Enhancement in dielectric, ferroelectric, and piezoelectric properties of BaTiO3- modified Bi0.5(Na0.4K0.1)TiO3 lead-free ceramics

In this paper, the effect of BaTiO3 on dielectric, ferroelectric, and piezoelectric properties was observed in (1-x)[Bi-0.5(Na0.4K0.1)TiO3] - xBaTiO(3) ceramics (BNKT-BT, with x = 0; 0.01; 0.02; 0.03 and 0.04). The phase formation and microstructure of BNKT-BT ceramics were examined by X-ray diffraction (XRD), the Raman scattering spectra, and scanning electron microscopy (SEM). A pure perovskite phase was observed in the ceramic samples, proving the dissolution of BaTiO3 into the lattice structure of the BNKT to form a homogeneous solid solution (x <= 0.04). At x = 0.02, the best physical properties of the BNKT-BT ceramics, such as density, rho = 5.86 g/cm(3) (98.5% of the theoretical density); electromechanical coupling factors (k(p)), 0.30; (k(t)), 0.31; remanent polarization (P-r), 17.2 mu C cm(-2); dielectric constant (epsilon(r)), 1354; and highest dielectric constant (epsilon(max)), 4037, were obtained. Further, the energy storage properties of 0.98Bi(0.5)(Na0.4K0.1)TiO3 - 0.02BaTiO(3) ceramics were studied and compared with the textured ceramics (the same composition), which were formed due to the high degree of orientation obtained by the template grain growth method. The textured ceramics showed lower remnant polarization, while the piezoelectric coefficient (d(31)) and electromechanical coupling coefficients (k(p) and k(t)) of the textured ceramics were found to increase by about 8%, 13.3%, and 19.4%, respectively. (C) 2019 Elsevier B.V. All rights reserved.