Tunable dielectric properties of BaZr0.2Ti0.8O3–Mg2SiO4–MgO composite ceramics

BaZr0.2Ti0.8O3–Mg2SiO4–MgO composites were prepared by a solid-state reaction method, and their dielectric and tunable characteristics were investigated for the potential application as microwave tunable materials. It is observed that the addition of Mg2SiO4–MgO into BaZr0.2Ti0.8O3 form ferroelectric (BaZr0.2Ti0.8O3)–dielectric (Mg2SiO4–MgO) composites. The dielectric constant and loss tangent of BaZr0.2Ti0.8O3–Mg2SiO4–MgO composites have been reduced and the overall tunability is maintained at a sufficiently high level. An anomalous relation between dielectric constant and tunability was observed: with the increase of Mg2SiO4 content (>30 wt%), the dielectric constant of composite decreases and the tunability increases. The anomalous increased tunability can be attributed to redistribution of the electric field. BaZr0.2Ti0.8O3–Mg2SiO4–MgO composites have tunability of 14.2–17.9% at 100 kHz under 2 kV/mm, indicating that it is a promising candidate material for tunable microwave applications requiring low dielectric constant.

Research highlights▶ BaZr0.2Ti0.8O3–Mg2SiO4–MgO composites were prepared and their dielectric and tunable characteristics were investigated. Ferroelectric (BaZr0.2Ti0.8O3)–dielectric (Mg2SiO4–MgO) composites were formed. An anomalous relation between dielectric constant and tunability was observed: with the increase of Mg2SiO4 content (>30%), the dielectric constant of composite decreases and the tunability increases.