Synthesis and order-disorder transition in a novel metal formate framework of [(CH sub(3)) sub(2)NH sub(2 )]Na sub(0.5)Fe sub(0.5)(HCOO) sub(3)

• Published in: Dalton transactions : an international journal of inorganic chemistry 2014-10, Vol.43 (45), p.17075-17084
• Main Authors: Maczka, Miroslaw, Pietraszko, Adam, Macalik, Lucyna, Sieradzki, Adam, Trzmiel, Justyna, Pikul, Adam
• Format: Article
• Language: English
• Subjects: Cations; Dielectrics; Ferromagnetism; Metal formates; Order disorder; Phase transformations; Symmetry; Synthesis (chemistry)
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c4dt02586e

We report the synthesis, crystal structure, thermal, dielectric, Raman, infrared, and magnetic properties of [(CH sub(3)) sub(2)NH sub(2 )][Na sub(0.5)Fe sub(0.5)(HCOO) sub(3)] (DMNaFe), the first metal formate framework templated by organic cations, presenting an ABO sub(3) perovskite architecture with NaO sub(6) octahedra as building blocks of the framework. On the basis of Raman and IR data, assignment of the observed modes to respective vibrations of atoms is proposed. We have found that DMNaFe undergoes a structural phase transition at 167 K on cooling. According to the X-ray diffraction, the compound shows R3&cmb.macr; symmetry at 293 K and triclinic P1&cmb.macr; symmetry at 110 K. The DMA super(+) cations are dynamically disordered in the high-temperature phase and the phase transition is associated with ordering of the DMA super(+) cations and distortion of the metal formate framework. The dielectric studies reveal pronounced dielectric dispersion that can be attributed to slow dynamics of the DMA super(+) cations. Based on the low-temperature magnetic studies, this compound is a weak ferromagnet with a critical temperature 8.5 K.