Berlin 2015 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 17: Focused Session on GHz Dielectrics: Materials for Mobile Communication II (DF with HL/MM)

DF 17.2: Talk

Thursday, March 19, 2015, 15:30–15:50, EB 407

Titanate-based paraelectric glass-ceramics for applications in GHz electronics — •Hubertus Braun^1,2,3, Martin Letz², Martun Hovhannisyan², and Hans-Joachim Elmers¹ — ¹Johannes-Gutenberg Universität Mainz — ²SCHOTT AG, Mainz — ³Graduate School Materials Science in Mainz

In the current work, titanate-based glass-ceramics (TiO₂ > 45 mol %) in the La₂O₃-TiO₂-SiO₂-B₂O₃ system are developed (ε_r ≈ 20-30, Qf ≈ 10.000 GHz, |τ_f| < 10 ppm/K) which show promising properties as microwave materials and offer numerous advantages in comparison to conventional sintered ceramics. Glass-ceramics which are obtained via a true glassy phase are comparatively new in this field and will be presented as suitable alternative. Glass-ceramics are produced in a two step process: At first, a basic glass is casted in a conventional glass production process. Then the glass undergoes a temperature treatment with a defined temperature profile to initiate a controlled partial crystallization of desired paraelectric phases inside the glassy matrix. Obtaining materials via a homogeneous glassy phase enables intrinsically pore-free materials with comparatively superior surface properties. The effect of solid solution type doping on the dielectric properties and glass stability is investigated. The effect of solid solution type doping on the A(La) and B(Ti) site of the crystalline phases with ions of similar ionic radius is investigated concerning their influence on the dielectric properties and glass stability. Further the materials are analyzed concerning suitability for dielectric loaded antenna applications.