PZT materials

By variation of ceramic volume fraction and selection of the best fitting PZT material we can as well adjust the dielectric constant of the piezocomposite within a wide range. Therefore, we can choose the best piezocomposite material for each probe type to get optimum pulse form and amplitude. 

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While designing or using STM at low or high temperatures, the variation of piezoelectric coefficients with temperature has to be considered seriously. The variation differs for different PZT materials. Fig. 9.5 shows measured variations of d-i for several commonly used PZT materials with temperature. 

A wide array of ferroelectric, piezoelectric and pyroelectric materials have titanium, zirconium and zinc metal cations as part of their elemental composition Many electrical materials based on titanium oxide (titanates) and zirconium oxide (zirconates) are known to have structures based on perovskite-type oxide lattices Barium titanate, BaTiOs and a diverse compositional range of PZT materials (lead zirconate titanates, Pb Zr Tij-yOs) and PLZT materials (lead lanthanum zirconate titanates, PbxLai-xZryTii-yOs) are among these perovskite-type electrical materials. 

Applications that have received attention, and the material properties that enable them, are shown in Figure 27.1. These applications are reviewed in detail in Waser and Ramesh. Decoupling capacitors and filters on semiconductor chips, packages, and polymer substrates (e.g., embedded passives ) utilize planar or low aspect ratio oxide films. These films, with thicknesses of 0.1 to 1 J,m, are readily prepared by CSD. Because capacitance density is a key consideration, high-permittivity materials are of interest. These needs may be met by morpho-tropic phase boundary PZT materials, BST, and BTZ (BaTi03-BaZr03) solid solutions. Phase shifters (for phase array antennas) and tunable resonator and filter applications are also enabled by these materials because their effective permittivity exhibits a dependence on the direct current (DC) bias voltage, an effect called tunability. 

No chemical interactions between the sample solution and PZT. Especially aggressive, acidic solutions can dissolve constituents out of the PZT material. The impurities can cause photoacoustic perturbation signals which create much interference in weakly absorbing solutions. The use of bare piezooeramic disks or piezoceramic tubes as a sample container represents an undesirable source of contamination. It is found that even surface-treated (gold-plated) piezo tubes are not resistant to many acids. 

Dependence of mean polarization (P3) on the applied electric field is shown in Fig. 4.39a for perovskite PZT material parameters, Dirac-delta distribution T(/ ) = 8 (/ — Ro), fixed temperature T < Tc, freezing radius Rf(T) and different nanoparticle radii Rq. Curves for Rq < Rf correspond to the Langevin-like law, while the curves 5-7 for Ro>Rf indicate the hysteresis loop appearance. Solid curves in Fig. 4.39b are Langevin-like law Pi(Eo)) for different nanoparticle... 

Electro-mechanical vibrations of PZT bodies can be solved in a similar manner to the corresponding mechanical vibration problem, but with additional variables. The constitutive laws of PZT materials are represented, as follow (Holland EerNisse 1969) and (Kawabata 1973),... 

Doping the PZT material with donor or acceptor ions changes its properties dramatically. Donor doping with ions such as Nb or Ta + provides soft PZTs, like PZT-5, because of the facility of domain motion due to the resulting Pb-vacancies. On the other hand, acceptor doping with Fe + or Sc + leads to hard PZTs, such as PZT-8, because the oxygen vacancies will pin domain wall motion. 

Fig. 4.1. Qualitative representation of hysteresis loops of PZT material (a) polarization P and (b) strain e as functions of the applied electric field strength E.

When the pyroelectric properties of FVDF film was first studied in 1969 (7-10), the apfdication pyroelectric devices using monocrystalline TGS. LiTaOj and polycrystal-line PbTiO,. and PZT materials applied to IR nidiatioo detectioo had already been established in various fields involvi space, engineering, and home use. PVDF film improved for p and tan h values could be utilized instead of these materials as the low-cost, single IR detector for home use. though performance has been inferior to other pyroelectric detectors because of the small p value. 

As an example of the effect of solid solution substitutions on crystal structure and properties, consider the PbZrOj-PbTiOj system (PZT materials). Several compositions within this system are important for piezoelectric transducers, and, with fairly large concentrations of La ions (PLZT materials), are of potential for imaging and storage devices. As mentioned earlier, PbZr03... 

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