| Affiliation: | 1. School of Optical and Electronic Information, Key Lab of Functional Materials for Electronic Information (B) of Ministry of Education, Huazhong University of Science and Technology, Wuhan, P. R. China
Wenzhou Institute of Advanced Manufacturing Technology, Huazhong University of Science and Technology, Wenzhou, P. R. China;2. School of Optical and Electronic Information, Key Lab of Functional Materials for Electronic Information (B) of Ministry of Education, Huazhong University of Science and Technology, Wuhan, P. R. China;3. State Key Laboratory of Advanced Materials and Electronic Components, Guangdong Fenghua Advanced Technology Holding Co. Ltd., Zhaoqing, P. R. China |
| Abstract: | Ca3SnSi2-xGexO9 (0 ≤ x ≤ 0.8) and (1–y) Ca3SnSi1.6Ge0.4O9 – y CaSnSiO5 – 2 wt% LiF (y = 0.4 and 0.5) microwave dielectric ceramics were prepared by traditional solid-state reaction through sintering at 1250°C–1425°C for 5 h and at 875°C for 2 h, respectively. Ge4+ replaced Si4+, and Ca3SnSi2-xGexO9 (0 ≤ x ≤ 0.4) solid solutions were obtained. At 0.1 ≤ x ≤ 0.4, the Ge4+ substitution for Si4+ decreased the sintering temperature of Ca3SnSi2-xGexO9 from 1425 to 1300°C, the SnO6 octahedral distortions, and the average CaO7 decahedral distortions, which affected the τf value. The large average decahedral distortions corresponded with nearer-zero τf values at Ca3SnSi2-xGexO9 (0.1 ≤ x ≤ 0.4) ceramics. The τf value and sintering temperature of Ca3SnSi2-xGexO9 (x = 0.4) ceramic were adjusted to near-zero by CaSnSiO5 and decreased to 875°C upon the addition of 2 wt% LiF. The (1 – y) Ca3SnSi1.6Ge0.4O9 – y CaSnSiO5 – 2 wt% LiF (y = 0.5) ceramic sintered at 875°C for 2 h exhibited good microwave dielectric properties: εr = 10.3, Q × f = 14 300 GHz (at 12.2 GHz), and τf = ?5.8 ppm/°C. |
