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oai:docta.ucm.es:20.500.14352/942442025-04-25T23:57:53Zcom_20.500.14352_14col_20.500.14352_15

00925njm 22002777a 4500 dc Sadin, Younes author Taheri-Nassaj, Ehsan author Schmidt, Rainer author Yourdkhani, Amin author Myllymäki, Sami author Jantunen, Heli author Barzegar-Barfrooei, Hadi author 2024 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 degrees C and 625 degrees C, 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 epsilon r values of 5.85 and 5.62 at 14 GHz, and high quality factors Qxf of 25,200 and 23,450 GHz at 14 GHz were detected. Large negative tau f of -105 and -106 ppm/degrees C were obtained, which are uncommon but highly valuable for offsetting positive tau f values of other systems. Moderate Li+-ion conduction was detected in both compounds by ac impedance spectroscopy. Younes Sadin, Ehsan Taheri-Nassaj, Rainer Schmidt, Amin Yourdkhani, Sami Myllymäki, Heli Jantunen, Hadi Barzegar -Barfrooei, Novel LiCa(PO3)3 and LiSr(PO3)3 microwave dielectric ceramics, Journal of the European Ceramic Society, Volume 44, Issue 3, 2024, Pages 1617-1626, ISSN 0955-2219, https://doi.org/10.1016/j.jeurceramsoc.2023.10.030. 0955-2219 10.1016/j.jeurceramsoc.2023.10.030 https://hdl.handle.net/20.500.14352/94244 https://doi.org/10.1016/j.jeurceramsoc.2023.10.030 Novel LiCa(PO3)3 and LiSr(PO3)3 microwave dielectric ceramics