Issue 6, 2016

Experimental and theoretical studies of structural phase transition in a novel polar perovskite-like [C2H5NH3][Na0.5Fe0.5(HCOO)3] formate

Abstract

We report the synthesis, single crystal X-ray diffraction, and thermal, dielectric, Raman and infrared studies of a novel heterometallic formate [C2H5NH3][Na0.5Fe0.5(HCOO)3] (EtANaFe). The thermal studies show that EtANaFe undergoes a second-order phase transition at about 360 K. X-ray diffraction data revealed that the high-temperature structure is monoclinic, space group P21/n, with dynamically disordered ethylammonium (EtA+) cations. EtANaFe possesses a polar low-temperature structure with the space group Pn and, in principle, is ferroelectric below 360 K. Dielectric data show that the reciprocal of the real part of dielectric permittivity above and below the phase transition temperature follows the Curie–Weiss, as expected for a ferroelectric phase transition. Based on theoretical calculations, we estimated the polarization as (0.2, 0, 0.8) μC cm−2, i.e., lying within the ac plane. The obtained data also indicate that the driving force of the phase transition is ordering of EtA+ cations. However, this ordering is accompanied by significant distortion of the metal formate framework.

Graphical abstract: Experimental and theoretical studies of structural phase transition in a novel polar perovskite-like [C2H5NH3][Na0.5Fe0.5(HCOO)3] formate

Supplementary files

Article information

Article type
Paper
Submitted
18 Nov 2015
Accepted
16 Dec 2015
First published
18 Dec 2015

Dalton Trans., 2016,45, 2574-2583

Author version available

Experimental and theoretical studies of structural phase transition in a novel polar perovskite-like [C2H5NH3][Na0.5Fe0.5(HCOO)3] formate

M. Ptak, M. Mączka, A. Gągor, A. Sieradzki, A. Stroppa, D. Di Sante, J. M. Perez-Mato and L. Macalik, Dalton Trans., 2016, 45, 2574 DOI: 10.1039/C5DT04536C

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