The role of defects in the pressure-induced octahedral tilting in Prussian blue analogues

We propose a high-pressure study of two Prussian blue analogues, Mn[Co(CN)6]0.67 and MnPt(CN)6. Our high-pressure XRD study shows a phase transition from cubic to rhombohedral symmetry driven by octahedral tilting---like the octahedral rotations in perovskites. However, we could not reliably compare the magnitude of the tilting, as it is manifested in the positions of the cyanide linkers, which cannot be accurately determined from XRD in the presence of heavy metals. Understanding the factors that influence the amplitude of the tilting distortion is important, as tilting impacts the magnetic pathways and the electrochemical performance. In addition, exploring tilting in Prussian blue analogues is of interest from a fundamental viewpoint, to compare to the wealth of literature on oxide perovskites. This will be the first neutron study on pressure-induced rotations in these systems.