Pyroelectricity

Piezoelectric materials are also pyroelectric. They produce electric charge as they undergo a temperature change. When their temperature is increased, a voltage develops having the same orientation as the polarization voltage. When their temperature is decreased, a voltage develops having an orientation opposite to the polarization voltage, creating a depolarizing field with the potential to degrade the state of polarization of the part.

The maximum electric field which arises due to a temperature shift is:

where
E = induced electric field [volts m-1]
α = pyroelectric coefficient [C K-1 m2]
ΔT = temperature difference [K]
K3 = dielectric constant
ε0 = permittivity of free space [Fm-1]

For PZT piezoceramic, α is typically ~ 400x10-6 C K-1 m2.

Previous PageNext Page

Subjects: Physics