Improvement of dielectric thermal stability of BST ferroelectric material for tunable applications

100(1 − y)wt%(Ba0.6Sr0.4)(Ti0.8Zr0.2)O3–100y wt%MgO (BSTZ20–MgO, y = 0.4, 0.5, 0.6, 0.7) composite ceramics were synthesized via a solid-state reaction route, aiming at improving the dielectric thermal stability of BST for tunable applications. Excellent dielectric thermal stability (low temperature coefficient of permittivity value) was gained in this system. According to our experiment, diffuse phase transition (DPT) induced by Zr ion substitution, ferroelectric-dilution effect of MgO phase and grain size refinement were considered as contributions to this good dielectric thermal stability.

In this study, we intended to improve the dielectric thermal stability of BST system through diffuse phase transition by Zr4+ substitution and dilution effect of MgO. It is amazing that 40 wt%BSTZ20–60 wt%MgO sample (BM3) exhibited an excellent dielectric performance: low ɛr (88) and tan δ (0.00027) with a moderate tunability (6.2% at 3 kV/mm) at 20 °C and 10 kHz, and an extremely low TCP value (−0.003 °C−1, −40 to 60 °C). Such excellent dielectric thermal stability (low TCP) was favorable for the temperature-stable tunable devices.Figure optionsDownload as PowerPoint slideHighlights
► BST ferroelectric material was modified through Zr4+ substitution and MgO, aiming at improving its temperature stability (or lowering the TCP value).
► An extremely low TCP value (−0.003 °C−1 within −40 to 60 °C) was gained in BM3: 40 wt%(Ba0.6Sr0.4)(Ti0.8Zr0.2)TiO3–60 wt%MgO composite ceramics.
► Wonderful dielectric properties – low dielectric constant and loss, moderate tunability, and preferable microwave performance – were also obtained in BM3.
► These good characteristics were favorable for the microwave tunable devices.