Remote, noncontact, temperature sensing is possible by focusing radiation from the source onto a pyroelectric material and by using the charge that appears on its surface as a measure of temperature. A sensor is required to measure temperature in the range 100–200°C. To work in this range the material must have a ferroelectric Curie temperature greater than 200°C, because otherwise it ceases to be pyroelectric in the sensing range. The signal is maximized by selecting a material with the largest possible pyroelectric coefficient. Use the data for pyroelectrics in Appendix A, Section A8, to make a selection.

Data From Appendix A8

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Table A.8 Piezoelectric, Pyroelectric and Ferroelectric Materials Ferroelectric Materials Dielectric Constant (-) Breakdown Potential (MV/m) Barium titanate 3400 4.2 PLZT 2500 12 PZT, hard 1300 11 PZT, soft 2700 11