Influence of chemically synthesized powder addition on K0.5Na0.5NbO3 ceramic’s properties

Abstract

A new strategy to produce lead-free K0.5Na0.5NbO3 (KNN) piezoceramics with reliable and improved piezoelectric performance is presented for the first time. KNN powders were synthesized using two distinct synthesis routes: a mechanochemical activation-assisted solid-state route (KNNSSR) and a sol–gel modified Pechini method (KNNchem). KNNchem powders were mixed with KNNSSR at different weight ratios (0, 3, 5, 10 and 20 wt%), and the mixtures were conventionally consolidated and sintered at 1130 °C for 2 h. It was found that KNNchem powders influence crystal phase, microstructure and piezoelectric properties of the sintered pellets. Gradually increasing KNNchem content promotes the conversion of the undesired phase present in KNNSSR into the stoichiometric one. It is also proved that the addition of KNNchem between 5 and 10 wt% improves piezoelectric properties, eventually leading to a d33 piezoelectric charge constant value of 113–115 pC/N. These values are among the highest reported for undoped KNN ceramics obtained by conventional sintering.

Mechanochemical synthesis of nanostructured and composite oxide ceramics: From mechanisms to tailored properties

“…The homogenization piezoelectric properties of KNN ceramics could be improved by adding the same chemical dose of KNN powder. 175 The research conducted by Lee et al 176 reinforces the efficiency of mechanochemical synthesis. In Figure 12A, with only 5-10 min of ball milling the characteristic diffraction peaks related to perovskite structure began to appear.…”

“…With extension of the activation time, the agglomeration of large pieces gradually decreased. The homogenization piezoelectric properties of KNN ceramics could be improved by adding the same chemical dose of KNN powder 175 …”