No abstract

Doping effects of CuO on the sintering behavior and electrical properties of 0.94(Bi[Formula: see text]Na[Formula: see text]TiO3–0.06(BaTiO[Formula: see text]–[Formula: see text]CuO (BNT–BT6–[Formula: see text]Cu) lead-free piezoceramic obtained by the conventional solid-state reaction method were investigated. Regarding the undoped system, it is already known that it presents the best densification values when it is sintered at 1150[Formula: see text]C, however, the doped system was sintered at 1150[Formula: see text]C, 1100[Formula: see text]C, 1050[Formula: see text]C, 1025[Formula: see text]C, and 975[Formula: see text]C to determine the effect of Cu on the densification process. Therefore, it was obtained that the CuO-doped samples sintered at 1050[Formula: see text]C presented the highest density values and therefore were the ones chosen to perform the characterization tests together with the undoped system. The samples were characterized using X-ray diffraction (XRD), Raman microspectroscopy, and scanning electron microscopy (SEM) analysis, whereas the ferroelectric and dielectric properties were evaluated by means of ferroelectric hysteresis loops and impedance spectroscopy studies. As a result, the addition of CuO allowed an improvement in sinterability and densification, with the subsequent grain growth, and the improvement of the piezoelectric coefficient ([Formula: see text].

Here, (K0.44Na0.52Li0.04)(Nb0.9−xTa0.1Sbx)O3 [KNL−(N0.9−xTSx)] lead-free ceramics with potential technological applications are made through B-position substitution on the perovskite structure by Sb ions. This strategy generates crystal structure changes and stabilizes a tetragonal symmetry, T, giving place to an orthorhombic (O–T) phase boundary close to room temperature. Specifically, our results establish that an increase in relative volume fractions of the T on the O–T phase boundary produces an increase in functional properties. More relevantly, this improvement in properties is accompanied by controlling the grain size. Therefore, an increase in grain size promotes the increased domain size, favoring more domain wall motion and domain switching. Both effects result in an increase in the d33 coefficient. Finally, we believe this work helps to understand the factors that determine the improvement in the functional properties of the KNN–based piezoelectric ceramics.