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Nb doped CoFe2O4 ferrites (Denoted: Co1.2Fe1.7Nb0.1O4) was prepared by conventional solid state reaction method at calcination temperature 1300 C. The tuning of both electrical and magnetic poling on the prepared samples shows suppression of (111) peak as observed in X-ray diffraction study implying that (111) is the easy magnetic axis in polycrystalline cobalt ferrite and it responds to both electric and magnetic field. Furthermore, the strain derivative of 84 × 10−9 Oe−1 at a field of 790 Oe is observed from magnetostriction measurement. Converse magnetoelectric effect was observed on an electrically poled sample where the sample got magnetized upon electrical poling. The value of linear magnetoelectric coefficient obtained was 150 mV/cm.Oe which is unusually high for a single phase material and at room temperature and this may be due to the d0 configuration of Nb. The observed linear magnetoelectric coefficient and room temperature PE loop was obtained suggesting that the Co1.2Fe1.7Nb0.1O4 material could be useful for magnetoelectric sensor applications.

The structural and magnetic properties of bulk polycrystalline CoFe 2O4 and niobium substituted Co1.1Fe 1.85Nb0.05O4 prepared by solid state reaction method, are presented in this paper. The lattice parameter of Co 1.1Fe1.85Nb0.05O4 is seen to be more than that of CoFe2O4. Saturation magnetization, first order magnetocrystalline anisotropy constant calculated using law of approach to saturation and magnetostriction of Co1.1Fe1.85Nb 0.05O4 are seen to be less than those of CoFe 2O4. Longitudinal magnetostriction of Co 1.1Fe1.85Nb0.05O4 measured at room temperature is -123 � 10-6 at a field of 2.2 kOe, with enhanced strain derivative. Field induced trigonal distortion was observed at 2.2 kOe in Co1.1Fe1.85Nb0.05O4 from the analysis of powder XRD patterns. Co1.1Fe1.85Nb 0.05O4 exhibits ferroelectric and magnetoelectric properties. � 2014 Elsevier B.V. All rights reserved.