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Ion-Irradiation Study of the “Exotic” Mineral Neptunite: LiNa2K(Fe,Mg,Mn)2Ti2Si8O24

  • Ray K. Eby (a1), L. M. Wang (a1), G. W. Arnold (a2) and R. C. Ewing (a1)

Abstract

Single crystals of the silicate neptunite were irradiated with 600 keV Ar2+ and 1.5 MeV Kr+ and analysed by transmission electron microscopy. Amorphization was observed in a surface layer several hundred angstroms thick following Ar2+ irradiations up to 5.0×l013 Ar/cm2, yet the Ar2+ ions travelled an average of 1/2 μm in depth. The microstructure of the amorphous surface layer depends on the ion fluence, but the amorphous layer thickness remained constant. At the highest fluence, a narrow region below the amorphous layer shows a brittle-to-ductile strain transition, due to tensional volume-expansion of the adjacent ductile amorphous layer. With 1.5 MeV Kr1+, amorphization of the electron transparent region was completed after a fluence of 1.7×l014 Kr+/cm2, and no further damage was observed up to 5.1×1015 Kr+/cm2. However, following a low fluence of 2.0×1011 Kr+/cm2, a single crystal of neptunite became a polycrystalline aggregate (grain size 10 nm) within 7 days of room temperature aging.

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References

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1. Ewing, R.C., Chakoumakos, B.B., Lumpkin, G.R. and Murakami, T., MRS Bulletin May 16, 58 (1987).
2. Wong, M.S., Karioris, F.G. and Cartz, L., Rad. Effects 106, 107 (1988).
3. Wang, L.M., Eby, R.K., Janeczek, J. and Ewing, R.C., Nucl. Instr. and Meth. B (in press).
4. Allen, C.W., Funk, L.L., Ryan, E.A. and Ockers, S.T., Nucl. Instr. and Meth. B 40/41. 553 (1989).
5. Fisher, R.X.. J. Appl. Cryst. 18, 258 (1985).
6. Biersack, J.P. and Haggmark, L.G., Nucl. Instr. and Meth. 174, 257 (1980).

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