Microstructures and dielectric properties of Ba0.6Sr0.4TiO3–MgO ceramics prepared by non-aqueous gelcasting and dry pressing

Non-aqueous gelcasting and dry pressing were used to prepare 45 wt% Ba0.6Sr0.4TiO3–55 wt% MgO (BSTM) ceramics. The effects of different forming methods on the microstructures and dielectric properties of the BSTM ceramics were investigated. The densities of the BSTM ceramics prepared by non-aqueous gelcasting are lower but more uniform than that of the BSTM ceramics prepared by dry pressing. The XRD analysis illustrates that phase compositions are completely the same no matter what forming method is adopted. The SEM results show that the BSTM green samples and sintered ceramics prepared by non-aqueous gelcasting are more uniform than that prepared by dry pressing. Furthermore, it is found that the BSTM ceramics prepared by non-aqueous gelcasting have higher and more uniform dielectric constant, tunability and loss tangent (measured at 10 kHz and 20 °C). Meanwhile, the BSTM ceramics prepared by non-aqueous gelcasting have higher dielectric constant and lower Q × f value (namely more loss) when they are measured at microwave frequencies.

Graphical abstractThe non-aqueous gelcasting and dry pressing were used to prepare 45 wt% Ba0.6Sr0.4TiO3–55 wt% MgO (BSTM) ceramics. Microstructures and dielectric properties of the BSTM ceramics prepared by the two forming methods have been investigated. It is found that the non-aqueous gelcasting has considerable effects on the microstructures and dielectric properties of the BSTM ceramics.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Densities of the ceramics prepared by non-aqueous gelcasting are more uniform. ► Green samples and ceramics prepared by non-aqueous gelcasting are more uniform. ► Non-aqueous gelcasting has great effect on dielectric properties of the ceramics.