Developments in Ceramic Materials Research

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In: Developments in Ceramic Materials Research ISBN 978-1-60021-770-8 Editor: Dena Rosslere, pp. 211-240 © 2007 Nova Science Publishers, Inc. Chapter 7 PROGRESS IN POROUS PIEZOCERAMICS R. Ramesh * , H. Kara # , Ron Stevens and C. R. Bowen Department of Engineering and Applied Sciences, University of Bath, Bath BA27AY, UK * Naval Physical and Oceanographic Laboratory, Cochin-682 021, India # Johnson Mathey Ltd., UK ABSTRACT Synthesis, characterization, device fabrication, modeling and underwater evaluation of porous piezoceramics used in the form of 3-3 piezocomposites are discussed in detail. Piezocomposites have drawn considerable attention in recent years due to their potential application in medical ultrasonic and underwater transducers. Piezocomposites with 3-3 connectivity are produced from porous piezoceramics by filling the pores with suitable polymer materials. In this two-phase material, the PZT and the polymer are selfconnected in three dimensions. Synthesis of porous PZT structure by two techniques, namely, BURnout Plastic Spheres (BURPS) and foam reticulation techniques used to obtain wide range of porosity are described. Samples with ceramic volume fraction ranging from 10% to 100% are synthesised and are characterized in terms of their microstructure, piezoelectric charge (d33, d31) and voltage (g33,g31) coefficients, the hydrostatic coefficients (dH and gH) and hydrostatic Figure-of-Merit. Variations in dielectric, mechanical and piezoelectric properties as a function of ceramic volume fraction/ porosity are discussed. The experimental results are compared with that of a simple analytical model. Finite element modeling (FEM) studies are carried out on hydrophones constructed from porous and dense PZT discs. An axisymmetric model is proposed for dense PZT hydrophone and is validated by an analytical model. A 3dimensional model is proposed for porous PZT hydrophones. The FEM results agree well with that of the experiments. Details of the hydrophones fabricated with PZT-air and PZT-polymer composites with different configurations are presented. The acoustic performance of the transducers is evaluated underwater. The receiving sensitivity, the electrical impedance spectra and the directional response of the hydrophones are measured in the frequency range (10-100) kHz. These studies show that the 3-3 piezocomposite transducers have better properties than the transducers made out of dense PZT. The improved properties are the higher hydrostatic coefficients, higher receiving sensitivity and flat response over a wide frequency range. This suggests that the 3-3
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DEVELOPMENTS IN CERAMIC MATERIALS R
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Copyright © 2007 by Nova Science P
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PREFACE Ceramics are refractory, in
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Preface ix crystals is discussed. A
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Preface xi spectra and the directio
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2 Leslie G. Cecil comprehensive dat
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4 Leslie G. Cecil Ringle et al. (19
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6 Leslie G. Cecil The main architec
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8 Leslie G. Cecil can study “the
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10 Leslie G. Cecil Middleton et al.
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12 Leslie G. Cecil The laser ablate
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14 Leslie G. Cecil There are two ge
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16 Leslie G. Cecil distinct recipes
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18 Leslie G. Cecil second group (Fi
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20 Leslie G. Cecil The Vitzil-Orang
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22 Leslie G. Cecil Table 3. Mahalan
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24 Leslie G. Cecil Ixlú and Ch’i
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26 Leslie G. Cecil structures (D. R
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28 Leslie G. Cecil paste and Macanc
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30 Leslie G. Cecil Bieber, A. M. Jr
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32 Leslie G. Cecil Kepecs, S. M., a
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34 Leslie G. Cecil Schele, L., Grub
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36 Z. C. Li, Z. J. Pei and C. Tread
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54 T. T. Basiev, V. A. Demidenko, K
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62 I, % 100 80 60 40 20 0 T. T. Bas
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68 Fluorescence, a.u. 1 T. T. Basie
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70 Fluorescence, a.u. 1 0.1 0.01 0.
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78 k, cm -1 20 18 16 14 12 10 8 6 4
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82 Photon counts 300 250 200 150 10
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84 Fluorescence, a.u. I transfer ,
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86 ln(I transfer (t)) -4.2 -4.4 -4.
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88 Fluorescence, a.u. I transfer ,
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In: Developments in Ceramic Materia
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Synthesis, Spectroscopic and Magnet
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a c Synthesis, Spectroscopic and Ma
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Transmission Transmission Transmiss
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Sm (J/Kmol) Sm (J/Kmol) 15 10 5 Syn
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Intensity (a.u.) Intensity (a.u.) 8
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The Use of Ceramic Pots in Old Wors
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3.2. Wall-in Positions The Use of C
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IACC ( τ ) = t2 ∫ The Use of Cer
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Coloured ZrSiO4 Ceramic Pigments 26
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282 calcium, 11, 19, 20, 64, 92 Cal
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284 emission, xi, 73, 83, 87, 90, 9
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286 J Japan, 59, 60, 72, 93, 215, 2
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288 phonons, 80, 120 phosphates, 98
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290 single crystals, ix, 54, 56, 57
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292 XRD, 56, 62 yield, 82, 94, 176,
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