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SCHOTT solutions no. 1/2012 > Material Development

SCHOTT researchers use an X-ray diffractometer to analyze the crystal structure of the material during the manufacturing process. Photo: SCHOTT/C. Costard

Fit for High-End Applications

Glass-ceramics can be used as components in high-power gigahertz antennas and high-frequency filters. The research department at SCHOTT has developed initial prototypes together with a manufacturer.

Thilo Horvatitsch

Studying existing materials can reveal potential one could never have imagined. Glass-ceramic, for instance, grew to be popular mainly as a temperature resistant material for use in the kitchen (CERAN® cooktop panels) and astronomy (ZERODUR® telescope mirrors). SCHOTT researchers have now found out that the principle of allowing crystalline phases with defined properties in a glass melt to crystallize can be used in a completely different application that holds great promise for the future: mobile communications. Glass-ceramics are well-suited for use here as components in extremely high-power antennas, transmitter masts or GPS applications, for instance.

The young researcher and doctoral candidate Hubertus Braun was responsible for the fundamental development work in cooperation with the Johannes Gutenberg University in Mainz as part of receiving his diploma. While doing his research work at SCHOTT, the 26-year-old physicist managed to manufacture an initial antenna material. And was thus successful in a number of ways: the first glass-ceramic antenna prototypes have already been manufactured in cooperation with the British firm Sarantel. In addition, Hubertus Braun’s work earned him a natural and engineering sciences award worth 5,000 euros from the Vodafone Foundation.

This development was by no means a product of chance. On the one hand, the immense future potential glass-ceramics offer has been a topic for research at SCHOTT for some time (see also Material with Future Potential). On the other hand, demand for materials for antennas in the gigahertz range and the respective high-frequency filters has continued to grow in recent years, particularly in satellite navigation, mobile communications and microwave electronics. So-called dielectric (ceramic) materials are vital components of these high-end applications. They allow for miniaturization of the antennas and improved efficiency and are less susceptible to interference during operation than conventional components made of metal.
When used as an antenna material, glass-ceramic allows for miniaturization of the components and improved efficiency during operation. Photo: SCHOTT/C. Costard

“The goal of my work was to produce these dielectric ceramic materials as glass-ceramics and show what potential they offer for mobile communications applications,” researcher Braun explains. The concrete result is an antenna material that offers important advantages over the ceramic materials used in the past that were manufactured using powder and sintering processes. This glass-ceramic is also known for its extremely low loss of electromagnetic radiation. Furthermore, it is extremely homogeneous and nonporous. For this reason, metal coatings that are applied later on adhere much better than they do to a porous sintered ceramic and are unable to penetrate into the material and possibly impair performance. Glass-ceramics also offer advantages in that they can be mass-produced.
SCHOTT has already started performing industrial research based on the results of this work that a patent has already been filed for. “Our initial results proved to be better than we expected. Now, it is up to us to assess the application-specific marketability and further refinement of this material,” Hubertus Braun concludes. <|