Microwave Dielectric Properties of Alumina-based Ceramics, Containing TiO₂ and Titanate

Abstract

Doping effect of TiO₂, CaTiO₃ and SnO₂-TiO₂ on the characteristics of the Aluminabased ceramics have been investigated for the application of microwave dielectric device. Conventional alumina ceramics widely used for microelectronic device had fairly large temperature coefficient of resonance frequency(τ). Doping of TiO₂, CaTiO₃ and SnO₂-TiO₂ was found to decrease τ, and 85mol%Al₂O₃-4.5mol%SnO₂-10.5mol%TiO₂ ceramics showed the lowest tanδ of 2×10^-5 and τ of 21ppm°C^-1 at 7GHz. It can be concluded that the low tan δ is closely related to the uniform decomposition of Al₂TiO₅ in the ceramics by slow cooling during firing process.