University of Oulu

Ohsato, H., Varghese, J., Kan, A., Kim, J. S., Kagomiya, I., Ogawa, H., Sebastian, M. T., & Jantunen, H. (2021). Volume crystallization and microwave dielectric properties of indialite/cordierite glass by TiO2 addition. Ceramics International, 47(2), 2735–2742.

Volume crystallization and microwave dielectric properties of indialite/cordierite glass by TiO2 addition

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Author: Ohsato, Hitoshi1,2; Varghese, Jobin1,3; Kan, Akinori4;
Organizations: 1Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, 90014, Oulu, Finland
2Department of Research, Nagoya Industrial Science Research Institute, Nagoya, 464-0819, Japan
3Microsystems, LTCC and HTCC, Fraunhofer IKTS, Winterbergstraße 28, Dresden, 01277, Germany
4Faculty of Science and Technology, Meijo University, Nagoya, 468-8502, Japan
5Department of Material Science and Engineering, Hoseo University, Asan, 336-795, South Korea
6Department of Material Science and Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
Format: article
Version: accepted version
Access: embargoed
Persistent link:
Language: English
Published: Elsevier, 2021
Publish Date: 2023-01-15


Indialite/cordierite (Mg₂2Al₄Si₅O₁₈) glass-ceramics with a low dielectric constant of 4.7 and a high Qf of >200 × 10³ GHz are predicted for use as micro/millimeter-wave materials in the fifth generation (5G) mobile communication systems. The glass-ceramics have a serious cracking problem caused by the anisotropic crystal growth during the surface crystallization. In this paper, the cracking was prevented by adding TiO₂ which acts as a seed. The glass-ceramics produced without cracking were composed of spherical crystals of approximately 10 μm diameter, formed by volume crystallization. Precipitated phases of the glass-ceramics crystallized at 1200–1350 °C/10 h and 20 h were indialite, cordierite, Al₂TiO₅ and rutile. The glass-ceramics crystallized for 10 h were analyzed by the Rietveld method. Indialite precipitated as an intermediate metastable compound at the lower temperature of 1200 °C and transformed to cordierite at the crystallization temperature. The reaction between cordierite and TiO₂ produced the new Al₂TiO₅ phase. The amounts of Al₂TiO₅ and rutile affected the microwave dielectric properties. In particular, the amount of rutile affected the TCf. In the cases of 10 wt % added TiO₂, and the crystallized at 1250 °C for 10/20 h the TCf values were improved to -2/-8 ppm/°C.

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Series: Ceramics international
ISSN: 0272-8842
ISSN-E: 1873-3956
ISSN-L: 0272-8842
Volume: 47
Issue: 2
Pages: 2735 - 2742
DOI: 10.1016/j.ceramint.2020.09.126
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
213 Electronic, automation and communications engineering, electronics
Funding: Visiting professor Hitoshi Ohsato is grateful to JSPS KAKENHI Grant Numbers 22560673, 25420721, JP16K06735 and Nokia Foundation 2016 for supporting this work for the Nokia Visiting Professors Project 201700003. Professor Heli Jantunen and Dr. Jobin Varghese are grateful to European Research Council Project No. 24001893 for financial assistance.
Copyright information: © 2020 Elsevier Ltd and Techna Group S.r.l. All rights reserved. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http:/