https://doi.org/10.1351/goldbook.08795
Dielectric material with a permanent or quasi-permanent electric dipole.
Notes:
- A real-charge electret is obtained by the charge carrier injection onto the surface or into a parent dielectric material. It may contain either positive or negative excess charges or both, which must be trapped so that a good insulating parent dielectric material such as a fluoropolymer must be used.
- An oriented-dipole electret is obtained by poling a parent dielectric material with dipolar groups at a temperature above the glass transition temperature
- Electrets are electric equivalents of magnets; electric magnets. Some oriented-dipole electrets are ferroelectric polymers and piezoelectric polymers. Quartz is an example of the natural electret.