Eu3+ ions doped Cu1−xCoxEu0.025Fe1.975O4 spinel ferrite nanocrystals: insights on structural, cation distribution, magnetic properties, and switching field distribution

Abstract

In the present investigation, the sol–gel auto-combustion process was used to synthesize spinel ferrite nanoparticles Cu_1−xCo_xEu_0.025Fe_1.975O₄ with x = 0.0, 0.25, 0.5, 0.75, and 1. Through the use of various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersion X-ray analysis (EDX), Fourier transform Infrared analysis (FTIR), and magnetic measurements, the as-prepared ferrite nanoparticles have been examined and characterized. The X-ray diffraction (XRD) spectra confirmed the presence of a tetragonal spinel structure in the sample (x = 0), and the structure transformed into a cubic spinel with a space group of Fd3m as the Co content was increased. The lattice parameter changed from tetragonal phase with a = 5.820 Å and c = 8.710 Å for x = 0.00 to cubic phase with a = 8.372 Å for x = 1.00. The crystal size increases from 23.45 nm for x = 0.00 to 25.03 for x = 1.00 with increase in the amount of Co²⁺ content. The cation distribution for Cu_1−xCo_xEu_0.025Fe_1.975O₄ spinel ferrites has been estimated. Scanning electron microphotographs (SEM) of the prepared spinel ferrite samples demonstrated well-defined crystalline nanoparticles. The existence of every major element (Co, Cu, Fe, Eu, and O) and no discernible impurities in the samples is confirmed by the EDX analysis. FTIR spectra of Cu_1−xCo_xEu_0.025Fe_1.975O₄ committed the formation of the spinel nanoferrites and confirmed the solid-state reaction completion. The values of saturation magnetization (M_s), coercivity (H_c), remnant magnetization (M_r), magnetic moment (μ_B), squareness ratio (M_r/M_s) and anisotropy constant (K) have been estimated from the magnetic measurements. The (M_s) values increase from 22.561 emu/g for x = 0.00 to 68.794 emu/g for x = 1.00 while the (H_c) values decrease from 1898Oe for x = 0.00–1023 Oe for x = 1.00 with increasing the Co²⁺ content. The minor Eu⁺³ doped Cu_1−xCo_xEu_0.025Fe_1.975O₄ nanoferrites’s switching field distribution (SFD) evaluations were calculated by considering the first derivative of the demagnetization data.

Graphical Abstract