Piezoelectric property determination

11 Pyroelectric Ceramics and Thin Films Characterization, Properties and Selection 

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Mason (1355) determined the elastic, dielectric, and piezoelectric constants of potassium and ammonium dihydrogen phosphate. He concluded that there are two distinct sets of H bonds in the ammonium salt—one set (N—H to O of PO4) is influential in thermal and specific heat anomalies, and the other set (part of the H2PO4 groups) affects the dielectric and piezoelectric properties. As mentioned earlier, a H... 

PHAs have rapidly gained interest both in research and industry due to their structural versatility and characteristics such as biodegradability, insolubility in water, nontoxicity, biocompatibility, piezoelectric property, thermoplasticity and or elastomeric properties, which make them favourable to be used in the packaging industry, medicine, pharmacy, agriculture, food industry and in the paint industry. The chemical and physical properties of the polymer are dependent on the monomeric composition which is determined by the producing microorganism and their nutrition. So far scl-PHAs are being studied extensively due to their easier... 

Besides the standard weighing methods, it has also been proposed to use the piezoelectric properties of quartz for mass determination. Change in the weight of a sample that has been deposited direcdy on the quartz surface, causes a change in the oscillation frequency of the quartz crystal. Mass changes as small as 10" g can be determined by this method. The changes in frequency with temperature must be established by calibration, or the experimentation must be done isothermally. 

Some ceramic and polymer materials also display piezoelectric properties. For ceramics these include polycrystal hne materials based on solid solutions of Pb(Zr, Ti)03. The ratio of zirconium and titanium constituents help to determine the crystal symmetry structure that results after heating and then cooling of the samples. Modern piezoelectric ceramics are referred to as PZT ceramics. Other materials such as barium, strontium, caldmn, and/or trivalent rare earth elements can be added to the ceramics in small quantities to modify the piezoelectric properties. 

Analysts typically determine the piezoelectric properties of materials by studying the resonance characteristics of an appropriately shaped specimen subjected to a varied electric field. Details of the experimental setup are gjven in References 18 and 19- Investigations into the utility of PZT thin films for micromotors and other devices are also in progress. Fundamental properties of these films, such as piezoelectric coupling coefficients, have been measured by laser interferometry. ... 

The flat surfaces of the samples were potished, cleaned and coated with silver electrode to get a better Ohmic contact for electric properties measurement. There are total five different electrode size used for electrode size study, as tist in Table-1. After electrode coating, the samples were poled under 3.0 kV/mm electric field at elevated temperature lOO C for Ih in the silicone oil bath. After polarization, the piezoelectric properties were surveyed with an HP4194A Impedance/ Gain-Phase Analyzer and Berlincourt ds3 meter based on the IEEE standards [IEEE, 1987]. Resonant spectrum of the samples was determined in the frequency range from 100 kHz to 1500 kHz, and the results were recorded by a PC base data acquisition system. 

Due to the complicated nature of the piezoelectric properties of polymeric materials, it is extremely difficult to exactly determine which theoretical model is closest to presenting the real mechanisms. However, the theoretical models proposed by researchers are useful in providing insight into the physical basis of the observed piezoelectricity. 

The piezoelectric properties of semicrystalline polymers, such as PVDF and its copolymers, are determined by the remnant polarization in the materials and the... 

Determine the pressure in a pipe of diameter d = 1cm, and with thicknesses q = f2 = 25 pm. Assume the same voltage change and the same piezoelectric properties as in the previous example. Thus, Oi = 3.1 MPa. Assume copper electrodes... 

In the ceramics field many of the new advanced ceramic oxides have a specially prepared mixture of cations which determines the crystal structure, through the relative sizes of the cations and oxygen ions, and the physical properties through the choice of cations and tlreh oxidation states. These include, for example, solid electrolytes and electrodes for sensors and fuel cells, fenites and garnets for magnetic systems, zirconates and titanates for piezoelectric materials, as well as ceramic superconductors and a number of other substances... 

In this book those ferroelectric solids that respond to shock compression in a purely piezoelectric mode such as lithium niobate and PVDF are considered piezoelectrics. As was the case for piezoelectrics, the pioneering work in this area was carried out by Neilson [57A01]. Unlike piezoelectrics, our knowledge of the response of ferroelectric solids to shock compression is in sharp contrast to that of piezoelectric solids. The electrical properties of several piezoelectric crystals are known in quantitative detail within the elastic range and semiquantitatively in the high stress range. The electrical responses of ferroelectrics are poorly characterized under shock compression and it is difficult to determine properties as such. It is not certain that the relative contributions of dominant physical phenomena have been correctly identified, and detailed, quantitative materials descriptions are not available. 

Non-labelled immunosensors rely on various principles (Fig. 3.27.A). Either the antibody or the antigen is immobilized on the solid matrix to form a sensing device. The solid matrix should be sensitive enough at the surface to detect immunocomplex formation. Electrode, membrane, piezoelectric and optically active surfaces may in principle be used to construct non-labelled immunosensors. The antigen or antibody to be determined is dissolved in a solution and reacted with the complementary matrix-bound antibody or antigen to form an immunocomplex that alters the physical e.g. the electrode potential or intrinsic piezofrequency) or optical properties of the... 

The high-frequency dielectric constant is determined by the effects of electronic polarization. An accurate estimate of this property lends confidence to the modeling of the electronic polarization contribution in the piezoelectric and pyroelectric responses. The constant strain dielectric constants (k, dimensionless) are computed from the normal modes of the crystal (see Table 11.1). Comparison of the zero- and high-frequency dielectric constants indicates that electronic polarization accounts for 94% of the total dielectric response. Our calculated value for k (experimental value of 1.85 estimated from the index of refraction of the P-phase of PVDF. ... 

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