SrGa 12 O 19 : The first low- ε r Ga-based microwave dielectric ceramic with anomalous positive τ f
2024; Springer Science+Business Media; Volume: 13; Issue: 9 Linguagem: Inglês
10.26599/jac.2024.9220947
ISSN2227-8508
AutoresYang Yang, Weishuang Fang, Huixing Lin, Jie Li, Huaicheng Xiang, Ying Tang, Lei Li, Liang Fang,
Tópico(s)Dielectric properties of ceramics
ResumoDielectric ceramics with low ε r , high Q × f , and near-zero τ f in the microwave bands are key materials used in fifth/sixth-generation (5G/6G) telecommunication, while the τ f of most low- ε r microwave dielectric ceramics is relatively negative. In this work, the first low- ε r Ga-based ceramic SrGa 12 O 19 with anomalous positive τ f was reported, and the cause of positive τ f , intrinsic polarization and loss mechanism were systematically studied. According to XRD and TEM, SrGa 12 O 19 ceramic formed a pure hexagonal magnetoplumbite structure with the spinel block and the rock-salt block stacking along the crystallographic c -axis. When sintered at 1430 °C, it possessed the optimal microwave dielectric properties of low ε r of 14.46, high Q × f of 64,705 GHz, and exceptional positive τ f of +55.7 ppm/°C, along with a low linear thermal expansion coefficient ( α L ) of 11.617 ppm/°C. The large positive deviation between ε r and ε r (C-M) of 45.31% resulted from the rattling effect of atoms in a rock-salt block. The unique positive τ f (+55.7 ppm/°C) was governed by the rattling effect, resulting in a positive τ αm of 8.489 ppm/℃ and a large negative τ ε of −132.864 ppm/℃. The P-V-L chemical bond theory showed the greater contribution of the spinel block to f i (52.95%), ε (55.15%), E (56.87%) and U (74.88%) than those of the rock-salt block. The intrinsic dielectric properties were analyzed using infrared reflectivity spectra. The favorable performances of SrGa 12 O 19 ceramic indicated it is a novel τ f compensator. This selection of compounds with different structural layer combinations provides a new idea for exploring excellent microwave dielectric ceramics.
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