University of Oulu

Wu, Y.-C., Tseng, H.-T., Hsi, C.-S., Juuti, J., & Hsiang, H.-I. (2022). Low dielectric loss ceramics in the Mg4Nb2O9-ZnAl2O4-TiO2 ternary system. Journal of the European Ceramic Society, 42(2), 448–452.

Low dielectric loss ceramics in the Mg₄Nb₂O₉-ZnAl₂O₄-TiO₂ ternary system

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Author: Wu, Yu-Chuan1; Tseng, Hsiao-Ting2; Hsi, Chi-Shiung2;
Organizations: 1Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei, Taiwan
2Department of Materials Science and Engineering, National United University, Miaoli, Taiwan
3Microelectronics and Materials Physics Laboratory, Department of Electrical Engineering, University of Oulu, Oulu, 90014, Finland
4Department of Resources Engineering, National Cheng Kung University, Tainan, Taiwan
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 1 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2023-11-02


This study used a traditional solid-state reaction method to prepare a series of composite ceramics in the 0.7Mg₄Nb₂O₉-(0.3-x)ZnAl₂O₄-xTiO₂ ternary system. Crystalline phases and microstructure of Mg₄Nb₂O₉-ZnAl₂O₄-TiO₂ dielectric ceramic composites were investigated and correlated with the relevant dielectric properties. It was observed that the addition of Ti⁴⁺ substituted Nb⁵⁺ in the Mg₄Nb₂O₉ structure, which promoted the decomposition of Mg₄Nb₂O₉ to form the second phase, Mg₅Nb₄O₁₅, during sintering. The synergistic effect of ZnAl₂O₄-TiO₂ co-doping promoted the Mg₄Nb₂O₉ ceramic densification. The sample (0.7Mg₄Nb₂O₉-(0.3-x)ZnAl₂O₄-xTiO₂) with x = 0.15−0.2 exhibited dielectric constants of 13–14, larger than those of ZnAl₂O₄, Mg₄Nb₂O₉ and Mg₅Nb₄O₁₅, due to the NbO₆ octahedra distortion resulting from the substitution of Al³⁺/Ti⁴⁺ for Nb⁵⁺ in Mg₄Nb₂O₉ and Mg₅Nb₄O₁₅. The long-range order of the NbO₆ octahedra was enhanced by co-doping ZnAl₂O₄ and TiO₂, thereby enhancing the Qxf value. A dielectric constant of 13.1, Qxf value of 366,000 GHz and a τf of −60.8 ppm/°C were obtained from 1300 °C sintered 0.7Mg₄Nb₂O₉-0.15ZnAl₂O₄-0.15TiO₂. These results show that 0.7Mg₄Nb₂O₉-0.15 ZnAl₂O₄-0.15TiO₂ ceramic is a good candidate for microwave electronic device applications.

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Series: Journal of the European Ceramic Society
ISSN: 0955-2219
ISSN-E: 1873-619X
ISSN-L: 0955-2219
Volume: 42
Issue: 2
Pages: 448 - 452
DOI: 10.1016/j.jeurceramsoc.2021.10.059
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: This work was supported by the Ministry of Science and Technology, Taiwan (MOST 105-2221-E-239-002-).
Copyright information: © 2021. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http:/