Phase structures and electrical properties of (1−x)(K0.48Na0.52)NbO3–x(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead-free ceramics

Abstract

Abstract Lead-free ceramics (1− x )(K 0.48 Na 0.52 )NbO 3 – x (Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O 3 doped with 1.0 mol% MnO 2 were prepared using a solid-state reaction technique. The phase transition behavior and electrical properties of the ceramics were studied. Results show that (Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O 3 diffuses into (K 0.48 Na 0.52 )NbO 3 to form a new solid solution, and induces a phase structure transition from orthorhombic to tetragonal phase with the increase of x . At 0.04≤ x ≤0.06, coexistence of the orthorhombic and tetragonal phases is observed, and enhanced piezoelectric properties are achieved in this region due to the polymorphic phase transition near room temperature. The doping of MnO 2 effectively promotes the densification of the ceramics and further enhances the piezoelectric and dielectric properties at room temperature. The ceramics with 0.04≤ x ≤0.06 and 1.0 mol% MnO 2 possess excellent electrical properties: d 33 ⁎ =200–262 pm/V, d 33 =153–182 pC/N, e r =763–976, tan δ =0.054–0.060, T c =268–312 °C. Moreover, samples with single tetragonal phase at x =0.07 have a good temperature stability in the temperature range of 25–150 °C due to the shift of the orthorhombic to tetragonal polymorphic phase transition below room temperature.