Structural Properties of (Ba0.97Ca0.03Ti0.985Sn0.015O3)-(K0.5Na0.5NbO3) Lead-free Electroceramics

Abstract

The lead-free Ba0.97Ca0.03Ti0.985Sn0.015O3(BCTS)-K0.5Na0.5NbO3 (KNN) (BCTS and BCTS + 1 wt. % KNN) electroceramics were synthesized by solid-state reaction and studied their structural, microstructural, dielectric, and ferroelectric properties. BCTS and BCTS + 1 wt. % KNN samples revealed the formation of perovskite structure without any trace of impurity. At room temperature, BCTS exhibits the tetragonal structure, while BCTS + 1 wt. % KNN shows an orthorhombic structure, which is evidenced by XRD and Raman spectroscopy study. Dense microstructure with average grain size of 1.75 µm and 1.67 µm, having bulk densities of 5.73 g/cm3 and 5.48 g/cm3 are observed for BCTS and BCTS + 1 wt. % KNN ceramics respectively. The dielectric study with respect to temperature depicts three polymorphic structural transitions corresponding to the rhombohedral to orthorhombic (TR–O), orthorhombic to tetragonal (TO–T) and tetragonal to cubic (TC) structure. BCTS ceramic exhibited TR–O at – 50 °C, TO–T at 16 °C and TT–C at 125 °C. P-E hysteresis loop at various temperatures provides information about the ferroelectric to paraelectric structural transition for BCTS ceramics and supports the temperature-dependent dielectric and Raman spectroscopy studies.