Effect of rare earth radius and concentration on the structural and transport properties of doped Mn–Zn ferrite

• Published in: Journal of magnetism and magnetic materials 2007-04, Vol.311 (2), p.545-554
• Main Authors: Ateia, E., Ahmed, M.A., El-Aziz, A.K.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity phenomena in semiconductors and insulators; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Diffraction patterns; Electronic transport in condensed matter; Exact sciences and technology; Ferrite; Permittivity (dielectric function); Physics; Porosity; Rare earth; Sintering catalyst; Thermoelectric and thermomagnetic effects
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2006.08.014

Dielectric constant ( ε′), AC conductivity ( σ), and seebeck coefficient ( S) have been measured for the ferrite samples of the general formula Mn 0.5Zn 0.5R yFe 2O 4; where R=Dy, Gd, Sm, Ce, and La prepared by standard ceramic technique and sintered at 1200 °C with a heating rate 4 °C/min. X-ray diffractograms show that all samples posses the spinel structure with the appearance of small peaks representing secondary phases. There is a lowering in the porosity starting after Sm-doped samples due to the presence of the secondary phases, which limits the grain growth. Due to seebeck measurements the manganese–zinc (Mn–Zn) ferrite doped with the rare earth has been classified as P-type semiconductors. It is possible to increase the electrical resistivity by using a small quantity of Dy 3+ ions substitutions owing to the structural heterogeneity generated by the insulating intergranular layers. The isolation of the grains is the most promising approaches for further reduction in the eddy current losses at the operating frequencies.