Cattermull John, Roth Nikolaj, Cassidy Simon J, Pasta Mauro, Goodwin Andrew L
Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
J Am Chem Soc. 2023 Nov 8;145(44):24249-24259. doi: 10.1021/jacs.3c08751. Epub 2023 Oct 25.
We study the phenomenology of cooperative off-centering of K ions in potassiated Prussian blue analogues (PBAs). The principal distortion mechanism by which this off-centering occurs is termed a "K-ion slide", and its origin is shown to lie in the interaction between local electrostatic dipoles that couple through a combination of electrostatics and elastic strain. Using synchrotron powder X-ray diffraction measurements, we determine the crystal structures of a range of low-vacancy KM[Fe(CN)] PBAs (M = Ni, Co, Fe, Mn, Cd) and establish an empirical link between composition, temperature, and slide-distortion magnitude. Our results reflect the common underlying physics responsible for K-ion slides and their evolution with temperature and composition. Monte Carlo simulations driven by a simple model of dipolar interactions and strain coupling reproduce the general features of the experimental phase behavior. We discuss the implications of our study for optimizing the performance of PBA K-ion battery cathode materials and also its relevance to distortions in other, conceptually related, hybrid perovskites.
我们研究了钾化普鲁士蓝类似物（PBAs）中钾离子协同偏心的现象学。这种偏心发生的主要畸变机制被称为“钾离子滑动”，其起源在于通过静电和弹性应变的组合耦合的局部静电偶极子之间的相互作用。利用同步辐射粉末X射线衍射测量，我们确定了一系列低空位KM[Fe(CN)] PBAs（M = Ni、Co、Fe、Mn、Cd）的晶体结构，并建立了成分、温度和滑动畸变幅度之间的经验联系。我们的结果反映了导致钾离子滑动及其随温度和成分演变的共同基本物理原理。由偶极相互作用和应变耦合的简单模型驱动的蒙特卡罗模拟再现了实验相行为的一般特征。我们讨论了我们的研究对于优化PBA钾离子电池阴极材料性能的意义，以及它与其他概念相关的混合钙钛矿中的畸变的相关性。
