Ferroelectric and piezoelectric properties of Ca2+ and Sn4+ substituted BaTiO3 lead-free electroceramics on the emphasis of phase coexistence

The Ba1-xCaxTi1-ySnyO3 (abbreviated as BCxTSy, x = 0.01, y = 0.01; x = 0.03, y = 0.015; x = 0.05, y = 0.02; and x = 0.07, y = 0.025 mol.) electroceramics were synthesized by solid-state reaction method and investigated their structural, dielectric, ferroelectric and piezoelectric properties. Rietveld refinement of X-ray diffraction data for the composition x = 0.03, y = 0.015 reveals the phase co-existence of two non-centrosymmetric orthorhombic (Amm2) (7.71%) thorn tetragonal (P4mm) (92.29%) lattice symmetries near room temperature which is also evidenced by temperature-dependent Raman and dielectric studies. All compositions reveal the dense microstructure having relative density similar to 92%-96% and average grain size similar to 10.7-22.5 mu m. The phase diagram based on dielectric study suggests that the composition x = 0.03, y = 0.015 reveals T( R-O) similar to -60 degrees C, T( O-T) similar to 19 degrees C and TC similar to 126 degrees C with Pr = 11.80 mu C/cm(2), E-c = 3.5 kV/cm, P-max = 21.92 mu C/cm(2), d(33)* = 505.5 pm/V, d(33) = 287 pC/N and electrostrictive coefficient (Q(33)) = 0.036 m(4)/C-2 properties which could be useful for developing the piezoelectric AC devices. Here, we have achieved the phase-coexistence of two non-centrosymmetric lattice symmetries near room temperature to invoke the reliable ferroelectric and piezoelectric properties and discussed the results with the structure-property-composition relation.