Abnormal dielectric behavior of glaserite-type Ba3−xSrxMgSi2O8 solid solution
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 m...
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Tsinghua University Press
2025-02-01
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| Series: | Journal of Advanced Ceramics |
| Subjects: | |
| Online Access: | https://www.sciopen.com/article/10.26599/JAC.2024.9221020 |
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| Summary: | 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 P3¯ for x ≤ 0.5, relatively high symmetry P3¯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. |
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| ISSN: | 2226-4108 2227-8508 |