(1-x)Pb(Zn_1/3Nb_2/3)O₃-xPbTiO₃ ((1-x)PZN-xPT in short) is one of the most important piezoelectric materials. In this work, we extensively investigated (1-x)PZN-xPT (x = 0.07–0.11) ferroelectric single crystals using in-situ synchrotron μXRD, complemented by TEM and PFM, to correlate microstructures with phase transitions. The results reveal that (i) at 25 °C, the equilibrium state of (1-x)PZN-xPT is a metastable orthorhombic phase for x = 0.07 and 0.08, while it shows coexistence of orthorhombic and tetragonal phases for x = 0.09 and x = 0.11, with all ferroelectric phases accompanied by ferroelastic domains; (ii) upon heating, the phase transformation in x = 0.07 is Orthorhombic → Monoclinic → Tetragonal → Cubic. The coexistence of ferroelectric tetragonal and paraelectric cubic phases was in-situ observed in x = 0.08 above Curie temperature (T_C), and (iii) phase transition can be explained by the evolution of the ferroelectric and ferroelastic domains. These results disclose that (1-x)PZN-xPT are in an unstable regime, which is possible factor for its anomalous dielectric response and high piezoelectric coefficient.

（1-x）Pb（Zn _1/3 Nb _2/3）O ₃ -xPbTiO ₃（简称（1-x）PZN-xPT）是最重要的压电材料之一。在这项工作中，我们使用原位研究了（1-x）PZN-xPT（x = 0.07-0.11）铁电单晶同步加速器μXRD，辅以TEM和PFM，使微结构与相变相关。结果表明：（i）在25°C下，（x）= 0.07和0.08时，（1-x）PZN-xPT的平衡状态为亚稳态斜方晶相，当x = 0.09和（x）0.06时，它显示正交相和四方相共存。 x = 0.11，所有铁电相都带有铁弹性域；（ii）加热后，x = 0.07的相变为正交晶→单斜晶→四方晶→立方晶。在居里温度（T _C）以上x = 0.08处原位观察到铁电四方相和顺电立方相的共存）和（iii）相变可以通过铁电和铁弹性畴的演化来解释。这些结果表明（1-x）PZN-xPT处于不稳定状态，这可能是其异常介电响应和高压电系数的可能原因。