Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
Adv Mater. 2023 Jun;35(24):e2300257. doi: 10.1002/adma.202300257. Epub 2023 May 1.
Antiferroelectrics, which undergo a field-induced phase transition to ferroelectric order that manifests as double-hysteresis polarization switching, exhibit great potential for dielectric, electromechanical, and electrothermal applications. Compared to their ferroelectric cousins, however, considerably fewer efforts have been made to understand and control antiferroelectrics. Here, it is demonstrated that the polarization switching behavior of an antiferroelectric can be strongly influenced and effectively regulated by point defects. In films of the canonical antiferroelectric PbZrO , decreasing oxygen pressure during deposition (and thus increasing adatom kinetic energy) causes unexpected "ferroelectric-like" polarization switching although the films remain in the expected antiferroelectric orthorhombic phase. This "ferroelectric-like" switching is correlated with the creation of bombardment-induced point-defect complexes which pin the antiferroelectric-ferroelectric phase boundaries, and thus effectively delay the phase transition under changing field. The effective pinning energy is extracted via temperature-dependent switching-kinetics studies. In turn, by controlling the concentration of defect complexes, the dielectric tunability of the PbZrO can be adjusted, including being able to convert between "positive" and "negative" tunability near zero field. This work reveals the important role and strong capability of defects to engineer antiferroelectrics for new performance and functionalities.
反铁电体在电场作用下会发生相转变，表现为双滞后极化反转，在介电、机电和电热应用方面具有很大的潜力。然而，与铁电体相比，人们对反铁电体的理解和控制要少得多。本文证明，点缺陷可以强烈影响和有效调节反铁电体的极化反转行为。在典型的反铁电体 PbZrO 薄膜中，沉积过程中降低氧压（从而增加原子动能）会导致出人意料的“类铁电”极化反转，尽管薄膜仍处于预期的反铁电正交相。这种“类铁电”开关与轰击诱导点缺陷复合物的形成有关，这些复合物固定了反铁电-铁电相界，从而有效地延迟了在变化的电场下的相变。有效钉扎能通过温度相关的开关动力学研究来提取。反过来，通过控制缺陷复合物的浓度，可以调整 PbZrO 的介电可调谐性，包括能够在零场附近在“正”和“负”可调谐性之间转换。这项工作揭示了缺陷在反铁电体工程中的重要作用和强大能力，以实现新的性能和功能。
