Electrical properties and high figure-of-merit of dielectric tunable (1–x)Ba(Zr0.25Ti0.75)O3–xMgO thick films prepared by tape-casting

•(1−x)Ba(Zr0.25Ti0.75)O3–xMgO thick films were prepared by tape-casting.•Dielectric tenability was 92.54 ~ 30.56% at 42 kV/cm, room temperature and 1 kHz.•High figure-of-merit, 103.97 ~ 219.86, of these films was attained.•Dielectric dispersion of these films was described by the Lorentz-type relation.•(ɛ(0) / ɛ(E))3 vs. (E2) was fitted by the Johnson’s equation according to Devonshire’s theory.

(1−x)Ba(Zr0.25Ti0.75)O3−xMgO (x = 0.0, 0.1, 0.2, 0.3, 0.4) thick films were prepared by using a solid state reaction and tape-casting method. It is found that Mg not only exists in the MgO but also in the Ba(Zr0.25Ti0.75)O3 detected by X-ray diffraction, field-emission scanning electron microscopy, transition electron microscopy and energy dispersive spectrum. With the increase of MgO content, the Curie temperature of thick films shifts from room temperature (283 K) of x = 0.0 to lower temperature (153 – 173 K). The dielectric relaxation properties of thick films were described by a Lorentz relation and the dc bias electric field dependences of the dielectric permittivity were described by a Johnson’s phenomenological equation based on Devonshire’s theory. The dielectric tunability, loss angle tangent and figure-of-merit of x = 0.4 at room temperature and 42 kV/cm were 30.56%, 0.00139 and 219.86, respectively.