Eliminating the negative effect of monoclinic Nb ₂ O ₅ on electrical properties of (K _0.5 Na _0.5 )NbO ₃ ceramics by two‐step sintering

Abstract This study investigates the electrical properties of (K _0.5 Na _0.5 )NbO ₃ ( KNN ) lead‐free piezoelectric ceramics prepared by using monoclinic Nb ₂ O ₅ as the starting material. The results reveal that the samples prepared by two‐step sintering procedure are much better than those prepared by conventional sintering procedure. The piezoelectric constant ( d ₃₃ ) reaches the value measured from the samples prepared from orthorhombic Nb ₂ O ₅ , suggesting the two‐step sintering procedure could be an effective method to remove the negative effect of monoclinic Nb ₂ O ₅ . The underlying mechanism for the improving effect is discussed.