Structural and magnetic evaluations of rare-earths (Tb, Pr, Ce, Gd, Y)-doped spinel ferrites for high frequency and switching applications

Abstract

NiZn nanoferrites doped with rare-earth cations having stoichiometric composition such as Ni0.5Zn0.5R0.02Fe1.98O4 (R = Tb, Pr, Ce, Gd, Y) were prepared by sol–gel technique. The same amount of Ni and Zn with constant ratio of different rare-earths ions were doped to investigate the variations in the properties. X-ray diffraction (XRD), Field emission electron microscope (FESEM), and vibrating sample magnetometer (VSM) were used to investigate the structure, morphology, and magnetic properties of rare-earth doped NiZn nanoferrites, respectively. X-ray density, bulk density, and porosity were also calculated. Phase, crystallite size, structure, d-spacing, lattice parameter, micro strain, and cell volume are also calculated. XRD patterns were refined using Rietveld refinement method. The refinement was implemented by materials analysis using diffraction (MAUD). Bertaut method was used to evaluate the bond lengths, site radii, and shared and unshared edges. Single phase for all rare-earth-doped NiZn nanoferrites was confirmed from refined patterns. GOF (goodness of fit) was in the range which verifies the good matching of patterns with the standard patterns. The micrographs depicted the different morphologies of the rare-earths-doped NiZn ferrites which confirms the behavior of rare-earth ions in NiZn ferrites. Saturation, initial permeability, anisotropy (Ka), coercivity, Y-K angles, remanence, and magnetic moments were measured from magnetic loops using VSM. Y- and Gd-doped NiZn nanoferrites demonstrated better magnetic properties as compared to other rare-earth-doped NiZn ferrites. Switching field distribution response from the prepared nanoferrites was also investigated. High-frequency response depicted the use of these nanoferrites in microwave frequency regions such as S, X, and Ku band because of their strong magnetization response.