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

R H Kadam,D R Mane,Sagar E Shirsath,R B Borade,K M Batoo,M L Mane

doi:10.1039/d0ra05274d

Abstract

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.

Highlights

Nanocrystalline spinel oxides such as ferrites display integral properties of magnetization and electrical insulation simultaneously and have attracted enormous attention of researchers and have prompted them to intensively investigate these systems
S decreased from 39.37 m2 gÀ1 to 34.47 m2 gÀ1 as Dy was substituted. This decrease was related to the increased DXRD of the samples with Dy substitution
The Dy substitution resulted in an increase in tensile strain in the materials from 3.1 (x 1⁄4 0.0) to 4.3 Â 10À4 (x 1⁄4 0.045), consistent with the lattice length having increased from 8.340 to 8.545 A

Summary

Introduction

Nanocrystalline spinel oxides such as ferrites display integral properties of magnetization and electrical insulation simultaneously and have attracted enormous attention of researchers and have prompted them to intensively investigate these systems. Properties of spinel ferrite have been shown to be modi ed by substitutions of rare earth (RE3+) ions at the octahedral B site.[14] These modi cations have been attributed to the RE3+ ions having large magnetic moments, very large magnetostriction and large magnetocrystalline anisotropy as a result of their strong spin–orbit coupling of the angular momentum and unpaired 4f electrons. The substitution of RE3+ into ferrites can establish the 4f–3d couplings that govern magnetocrystalline anisotropy and improve the magnetic properties of the ferrites.[15,16] RE3+ oxides have good electrical resistivity of >105 U cm at room temperature.[17,18] Among the RE3+ ions, substitution of Dy3+ ions have yielded marked improvements in the

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