Infrared spectra of iron, zinc and magnesium fluorides: I. Analysis of results

Publisher Website
Google Scholar
Abstract
In this work the authors review the different models and methods used to analyse the IR reflection spectra of iron, zinc and magnesium fluorides, between 4.2 and 300 K. They especially show that the four-parameter oscillator model, presented by Gervais (1974), gives results similar to those obtained by other methods, but also a more accurate determination of the longitudinal-mode frequencies. The authors have shown clearly, for the mode A2u, the occurrence of abnormal behaviour of the longitudinal frequencies with temperature. This result allowed them to consider, for zinc and magnesium fluorides, the presence of an incipient ferroelectric order at low temperature. They show also how they have been forced to consider an additional oscillator in the symmetry spectrum Eu.