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  • 1
    Electronic Resource
    Electronic Resource
    Characteristics of the electromechanical response and polarization of electric field biased ferroelectrics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 2549-2555 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electromechanical and dielectric responses of ferroelectric materials near paraelectric–ferroelectric (PF) phase transitions are examined both experimentally and theoretically. It is shown that the type of PF transition, i.e., first order and continuous transitions, and diffused phase transition found in relaxor ferroelectrics, has marked effect on the electromechanical and dielectric response behavior for materials under electric field bias. It is demonstrated that an exceptionally large piezoelectric and electromechanical response can be achieved in materials with a first order PF transition. For example, in Ba1−xSrxTiO3 (x∼0.35) ceramics at room temperature, a piezoelectric d33 larger than 1500 pm/V with very little frequency dispersion can be obtained. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358785
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  • 2
    Electronic Resource
    Electronic Resource
    Phase stabilities of "morphotropic" phases in Pb(Zn1/3Nb2/3)O3–PbTiO3 single crystals (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1918-1920 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Based on the optic and dielectric data acquired under different mechanical and electric conditions and temperature, we show that an orthorhombic phase exists near the morphotropic phase boundary (MPB) (on both the rhombohedral and tetragonal sides of MPB). Because of the proximity of the free energy of this phase to the two other morphotropic phases, i.e., the rhombohedral and tetragonal phases, the experimentally observed phases and phase diagrams near MPB depend crucially on the mechanical and electric conditions as well as the sample history. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1461902
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  • 3
    Electronic Resource
    Electronic Resource
    Processing and properties of 15–70 MHz 1–3 PZT fiber/polymer composites (2000)
    Springer
    Materials research innovations 3 (2000), S. 324-331 
    Details
    ISSN: 1433-075X
    Keywords: Keywords 1–3 Composite ; Piezoelectrics ; Fiber composite ; High frequency transducers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  This paper reports on the fabrication and characterization of fine scale piezoelectric composites with 1–3 connectivity using fibers derived from a metal alkoxide sol-gel process. Using this technique, pure thickness mode resonance for this type of composite has been increased from 15 MHz up to 70 MHz by maintaining pillar aspect ratio requirements. Piezoceramic fibers of Nb or La modified lead zirconate titanate (PZT) were produced with final diameters ranging from 15 to 50 µm. Composites having 1–3 connectivity were produced using the fibers as pillars. Composites could be fabricated with volume fractions from 10 to 45% allowing tailoring of both the dielectric constant and acoustic impedance without degrading coupling. Dielectric constant, polarization and coercive field values varied slightly from bulk values due to clamping by the polymer matrix, increasing as the fiber diameter decreased. Composites with resonance frequencies ranging from 15 to 70 MHz were studied. The thickness dependence of the properties gave indications to radial mode/thickness mode interactions at pillar aspect ratios near 1.7 to 1 thickness to diameter. Coupling coefficients (kt) from 58% to 73% with mechanical quality factors 〈15 were detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100190000060
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  • 4
    Electronic Resource
    Electronic Resource
    Modelling the ageing phenomena in 0.9PMN-0.1PT relaxor ferroelectric ceramics (1989)
    Springer
    Journal of materials science 8 (1989), S. 771-776 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01730133
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  • 5
    Electronic Resource
    Electronic Resource
    Optimum TiB2 ceramic powder for composite thermistors (1990)
    Springer
    Journal of materials science 9 (1990), S. 611-612 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00725894
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  • 6
    Electronic Resource
    Electronic Resource
    Dielectric and piezoelectric properties of perovskite materials at cryogenic temperatures (1999)
    Springer
    Journal of materials science 34 (1999), S. 469-473 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Dielectric and piezoelectric properties of perovskite materials including La modified Pb(Zr, Ti)O3 (PZT's), (Ba, Sr)TiO3 (BST) polycrystalline ceramics and Pb(Zn1/3 Nb2/3)O3-PbTiO3 (PZN-PT) single crystals were investigated for capacitor and actuator applications at cryogenic temperatures. PZTs were compositionally engineered to have decreased Curie temperatures (Tc) by La and Sn doping in order to compensate for the loss of extrinsic contributions to piezoelectricity at cryogenic temperatures. Enhanced extrinsic contributions resulted in piezoelectric coefficients (d33) as high as 250 pC/N at 30 K, superior to that of conventional DOD Type PZT's (d33~100 pC/N). This property enhancement was associated with retuning to the MPB at cryogenic temperatures. 5/95 BST with a dielectric maximum at 57 K was investigated to obtain high electrostrictive properties or E-field induced piezoelectricity. Coupling coefficients (k31) 25% comparable to those of the cryogenic PLZT piezoelectrics were observed at d.c. bias of 1.5 kV/cm and 50 K. Though significantly lower than the room temperature values, PZN-PT rhombohedral single crystals exhibited d33〉 500 pC/N at 30 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004578225228
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  • 7
    Electronic Resource
    Electronic Resource
    On short range ordering in the perovskite lead magnesium niobate (1990)
    Springer
    Journal of materials science 25 (1990), S. 3461-3466 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The structural ordering characteristics of lead magnesium niobate (PMN) and solid solutions (PMN-PT) of PMN with lead titanate have been investigated using transmission electron microscopy (TEM). It is proposed that short range, non-stoichiometric 1∶1 ordering of the Mg and Nb cations on an F-centred superlattice generates space charges which dominate the kinetics of the ordering process and inhibit the development of long-range order. Furthermore, it is demonstrated that by introducing off-valent La3+ ions on to the A-site sublattice, the local charges can be at least partially-compensated and an increase in the extent of structural ordering is consequently observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00575371
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  • 8
    Electronic Resource
    Electronic Resource
    Double-step lamination of grain-oriented Y-Ba-Cu-O superconducting ceramics (1992)
    Springer
    Journal of materials science 27 (1992), S. 3594-3598 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The uniformity of grain alignment and anisotropic superconducting properties were investigated in laminated tape-cast YBa2Cu3O7−x ceramics. Large, platey YBa2Cu3O7−x grains were prepared by gentle grinding of pellets prepared by liquid-phase sintering. A mixture of pre-reacted BaCuO2 and CuO was added as a molten flux. The grain-oriented specimens were then prepared by tape-casting followed by lamination and sintering. A high degree of grain orientation was observed near the surface of the specimen. Successive polishing and X-ray diffraction studies revealed that the effective depth of the oriented layer was approximately 200 μm. The small anisotropy observed in the critical current density calculated from the magnetization provided additional evidence for the non-uniformity of the grain alignment across the sample. By reducing the thickness of the laminated sample to the effective depth for obtaining a uniform structure, polycrystalline ceramic samples with a homogeneous and high degree of grain orientation were obtained by a double lamination method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01151838
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  • 9
    Electronic Resource
    Electronic Resource
    Composite PTCR thermistors utilizing conducting borides, silicides, and carbide powders (1991)
    Springer
    Journal of materials science 26 (1991), S. 145-154 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ceramic-polymer composite thermistors using conducting boride, silicide, and carbide powders that include TiB2, ZrB2, NbB2, NbSi2, WSi2, MoSi2, and TiC have been fabricated. Percolation and subsequent PTCR effects were observed for all the powders in both semi-crystalline (polyethylene) and amorphous (epoxy) polymer matrix materials, however, as found for carbon black and metal fillers, both niobate powders did not exhibit a PTCR effect in the amorphous polymer. Results indicate that percolation and PTCR behaviour are related to the powder characteristics (size/distribution), composite microstructure and ceramic-polymer interface. Composite thermistors with room temperature resistivities as low as 1 Ω cm and a nine-order of magnitude change (Δϱ) at 1 kHz (12 Δϱ at d.c.) were achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00576045
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  • 10
    Electronic Resource
    Electronic Resource
    Fabrication of fine-grain piezoelectric ceramics using reactive calcination (1991)
    Springer
    Journal of materials science 26 (1991), S. 4411-4415 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fine-grain piezoelectric ceramics with the formula Pb(Zr0.53Ti0.47)O3(PZT) were prepared by a reactive calcination process. Using conventional materials and processing techniques, highly reactive powders of PZT were achieved by calcining to or near the point of maximum volume expansion, whereby associated morphological changes resulted in highly reactive powder. Upon milling, powders 〈0.3 μm were readily obtained allowing densification at temperatures 〈1000°C. The B-site precursor method, whereby the ZrO2 and TiO2 oxides were pre-reacted prior to reaction with PbO, further enhanced reactivity by eliminating intermediate reactions and subsequent phase(s) which can hinder densification and overall homogeneity. Highly dense piezoceramics with grain sizes ∼1 to 2 μm exhibiting dielectric and piezoelectric characteristics comparable to conventionally prepared large grain size materials were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00543660
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