Ultralow loss CaMgGeO4 microwave dielectric ceramic and its chemical compatibility with silver electrodes for low-temperature cofired ceramic applications

Xiang, H; Li, C; Jantunen, H; Fang, L; Hill, AE

Abstract

ABSTRACT: A new ultralow dielectric loss cofired CaMg-
GeO4 dielectric material with olivine structure was fabricated
by the solid-state route. The X-ray patterns, Rietveld
refinement, and microstructure revealed the characteristics of
the synthesized material. CaMgGeO4 ceramic belongs to the
orthorhombic system with a Pbmn space group. Sintered at
1300°C for 6h, the ceramic exhibited a densification of 96.5%,
an ultrahigh quality factor (Q × f) of 124 900 GHz (tan δ =
1.24 × 10−4) at a frequency of 15.5 GHz, a permittivity (εr) of
6.71, and a temperature coefficient of resonant frequency (τf)
of −73.7 ppm/°C, and the average coefficient of thermal
expansion of CaMgGeO4 was 12.4 ppm/°C. The sintering
temperature of the CaMgGeO4 ceramic was reduced from
1300 to 940 °C with the addition of 5 wt % B2O3. The CaMgGeO4 + 5 wt % B2O3 ceramics exhibited favorable microwave
dielectric performances: Q × f = 102,000 GHz (at 16.4 GHz), εr = 5.80, and τf = −64.7 ppm/°C, respectively. In addition, the
CaMgGeO4 ceramic did not react with Ag electrodes, which could be advantageous in low-temperature cofired ceramic
multilayer microwave devices.
KEYWORDS: Microwave dielectric properties, CaMgGeO4, LTCC, ultralow dielectric loss

Citation

Xiang, H., Li, C., Jantunen, H., Fang, L., & Hill, A. (2018). Ultralow loss CaMgGeO4 microwave dielectric ceramic and its chemical compatibility with silver electrodes for low-temperature cofired ceramic applications. ACS sustainable chemistry & engineering, 6(5), 6458-6466. https://doi.org/10.1021/acssuschemeng.8b00220

• Journal Article Type: Article
• Acceptance Date: Mar 21, 2018
• Online Publication Date: Mar 26, 2018
• Publication Date: Mar 26, 2018
• Deposit Date: Apr 9, 2018
• Journal: ACS Sustainable Chemistry & Engineering
• Publisher: American Chemical Society
• Volume: 6
• Issue: 5
• Pages: 6458-6466
• DOI: https://doi.org/10.1021/acssuschemeng.8b00220
• Publisher URL: http://dx.doi.org/10.1021/acssuschemeng.8b00220
• Related Public URLs: https://pubs.acs.org/journal/ascecg