dielectrices

Dielectrices are insulating materials that can be polarized by an electric field. In physics and electrical engineering, dielectrices are used to separate conducting elements and to store electric energy in devices such as capacitors. The primary property of dielectrices is their ability to permit an electric field to exist within them while limiting current flow, which is quantified by their dielectric constant (relative permittivity, ε_r) and their dielectric strength.

The dielectric constant describes how much dielectrices increase the capacitance of a system compared with vacuum. Dielectrices also exhibit loss, quantified by the loss tangent (tan δ), which measures energy dissipated as heat. Across frequency and temperature, ε_r and tan δ can vary. Other important factors include dielectric strength (breakdown voltage), thermal stability, moisture resistance, and mechanical properties.

Dielectrices are classified by composition: ceramics (such as titanates and ferrites), polymers (films like PET, polyimide; specialized resins), glasses, liquids, and composites. They can be ferroelectric, paraelectric, or non-polar, influencing the temperature dependence of ε_r and loss.

In practical use, dielectrices determine capacitor performance, insulation in cables, electronics packaging, and high-voltage equipment. The selection depends on the required capacitance, voltage rating, temperature range, frequency, and environmental exposure. Processing methods, such as sintering for ceramics or casting and extrusion for polymers, affect density, porosity, and electrical behavior.

Standards and testing include measurements of ε_r at defined frequencies, tan δ, dielectric strength, and long-term reliability under humidity and temperature cycling.