Dielectric Strength (aka Dielectric Breakdown, [=] V/m)
The electrical potential per unit dielectric thickness at which the dielectric undergoes electrical breakdown.
The material's dielectric permittivity, expressed as a ratio relative to the permittivity of vacuum; expresses the force between two point charges in a material.
Dielectric Loss ([=] unitless)
A measure of a material's tendency to dissipate electromagnetic energy as heat. The loss angle describes the angle between the capacitor's impedance vector and the negative reactance axis; the loss tangent (aka the dissipation factor, the reciprocal of the quality factor) is the tangent of the loss angle, and is the ratio of the resistive power loss to the reactive power oscillating in the capacitor.
"Dielectric loss tends to be higher in materials with higher dielectric constants. This is the downside of using these materials in practical applications."
Teflon (PTFE) dielectric constant 2.0 - 2.1 dielectric strength 1000 loss tangent 0.00028 @ 3 GHz
Fused Silica dielectric constant 3.8 dielectric strength loss tangent
dielectric constant dielectric strength loss tangent