BST (Barium Strontium Titanate) is a multi-component single phase material with a Curie peak that can be moved by modifying the barium to strontium ratio. These different ratios allow a wide variation of properties for applications like:
- Filled polymers
- Microwave components
- Implanted medical devices
- Aerospace components
- Standard capacitors
Curie temperature of Ferro BSTs with different BaXSr1-XTiO3 (from literature).
Processing Information for Fired Applications
| Firing temperature |
1340°C for 2 hours |
| Setter selection |
Zirconia |
| Composition |
Pb and Cd Free |
Typical Physical Properties for Ba0.55Sr0.45TiO3
Particle Size (µm)
D10 (Horiba)
D50 (Horiba)
D90 (Horiba) |
0.66
1.44
3.81 |
| Surface Area (m2/g) |
1.87 |
These properties can be manipulated to make the powder coarser or finer depending on customer requirements. The (Ba/Sr)/Ti ratio can be fine tuned to offer optimum performance in the respective application as well.
Typical Electrical Properties for Ba0.55Sr0.45TiO3, based on Ferro fired disc measurements.
| Dielectric Constant, K (@ 25°C, 1 kHz) |
2367 |
| DF (%) @ 1 kHz |
0.19 |
| DF (%) @ 1 MHz |
0.09 |
| Curie Point (°C) |
-15 |
| K @ Curie Point |
5717 |
| DF 1 kHz @ Currie Point |
0 |
Properties of experimental BST powders
| Ba/Sr mole ratio |
Ba55/Sr45 |
Ba70/Sr30 |
Ba70/Sr30 |
| (Ba+Sr)/Ti mole ratio |
0.990 |
1.000 |
0.998 |
| D10 (µm) |
0.66 |
0.36 |
1.02 |
| D50 (µm) |
1.44 |
0.59 |
2.65 |
| D90 (µm) |
3.81 |
1.10 |
4.92 |
| Surface Area (m2/g) |
1.87 |
6.39 |
1.17 |
| K @ 10% in PC |
85 |
81 |
95 |
| K dispersed in BST |
1131 |
707 |
3499 |
The values shown for 10% dispersion in 90% propylenecarbonate (PC, K=64) are measured with a HP fluid cell and an Agilent 4284A impedance analyzer at 1 MHz. K of the dispersed particles is calculated accord-ing to the original Lichtenecker formula:
log K = v1logK1 + v2logK2
where v1 and v2 = PC and BST volume fractions and K1 and K2 = PC and BST K values.
BST shows promise in a number of applications, ranging from filled polymer to targeted fired medical applications. A number of advantages of this material are observed because it is a single phase material that offers properties beyond the mixing of various barium and strontium titanates. These translate into potential unique application areas especially for high frequency applications.