图4c显示了随机取向织构化NN-10BTS-xNS陶瓷的d33随组分变化图可以明显看出随着NS的含量增加首先增加然后降低。15T和15R都获得了最高的压电系数分别是330 pCN和423 pCN主要得益于相结构共存、RFNs和局部不均匀性带来的高εr和TMs贡献的高Pr。与随机陶瓷相对比所有相同组成的织构化陶瓷的压电系数表现出不同幅度增强而幅度的不同与相结构有很大的关系。可以发现具有O-T相界的0

Figure 4c shows the d33 versus composition plot for randomly oriented/textured NN-10BTS-xNS ceramics, and it is evident that d33 first increases and then decreases with increasing NS content. The highest piezoelectric coefficients were achieved for 1.5T and 1.5R, which were 330 pC/N and 423 pC/N, respectively, mainly due to the high εr and TMs contributions from the coexistence of phases, RFNs, and local inhomogeneity. Compared to the randomly oriented ceramics, all textured ceramics with the same composition exhibited varying degrees of enhancement in piezoelectric coefficients, which were strongly correlated with the phase structure. It was found that the d33 enhancement rate of 0R with O-T phase boundary was 64% after texturing, while that of 1.5R ceramics with O-T-PC phase boundary was only 28%, and the enhancement rate was lower than that of other lead-free piezoelectric ceramics, similar to that of relaxor-based lead-based piezoelectric ceramics. A large number of studies on piezoelectric crystallography have shown that different engineered domain structures directly affect the level of piezoelectric activity. The ways in which the engineered domain structure affects piezoelectric performance mainly depend on the number of electric domains with equal energy constituting the domain structure, denoted as N, and the angle θ between the electric field and the polarization vector. The more N and the smaller θ, the more the electric domains are prone to flip under the induction of the electric field, resulting in higher piezoelectric performance. Along the <001>c direction, the O, T, and R phases form "4O", "1T", and "4R" structures, respectively. Among them, the O phase has the largest N value and the smallest θ, which is most likely to induce higher longitudinal piezoelectric response, followed by the R phase, and finally the T phase. Although the XRD pattern indicates that the 0T composition mainly consists of T phase, the O-T phase transition position still covers room temperature, with a small amount of O phase, which benefits from the engineered domain structure of the O phase, leading to a large enhancement rate of d33 for the 0T composition. In the 1.0T, 1.5T, and 2.0T compositions dominated by the T-PC phase, the T phase structure only has a "1T" engineered domain structure. Although the PC phase has a triclinic tilt feature, it has high symmetry and is related to RFNs, which cannot generate very effective engineered domain structures, thus suppressing the significant enhancement of the piezoelectric response. Moreover, the response of the dielectric constant was generally suppressed in the textured relaxor piezoelectric ceramics, which again suppressed the piezoelectric enhancement brought about by texturing.