High-pressure synthesis and crystal structure analysis of NaMn2O4 with the calcium ferrite-type structure |
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| Authors: | Junji Akimoto Junji Awaka Yasuhiko Takahashi Kazuyasu Tokiwa |
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| Institution: | a National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
b Department of Applied Electronics, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan |
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| Abstract: | Single crystals of a new sodium manganese oxide, NaMn2O4, were synthesized for the first time using a high-temperature and high-pressure technique. The NaMn2O4 single crystal is black, has a needle shape, and crystallizes in the orthorhombic calcium ferrite-type structure, space group Pnam with  ,  ,  ,  , and Z=4. The structure was determined from a single-crystal X-ray study and refined to the conventional values R=0.041 and wR=0.034 for 1190 observed reflections. The framework structure is built up from edge-sharing chains of MnO6 octahedra that condense to form one-dimensional tunnels in which the sodium atoms are located. The Mn-O bond distance and bond valence analyses revealed the manganese valence Mn3+/Mn4+ ordering in the two “double rutile” chains of NaMn2O4. |
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| Keywords: | NaMn2O4 Sodium manganese oxide Calcium ferrite High-pressure synthesis Single-crystal X-ray diffraction Structure analysis Charge ordering |
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