised samples at 300 K and 15 K temperatures were obtained by VSM. The results showed that all Gd3+ doped samples exhibited a ferromagnetic nature at 300 K and enhanced hard magnetic nature at 15 K. The maximum saturation magnetisation (MS) was observed for x = 0.025 at both the temperatures (31.66 emu/g at 300 K and 39.65 emu/g at 15 K). The HC values were found in the range of 169.23–557.29 Oe at 300 K and 374.69–749.85 Oe at 15 K. The observed SQR (Mr/Ms) values revealed the single domain structure of prepared samples.