Proton Magnetic Resonance Study of Ferroelectric Potassium Ferrocyanide Trihydrate

Abstract

Proton magnetic resonance and vibrational spectra of potassium ferrocyanide trihydrate have been studied between 77° and 300°K. From the observed two sets of O–H stretching frequencies it has been possible to suggest the probable positions of four previously undetermined water molecules in the unit cell. Changes in the vibrational spectra and in the proton resonance second moment in the neighborhood of the Curie point indicate that the onset of ferroelectric behavior is associated with a dynamical orientational ordering of the hydrogen‐bonded water molecules. Apparently there is also a contribution to the spontaneous polarization and internal field from displacements and polarizability of the K⁺ and Fe(CN)₆^—4 ions.