Maity Sumit Ranjan, Ceretti Monica, De Barros Ruben, Keller Lukas, Schefer Jürg, Cervellino Antonio, Rodríguez Velamazan J Alberto, Paulus Werner
Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut Villigen CH-5232 Switzerland
University of Geneva, Department of Quantum Matter Physics (DQMP) 24, Quai Ernest Ansermet CH-1211 Genève 4 Switzerland.
Mater Adv. 2022 Dec 13;4(2):651-661. doi: 10.1039/d2ma00833e. eCollection 2023 Jan 23.
Non-stoichiometric 214-nickelates with Ruddlesden-Popper (RP) type frameworks emerged as potential candidates for mixed electronic/ionic conductors in the intermediate temperature range. In this work we investigated structural aspects of the oxygen ion mobility diffusion mechanisms in non-stoichiometric NdNiO nickelates by X-ray (laboratory and synchrotron) as well by neutron diffraction. Temperature dependent synchrotron powder diffraction revealed a phase diagram of unprecedented complexity, involving a series of highly organized, 3D modulated phases related to oxygen ordering below 800 K. All phase transitionsimply translational periodicities exceeding 100 Å, and are found to be of 1 order, together with fast ordering kinetics. These surprising structural correlations, induced by the presence of interstitial oxygen atoms, suggest a collective phason-like oxygen diffusion mechanism together with dynamical contributions from the aperiodical lattice creating shallow diffusion pathways down to room temperature.
具有Ruddlesden-Popper（RP）型结构的非化学计量比214镍酸盐在中温范围内成为混合电子/离子导体的潜在候选材料。在这项工作中，我们通过X射线（实验室和同步加速器）以及中子衍射研究了非化学计量比钕镍酸盐中氧离子迁移扩散机制的结构方面。温度依赖的同步加速器粉末衍射揭示了一个前所未有的复杂相图，涉及一系列高度有序的三维调制相，这些相与800K以下的氧有序化有关。所有相变意味着平移周期超过100Å，并且发现它们是一级的，同时具有快速的有序动力学。由间隙氧原子的存在引起的这些惊人的结构相关性表明，存在一种类似相位子的集体氧扩散机制，以及来自非周期性晶格的动态贡献，从而形成了一直到室温的浅扩散路径。
