Synthesis and characterizations of KNN ferroelectric ceramics near 50/50 MPB

Abstract Lead free ferroelectric ceramics near the morphotropic phase boundary (MPB) of K x Na 1− x (NbO 3 )/KNN system (where x =0.48, 0.50, 0.52) were synthesized in the single perovskite phase by the partial co-precipitation synthesis route. The compositional dependences of phase, structure and electrical properties were studied in detail. X-ray diffraction (XRD) study revealed the coexistence of orthorhombic and monoclinic structures in K 0.50 N 0.50 NbO 3 . SEM characterization of the sintered KNN ceramics revealed dense and homogeneous packing of grains. Room temperature (RT) dielectric constant ( e r ) ∼648, dielectric loss (tan δ) ∼0.05 at 100 kHz, a relatively high density ( ρ ) ∼4.49 g/cm 3 , remnant polarization ( P r ) ∼11.76 μC/cm 2 , coercive field ( E c ) ∼9.81 kV/cm, Curie temperature ( T c ) ∼372 °C and piezoelectric coefficient ( d 33 ) ∼71 pC/N observed in K 0.50 N 0.50 NbO 3 suggested that it can be an important lead free ferroelectric material.