Electrical properties and magnetoelectric effect in Ni0.75Co0.25Fe2O4+Ba0.8Pb0.2TiO3 composites

Magnetoclectric (ME) phenomenon has been observed in several single phase materials in which simultaneous electric and magnetic ordering co-exists and in two-phase composites in which the participating phases are ferrite and ferroelectric. Hence, ME composites with composition xBa(0.8)Pb(0.2)TiO(3) + (1-x)Ni0.75CO0.25Fe2O4 in which x varies as 0.0, 0.55, 0.70, 0.85 and 1.0 were prepared by ceramic method. The presence of both phases was confirmed by x-ray diffraction technique. The variation of resistivity and thermoemf of the composites with temperature was studied. The variation of dielectric constant (epsilon') with frequency (100 Hz to 1 MHz) and with temperature at different frequencies viz. 1, 10, 100 kHz and 1 MHz has been also studied. The AC conductivity is derived from dielectric constant (epsilon') and loss tangent (tan delta). The nature of conduction has been discussed with the help of polaron hopping model. The static value of the ME conversion factor i.e. DC (ME)(H) was studied as a function of intensity of the magnetic field. The maximum value of DC (ME)(H) was found to be 140 muV cm(-1) Oe(-1). (C) 2002 Elsevier Science B.V. All rights reserved.