Synthesis and investigation of (1-x)K0.5Na0.5NbO3-(x)CaSnO3 lead free perovskite ceramics of high dielectric and piezoelectric properties for transducer applications

The conventional solid state reaction technique was used to synthesize a piezoelectric material of (K0.5Na0.5)NbO3 (KNN) and CS doped KNN ((0.94)K0.5Na0.5NbO3-(0.06)CaSnO3 (KNN-CS (94/06) and (0.96)K0.5Na0.5NbO3-(0.04)CaSnO3 (KNN-CS (96/04)). X-ray powder diffraction analysis confirms the phase formation with structural distortion and existent of the zero secondary phase of synthesized ceramics. Orthorhombic (O) and tetragonal (T) phases exist in pure KNN and CS at room temperature. As significance, we exemplify that the KNN-CS (94/06 and 96/04) possess the coexistence of two phases (O-T) across the morphotropic phase boundary (MPB) by investigating the Bragg peaks position of XRD data. ABO(3)-type oxides were incorporated into a K0.5Na0.5NbO3 ceramic, where the B-site is occupied by transition elements to strengthen the electrical properties. CaSnO3 was chosen to construct the K0.5Na0.5NbO3 based solid solution by altering the tolerance factor and ionic polarizability. As a consequence, the KNN-CS (96/04) ratio affirms the high electric polarizability due to Ca2+ and Sn4+ being substituted for the A and B-sites of KNN. The diffuseness of dielectric permittivity confirms relaxor behavior using a modified Curie-Weiss law. At a poling electric field of 3.6 kV/mm, the piezoelectric coefficient d(33) of CS doped KNN (KNN-CS (96/04)) was found to be 430 pC/N.

Automated summary

The traditional solid state reaction technique was employed to synthesize piezoelectric materials of (K0.5Na0.5)NbO3 (KNN) and CS doped KNN ((0.94)K0.5Na0.5NbO3-(0.06)CaSnO3 (KNN-CS (94/06) and (0.96)K0.5Na0.5NbO3-(0.04)CaSnO3 (KNN-CS (96/04)). The addition of CaSnO3 into KNN was found to significantly enhance the electrical properties, particularly in the KNN-CS (96/04) composition.