CoFe Prussian Blue Analogues under Variable Pressure. Evidence of Departure from Cubic Symmetry: X-ray Diffraction and Absorption Study

Energy dispersive X-ray diffraction and X-ray absorption spectra of two CoFe Prussian blue analogues were collected under variable pressure at room temperature: one of them is essentially composed of Co IIand Fe IIIions and undergoes a Co II−Fe III→ Co III−Fe IIpressure-induced electron transfer, whereas the other is essentially composed of Co IIIand Fe IIions whatever the pressure. In both compounds, the Co III−Fe IIphase undergoes a structural distortion upon compression. The alkali cation free CoFe Prussian blue analogue, in which the pressure-induced electron transfer occurs, exhibits a more complicated interplay between structural and electronic events. Key interatomic interactions are proposed to account for the pressure behavior of both Co III−Fe IIand Co II−Fe IIIphases.