5.5.5 Common Pyroelectric Materials

Most of the inorganic pyroelectrics (including ferroelectrics) are perovskite structured. For a general discussion on pyroelectric materials, you can refer to the review article by Roger Whatmore.*

The most common materials are tabulated below.

       5.5.5.1 Triglycine Sulphate (TGS)

• High pyroelectric coefficient

• Fragile and water-soluble, difficult to handle and cannot be used in devices where it would be subjected to either a hard vacuum or high humidity as it tends to decompose

• Can be modified to withstand temperatures above Curie point without depoling

• Used in thermal imaging cameras

       5.5.5.2 Polyvinylidene Fluoride (PVDF)

• Poor pyroelectric coefficient
  

• Readily available in large areas of thin film
  

• More stable to heat, vacuum and moisture than TGS, mechanically robust
  

• Low heat conductivity and low permittivity
  

• High loss tangent

• Commonly used for burglar alarms

       5.5.5.3 Perovskite Ferroelectric Ceramics

• Generally robust and insensitive to moisture and vacuum
  

• High pyroelectric coefficient and low loss
  

• Better operation near T_C

• Strong dependence on composition
  

• As a very approximate guide, for large area applications, low dielectric constant materials such as PVDF are preferred while for small area applications, materials with large dielectric constant such as perovskite oxides are preferred.