Evolution of Phase Transformation on Microwave Dielectric Properties of BaSi<i><sub>x</sub></i>O<sub>1+2<i>x</i></sub> Ceramics and Their Temperature-Stable LTCC Materials
oleh: Tailai Wen, Yulu Luo, Zehang Zeng, Xiaotian Liu, Changzhi Yin, Yiyang Cai, Xiaoxiao Li, Kang Du, Wen Lei, Shengxiang Wang
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2023-05-01 |
Deskripsi
BaSi<i><sub>x</sub></i>O<sub>1+2<i>x</i></sub> (1.61 ≤ <i>x</i> ≤ 1.90) and LiF-doped BaSi<sub>1.63</sub>O<sub>4.26</sub> ceramics were prepared by using a traditional solid-state method at the optimal sintering temperatures. The evolution of phase compositions of BaSi<i><sub>x</sub></i>O<sub>1+2<i>x</i></sub> (1.61 ≤ <i>x</i> ≤ 1.9) ceramics was revealed. The coexistence of Ba<sub>5</sub>Si<sub>8</sub>O<sub>21</sub> and Ba<sub>3</sub>Si<sub>5</sub>O<sub>13</sub> phases was obtained in BaSi<i><sub>x</sub></i>O<sub>1+2<i>x</i></sub> (1.61 ≤ <i>x</i> ≤ 1.67) ceramics. The BaSi<sub>2</sub>O<sub>5</sub> phase appeared inBaSi<i><sub>x</sub></i>O<sub>1+2<i>x</i></sub> (1.68 ≤ <i>x</i> ≤ 1.90) ceramics. At 1.68 ≤ <i>x</i> ≤ 1.69, only BaSi<sub>2</sub>O<sub>5</sub> and Ba<sub>3</sub>Si<sub>5</sub>O<sub>13</sub> phases existed. With the further increase in <i>x</i>, the Ba<sub>5</sub>Si<sub>8</sub>O<sub>21</sub> phase appeared, and BaSi<sub>2</sub>O<sub>5</sub>, Ba<sub>5</sub>Si<sub>8</sub>O<sub>21</sub> and Ba<sub>3</sub>Si<sub>5</sub>O<sub>13</sub> phases coexisted in BaSi<i><sub>x</sub></i>O<sub>1+2<i>x</i></sub> (1.70 ≤ <i>x</i> ≤ 1.90) ceramics. The phase compositions of BaSi<i><sub>x</sub></i>O<sub>1+2<i>x</i></sub> (1.61 ≤ <i>x</i> ≤ 1.90) ceramics were controlled by the ratio of Ba:Si. The BaSi<i><sub>x</sub></i>O<sub>1+2<i>x</i></sub> (<i>x</i> = 1.68) ceramics with 98.15 wt% Ba<sub>3</sub>Si<sub>5</sub>O<sub>13</sub> and 1.85 wt% BaSi<sub>2</sub>O<sub>5</sub> phases exhibited a negative <i>τ<sub>f</sub></i> value (−37.53 ppm/°C), and the good microwave dielectric properties of <i>ε<sub>r</sub></i> = 7.51, <i>Q</i> × <i>f</i> = 13,038 GHz and <i>τ<sub>f</sub></i> = +3.95 ppm/°C were obtained for BaSi<sub>1.63</sub>O<sub>4.26</sub> ceramics with 70.05 wt% Ba<sub>5</sub>Si<sub>8</sub>O<sub>21</sub> and 29.95 wt% Ba<sub>3</sub>Si<sub>5</sub>O<sub>13</sub> phases. The addition of LiF sintering aids were able to reduce the sintering temperatures of BaSi<sub>1.63</sub>O<sub>4.26</sub> ceramics to 800 °C. The phase composition of BaSi<sub>1.63</sub>O<sub>4.26</sub> ceramics was affected by the sintering temperature, and the coexistence of Ba<sub>5</sub>Si<sub>8</sub>O<sub>21</sub>, Ba<sub>2</sub>Si<sub>3</sub>O<sub>8</sub>, BaSi<sub>2</sub>O<sub>5</sub> and SiO<sub>2</sub> phases was achieved in BaSi<sub>1.63</sub>O<sub>4.26</sub>-3 wt% LiF ceramics. The BaSi<sub>1.63</sub>O<sub>4.26</sub>-3 wt% LiF ceramics sintered at 800 °C exhibited dense microstructures and excellent microwave dielectric properties (<i>ε<sub>r</sub></i> = 7.10, <i>Q</i> × <i>f</i> = 12,463 GHz and <i>τ<sub>f</sub></i> = +5.75 ppm/°C), and no chemical reaction occurred between BaSi<sub>1.63</sub>O<sub>4.26</sub>-3 wt% LiF ceramics and the Ag electrodes, which indicates their potential for low-temperature co-fired ceramic (LTCC) applications.