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Dimorphism in iron(II) methylphosphonate: Low-temperature crystal structure and temperature-dependent Mössbauer studies of a new form of the layered weak ferromagnet Fe[(CH3PO3)(H2O)] |
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| Authors: | Philippe Lé one,Pierre Palvadeau,Alain Meerschaut,Elvira M. Bauer,Pavel Fabritchnyi |
| Affiliation: | a Laboratoire de Chimie des Solides, Institut des Matériaux Jean Rouxel, UMR CNRS 6502, 2, rue de la Houssiniere, B.P. 33229, FR-44322 Nantes, Cedex 3, France b CNR—Istituto di Struttura della Materia, via Salaria Km 29.5, C.P. 10, I-00016, Monterotondo Stazione (Roma), Italy c Department of Chemistry, M.V. Lomonosov Moscow State University, 119899 Moscow V-234, Russia |
| Abstract: | A second form of the literature-known layered weak ferromagnet Fe[(CH3PO3)(H2O)] has been isolated. The crystal structure determination of this new form (2) has been carried out at T=300, 200 and 130 K. It crystallizes in the orthorhombic space group Pmn21: a=5.7177(11), b=8.8093(18),  , while form (1) crystallizes in the space group Pna21: a=17.58(2), b=4.814(1),  . Mössbauer spectroscopy on form (2) has been performed in the temperature range 4-300 K; and, at  , a drastic change in the quadrupole splitting (ΔE) and a broadening of the doublet components is noticed. But surprisingly, on cooling the crystal, no structural change is observed, which could account for the increase in ΔE. Below  , 57Fe spectra transform into hyperfine splitting patterns which reveal a magnetically ordered state in agreement with the results of earlier magnetic susceptibility studies. |
| Keywords: | Iron phosphonate Polymorphs Crystal structure Mö ssbauer spectroscopy |
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