Gabilondo Eric A, Newell Ryan J, Broughton Rachel, Koldemir Aylin, Pöttgen Rainer, Jones Jacob L, Maggard Paul A
Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA.
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-8204, USA.
Angew Chem Int Ed Engl. 2024 Jan 22;63(4):e202312130. doi: 10.1002/anie.202312130. Epub 2023 Sep 25.
The removal of lead from commercialized perovskite-oxide-based piezoceramics has been a recent major topic in materials research owing to legislation in many countries. In this regard, Sn(II)-perovskite oxides have garnered keen interest due to their predicted large spontaneous electric polarizations and isoelectronic nature for substitution of Pb(II) cations. However, they have not been considered synthesizable owing to their high metastability. Herein, the perovskite lead hafnate, i.e., PbHfO in space group Pbam, is shown to react with SnClF at a low temperature of 300 °C, and resulting in the first complete Sn(II)-for-Pb(II) substitution, i.e. SnHfO . During this topotactic transformation, a high purity and crystallinity is conserved with Pbam symmetry, as confirmed by X-ray and electron diffraction, elemental analysis, and Sn Mössbauer spectroscopy. In situ diffraction shows SnHfO also possesses reversible phase transformations and is potentially polar between ≈130-200 °C. This so-called 'de-leadification' is thus shown to represent a highly useful strategy to fully remove lead from perovskite-oxide-based piezoceramics and opening the door to new explorations of polar and antipolar Sn(II)-oxide materials.
由于许多国家的相关立法，从商业化的钙钛矿氧化物基压电陶瓷中去除铅已成为材料研究领域近期的一个主要课题。在这方面，锡（II）钙钛矿氧化物因其预计的大自发极化以及可替代铅（II）阳离子的等电子性质而备受关注。然而，由于其高亚稳性，它们一直被认为无法合成。在此，钙钛矿铪酸铅，即空间群为Pbam的PbHfO，被证明在300 °C的低温下与SnClF反应，从而首次实现了完全的锡（II）替代铅（II），即SnHfO。在这种拓扑转变过程中，通过X射线和电子衍射、元素分析以及锡穆斯堡尔光谱证实，Pbam对称性得以保持，产物具有高纯度和结晶度。原位衍射表明，SnHfO在约130 - 200 °C之间也具有可逆的相变，并且可能具有极性。因此，这种所谓的“去铅化”被证明是一种非常有用的策略，可从钙钛矿氧化物基压电陶瓷中完全去除铅，并为极性和反极性锡（II）氧化物材料的新探索打开大门。
