Calculation of the Raman frequency and the damping constant (linewidth) of the stretching modes for the metal-organic compound DMMg close to the paraelectric-ferroelectric transitions

YURTSEVEN H. H., Aslan A.

FERROELECTRICS, vol.526, no.1, pp.9-15, 2018 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 526 Issue: 1
  • Publication Date: 2018
  • Doi Number: 10.1080/00150193.2018.1456135
  • Journal Name: FERROELECTRICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.9-15
  • Middle East Technical University Affiliated: Yes

Abstract

We calculate the Raman frequencies of the two stretching modes of as a function of temperature close to the paraelectric-ferroelectric transition (Tc = 270K) in (CH3)(2)NH2Mg(HCOO)(3) referred as DMMg. By assuming that the Raman frequencies of those two modes which exhibit anomalous behaviour near Tc due to the ordering of the dimethlyammonium cations (DMA(+)) as observed experimentally, are associated with the spontaneous polarization (order parameter), their Raman frequencies and damping constants are predicted at various temperatures. The two models (pseudospin-phonon coupled and energy-fluctuation models) are used for the prediction of the damping constant which also explain the critical behaviour of the observed FWHM data for the stretching modes close to the paraelectric-ferroelectric transition in DMMg.