Pyroelectric piezoelectric compensation

Newnham RE, Sundar V, Yimnirun R, Su J, Zhang QM (1997) Electrostriction nonlinear electromechanical coupling in solid dielectrics. J Phys Chem 101 10141-10150 Ploss B, Ploss B, Shin FG, Chan HLW, Choy CL (2000) Pyroelectric or piezoelectric compensated ferroelectric composites. Appl Phys Lett 76 2776-2778 Poddar S, Ducharme S (2013) Measurement of the flexoelectric response in ferroelectric and relaxor polymer thin films. Appl Phys Lett 103 202901... 

All pyroelectric materials are piezoelectric and therefore develop electric charges in response to external stresses that may interfere with the response to radiation. This can largely be compensated for by the provision of a duplicate of the detecting element that is protected from the radiation by reflecting electrodes or masking, but which is equally exposed to air and mounting vibrations. The principle is illustrated in Fig. 7.7. The duplicate is connected in series with the detector and with its polarity opposed so that the piezoelectric outputs cancel. This results in a small reduction in sensitivity (< 3 dB) but compensation is an... 

As mentioned above, LC elastomers, especially LSCE with monodomain order, anisotropic LC networks, and gels, may be optimized to make a kind of smart material for molecular switching and piezoelectric or pyroelectric sensors, because of their sensitivity to environmental conditions (electric or stress fields, temperature, and radiation, etc.) and memory effect. Other applications include wave-guide, polarizers, optical filters, alignment, and compensation films for LCD displays. 

Although piezoelectric properties such as relative permittivity and piezoelectric coefficients change with the temperature, the total effect for the calibration of PZT sensors far below the Curie temperature is very small. However, PVDF foils show a significant temperature dependence of the pyroelectric properties in addition to their temperature depending piezoelectric features. Thus PVDF sensors are quite temperature sensitive, and in general, an appropriate temperature compensation is necessary. This behaviour, however, can be improved by special forming and spatial distribution of the PVDF sensors [100]. 

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