| Title |
Tunable Dielectric Properties and Curie Temperature with BST Thick Films |
| Authors |
김인성(Kim In-Sung) ; 송재성(Song Jae-Sung) ; 민복기(Min Bok-Ki) ; 전소현(Jeon So-Hyun) |
| Keywords |
가변 유전체 ; 큐리 온도 ; 고주파 가변 소자 ; 후막 유전체 Tunable Dielectrics ; BST |
| Abstract |
The properties of tunable dielectric materials on RF frequency band are important high tunability and low loss for RF variable devices, variable capacitor, phased array antenna and other components application. Various composite of BST(barium strontium titanate) ratio combined with other non-electrical active oxide ceramics have been formulated for such uses. We present the tunable properties and Curie temperature on BST thick films. The grain growth of the weight ratio of BaTiO_3 increased. This can be explained by the substitute Sr^{2+} ion for Ba^{2+} ion in the BaTiO_3 system. The Curie temperature was shifted to lower temperature with increasing SrTiO_3in the BaTiO_3-SrTiO_3 system, because of decreasing the lattice constant. Also, the dielectric constant, tunability and K-factor of (Ba_xSr_{1-x})TiO_3 at over the Curie temperature decreased, at over the 60°C fixation, maximum dielectric constant at Curie temperature and hence sharper phase transformation occurred at Curie temperature. The result were interpreted as a process of internal stress relaxation resulting form the increase of 90° domains induced the BST. As a result, It is concluded that over the Curie temperature, frequency response and DC field effect for the tunable properties of BST thick film are suppressed by the transition broadening. For the application of tunable devices, that the curie temperature was investigated to be increased. |