Browsing by Author "Park, Dong-Soo"

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    Design and characterization of broadband magnetoelectric sensor
    Park, Chee-Sung; Ahn, Cheol-Woo; Ryu, Jungho; Yoon, Woon-Ha; Park, Dong-Soo; Kim, Hyoun-Ee; Priya, Shashank (American Institute of Physics, 2009-05-01)
    In this study, we present a broadband magnetoelectric (ME) sensor design comprising of Metglas and piezoelectric ceramic laminate composite. A systematic study was conducted to elucidate the role of various composite variables toward the ME response [longitudinal-transverse (LT) mode] over the applied range of magnetic dc bias. The broadband behavior was characterized by flat ME responses over a wide range of magnetic dc bias at frequency of 1 kHz. The variation in ME coefficient as a function of magnetic dc bias was found to be significantly dependent on the size and shape of the laminate composites, the number of Metglas layers, and composite structure of sandwich versus unimorph. By adjusting these variables, we were able to achieve near-flat ME response over a magnetic bias range of 90-220 Oe. ME coefficient was also measured as a function of frequency, and at electromechanical resonance the peak value was found to be almost independent of applied magnetic bias in the range of 90-220 Oe. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3117484]
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    Enhanced domain contribution to ferroelectric properties in freestanding thick films
    Ryu, Jungho; Priya, Shashank; Park, Chee-Sung; Kim, Kun-Young; Choi, Jong-Jin; Hahn, Byung-Dong; Yoon, Woon-Ha; Lee, Byoung-Kuk; Park, Dong-Soo; Park, Chan (American Institute of Physics, 2009-07-15)
    We report the success in fabricating clamped, "island," and freestanding 10 mu m thick piezoelectric films using aerosol deposition. The deposition was conducted at room temperature by impinging the piezoelectric particles flowing through the nozzle onto platinized silicon (Pt/Ti/SiO(2)/Si) substrate and crystallization was conducted by annealing at 700 degrees C. Freestanding films were synthesized by increasing the cooling rate from annealing temperature to room temperature which resulted in large internal stress between the substrate and film interface. Dielectric and ferroelectric characterizations showed enhanced ferroelectric performance of freestanding films as compared to continuous or clamped film which was associated to increased domain contribution due to decrease in degree of clamping as further confirmed by piezoforce microscopy. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3181058]
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    Piezoelectric and Magnetoelectric Thick Films for Fabricating Power Sources in Wireless Sensor Nodes
    Priya, Shashank; Ryu, Jungho; Park, Chee-Sung; Oliver, Josiah; Choi, Jong-Jin; Park, Dong-Soo (MDPI, 2009-08-17)
    In this manuscript, we review the progress made in the synthesis of thick film-based piezoelectric and magnetoelectric structures for harvesting energy from mechanical vibrations and magnetic field. Piezoelectric compositions in the system Pb(Zr,Ti)O₃– Pb(Zn₁/₃Nb₂/₃)O₃ (PZNT) have shown promise for providing enhanced efficiency due to higher energy density and thus form the base of transducers designed for capturing the mechanical energy. Laminate structures of PZNT with magnetostrictive ferrite materials provide large magnitudes of magnetoelectric coupling and are being targeted to capture the stray magnetic field energy. We analyze the models used to predict the performance of the energy harvesters and present a full system description.
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    Stress-controlled Pb(Zr0.52Ti0.48)O-3 thick films by thermal expansion mismatch between substrate and Pb(Zr0.52Ti0.48)O-3 film
    Han, Guifang; Ryu, Jungho; Yoon, Woon-Ha; Choi, Jong-Jin; Hahn, Byung-Dong; Kim, Jong-Woo; Park, Dong-Soo; Ahn, Cheol-Woo; Priya, Shashank; Jeong, Dae-Yong (American Institute of Physics, 2011-12-15)
    Polycrystalline Pb(Zr0.52Ti0.48)O-3 (PZT) thick films (thickness similar to 10 mu m) were successfully fabricated by using a novel aerosol deposition technique on Si wafer, sapphire, and single crystal yitria stabilized zirconia (YSZ) wafer substrates with Pt electrodes and their dielectric, ferroelectric, and piezoelectric properties, and in-plane stresses were investigated. The films with different stress conditions were simply controlled by the coefficient of thermal expansion (CTE) misfit of PZT films and substrates. The results showed that the films bearing in-plane compressive stress deposited on the YSZ and sapphire substrates have superior dielectric, ferroelectric (similar to 90%), and piezoelectric (>200%) properties over that of the Si wafer. Among these three substrates, YSZ shows superior properties of the PZT films. However, films on Si wafer with tensile stress present lower properties. We believed that in-plane compressive stresses within the films are benefited, the formation of c-domain parallel to the thickness direction resulting in the higher piezoelectric properties. These results suggest that the properties of polycrystalline PZT thick films can be adjusted by simply choosing the substrates with different CTEs. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3669384]