Correlation of the microstructure and microwave properties of Ba0.6Sr0.4TiO3 thick-films

Inkjet‐Printed Metal‐Insulator‐Metal Capacitors for Tunable Microwave Applications

“…This is considerably lower than the relative permittivity of bulk Ba 0.6 Sr 0.4 TiO 3 25 at room temperature and is due to the high porosity and the small grain size of the printed films. 24,26 Previous investigations showed that a lower porosity can be achieved by using a mixture of coarse and fine grained powders 27 or a higher amount of sintering additive. 19 The dielectric loss of the material increases with frequency.…”

“…This behavior is known for tunable dielectric ceramics. 4,22,26,27 At f = 3 GHz, the BST-ZnO-B 2 O 3 thick films show a dielectric loss of tan d = 0.043 AE 0.004. At 10 GHz, the dielectric loss is increased to tan d = 0.073 AE 0.007, which is comparable to undoped screen-printed thick films, sintered at 1150-1200°C.…”

“…At 10 GHz, the dielectric loss is increased to tan d = 0.073 AE 0.007, which is comparable to undoped screen-printed thick films, sintered at 1150-1200°C. 26 Previous investigations have shown that the dielectric loss of BST thick films at microwave frequencies are mainly affected by impurities of the material, whereas the microstructure of the films plays a less significant role. 6,22,26 Figure 3b shows the tunability of the films at different frequencies.…”

“…26 Previous investigations have shown that the dielectric loss of BST thick films at microwave frequencies are mainly affected by impurities of the material, whereas the microstructure of the films plays a less significant role. 6,22,26 Figure 3b shows the tunability of the films at different frequencies. In the investigated range, the films show a frequency-independent behavior, which is in good agreement with previous investigations on BST thick films 28 and thin films.…”

Implementation of Ba0.6Sr0.4TiO3‐ZnO‐B2O3 based tunable microwave phase shifters in LTCC technology

“…Among all technologies, BST thick‐films have several advantages such as adequate dielectric loss, low power consumption, and a high tuning speed . Nevertheless, due to the high sintering temperature above 1100°C for pure BST thick‐films, the fabrication of tunable components based on silver or gold electrodes is limited to planar structures which are patterned lithographically after the sintering process. However, these planar varactors, like interdigital capacitors (IDC), still require high tuning voltages and are limited regarding their tunability due to their low breakdown voltage or need of an additional passivation layer .…”