High piezoelectric and dielectric constant of Fe/In Co-doped KNN-based ceramics regulated by lattice distortion

The new (0.96- x )(K 0.48 Na 0.52 Nb 0.96 Sb 0.04 )O 3 -0.04(Bi 0.5 Ag 0.5 )ZrO 3 - x (Fe 2 O 3 -In 2 O 3 ) ceramics with high dielectric, and electromechanical coupling properties were designed. In this work, the effect of KNN-based ceramics lattice distortion (c/a) and microstructure on the electrical properties was explored by varying the doping amount of Fe 3+ and In 3+ . The problem of a large number of oxygen vacancies generated by the volatilization of K and Na can be well solved by introducing Fe 3+ and In 3+ . The bulk density increases significantly and the maximum value is about 4.52 g/cm 3 .The sample with x = 0.003 has the smallest c/a, and exhibits the best piezoelectric and dielectric properties ( d 33 = 536 pC/N, ε r = 3432 and k p = 55.8 %). Low doping concentration of Fe 2 O 3 is considered a “soft” addition for KNN-based piezoelectric ceramics. The study of this mechanism provides a new idea to regulate the electrical performance of KNN-based ceramics.