Lead‐free potassium sodium niobate (KNN) ferroelectrics have emerged as promising alternatives to lead‐based materials due to their reduced toxicity and sometimes enhanced properties. The opportunity to modify the ferroelectric properties by doping, nevertheless, differs from lead‐based ceramics. A much lower impact with increasing dopant concentration was observed. This study systematically investigates the differences in defect chemistry of Na0.475K0.475Li0.065Nb0.92Ta0.08O3 ceramics through iron (Fe) acceptor doping and calcium (Ca) donor doping at varying concentrations. From the defect chemical point of view, it becomes evident that the impact of intrinsic defects on the electrical properties exceeds the effect of extrinsic defects induced by doping. The performance of the donor‐doped (Ca2+) ceramics closely resembles that of undoped KNN. Thus, hardly any change in ferroelectric properties and conductivity is observed. For the Fe‐doped samples, the conductivity and its contribution to the dielectric loss increased, which is not to the benefit of an application as a ferroelectric. Therefore, the concepts of “softening” and “hardening” of ferroelectric properties by doping are incompatible with regularly sintered KNN ceramics.

中文翻译：

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铁受体掺杂和钙供体掺杂对铌酸钠基无铅压电陶瓷的影响

无铅铌酸钾钠 (KNN) 铁电体由于其毒性降低且有时性能增强，已成为铅基材料的有前景的替代品。然而，通过掺杂改变铁电特性的机会与铅基陶瓷不同。观察到掺杂剂浓度增加的影响要低得多。本研究系统地研究了Na缺陷化学的差异0.475K0.475李0.065铌0.92塔0.08氧3通过不同浓度的铁 (Fe) 受体掺杂和钙 (Ca) 供体掺杂来制备陶瓷。从缺陷化学的角度来看，很明显，本征缺陷对电性能的影响超过了掺杂引起的外在缺陷的影响。供体掺杂（Ca2+) 陶瓷与未掺杂的 KNN 非常相似。因此，几乎没有观察到铁电性质和电导率的任何变化。对于掺铁样品，电导率及其对介电损耗的贡献增加，这不利于铁电体的应用。因此，通过掺杂实现铁电性能的“软化”和“硬化”的概念与常规烧结的KNN陶瓷是不相容的。