A series of Ni‐Mn‐Zn mixed spinel ferrite doped with Sm3+ ions is prepared by using sol‐gel auto‐combustion technique. Single phase cubic spinel structure of all the samples is confirmed by using XRD analysis. Incorporation of Sm3+ ions in Ni‐Mn‐Zn ferrites increases the lattice parameter from 8.4105 to 8.4134 Å. Williamson – Hall (W‐H) and strain size plot (SSP) analysis confirms the tensile‐type strain induced in the crystal lattice, which increases with the addition of Sm3+ ions. Average crystallite size estimated from Scherrer equation is found in the range 21.7–24.9 nm, which in good agreement with the results obtained from W‐H and SSP analysis. Infrared spectra recorded in the range 350–800 cm−1 reveals the characteristic features of spinel ferrites. Higher frequency band ν1 is observed near 580 cm−1 and lower frequency band ν2 is observed near 380 cm−1. By using the IR data, elastic constant (stiffness constant) and elastic moduli (Young's modulus, bulk modulus, and rigidity modulus) are estimated. Debye temperature obtained from Anderson formula ranging from 535 to 562 K and from Waldron equation ranging from 676 to 713 K with the substitution of Sm3+ ions.

No abstract

Polycrystalline Co-Zn nanoferrites doped with rare earth Dy3+ ions having general chemical formula Co0.9Zn0.2DyxFe1.9-xO4 (x = 0.0, 0.015, 0.03, 0.045 and 0.06) were synthesized via sol-gel auto-combustion route. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform Infrared Spectra (FTIR) were performed to investigate the structural, microstructral, surface morphology and elastic properties. Well indexed XRD patterns confirm the phase purity and cubic spinel structure of the samples. Fractional doping of Dy3+ ions shifts the Bragg’s lines slightly towards the lower angles which in turn increases the lattice lengths from 8.3795 Å to 8.3834 Å. The strain induced in the crystal lattice was estimated by using Williamson-Hall and Size – Strain Plot methods. Both methods confirm that the tensile type strain was induced in the crystal lattice and increases with the substitution of Dy3+ ions. Surface morphology of the samples was studied by using SEM images which reveals that the grains are almost spherical in nature and the size obtained is analogues with XRD results. FTIR spectra shows the existence of two main absorption bands within the wave number range 388 – 586 cm−1 which confirm the characteristics of spinel ferrites. Elastic properties were estimated by using FTIR data. Elastic moduli and Debye temperature increases with the substitution of Dy3+ ions which are interpreted on the basis of interatomic bondings.