Effect of yttrium doping on the physical properties of Mg-Zn ferrite: A detailed study

A series of Mg0.6Zn0.4Yx Fe2-x04 (0.0 ≤ x ≤ 0.3) spinel ferrites were synthesised via the sol-gel technique with sucrose as fuel to investigate the influence of Y3 + substitution on the structural, thermal, elastic, optical, electrical, and magnetic properties. X-ray diffraction (XRD) confirmed the formation of single-phase cubic spinel structures for all compositions, with increase in lattice parameters from 8.4067 Å to 8.5139 Å. The increase in lattice parameter was due to the larger ionic radius of yttrium (0.90 Å) ions as compared to magnesium (0.72 Å) and zinc (0.74 Å) ions. FESEM images revealed agglomerated grains due to sintering process, and EDAX analysis confirmed the stoichiometric presence of Mg, Zn, Fe, Y, and O. Fourier-transform infrared spectroscopy (FTIR), exhibits vibrational band 566 cm−1 attributed to (tetrahedral) A site and 430 cm−1 to (octahedral) B sites. Elastic properties such as Young’s, shear, and bulk modulus was found to decrease with Y3+ content, whereas Poisson’s ratio remains the same for all samples. UV-Visible analysis gives optical band gap ranging from 1.78 to 1.97 eV, influenced by quantum confinement and structural modifications due to Y3+ substitution. The observed AC conductivity with frequency can be attributed to the Maxwell-Wagner interfacial polarization, which stems from the heterogeneous nature of the ferrite material, composed of grains and grain boundaries with varying electrical properties. Magnetic measurements carried out using vibrating sample magnetometry. Y³ ⁺ doping increases coercivity due to enhanced anisotropy, lattice strain, and domain wall pinning, while the remanent magnetization remains nearly unchanged because the net sublattice magnetization balance is preserved. The combined results demonstrate that Y3+ substitution effectively modulates the crystal structure, optical absorption, and magnetic softness of MgZnFe2O4, making these materials promising candidates for multifunctional magnetic and optoelectronic applications.