Engineers designing millimeter-wave communication modules constantly battle signal loss, and a new study reports that controlling crystal phases inside a silica-based ceramic can push that loss to remarkably low levels. Researchers systematically investigated SiO₂-based glass/ceramic filler composites intended for low-temperature co-fired ceramics (LTCCs), materials valued for their dielectric performance and compatibility with low-temperature sintering processes used in mmWave modules.
The team varied sintering temperature and tracked how the crystalline phases evolved. As temperature increased, the structures changed from quartz to a mixed quartz–cristobalite phase and finally to cristobalite. The mixed-phase sample sintered at 900 °C proved the standout, showing the most stable dielectric-loss characteristics among the conditions studied.
That 900 °C sample achieved a dielectric constant of 4.5, an ultralow dielectric loss of 0.0006, and a high Q × f value of 20,400 GHz, which the authors report outperforms previously published glass-based LTCC materials. The researchers attribute these properties to suppression of ionic percolation during the crystallization of the mixed quartz and cristobalite phases, a mechanism they say clarifies how glass-phase transitions influence dielectric-loss behavior.
To demonstrate practical relevance, the team fabricated a multilayer-integrated mmWave RF filter chip operating near 28 GHz using the developed LTCC material. The device exhibited stable band-pass filtering characteristics near 28 GHz, with a low insertion loss of 0.9 dB and a figure of merit of 325.7, which the authors state outperforms previously reported LTCC-based RF filter materials.
The work, published as an open-access article in Advanced Composites and Hybrid Materials, addresses a gap the authors identify: despite the strong influence of glass-phase transformations on dielectric loss, systematic studies of the underlying mechanisms have remained limited. Their findings, they write, offer insight into designing low-permittivity LTCC systems through glass phase-engineered dielectric control. The article is being shared early as a peer-reviewed, accepted manuscript that is citable and carries a permanent DOI, subject to further edits before the final version of record.
Subject of Research: Phase engineering of SiO₂-based glass/ceramic low-temperature co-fired ceramics to suppress ionic percolation and reduce dielectric loss for millimeter-wave RF filters
Article Title: Suppressing ionic percolation in ultralow-loss SiO₂/glass composite low-temperature co-fired ceramics through quartz/cristobalite phase engineering for mmwave radio frequency filter applications
Article References: Choi, Y. G., Kim, H. T., Park, S. J., Lee, J., Kwon, N. Y., Kim, D.-Y., Lee, J.-Y., Park, S. J., Yeo, D. H., Heo, Y. W., Shin, H. S., & Chee, S.-S. (2026). Suppressing ionic percolation in ultralow-loss SiO₂/glass composite low-temperature co-fired ceramics through quartz/cristobalite phase engineering for mmwave radio frequency filter applications. Advanced Composites and Hybrid Materials. https://doi.org/10.1007/s42114-026-02141-7
Image Credits: AI Generated
DOI: 10.1007/s42114-026-02141-7
Keywords: LTCC, dielectric loss, quartz, cristobalite, ionic percolation, millimeter-wave, RF filter, SiO2 glass composite, sintering, Q × f value, 28 GHz, phase engineering
News Source: Denise Maddox. (October 29, 2026). Quartz–cristobalite phase mix delivers ultralow-loss LTCC for 28 GHz filters. Scienmag.
