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Not all piezoelectric materials can be poled. [18] Of decisive importance for the piezoelectric effect is the change of polarization P when applying a mechanical stress. This might either be caused by a reconfiguration of the dipole-inducing surrounding or by re-orientation of molecular dipole moments under the influence of the external stress.
In order to obtain a piezoelectric response, the material must first be poled in a large electric field. Poling of the material typically requires an external field of above 30 megavolts per metre (MV/m). Thick films (typically >100 μm) must be heated during the poling process in order to achieve a large piezoelectric response. Thick films are ...
Material & heterostructure used for the characterization (electrodes/material, electrode/substrate) Orientation Piezoelectric coefficients, d (pC/N) Relative permittivity, ε r Electromechanical coupling factor, k Quality factor Berlincourt et al. 1958 [30] BaTiO 3: d 15 = 270 ε 11 = 1440 k 15 = 0.57 d 31 = -79 ε 33 = 1680 k 31 = 0.49 d 33 ...
The piezoelectric coefficient or piezoelectric modulus, usually written d 33, quantifies the volume change when a piezoelectric material is subject to an electric field, or the polarization on the application of stress.
Ferroelectric materials are required by symmetry considerations to be also piezoelectric and pyroelectric. The combined properties of memory, piezoelectricity , and pyroelectricity make ferroelectric capacitors very useful, e.g. for sensor applications.
Lithium niobate (Li Nb O 3) is a synthetic salt consisting of niobium, lithium, and oxygen.Its single crystals are an important material for optical waveguides, mobile phones, piezoelectric sensors, optical modulators and various other linear and non-linear optical applications. [6]
The piezoelectric effect is exhibited by crystals (such as quartz or ceramic) for which an electric voltage across the material appears when pressure is applied. Similar to pyroelectric effect, the phenomenon is due to the asymmetric structure of the crystals that allows ions to move more easily along one axis than the others.
An exceptionally high-torque 'hybrid transducer' ultrasonic motor uses circumferentially-poled and axially-poled piezoelectric elements together to combine axial and torsional vibration along the contact interface, representing a driving technique that lies somewhere between the standing and traveling-wave driving methods.