A.D. Sheikh

Effect of the piezomagnetic NiFe2O4 phase on the piezoelectric Pb(Mg1/3Nb2/3)0.67Ti0.33O3 phase in magnetoelectric composites

The magnetoelectric (ME) effect in magnetoelectric composites is an induced electric polarization in response to an applied magnetic field and magnetization in response to an applied electric field. The individual phases NiFe2O4 (NFO), Pb(Mg1/3Nb2/3)0.67Ti0.33O3 (PMN-PT) and composites of (x)xa0NFO+(1−x) PMN-PT with x = 0.15, 0.30 and 0.45 were prepared using a solid-state reaction technique. The presence of NFO and PMN-PT was confirmed using x-ray diffraction. Scanning electron microscopy (SEM) images were used to study the microstructure of the composites. The connectivity scheme present in the ME composites was investigated from the microscope images. The connectivity scheme changes with change in the NFO content in the composites. A ferroelectric hysteresis loop (at 50xa0Hz) was obtained and studied at room temperature. Variation of the dielectric constant with temperature for all the composites was studied in the range 300–925xa0K. Here we report the effect of NFO mole fraction on connectivity schemes between NFO and PMN-PT grains, % porosity, magnetoelectric and magneto-dielectric effects in NFO/PMN-PT composites. The maximum value of the magnetoelectric voltage coefficient, 10.43xa0mVxa0cm−1xa0Oe−1, was obtained for 0.15xa0NFO+0.85 PMN-PT composites. The maximum value of the magneto-dielectric coefficient, 4.54, was obtained for 0.15xa0NFO+0.85 PMN-PT composites.

Dielectric, electrical and magnetoelectric characterization of (x)Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} + (1 - x)Pb{sub 0.93}La{sub 0.07}(Zr{sub 0.60}Ti{sub 0.40})O{sub 3} composites

The structural, electrical, dielectric, magnetic and magnetoelectric properties of (x)Ni0.8Zn0.2Fe2O4 + (1 − x)Pb0.93La0.07(Zr0.60Ti0.40)O3 (x = 0, 0.15, 0.30, 0.45 and 1) have been studied by means of various experimental techniques. Polycrystalline samples of this series have been prepared by the double sintering ceramic method. X-ray diffraction data analysis revealed purity of the composites. Microstructural analysis using scanning electron microscopy mode depicts the presence of two phases in contact with each other. Dielectric properties were studied at and well above room temperature. Temperature dependent variation of the dielectric constant show diffused phase transition which can be well described by fitting the Lorentz-type relation, eA/e=1+(T−TA)2/2δA2. Observation of well-saturated ferroelectric hysteresis loop and magnetic hysteresis loop for composites indicates that ferroelectric and magnetic ordering exist simultaneously at room temperature. The static value of magneto electric voltage coefficient (αE) has been studied as a function of magnetic field at room temperature for all the composites. The maximum value of αE is 7.53 mV/(cm Oe) for 85% PLZT–15% NZFO composites.