Structural, mechanical, dielectric properties and magnetic interactions in Dy³⁺-substituted Co–Cu–Zn nanoferrites

Sol-gel-synthesized Co-Cu-Zn ferrite nanoparticles diluted with Dy³⁺ ions were investigated in terms of their structural, morphological, elastic, magnetic and dielectric properties. X-ray diffraction patterns showed the formation of a single-phase cubic spinel structure. As the concentration of Dy³⁺ ions was increased, the lattice length gradually increased from 8.340 to 8.545 Å, obeying Vegard's law. The Williamson-Hall (W-H) method was employed to observe the change in the lattice strain. Crystallite size obtained from W-H plots followed a pattern similar to that observed using the Scherrer equation. The cation distribution suggested a strong preference of Dy³⁺ ions for the octahedral B site while Cu²⁺ and Fe³⁺ ions were distributed over both A and B sites. The microstructures of the samples were visualized using transmission electron microscopy. Mechanical properties such as stiffness constant, longitudinal and transverse wave velocities, Young's modulus, bulk modulus, rigidity modulus, Poisson's ratio and Debye temperature were investigated by acquiring infrared spectra recorded in the range of 300 to 800 cm^-1. Replacement of Fe³⁺ ions with the strongly magnetic Dy³⁺ ions increased the saturation magnetization and coercivity. Dielectric constant increased with Dy³⁺ substitution but decreased with applied frequency.