The Physics
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Dielectric Strength of Fused Quartz

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Bibliographic Entry Result
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Serway, Raymond A. & Jerry S. Faughn. College Physics. 6th ed. Canada: Thomson Learning, 2003: 519.
Material Dielectric Constant, k Dielectric Strength (V/m)
Fused Quartz 3.78 8 × 106
8 MV/m
Ruzyllo, Jerzy. silicon dioxide, SiO2. Semiconductor Glossary. Semiconductor Onesource. 2008. "Key parameters: energy gap Eg ~ 8eV, dielectric strength 5-15 × 106 V/cm depending on thickness" 500–1500 MV/m
Dalal, Nikesh and Jamie Rasmussen. Dielectric Strength of Various Material. The Electronics Workshop. 1997.
Material Dielectric Strength (V/m)
Quartz 8 × 106
8 MV/m
Judge, Arthur W. Aircraft and Automobile Materials of Construction, Volume II, Nonferrous and Organic Materials. London: Pitman, 1921: 477. "Silica has a dielectric constant of 3.5 to 3.6, and a dielectric strength of 600 volts per mil." 24 MV/m
Quartz - Fused (SiO2) - Material Information. Goodfellow Corporation. 2008.
Electrical Properties
Dielectric constant 3.8
Dielectric strength (kV mm-1) 25-40
Volume resistivity @25C (Ohm cm) 1018
25–40 MV/m

All insulating materials have a limit to how much electric field that they can withstand. The point at which the insulating properties of insulators (also called dielectrics) break down is known as the dielectric strength. This strength depends mostly on the atomic configuration of the material. When electrons attempt to flow through dielectrics, they become trapped or bound in between the atoms, suppressing the effects of the electric field. However, when the electric field exceeds the material's dielectric strength, the electrons have enough energy to pass between atoms and flow freely, greatly reducing or completely negating the insulating properties of the material.

The theoretical dielectric strength of a material typically varies from its practical dielectric strength because most materials with which we interact on a daily basis contain small defects, ranging from structural defects to impurities. Theoretical dielectric strengths are calculated with the assumption that the material in question is flawless.

The dielectric strength of fused quartz (silicon dioxide or SiO2) ranges from 8 MV/m to 1500 MV/m (1 MV = 1,000,000 V).

Jeffrey Wong -- 2008