Denticity and Mobility of the Carbonate Groups in AMCO3F Fluorocarbonates: A Study on KMnCO3F and High Temperature KCaCO3F Polymorph
[4]
- College de France, Paris Cedex (France); Sorbonne Univ.-UPMC Univ. Paris (France); Réseau sur le Stockage Electrochimique de l’Energie (RS2E), Amiens Cedex (France)
- Réseau sur le Stockage Electrochimique de l’Energie (RS2E), Amiens Cedex (France); Lab. de Réactivité et Chimie des Solides, Amiens Cedex (France); ALISTORE-European Research Inst., Amiens (France)
- Paul Scherrer Inst., Villigen (Switzerland)
- Skolkovo Inst. of Science and Technology, Moscow (Russia)
We report on a thorough structural study on two members of layered fluorocarbonates KMCO3F (M = Ca, Mn). The Ca-based member demonstrates a phase transition at ~320 °C, evidenced for the first time. The crystal structure of the high temperature phase (HT-KCaCO3F) was solved using neutron powder diffraction. A new Mn-based phase KMnCO3F was synthesized, and its crystal structure was solved from electron diffraction tomography data and refined from a combination of X-ray synchrotron and neutron powder diffraction. In contrast to other members of the fluorocarbonate family, the carbonate groups in the KMnCO3F and HT-KCaCO3F structures are not fixed to two distinct orientations corresponding to mono- and bidentate coordinations of the M cation. In KMnCO3F, the carbonate group can be considered as nearly “monodentate”, forming one short (2.14 Å) and one long (3.01 Å) Mn–O contact. This topology provides more flexibility to the MCO3 layer and enables diminishing the mismatch between the MCO3 and KF layers. This conclusion is corroborated by the HT-KCaCO3F structure, in which the carbonate groups can additionally be tilted away from the layer plane thus relieving the strain arising from geometrical mismatch between the layers. The correlation between denticity of the carbonate groups, their mobility, and cation size variance is discussed. KMnCO3 orders antiferromagnetically below TN = 40 K.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1410124
- Journal Information:
- Inorganic Chemistry, Vol. 56, Issue 21; ISSN 0020-1669
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
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