Pressure-Induced Octahedral Rotation in RbMn[Fe(CN)₆]

Abstract

Hydrostatic pressure effect on Prussian blue type network in RbMn[Fe(CN)₆] has been investigated by high-pressure vibrational spectroscopy. Frequencies of the CN stretching modes increase as pressure increases: dhω⁄dP=6.4 cm⁻¹/GPa for A_1g mode and 4.3 cm⁻¹/GPa for E_g mode. With further increase of pressure beyond ≈2 GPa, slope of the hω–P curve becomes fairly gradual. We ascribed the behavior to the in-plane rotation of FeC₆/MnN₆ octahedra, since it compensates the pressure-induced contraction in volume.