During the synthesis of Bi2Ge3O9 ceramics using Bi2O3 + 3GeO2 powders, the Bi4Ge3O12 phase was formed at low temperature (≤800 °C). Bi4Ge3O12 preferentially adopted GeO2-excess phase, and this phase was consistently present in the sintered Bi2Ge3O9 ceramic as a secondary phase. Therefore, Bi4Ge3O12 powder was first calcined and subsequently reacted with GeO2 powder to obtain the pure Bi2Ge3O9 ceramic through the following reaction: 1/2Bi4Ge3O12 + 3/2GeO2 → Bi2Ge3O9Formation of the Bi2Ge3O9 phase was initiated at temperature of 850 °C. The pure Bi2Ge3O9 ceramic sintered at 875 °C for 8 h had a dense microstructure with an average grain size of 2.7 μm. Furthermore, the pure Bi2Ge3O9 ceramic exhibited promising microwave dielectric properties for the advanced ceramic substrate: εr = 9.7, Q × f = 48,573 GHz and τf = −29.5 ppm/°C.
|Number of pages||6|
|Journal||Journal of the European Ceramic Society|
|Publication status||Published - 2017 Feb 1|
Bibliographical noteFunding Information:
We would like to acknowledge the financial support from the R&D Convergence Program of MSIP (Ministry of Science, ICT and Future Planning) and NST (National Research Council of Science & Technology) of Republic Korea (Grant CAP-13-02-ETRI).
- Advanced ceramic substrates
- BiGeO ceramics
- Microwave dielectric properties
ASJC Scopus subject areas
- Ceramics and Composites
- Materials Chemistry