Microstructure of Nanocrystalline Electrolytic $MnO_2$ (EMD)

Nanocrystalline Electrolytic $MnO_2$ (EMD)의 미세구조 연구

  • ;
  • Anqiang He (Department of Chemical & Materials Engineering, University of Alberta) ;
  • Arthur H. Heuer (Department of Materials Science & Engineering)
  • Published : 2003.06.01

Abstract

The microstructure of bulk electrolytic MnO₂ (EMD) was studied using x-ray diffraction and transmission electron microscopy (TEM). The bulk sample showed a typical powder x-ray diffraction pattern of EMD materials. TEM study showed that the structure of EMD is present at two length scales;grains, ∼0.2 ㎛ in diameter, and ∼10 nm crystallites within the grain. The electron beam microdiffraction study revealed that each grain is an assemblage of multiphase with a common crystallographic orientation, and_that ∼50% of the crystallites are Ramsdellite, ∼30% are ε-MnO₂, and ∼15% are Pyrolusite. The {1120}peak located at about 67° in powder XRD pattern as well as a high-resolution electron microscope (HREM) image of (0001) plane support the existence of ε-MnO₂ phase.

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References

  1. Chabre, Y. and Pannetier, J., 'Structural and Electrochemical Properties of the Proton/$\gamma$-$MnO_2$ System, Prog. Solid State Chem., 23, 1-130 (1995)
  2. Andersen, T. N., 'Effect of Some EMD Structural Features on Alkaline Discharge Capacity', Progress in Batteries and Battery Materials, 11, 105-129 (1992)
  3. Williams, R., Fredlein, R., Lawrance, G., Swinkels, D. and Ward, C., 'Effect of Deposition Conditions on the Structural, Chemical, Physical and Electrochemical Properties of EMD', Progress in Batteries and Battery Materials, 13, 102-112 (1994)
  4. de Wolff, P. M., Visser, J. W., Giovanoli, R. and Brutsch, R., '$\"{U}$ber $\varepsilon$-Mangandioxid', Chimia, 32, 257-259 (1978)
  5. Simon, D. E., Andersen, T. N. and Elliot, C. D., 'A Rietveld Refinement Model of EMD Powder Patterns', ITE Letters, 1(3), B1-B10 (2000)
  6. Heuer, A. H., He, A. Q., Hughes, P. J. and Feddrix, F. H., 'Microstructure of Electrolytic MnO2: A Transmission Electron Microscopy Study of Bulk Material', ITE Letters, 1(6), B50-B54 (2000)
  7. de Wolff, P. M., 'Interpretation of Some $\gamma$-$MnO_2$Diffraction Patterns', Acta Crystallogr., 12, 341-345 (1959)
  8. Heuer, A. H., Kim, C. H., Zhang, L. C. and He, A. Q., 'HREM Studies of Nanocrystalline Electrolytic $MnO_2$ (EMD)', Proc. of 7th Int. Symp. Adv. Phys. Fields, pp. 92-95, Tsukuba, Japan (2001)