通过变温XRD来表明相结构在温度场下的变化如图s3a所示可以看出在所有温度下的陶瓷都具有非常高的织构度f表明温度场不会影响整个陶瓷的择优取向。通过46°附近放大的图可以看出15T陶瓷的相结构变化和15R陶瓷相似可以明显在图中发现衍射峰向低角度移动不对称峰逐渐变宽成单峰表明随着温度的升高晶格膨胀相结构的对称性增加T-PC相逐渐向更高对称性的PC相转变这个转变过程为弥散型相变涉及温度较宽表明相结构具有

The variation of phase structure under temperature field can be demonstrated by variable temperature XRD, as shown in Figure S3a. It can be seen that all ceramics have very high texture degree f at all temperatures, indicating that the temperature field does not affect the preferred orientation of the entire ceramic. By zooming in on the region around 46°, it can be seen that the phase structure of 1.5T ceramic is similar to that of 1.5R ceramic. The diffraction peak gradually shifts to lower angles, and the asymmetric peak gradually becomes a single peak, indicating that with the increase of temperature, the lattice expands, the symmetry of the phase structure increases, and the T-PC phase gradually transforms into a higher symmetry PC phase. This transformation process is a diffuse phase transition, involving a wide temperature range, indicating that the phase structure has excellent temperature stability. According to previous reports, the temperature stability of NN-based piezoelectric ceramics mainly comes from the tilting of Nb-O octahedra.