@article{Liu2026, 
author = {Yao-Dong Liu and Kang Du and Yi-Yang Cai and Pin-An Tan and Rui-Zhao Li and Xiao-Qiang Song and Chang-Zhi Yin and Ming-Fei Cheng and Tauqeer Ahmad and Wen-Zhong Lu and Wen Lei},
title = {Crystal structure, chemical bond characteristics and microwave dielectric properties of low-permittivity Ca1–xMgxY2Ge3O10 ceramics with superlattice},
year = {2026},
journal = {Journal of Materiomics},
volume = {12},
number = {5},
keywords = {Microwave dielectric ceramics, Superlattice, Far-infrared spectroscopy, Near-zero τf},
url = {https://www.sciopen.com/article/10.1016/j.jmat.2026.101264},
doi = {10.1016/j.jmat.2026.101264},
abstract = {Ca1–xMgxY2Ge3O10 ceramics were synthesised using the solid-state reaction method. XRD analysis reveals that the solid solubility limit of Mg2+ in Ca1–xMgxY2Ge3O10 lies between x = 0.15 and 0.20. Multiple characterisation approaches, including Phillips–van Vechten–Levine theory and bond valence analysis, were employed to systematically elucidate the crystal structure and microwave dielectric properties. TEM analysis revealed a distinct superlattice structure in the material, characterised by an increased density of (001) planes along the [100] zone axis. The presence of superlattice in Ca0.9Mg0.1Y2Ge3O10 gives rise to a higher degree of lattice ordering, thereby reducing the intrinsic loss. The corrected dielectric constant shows a trend opposite to the αDT/Vm from Clausius–Mossotti (C–M) equation, primarily because of the rattling effect induced by Mg2+ substitution, which limits the applicability of the C–M equation. The intrinsic loss of CaY2Ge3O10 was assessed by far-infrared spectroscopy. Key factors governing the microwave dielectric properties include total lattice energy (Ut), ion activation energy (Ea), and packing fraction (P.F.), which collectively determine the variation in Q×f, whereas the average distortion of Y–O bonds (Ave(δY–O)), the rattling effect and proportion of Ge–O bonds in total polarizability (χ(Ge–O)/χ), primarily affect τf. The Ca0.9Mg0.1Y2Ge3O10 ceramic exhibits an enhanced Q×f, with microwave dielectric properties of εr = 10.1, Q×f = 106,440 GHz, and τf = −27.1 × 10−6 ℃−1. At x = 0.15, a reduced Ave(δY–O), a maximum χ(Ge–O)/χ, and a stronger rattling effect are observed, leading to a near-zero τf of −9.7 × 10−6 ℃−1, with εr = 10.3 and Q×f = 91,920 GHz.}
}