PZT fiber

High frequency applications in which the wavelength is comparable to the scale of the composite macrostructure, show the full potential of composite structures. Impedance, bandwidth, and radiation pattern can be controlled in such systems in a sophisticated manner impossible in single-phase systems. By prepoling PZT fibers or ribbons before the assembly of the composite, it is possible to construct polar solids of new type for use in complex transducer arrays operating in scanning and focusing modes. 

Figure 1. Cross sections of PZT fibers. Data are given in Table 1 and the text.

In 1999, Smart Material Corp. (Florida) in co-operation with smartfiber AG, Germany, established the production of PZT fibers by the ALCERU process ". They are made from Type... 

Table 1 Commercial PZT fibers and tubes offered by Smart Material...

A third process, the polysulfon spinning technology, has recently been developed by Fraunhofer IKTS and TU Dresden for PZT fiber fabrication with the benefit of room temperature processing and the use of environmental harmless solvent NMP (N-methylpyrrolidon) in small quantities. The process chart of the polysulphone process is sketched in Fig. 2. 

Strode, H.B.,PascuccL Mil.,Parish, M.V.,Bent, A.A., Shrout, T.R., 1999. Active PZT fibers a commercial production process. In Paper Presented to Proceedings of the SPIE, vol. 3675. Smart Structures and Materials 1999 Smart Materials Technologies, July 12, 1999. 

The reaction of lead acetate with TIP and ZIP in the Pb/(Zr+Ti) molar ratio of 1/1 produces acetato-alkoxo Pb-(Zr, Ti) complex as well, which can be used as a starting material for PZT fibers (Boulton et al., 19 Kamiya, 1993). The crystallization behavior of PbZr Tii (x = 0.3 and 0.52) gel fibers that have been made from the corresponding Pb-(Zr, Ti) complexes by hydrolyzing with a small amount of water without any organic additives is shown in Figure iS-/(Kamiya, 1993). It is seen that the formation of pyrochlore phase is suppressed and tetragonal PZT phase is resulted at 600 and 900°C for jc= 0.3 and 0.52, respectively. In the DSC traces of the 900°C-treated fibers (Fig. 18-8), endothermic... 

Figure 18-9. Polarization/electric field hysteresis of a 30 fstn lanthanum-doped PZT fiber and bulk sample (Meyer etal., 1998).

Boulton J.M., Teowee G., Uhlmann D.R. Sol-gel derived PZT fibers. Mater. Res. Soc. Synp. Proc. 

Sakka S., Kamiya K. The sol-gel transition in the hydrolysis of metal alkoxides in relation to the formation of glass fibers and films. J. Non-Ciyst. Solids 1982 48 31 16 Sakka S., Kamiya K., Makita K., Yamamoto Y. Formation of sheets and coating films from alkoxide solutions. J. Non-Cryst. Solids 1984 63 223-235 Sakka S., Yoko T., Fibers from gels. J. Non-Cryst. Solids 1992 147/148 394-403 Scholtz H., Sporn A., Ullrich A., Schoenecker A., Martin W. Fabrication and properties of sol-gel-derived PZT-fibers for 1-3 composites. Ceram. Trans. 1995 51 751-755 Sekine M., Katayama S., Mitomo M. Preparation of silicon oxynitride glass fibers by ammonolysis of silica gels. J. Non-Cryst. Solids 1991 134 199-207 Sowman H.G. Alumina-boria-silica ceramic fibers from the sol-gel process. In Sol-Gel Technology for Thin Films, Fibers, Preforms, Electronics, and Specialty Shapes, L.C. Klein, ed. Noyes Publication, 1988... 

H.B. Strock, M.R. Pascucci, M.V. Parish, A.A. Bent, T.R. Shrout, Active PZT fibers A commercial production process, in Smart Structures and Materials 1999 Smart Materials Technologies, ed. by M.R. Wuttig. Proceedings of SPIE (SPIE, Bellingham, 1999), pp. 22 31... 

The piezoelectric material itself may be a composite. For example, combinations of piezoelectric polymers and piezoelectric ceramics have been made. Spom and Schoenecker discuss ceramic fibers in a polymer matrix. First, PZT fibers with diameters <30 mm oriented uniaxially in a planar fiber architecture along with interdigital electrodes. Then the fiber/electrode architectures are embedded within glass fiber-reinforced polymers and the fibers are poled and become piezoelectric. 

Fig. 5.3 Experimental setup. Light from a frequency scanned cw diode laser is launched into a bitapered fiber to excite WGMs of the microresonator. The microresonator is held in a PZT fixture for tuning and locking purposes inset). Reprinted from Ref. 4 with permission. 2008 Optical Society of America...

Several oxide fibers on the basis of Zr02, Pb(Zr,Ti)03 (PZT), Y3AI5O12 (YAG) and YBa2Cu30x, which exhibit e.g. catalytic, magnetic, dielectric or superconducting properties, are currently under development or in evaluation for special applications. 

Composite piezoelectric transducers made from poled Pb-Ti-Zr (PZT) ceramics and epoxy polymers form an interesting family of materials which highlight the advantages of composite structures in improving coupled properties in soilds for transduction applications A number of different connection patterns have been fabricated with the piezoelectric ceramic in the form of spheres, fibers, layered, or three-dimensional skeletons Adding a polymer phase lowers the density, the dielectric constant, and the mechanical stiffness of the composite, thereby altering electric field and concentrating mechanical stresses on the piezoelectric ceramic phase. 

An optical fiber sensor is a new and an attractive AE sensor as alternative to the PZT sensor. It can ofier a number of advantages such as the longterm monitoring, the condition free from electro-magnetic noises, and the use of corrosive and elevated environments. One example applied to a pipe structure is illustrated in Fig. 3.14 (Cho, Arai et al. 2004). According to their results, the sensitivity depends on the number of fiber winding, and is still 10 times lower than a conventional PZT sensor. 

FIGURE 16 Additive pulse mode-locked laser. The output of the color center laser is coupled to an optical fiber. Self-phase modulation in the fiber adds bandwidth to the pulse, which is coupled back to the laser. The combination produces femtosecond-duration pulses. (OC, output coupler BS, beam splitter BTP, birefringent tuner plate HR, high reflector PZT, piezotransducer). 

In order to measure vibrations or acoustic wave propagation, an interferometer sensor can be embedded or surface-attached, and then interrogated by using a vibration or AE detection system. When fiber optic sensors are used for measurement of AEs, disadvantages of traditionally used PZT transducers for AE sensing such as their large size and their susceptibility to elec-... 

The 13 composites are the most examined and applied ones. They consist of individual PZT rods or fibers embedded in a poljuner matrix and oriented parallel to the poling direction. Fiber diameter and spacing, composite thickness, volumetric PZT content, aspect ratio (radius/length) of the fibers and the stiffness of the pol3uner matrix have an influence on the composite performance. The force transfer between the rods or fibers and the pol3rmeric matrix is due to shear-coupling at the poljuner-fiber interface or due to compressive coupling at the front end of the fiber bimdle. 

Active fiber composites (AFC), macro fiber composites (MFC) [88,97] and piezo fiber composites (PFC) [87,98] are advanced variants of 1-3 composites that are particularly designed for adaptronic applications. Those variants are based on a basic design developed at the Massachusetts Institute of Technology (MIT) [89,93-96]. For that purpose uniaxial arranged piezoceramic fibers from PZT are embedded in a polymer matrix and contacted via interdigital electrodes at the surface. Such composites have a high flexibility and robustness and can therefore be easily applied to components or structures... 

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