Inorganic compounds containing Mn(V) in tetrahedral coordination are known to show strong optical absorption, producing turquoise- to green-colored compounds . The existence of hypermanganate anion MnO43- has been found, for example, in the Ba5(PO4)3-x(MnO4)xCl . However, Mn(V) is very rarely found in oxides. The ability of Mn to be stabilized in mixed oxidation states leads in turn to interplay among spin, charge, and orbital degrees of freedom. In this sense, it has been recently reported that the electrochemical activity of the Mn(IV)/Mn(V) couple, plays a very important role in the discharge capacity of the nanostructured Li4Mn2O5 material .
In this work we show the characterization of a Sr-Mn (V) oxide with blue-greenish color and nominal composition Sr2(MnO4)(OH) . Atomically-resolved high angle annular dark field (HAADF) images acquired in a JEOL JEMARM200cF microscope shows that the Sr-Mn oxide crystallizes according to the apatite-type structure . In this structure, each Mn ion is coordinated by distorted oxygen tetrahedral giving rise to isolated MnO4 tetrahedra (Figure 1). Evidence of Mn(V) was shown by high energy resolution Electron Energy Loss Spectroscopy (EELS) (Figure 2a). However, contrast variations in the hexagonal tunnels of the apatite structure suggest either the direct imaging of light OH groups in the HAADF image or the presence of a heaviest element in these positions. Image simulation is used to elucidate the origin of such contrast because of the low stability of the sample under the electron beam prevents point-by-point spectroscopic analysis (Figures 2b and 2c).
 P. Jiang et al. Inorg. Chem. 52 (2013), pp.1349
 M. Uchida, J. Phys. Soc. Japan, 70 (2001), pp.1790
 M. Freire et al. Nat. Mat. 15 (2016), pp. 173
 E. J. Baran et al. Monatshefte für Chemie, 100 (1969), pp. 1674
 E. Banks et al. Inorg. Chem. 4 (1965), pp. 78
To cite this abstract:Isabel Gómez-Recio, Almudena Torres-Pardo, María Hernando , Aurea Varela, Marina Parras, Jose Maria Gonzalez-Calbet; Atomically-resolved insight of unusual Sr-Mn(V) oxyhydroxide. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/atomically-resolved-insight-of-unusual-sr-mnv-oxyhydroxide/. Accessed: September 20, 2021
EMC Abstracts - https://emc-proceedings.com/abstract/atomically-resolved-insight-of-unusual-sr-mnv-oxyhydroxide/