compositions but also the temperatures, as shown in Figure 5a. Such a phase boundary is obviously different from that of PZT (see Figure 5b). Regardless of the presence of MPB or PPT characteristics, the polarization of a piezomaterial can be more easily rotated among different symmetries when the compositions are located at the phase boundaries, inducing an enhancement in dielectric and piezoelectric properties. However, recent advances indicate that there is a limited improvement in the d 33 values for KNN materials with O−T or R−O phase boundaries, 90−105,250−252 which is also inferior to most PZT ceramics 5 or even textured KNN. 12 As a result, the formation of R−T boundaries that are similar to PZT may become necessary to further enhance the piezoelectric activity of KNN, because the easy rotations of polarization axes can be induced in compositions near such a phase boundary. 11,35,70,76,106−117 In addition, we recently confirmed this assumption in potassium−sodium niobate piezoceramics by experimental methods, 106−116 and a larger d 33 value has been attained by constructing R−T phase boundaries. 106−112