Novel LiCa(PO3)3 and LiSr(PO3)3 microwave dielectric ceramics
Sadin, Younes; Taheri-Nassaj, Ehsan; Schmidt, Rainer; Yourdkhani, Amin; Myllymäki, Sami; Jantunen, Heli; Barzegar -Barfrooei, Hadi (2023-11-20)
Avaa tiedosto
Sisältö avataan julkiseksi: 20.11.2025
Elsevier
20.11.2023
Sadin, Y., Taheri-Nassaj, E., Schmidt, R., Yourdkhani, A., Myllymäki, S., Jantunen, H., & Barzegar -Barfrooei, H. (2024). Novel LiCa(Po3)3 and LiSr(Po3)3 microwave dielectric ceramics. Journal of the European Ceramic Society, 44(3), 1617–1626. https://doi.org/10.1016/j.jeurceramsoc.2023.10.030
https://creativecommons.org/licenses/by-nc-nd/4.0/
© 2024. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http:/creativecommons.org/licenses/by-nc-nd/4.0/
https://creativecommons.org/licenses/by-nc-nd/4.0/
© 2024. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http:/creativecommons.org/licenses/by-nc-nd/4.0/
https://creativecommons.org/licenses/by-nc-nd/4.0/
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:oulu-202410256464
https://urn.fi/URN:NBN:fi:oulu-202410256464
Tiivistelmä
Abstract
Novel LiCa(PO3)3 and LiSr(PO3)3 phases were produced by conventional solid-state synthesis and formed into ceramic pellets followed by conventional sintering. The crystal structure, ceramic microstructure, microwave dielectric properties and ac conductivity were investigated. A triclinic space group P1- was obtained from Rietveld refinements, and the lattice vibration modes were determined by Raman spectroscopy. The optimum sintering conditions for LiCa(PO3)3 and LiSr(PO3)3 ceramics were 700 ℃ and 625 ℃, respectively, both for 10 h. Dense glass-free ceramic microstructures were confirmed by SEM. High relative densities of 94.6 % and 93.8 %, low microwave εr values of 5.85 and 5.62 at 14 GHz, and high quality factors Q×f of 25,200 and 23,450 GHz at 14 GHz were detected. Large negative τf of − 105 and − 106 ppm/°C were obtained, which are uncommon but highly valuable for offsetting positive τf values of other systems. Moderate Li+-ion conduction was detected in both compounds by ac impedance spectroscopy.
Novel LiCa(PO3)3 and LiSr(PO3)3 phases were produced by conventional solid-state synthesis and formed into ceramic pellets followed by conventional sintering. The crystal structure, ceramic microstructure, microwave dielectric properties and ac conductivity were investigated. A triclinic space group P1- was obtained from Rietveld refinements, and the lattice vibration modes were determined by Raman spectroscopy. The optimum sintering conditions for LiCa(PO3)3 and LiSr(PO3)3 ceramics were 700 ℃ and 625 ℃, respectively, both for 10 h. Dense glass-free ceramic microstructures were confirmed by SEM. High relative densities of 94.6 % and 93.8 %, low microwave εr values of 5.85 and 5.62 at 14 GHz, and high quality factors Q×f of 25,200 and 23,450 GHz at 14 GHz were detected. Large negative τf of − 105 and − 106 ppm/°C were obtained, which are uncommon but highly valuable for offsetting positive τf values of other systems. Moderate Li+-ion conduction was detected in both compounds by ac impedance spectroscopy.
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