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Nagoya-shi, Japan

Yasuda N.,Gifu University | Fuwa T.,Gifu University | Ohwa H.,Gifu University | Tachi Y.,Jfe Holdings | And 5 more authors.
Japanese Journal of Applied Physics | Year: 2011

The domain structures of the lead-based relaxor ferroelectric solid solution single crystal, 24Pb((In 1/2Nb 1/2)O 3-46Pb(Mg 1/3Nb 2/3)O 3-30PbTiO 3 (PT), near a morphotropic phase boundary (MPB) composition grown by the Bridgeman method were studied by polarized light microscopy (PLM), piezoresponse force microscopy (PFM) and scanning electron microscopy (SEM). The change in domain structures with poling from rhombohedral spindlelike domains of 3-5 μm width to orthorhombic domains of ∼20 μm width with rectangular cells with a size of 3- 5 μm, characterized with an antiferroelectic double hysteresis loop in the electric field-induced strain behavior, was found. Such domain structures were microscopically identified from SEM images as small circular tetragonal defects, planar monoclinic defects such as edge and screw dislocations with Burgers vector b along (110) cub and/or (100) cub directions and their agglomerate rectangular orthorhombic defects, also characterized by PFM. Hierarchical domain structures are discussed from the viewpoints of domain structures due to defects such as edge and screw dislocations originating in the chemical order region (COR) and the piezoelectric responses and dielectric properties. © 2011 The Japan Society of Applied Physics. Source


Naitoh T.,Electronics and Mechanics | Okura N.,Meijo University | Gotoh T.,Nagoya Institute of Technology | Kato Y.,Denso
Physics of Fluids | Year: 2014

A laminar vortex ring with swirl, which has the meridional velocity component inside the vortex core, was experimentally generated by the brief fluid ejection from a rotating outlet. The evolution of the vortex ring was investigated with flow visualizations and particle image velocimetry measurements in order to find the influence of swirling flow in particular upon the transition to turbulence. Immediately after the formation of a vortex ring with swirl, a columnar strong vortex along the symmetric axis is observed in all cases of the present experiment. Then the characteristic fluid discharging from a vortex ring with swirl referred to as "peeling off" appears. The amount of discharging fluid due to the "peeling off" increases with the angular velocity of the rotating outlet. We conjectured that the mechanism generating the "peeling off" is related to the columnar strong vortex by close observations of the spatio-temporal development of the vorticity distribution and the cutting 3D images constructed from the successive cross sections of a vortex ring. While a laminar vortex ring without swirl may develop azimuthal waves around its circumference at some later time and the ring structure subsequently breaks, the swirling flow in a vortex ring core reduces the amplification rate of the azimuthal wavy deformation and preserved its ring structure. Then the traveling distance of a vortex ring can be extended using the swirl flow under certain conditions. © 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4882683]. Source


Iwata M.,Electronics and Mechanics | Ido T.,Electronics and Mechanics | Maeda M.,Electronics and Mechanics | Ishibashi Y.,Nagoya University
Japanese Journal of Applied Physics | Year: 2014

The dielectric permittivity along the [001]c direction of the pseudocubic coordinate in Pb(Zn1/3Nb2/3)O3-8-PbTiO3(PZN-8%PT) was investigated in a wide temperature range of 30-640 °C. The determination of the Curie constant in PZN-8%PT was attempted, using the dielectric permittivity above the Burns temperature, to evaluate the bulk property in the ferroelectric phase as an average structure with reduced heterogeneity. It was confirmed that the reported temperature dependence of the spontaneous polarization can be quantitatively well reproduced on the basis of the Landau-type free energy. © 2014 The Japan Society of Applied Physics. Source

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