Browsing by Author "Petrov, Vladimir M."

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    Magnetoelectric Interactions in Lead-Based and Lead-Free Composites
    Bichurin, Mirza I.; Petrov, Vladimir M.; Zakharov, Anatoly; Kovalenko, Denis; Yang, Su-Chul; Maurya, Deepam; Bedekar, Vishwas; Priya, Shashank (MDPI, 2011-04-06)
    Magnetoelectric (ME) composites that simultaneously exhibit ferroelectricity and ferromagnetism have recently gained significant attention as evident by the increasing number of publications. These research activities are direct results of the fact that multiferroic magnetoelectrics offer significant technological promise for multiple devices. Appropriate choice of phases with co-firing capability, magnetostriction and piezoelectric coefficient, such as Ni-PZT and NZFO-PZT, has resulted in fabrication of prototype components that promise transition. In this manuscript, we report the properties of Ni-PZT and NZFO-PZT composites in terms of ME voltage coefficients as a function of frequency and magnetic DC bias. In order to overcome the problem of toxicity of lead, we have conducted experiments with Pb-free piezoelectric compositions. Results are presented on the magnetoelectric performance of Ni-NKN, Ni-NBTBT and NZFO-NKN, NZFO-NBTBT systems illustrating their importance as an environmentally friendly alternative.
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    Multiferroic Core-Shell Nanofibers, Assembly in a Magnetic Field, and Studies on Magneto-Electric Interactions
    Sreenivasulu, Gollapudi; Zhang, Jitao; Zhang, Ru; Popov, Maksym; Petrov, Vladimir M.; Srinivasan, Gopalan (MDPI, 2017-12-23)
    Ferromagnetic–ferroelectric nanocomposites are of interest for realizing strong strain-mediated coupling between electric and magnetic subsystems due to a high surface area-to-volume ratio. This report is on the synthesis of nickel ferrite (NFO)–barium titanate (BTO) core–shell nanofibers, magnetic field assisted assembly into superstructures, and studies on magneto-electric (ME) interactions. Electrospinning techniques were used to prepare coaxial fibers of 0.5–1.5 micron in diameter. The core–shell structure of annealed fibers was confirmed by electron microscopy and scanning probe microscopy. The fibers were assembled into discs and films in a uniform magnetic field or in a field gradient. Studies on ME coupling in the assembled films and discs were done by magnetic field (H)-induced polarization, magneto–dielectric effects at low frequencies and at 16–24 GHz, and low-frequency ME voltage coefficients (MEVC). We measured ~2–7% change in remnant polarization and in the permittivity for H = 7 kOe, and a MEVC of 0.4 mV/cm Oe at 30 Hz. A model has been developed for low-frequency ME effects in an assembly of fibers and takes into account dipole–dipole interactions between the fibers and fiber discontinuity. Theoretical estimates for the low-frequency MEVC have been compared with the data. These results indicate strong ME coupling in superstructures of the core–shell fibers.
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    Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites
    Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir M.; Qu, Hongwei; Srinivasan, Gopalan (MDPI, 2016-02-20)
    Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data.
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    Tunable magnetoelectric response of dimensionally gradient laminate composites
    Park, Chee-Sung; Avirovik, Dragan; Bichurin, Mirza I.; Petrov, Vladimir M.; Priya, Shashank (AIP Publishing, 2012-05-01)
    A magnetoelectric (ME) sensor exhibiting wideband behavior as a function of applied magnetic DC bias and frequency was designed by combining the dimensionally gradient piezoelectric layer with Metglas magnetostrictive layers in laminate configuration. The ME coefficient of the band in the DC magnetic range of 52-242 Oe was measured to be 3000 mV/cm Oe under the resonant condition of f = 107 kHz. The wideband in the AC magnetic field frequency range of 41-110 kHz had the ME coefficient in the vicinity of 260 mV/cm Oe under the conditions of H-AC = 1 Oe and H-DC = 70 Oe. This frequency-dependent ME behavior clearly showed two different states on each side of the resonance peak which could open the possibility of developing new applications such as magnetic field-controlled switches. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4720095]