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Structural and microwave dielectric properties of temperature-stable Ca1-xEuxMo1-xNbxO4 ceramics for dielectric resonator antenna applications
Author(s)
Gu, Xiaolong
Tang, Ying
Wu, Jiangtao
Zhang, Ning
Zhang, Siying
Hu, Changzheng
Pulphol, Phieraya
Xiang, Huaicheng
Fang, Liang
Date Issued
October 15, 2025
Type
Article
Abstract
Ca1-xEuxMo1-xNbxO4 (0.1 ≤ x ≤ 0.7) ceramics were synthesized through the co-substitution of Ca2+ and Mo6+ in CaMoO4 using Eu3+ and Nb5+. All samples exhibited tetragonal scheelite structures within the range of 0.1 ≤ x ≤ 0.6. However, at x = 0.7, a monoclinic fergusonite structure was observed, as the [Nb/MoO4] tetrahedron at the B-site transforms into a [Nb/MoO6] octahedron. As the substitution amount increases, εr (11.39–16.40), Q×f (21,950–82,930 GHz), and τf (−47.72 to +8.01 ppm/℃) all show a gradual increase. Notably, the τf value of this system can shift from negative to positive. The structural influence mechanism on the microwave dielectric properties in Ca1-xEuxMo1-xNbxO4 ceramics was clarified through various analytical methods, including ion polarizability, P-V-L chemical bond theory, bond valence theory, density of states (DOS), and electron localization function (ELF). Additionally, a resonant antenna designed and simulated using Ca0.4Eu0.6Mo0.4Nb0.6O4 meets the requirements for satellite communication.
Citation
Journal of Alloys and Compounds, 1042, 2025