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The total pyroelectric coefficient measured at constant stress is the sum of the pyroelectric coefficients at constant strain (primary pyroelectric effect) and the piezoelectric contribution from thermal expansion (secondary pyroelectric effect). Under normal circumstances, even polar materials do not display a net dipole moment.
The following table lists the following properties for piezoelectric materials The piezoelectric coefficients (d 33, d 31, d 15 etc.) measure the strain induced by an applied voltage (expressed as meters per volt). High d ij coefficients indicate larger
Toggle the table of contents. Piezoelectric coefficient. 1 language. ... The piezoelectric coefficient or piezoelectric modulus, usually written d 33, ...
Due to the unipolar axis characteristics of the pyroelectric crystal, it is characterized by asymmetry. Polarization due to changes in temperature, the so-called pyroelectric effect, is currently widely used in sensor technology. Pyroelectric crystals need to be very thin to prepare and are plated in a direction perpendicular to the polar axis.
The following table lists the Van der Waals constants (from the Van der Waals equation) for a number of common gases and volatile liquids. [ 1 ] To convert from L 2 b a r / m o l 2 {\displaystyle \mathrm {L^{2}bar/mol^{2}} } to L 2 k P a / m o l 2 {\displaystyle \mathrm {L^{2}kPa/mol^{2}} } , multiply by 100.
A ferroelectret, also known as a piezoelectret, is a thin film of polymer foams, exhibiting piezoelectric and pyroelectric properties after electric charging. Ferroelectret foams usually consist of a cellular polymer structure filled with air.
The 10 polar (pyroelectric) crystal classes: 1, 2, m, mm2, 4, 4mm, 3, 3m, 6, 6mm. The other 10 piezoelectric crystal classes: 222, 4 , 422, 4 2m, 32, 6 , 622, 6 2m, 23, 4 3m. For polar crystals, for which P ≠ 0 holds without applying a mechanical load, the piezoelectric effect manifests itself by changing the magnitude or the direction of P ...
Being pyroelectric, this material develops a voltage difference across two of its faces under changing temperature conditions; consequently, lead zirconate titanate can be used as a heat sensor. [5] Lead zirconate titanate is also ferroelectric , which means that it has a spontaneous electric polarization ( electric dipole ) that can be ...