Dielectric and Tunable Properties of Ba_0.6Sr_0.4TiO₃-Mg₂TiO₄ Composite Ceramics for Phase Shifter Applications

Abstract

The composite ceramics of barium strontium titanate (Ba _0.6 Sr _0.4 TiO ₃ , BST) with microwave dielectric magnesium titanate (Mg ₂ TiO ₄ , MT) were prepared using the traditional ceramic process. The XRD patterns analysis showed that the two-phase structures of BST and MT were formed. SEM observation revealed that the grain sizes were consistent with the BST. There is a significant depression in dielectric constant. The dielectric constant was decreased to 254 with composition of 40wt%BST-60wt%MT and dielectric loss was also reduced to 0.0007 at measurement frequency of 10 kHz. The tunability is about 34% for 40wt%BST-60wt%MT composition under applied electric field 3 kV/mm at 10 kHz. In addition, the microwave property of the composite ceramics was optimized compared with pure BST.

Keywords:

• Composite ceramics
• phase structure
• tunability
• microwave property

Acknowledgments

This research was supported by the Ministry of Sciences and Technology of China through 973-project under grant 2002CB613304, Shanghai Foundation Project under grant 06JC14070, Program for New Century Excellent Talents in University (NCET-04-0378) and Shanghai Pujiang Program.