dielektrikkina

A dielectric material is an insulating substance that responds to electric fields by polarizing its internal charge distribution. In electrical devices, dielectrics separate conductive regions, allow energy storage, and provide insulation to reduce unwanted current flow. Dielectrics are essential in capacitors, where they increase energy storage and modify the device’s electric field.

The key property of a dielectric is its permittivity, often expressed as ε = ε0εr, where ε0 is the vacuum permittivity and εr is the relative dielectric constant. Higher εr materials store more energy at a given field. Dielectrics also have a dielectric strength, the maximum electric field they can withstand before breakdown, and a dielectric loss that describes energy dissipation as heat. Polarization mechanisms include electronic, ionic, orientational, and interfacial effects, each with different responses to frequency and temperature. As frequency rises, some polarization mechanisms cannot follow the field, altering εr and increasing losses.

Common dielectric materials range from air and vacuum to polymers (such as polyethylene and polyimide), ceramics (including barium titanate-based ceramics), glass, and mica. Polymers tend to offer mechanical flexibility and high breakdown strength, while ceramics often provide high permittivity and temperature stability. Dielectrics can be isotropic or anisotropic and may be linear or nonlinear.

Applications span capacitors, cable insulation, transformer windings, and semiconductor devices where thin dielectric films serve as gate insulators or interlayer dielectrics. Practical design balances permittivity, breakdown strength, loss, temperature dependence, and cost to meet device requirements.