@article{Yang2025, 
author = {Jiaqing Yang and Peng Lei and Xiaoqiang Song and Changzhi Yin and Meng Zhang and Weicheng Lei and Yiyang Cai and Mingfei Cheng and Yaodong Liu and Zihang Chen and Yaqing Hu and Wenzhong Lu and Wen Lei},
title = {Abnormal dielectric behavior of glaserite-type Ba3−xSrxMgSi2O8 solid solution},
year = {2025},
journal = {Journal of Advanced Ceramics},
volume = {14},
number = {2},
pages = {9221020},
keywords = {microwave dielectric ceramics, abnormal dielectric behavior, ion size mismatch, [SiO4] tetrahedra tilting, phase transition, density functional theory (DFT)},
url = {https://www.sciopen.com/article/10.26599/JAC.2024.9221020},
doi = {10.26599/JAC.2024.9221020},
abstract = {The temperature coefficient of the resonant frequency (τf) of low-permittivity (εr) microwave dielectric ceramics is required to be near 0 ppm/°C for practical application. However, owing to the polarization mechanism, τf of low-εr microwave dielectric ceramics is generally negative. Here, a novel microwave dielectric ceramic, Ba3−xSrxMgSi2O8, with an abnormal positive τf at the applied temperature is presented. In this study, Sr2+ with a relatively small ionic radius was introduced to replace Ba2+, and a single-phase solid solution was formed (x > 0.5). Ba3−xSrxMgSi2O8 ceramics were discussed in glaserite-type topology with space groups of P 3¯ for x ≤ 0.5, relatively high symmetry P 3¯m1 for 0.5 < x < 2.5, and C2 for x ≥ 2.5. The εr peaks as a function of temperature initially shift to low temperatures and then return to high temperatures through an ion substitution strategy. Notably, remarkable microwave dielectric properties for BaSr2MgSi2O8 were observed: εr ≈ 14.2, Q×f ≈ 38,900 GHz, and τf ≈ +117 ppm/°C, which are superior to those of other low-εr silicate ceramics with positive τf values. Density functional theory simulation calculations revealed that the preferential occupation of Sr2+ ions could decrease the intrinsic formation energy and improve the microwave dielectric properties by mitigating the ionic size mismatch within the crystal structure. The present research offers a strategy for discovering novel microwave dielectric ceramics with abnormal τf values, which could serve as τf regulators in practical applications because of their low cost and excellent microwave dielectric properties.}
}