Study on the Structure and Properties of SrTiO3 Modified K0.5Na0.5NbO3 lead-Free Ceramics with a Sintering Aid of NiO

Abstract

In this experiment, a new piezoelectric ceramic system (1-x)K0.5Na0.5NbO3-xSrTiO3−0.4%molNiO (abbreviated as KNNST) with high properties and density was obtained by using K0.5Na0.5NbO3 (abbreviated as KNN) as matrix, adding new component SrTiO3 and sintering aid NiO, and adopting traditional solid-state sintering process at lower sintering temperature. XRD, SEM and other modern test analysis show that when a small amount of sintering aid NiO is added, KNNST ceramic samples with SrTiO3 doping in the range of 0 ≤ x ≤ 0.08 can form a single perovskite structure without any impurity phase. When 0.02 < x < 0.06, KNNST ceramics exist a polymorphic phase boundary (PPB) between orthorhombic and tetragonal phases, and thus excellent properties were obtained when x = 0.04, they are respectively d 33 = 287pC/N, k p = 48%, ε r = 1216, tanδ = 2.2%, T C = 373°C, P r = 26.5 μC cm−2, E C = 2.06 kV mm−1. This shows that by introducing new component and adding sintering aid, a new phase boundary can be constructed, a new solid solution ceramic can be formed, and the compactness and electrical properties of the KNNST ceramics can be improved. This provides an effective way to improve the properties of KNN based piezoelectric ceramics, and also provides hope for practical applications.