Exploring the structural, Mossbauer and dielectric properties of Co super(2+) incorporated Mg sub(0.5)Zn sub(0.5-x)COxFe sub(2)O sub(4) nanocrystalline ferrite

• Published in: Journal of magnetism and magnetic materials 2014-06, Vol.360, p.21-33
• Main Authors: Hashim, Mohd, Meena, S S, Kotnala, R K, Shirsath, Sagar E, Bhatt, Pramod, Kumar, Shalendra, Senturk, Erdogan, Kumar, Ravi, Gupta, Nidhi, Alimuddin, Alimuddin
• Format: Article
• Language: English
• Subjects: Dielectric properties; Ferrite; Morphology; Mossbauer effect; Mossbauer spectroscopy; Nanocrystals; Scanning electron microscopy; X-rays
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2014.01.047

The nanocrystalline Mg sub(0.5)Zn sub(0.5-x)Co sub(x)Fe sub(2)O super(4) (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) ferrites have been synthesized by sol-gel auto ignition method. Rietveld refinement of X-ray diffraction (XRD) patterns of all concentrations show mixed cubic spinel structure. The lattice constant values infer decreasing trend from 8.420 to 8.392 A with the substitution of Co super(2+). The crystallite size calculated from Scherer formula lies in the range between 28 and 37 nm which confirms the nanocrystalline nature of synthesized samples. In order to study the morphology and phase structure of the synthesized samples, samples were examined by transmission electron microscopy (TEM). Scanning electron microscopy (SEM) confirmed the homogeneous and well defined surface morphology of the synthesized samples. The elemental analysis as obtained from energy dispersive X-ray (EDAX) is in close agreement with the expected composition from the stoichiometry of reactant solutions used. The valence states of the Co super(2+) ions have been confirmed with the help of X-ray photoelectron spectroscopy. Magnetization results obtained from the vibrating sample magnetometer (VSM) confirm that the substitution of Co super(2+) for Zn super(2+) caused an increase in the saturation magnetization and coercivity. The dependence of Mossbauer parameters, viz., line width, isomer shift, quadrupole splitting and hyperfine magnetic field on Co super(2+) substitution have been analyzed. Cation distribution estimated from XRD and Mossbauer spectroscopy are in good agreement with each other. The frequency dependent dielectric properties were studied by measuring dielectric constant ([varepsilon]') and ac conductivity ([sigma] sub(ac)) at 300 K in the frequency range of 50 Hz-5 MHz. The highest value for [varepsilon]' and [sigma] sub(ac) is observed for x = 0.5.