Change in the short range order in the Al - γ-MnOOH mixed system by mechanical stressing

S. Sekino, Tetsuhiko Isobe, M. Senna, T. Shinohara, F. Wagatsuma, K. Sumiyama, K. Suzuki

Research output: Chapter in Book/Report/Conference proceedingChapter

5 Citations (Scopus)

Abstract

The process of complex formation between Al and γ-MnOOH by milling was studied by 27Al-NMR, ESR and SQUID. With the progress of milling, partial amorphization took place with a swift loss of Al crystallinity. Nano-scale homogeneity increased rapidly from 10% to 70% in the first 3h of milling and approached 90% after milling for 30h. The ESR signal with g=2.009±0.003 and the hyperfine structure parameter, |A|, 81.4×10-4cm-1, appeared and increased with milling time, indicating partial and gradual change in the ionic Mn state from Mn(III) to Mn(II). At the same time, the magnetization increased, at temperatures lower than 50K. This is also attributed to the yield of the paramagnetic Mn(II) ions, i.e., and the evolution of paramagnetism from the temperature insensitive helimagnetism of the intact γ-MnOOH. A new peak at around 0 ppm appeared in 27Al-NMR spectra after milling a mixture, indicating the partial oxidation of Al. From the observations, we conclude that O2- and/or OH- ions transfer from γ-MnOOH to the vicinity of Al atoms, resulting in a redox reaction during milling. A linear relationship with negative inclination was obtained between the Knight shift (K) of 27Al-NMR and molar susceptibility (χ) for a milled mixture characterized in the temperature range of 10-290K. This fact suggests that Mn atoms are close to Al atoms and induce the hyperfine field at Al nuclei.

Original languageEnglish
Title of host publicationMaterials Science Forum
PublisherTrans Tech Publ
Pages363-368
Number of pages6
Volume312
Publication statusPublished - 1999
EventProceedings of the 1998 International Symposium on Metastable, Mechanical Alloyed and Nanocrystalline Materials, ISMANAM-98 - Wollongong, Sydney, Aust
Duration: 1998 Dec 71998 Dec 12

Other

OtherProceedings of the 1998 International Symposium on Metastable, Mechanical Alloyed and Nanocrystalline Materials, ISMANAM-98
CityWollongong, Sydney, Aust
Period98/12/798/12/12

Fingerprint

Nuclear magnetic resonance
Atoms
Paramagnetic resonance
Ions
Paramagnetism
Amorphization
Redox reactions
SQUIDs
Temperature
Magnetization
Oxidation
hydroxide ion

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Sekino, S., Isobe, T., Senna, M., Shinohara, T., Wagatsuma, F., Sumiyama, K., & Suzuki, K. (1999). Change in the short range order in the Al - γ-MnOOH mixed system by mechanical stressing. In Materials Science Forum (Vol. 312, pp. 363-368). Trans Tech Publ.

Change in the short range order in the Al - γ-MnOOH mixed system by mechanical stressing. / Sekino, S.; Isobe, Tetsuhiko; Senna, M.; Shinohara, T.; Wagatsuma, F.; Sumiyama, K.; Suzuki, K.

Materials Science Forum. Vol. 312 Trans Tech Publ, 1999. p. 363-368.

Research output: Chapter in Book/Report/Conference proceedingChapter

Sekino, S, Isobe, T, Senna, M, Shinohara, T, Wagatsuma, F, Sumiyama, K & Suzuki, K 1999, Change in the short range order in the Al - γ-MnOOH mixed system by mechanical stressing. in Materials Science Forum. vol. 312, Trans Tech Publ, pp. 363-368, Proceedings of the 1998 International Symposium on Metastable, Mechanical Alloyed and Nanocrystalline Materials, ISMANAM-98, Wollongong, Sydney, Aust, 98/12/7.
Sekino S, Isobe T, Senna M, Shinohara T, Wagatsuma F, Sumiyama K et al. Change in the short range order in the Al - γ-MnOOH mixed system by mechanical stressing. In Materials Science Forum. Vol. 312. Trans Tech Publ. 1999. p. 363-368
Sekino, S. ; Isobe, Tetsuhiko ; Senna, M. ; Shinohara, T. ; Wagatsuma, F. ; Sumiyama, K. ; Suzuki, K. / Change in the short range order in the Al - γ-MnOOH mixed system by mechanical stressing. Materials Science Forum. Vol. 312 Trans Tech Publ, 1999. pp. 363-368
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AU - Sekino, S.

AU - Isobe, Tetsuhiko

AU - Senna, M.

AU - Shinohara, T.

AU - Wagatsuma, F.

AU - Sumiyama, K.

AU - Suzuki, K.

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