Electric properties of SrTiO₃ Modified (Na_0.48K_0.48Li_0.04)Nb_0.04Ta_0.05Sb_0.06O₃ Lead-Free Ceramics

In this paper, the effects of SrTiO₃ are investigated by using the solid-state reaction method for (Na_0.48K_0.48Li_0.04) Nb_0.04Ta_0.05Sb_0.06O₃ lead free ceramics (Na_0.48-xK_0.48-xLi_0.04Srx)Nb_0.04-xTixTa_0.05Sb_0.06O₃). The structural, dielectric, piezoelectric, and ferroelectric properties are discussed in detail. When the amount of SrTiO₃ dopants was increased, the phase transition temperature TO-T and Tc drastically decreased, and the phase coexistence of the orthorhombic and tetragonal phases occurred at x=0.005-0.008, leading to a significant enhancement in the electric properties of the samples. The ceramics with x=0.007 exhibited good electrical properties (d33 = 280 pCN^-1, kp = 47%, e = 1666, g33 = 19 (10-3Vm/N), d33 × g33 = 5202 (10-15m²/N), Pr = 15.1 μC/cm², and Ec = 14.2 kV/cm) compared with the pure NKN-based samples (d33 = 226 pCN^-1, kp = 44%, er = 1250, tan d = 3%, g33 = 20 (10-3Vm/N), d33 × g33 = 4615 (10-15m²/N), Pr = 9.25 μC/cm², and Ec = 9.7 kV/cm). In particular, the tan d loss of the proposed samples is only 2%, which is quite small compared to the reported data.