Berlin 2012 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 17: Focus Session: Alternative energies – Compensation of long- and short-term fluctuations (jointly with DY)

DF 17.3: Topical Talk

Thursday, March 29, 2012, 16:00–16:30, EB 107

Glasses and glass ceramics as dielectrics for high power capacitors. — •Martin Letz — Schott AG, Mainz, Germany

Temperature stable, reliable and long lasting capacitors are a key component for high power electronics enabling large amount of fluctuating energy sources in the public electricity grid. Since many decades inorganic materials are known as excellent dielectrics. Among these thin foils made from alkaline free special glass are known for their very good homogeneity and excellent surface roughness. Such glass foils can reach dielectric breakdown strengths of 690 kV/mm (measured at 0.025 mm thickness) and more. Due to their excellent thermal stability they can be used for temperatures up to 500 °C as dielectrics in capacitors. A further class of materials are glass ceramics obtained via a true homogeneous glassy phase. Here it is possible to crystallize out ferroelectric phases like BaTiO3 in form of nano crystallites leading to high dielectric constants. Obtained from a true glassy phase such glass ceramics are free of pores and reach dielectric breakdown strengths of 40kV/mm (measured at 0.2 mm thickness). The current development for such glasses and glass ceramics is presented which shows the possibility for obtaining high power capacitors which exceed the energy storage capacity of todays high power capacitor solutions by more than one order of magnitude.