Dielectric and piezoelectric properties of Fe2O3-doped (Na0.5K0.5)0.96Li0.04Nb0.86Ta0.1Sb0.04O3 lead-free ceramics

The effect of a small amount Fe2O3 (0.1-2 mol%) doping on the electrical properties of (Na0.5K0.5)0.96Li0.04Nb0.86Ta0.1Sb0.04O3 (NKLNTS) ceramics was investigated. It was found that the B-site substitution of Fe3+ does not change the crystal structure within the studied doping level and all modified ceramics have a pure tetragonal perovskite structure at room temperature. The addition of Fe2O3 can promote the sintering of NKLNTS ceramics, and simultaneously cause the grain growth so that Fe3+-doped NKLNTS compositions show degraded densification at higher doping level. Furthermore, the dielectric properties of the NKLNTS ceramics do not show a significant change by Fe2O3 doping. However, the addition of Fe2O3 was found to have a significant influence on the electric fatigue resistance and the durability against water. The presence of oxygen vacancies caused by the replacement of Fe3+ for B-site ions makes the NKLNTS ceramics harder.