When an electric field is applied to a material in a capacitor, the electric field causes polarization in the material through electronic, ionic, and molecular polarization. The three primary contributions to the dielectric constant are electronic, ionic, and molecular polarization. Electronic polarization responds the fastest, while ionic and molecular polarization respond slower. The four primary dielectric breakdown mechanisms are thermal, avalanche, discharge, and electrolytic. The breakdown strength can be improved through using high purity materials with low defect densities. Ferroelectrics exhibit spontaneous polarization without an applied electric field and have applications in non-volatile RAM, dynamic RAM, tunable microwave devices, pyroelectric detectors, piezoelectric sensors and actuators.