Microstructures and Microwave Dielectric Properties on Annealed Al₂O₃-TiO₂ Composite Ceramics

Abstract:

The large negative temperature coefficient of resonant frequency ( τ f ) of Al2O3 is a problem for applicable microwave/millimeter wave dielectrics. A Previous study reported that the τ f was improved by sintering with TiO2 and then annealing, where the annealing decompose the secondary phase of Al2TiO5. This study investigated the hold time of annealing. The Quality factor (Qf ) value decreased when the sample was annealed at 1100°C for 2hrs. While Al2TiO5 was not detected by X-ray powder diffraction, it was located around TiO2 by scanning transmission electron microscopy equipped with energy dispersive X-ray spectroscopy. It should be considered that the degradation of the Qf was caused by the existence of noncrystalline Al2TiO5 and new boundaries between noncrystalline Al2TiO5 and TiO2.

• Periodical: Key Engineering Materials (Volume 388)
• Pages: 251-254
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.388.251
• Online since: September 2008
• Authors: Yasuharu Miyauchi, Isao Kagomiya, Yukihiro Shimizu, Hitoshi Ohsato
• Keywords: Al₂O₃, Insulator, Microwave Dielectric Properties, Titania (TiO₂)

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