Far-infrared spectra and ferroelectricphase transition of KNO3

Publisher Website
Google Scholar
Abstract
Far-infrared reflectivity spectra of phases I, II and III of potassium nitrate were obtained over a range of 20-400 cm-1. The two infrared active lattice modes observed are described by parameters obtained from a classical oscillator analysis, which was confirmed by a Kramers-Kronig analysis. From the temperature dependence of the mode parameters and their contribution to the dielectric constant it was concluded the paraelectric phase I is a disordered arrangement of electric dipoles. From this it follows that the paraelectric-to-ferroelectric phase change is an order-disorder transition.