FERROELECTRIC PROPERTIES OF PYRIDINIUM PERIODATE

Polycrystalline pyridinium periodate has been studied over a wide rang e of temperature by differential thermal analysis, proton nuclear magn etic resonance (NMR) spectra and relaxation and complex dielectric per mittivity measurements. Two solid-solid phase transitions at 210 and 3 23 K have been revealed and the pyridinium cation reorientation in all three phases characterized. The polar properties of the intermediate phase have been demonstrated. The upper phase transition temperature a ppears to be the Curie point of a new ferroelectric compound. (C) 1998 American Institute of Physics. [S0021-9606(98)70239-9].