Dielectric properties 0-3 polymer ceramic composites

Rao, Y., Ogitani, S., Kohl, P, and Wong, C.P., High dielectric constant polymer-ceramic composite for embedded capacitor application, in Proceedings of the International Symposium on Advanced Packing Materials Processes, Properties, and Interfaces, IEEE, Piscataway, NJ, 2000. 

Ferroelectric composites are alternatives to standard piezoelectric and pyroelectric ceramics such as lead zirconate titanate (PZT) and BaHOs (BT). They combine the strong ferroelectric and dielectric properties of ceramics with the easy processing and good mechanical properties of polymers. Dispersion of micrometer-sized ferroelectric particles in an electrically passive epoxy matrix was first published by Furukawa et al. [1976] and later extended to ferroelectric matrices such as poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-3-fluoroethylene) (PVDF-TrFE) [Hsiang et al., 2001 Hilczer et al., 2002 Gimenes et al., 2004 Lam et al., 2005 Beloti et al., 2006]. However, the necessity of miniaturization of electronic components and... 

The ways of preparing and general properties of the composites of various types will first be described. Then their dielectric and electrect properties will be discussed, since they determine the piezo- and pyroelectricity of polymer-ceramic composites. The last-mentioned properties will be described in the last part of this chapter. 

We present in this section the results of a few studies of dielectric properties of 0-3 polymer-ceramic composites and compare some of those with the mixing rules described in Section U. 

Fiber preparation via the polymer precursor route provides many desirable properties for use in continuous-fiber ceramic matrix composites intended for high-temperature uses in oxidative and nonoxidative environments [65]. These fibers, especially those having low electrical conductivity and good dielectric properties, are being investigated for use in radiation-transparent structures, such as radomes [66]. 

Dipole moment of each BNN particle is calctrlated using Claussis-Mossotti equations. Clausius-Mossotti approximation is one of the most commonly used equations for calculating the bulk dielectric properties of inhomogeneous materials (Ohad and David, 1997). It is useful when one of the components can be considered as a host in which, inclusions of the other components are embedded. It involves an exact calculation of the field induced in the tmiform host by a single spherical or ellipsoidal inclusion and an approximate treatment of its distortion by the electrostatic interaction between the different inclusiorts. The Clausius-Mossotti equation itself does not consider any interaction between filler and matrix. This approach has been extensively used for studying the properties of two-component mixtures in which both the host and the inclusions possess different dielectric properties. In recent years, this approximation has been extensively applied to composites involving ceramics and polymers. 

Piezoelectricity is a property whereby mechanical strain produces dielectric polarization and, conversely, an applied electric field produces mechanical strain. Piezoelectricity is exhibited by piezoelectric crystals, polarized polymers, and composites, and is utilized in a variety of electromechanical transducers. To induce piezoelectricity in certain ceramic crystals, one must apply a high dc field to switch the polar axis of the crystals to the symmetry allowed directions nearest to the applied field. This process is called poling. 

Polymer composites are multiphase materials containing, usually, inorganic fillers or reinforcing materials embedded in an anurphous or polycrystalline matrix. The dielectric properties of the inclusions arc, usually, very different from those of the nutrix. For ferroelectric appUcatioos, inorganic ferroelectric materials (e.g.. ceramics) are often used u fillers. 

Although self-reinforced UHMWPE was effectively abandoned for orthopedic bearings, interest has continued in other UHMWPE matrix composites, driven partly by new initiatives in nanocomposites materials science and polymer science. Indeed, UHMWPE matrix composites have been employed industrially for decades, and researchers have continued to explore the effect of historical standard fillers on the mechanical and dielectric properties of UHMWPE [36—40]. Solid lubricants, such as glass, graphite, ceramics (e.g., kaolin, AI2O3), and molybdenum... 

Marin-Franch, P., D. L. Tunnicliffe, and D. K. Das-Gupta, Dielectric properties and spatial distribution of polarization of ceramic+polymer composite sensors. Materials Research Innovations, 4, 334—339, 2001. 

Considerable interest also has been directed at the use of multicomponent composites where, in theory, the most useful properties from each phase can be realized in the whole. This includes metallodielectric structures where a metallic phase imparts, for example, a high index or more exotic effect (e.g., plasmon resonance) and a low-loss or property-tunable dielectric phase. The dielectric phase can be ceramic or polymeric and also has included ferroelectric polymers, embedded nanoparticles, and organic/inorganic hybrids. ... 

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. 

Li Z, Grimsditch M, Xu X, Chan SK (1993) The elastic, piezoelectric and dielectric constants of tetragonal PbTiOs single crystals. Ferroelectrics 141 313-325 MarraSP, Ramesh KT, Douglas AS (1999) The Mechanical properties of lead-titanate/polymer 0-3 composites. Compos Sci Technol 59 2163-2173 Materials Data Sheets of APC International, Tokin, Ferroperm, Morgan Matroc, Siemens Mattiat OE (1971) Ultrasonic transducer materials. Plenum Press, Tokyo McLachlan DS, Blaszkiewicz M, Newnham RE (1990) Electrical resistivity of composites. J Am Ceram Soc 73 2187-2203... 

Although the uses of ceramic fibres in composite structures lie mainly in ceramic-matrix and metal-matrix composites, where their outstanding chemical and thermal resistance are important, there are a few applications in organic polymers. Their relevant properties are low thermal expansion, low electrical conductivity, low dielectric constant, high stiffness, good compressive strength, and in most cases complete resistance to combustion. On the other hand they are very brittle, hard to process, and mostly considerably more expensive than carbon and para-aramid fibres. They have, for example, been used in hybrid structures with carbon and para-aramid and in electronic circuit boards. The fibres available or potentially available include alumina, combinations of alumina with... 

Piezoceramic/polymer composite materials are a means of overcoming the limitations of both ceramic and polymer materials to provide complementary properties that produce a superior piezoelectric device. The polymer phase lowers the density of the material, providing better acoustic coupling to water as well as more easily adjusted buoyancy than that obtained for a high-density homogeneous ceramic. The low dielectric constant of the polymer phase effectively increases the coefficients and... 

Although the ceramic phase of the composite makes the material electroactive, many of the important properties of the material are derived primarily from the properties of the polymer. Also, the choice of polymer can determine whether the best ceramic sensitivity can be realized. The electrical properties to be considered are the resistivity p, the relative permittivity (dielectric constant) the dielectric loss, the dissipation factor D, the power factor F and the dielectric strength. The variation of these properties with changes in the likely environment should also be considered, since many of them vary with temperature, frequency and humidity. 

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