Abstract
Bi12GeO20 ceramics sintered at 800°C had dense microstructures, with an average grain size of 1.5 μm, a relative permittivity (εr) of 36.97, temperature coefficient of resonance frequency (τf) of −32.803 ppm/°C, and quality factor (Q × f) of 3137 GHz. The Bi12-xGeO20-1.5x ceramics were well sintered at both 800°C and 825°C, with average grain sizes exceeding 100 μm for x ≤ 1.0. However, the grain size decreased for x > 1.0 because of the Bi4Ge3O12 secondary phase that formed at the grain boundaries. Bi12-xGeO20-1.5x (x ≤ 1.0) ceramics showed increased Q × f values of >10 000 GHz, although the εr and τf values were similar to those of Bi12GeO20 ceramics. The increased Q × f value resulted from the increased grain size. In particular, the Bi11.6GeO19.4 ceramic sintered at 825°C for 3 h showed good microwave dielectric properties of εr = 37.81, τf = −33.839 ppm/°C, and Q × f = 14 455 GHz.
Original language | English |
---|---|
Pages (from-to) | 2361-2367 |
Number of pages | 7 |
Journal | Journal of the American Ceramic Society |
Volume | 99 |
Issue number | 7 |
DOIs | |
Publication status | Published - 2016 Jul 1 |
Keywords
- LTCC
- dielectric materials/properties
- grain growth
- grain size
- sinter/sintering
ASJC Scopus subject areas
- Ceramics and Composites
- Materials Chemistry