Designed morphotropic relaxor boundary ceramic exhibiting large electrostrain and negligible hysteresis
Designed morphotropic relaxor boundary ceramic exhibiting large electrostrain and negligible hysteresis
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DOI：
10.1016/j.actamat.2021.116720
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发表时间：
2021-04
期刊：
影响因子：
9.4
通讯作者：
Yang Yang-Yang;Chang Liu;Yuanchao Ji;Liqiang He;X. Ren
中科院分区：
文献类型：
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作者：
Yang Yang-Yang;Chang Liu;Yuanchao Ji;Liqiang He;X. Ren
具有大电应变和低滞后的机电材料强烈需要用于高精度致动器应用。尽管半个多世纪以来的广泛研究，但由于所谓的应变-滞后权衡，同时获得大的电应变和低的滞后仍然是一个挑战。在这里，我们报告了一种机制，以克服这种权衡：陶瓷组合物位于一个morphotropic弛豫边界（MRB），表现出增强的电应变和减少滞后相比，关闭MRB组合物。在Pb（Mg 1/3 Nb 2/3）O3-xPbTiO 3（PMN-xPT）中，通过掺杂La，改变准同型相界（MPB），得到了分离两个具有不同局部极性对称性的弛豫子的组分诱导相界MRB。MRB组分的0.227%的大电应变和3%的可忽略的滞后的性能是最好的，这通过在弛豫机电陶瓷的应变-滞后图中占据空白区域来证明。此外，这种MRB陶瓷在35至-35 °C的温度范围内保持大的电应变和低滞后。结合微观结构观察和朗道理论分析，建立了对MRB异常效应的理解：具有准同型纳米畴结构和较高局部结构不均匀性的MRB组分显示出更平坦的能量分布和更低的能垒，从而导致大的电应变和可忽略的滞后。我们的工作表明，MRB是一种有效的机制，设计弛豫材料，同时具有大的电应变和低滞后。我们预测，更高性能的MRB机电材料将被发现在适当掺杂的MPB系统。
Electromechanical materials with large electrostrain and low hysteresis are strongly desired for high-precision actuator applications. Despite extensive studies for more than half a century, it is still a challenge to obtain large electrostrain and low hysteresis simultaneously due to the so-called strain-hysteresis trade-off. Here, we report a mechanism to overcome this trade-off: a ceramic composition locating at a morphotropic relaxor boundary (MRB), exhibits enhanced electrostrain and reduced hysteresis as compared with off-MRB compositions. The MRB, a composition-induced boundary separating two relaxors with different local polar symmetries, is attained by transforming an morphotropic phase boundary (MPB) in Pb(Mg1/3Nb2/3)O3-xPbTiO3(PMN-xPT) through doping lanthanum. The performances of large electrostrain of 0.227% and negligible hysteresis of 3% of MRB composition are the best, as evidenced by occupying a virgin region in the strain-hysteresis chart of relaxor electromechanical ceramics. Moreover, this MRB ceramic maintains the large electrostrain and low hysteresis over a temperature range from 35 to -35 °C. The understanding of abnormal effects of MRB is established through combining microstructure observations and Landau theory analysis: the MRB composition with morphotropic nanodomain structure and higher degree of local structural heterogeneity shows a flatter energy profile with much lower energy barrier, thereby leading to a large electrostrain and negligible hysteresis. Our work demonstrates that the MRB is an effective mechanism to design relaxor materials with large electrostrain and low hysteresis simultaneously. We predict that more high-performance MRB electromechanical materials will be found in properly doped MPB systems.