Dielectric for high-voltage capacitors



Schott has developed a family of homogenous pore-free glass-ceramics for high energy density capacitors.

“Current capacitor technologies for high power applications are mostly based on polypropylene [PP] or N4700 ceramic. Both are limited to temperatures below 90°C due to loss of capacitance with N4700, or PP’s loss of reliability with rising temperatures,” said the firm.

Branded Poweramic, the materials are titanate-based, in an amorphous glassy phase, which improves the dielectric properties at higher field strength and expands the temperature range compared to ceramic capacitors, said Schott principal scientist Dr Martin Letz.

They are produced in a two-step process: Transparent glass with a totally amorphous structure is melted and hot-formed as a solid, amorphous glass. Then a time-temperature profile is applied to grow nano-sized crystals within the glass.

Poweramic is supplied as a qualified semi-finished product for the production of capacitors, upon request also in metallised form.

Applications are expected in many current capacitor forms, for example: door knob, hockey puck, single layer and surface mount, as well as custom designs.

Product Characteristics

(near to paraelectric)


Dielectric constant ε



Dielectric loss, tanδ



Max. operating temperature

+300 / °C

+200 / °C

Temperature coefficient

<15ppm/K Adjustable to exactly ’0′ on demand in a given temperature range

+2200 ppm/K


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