High electronic excitations provided by swift heavy ion (SHI) irradiation of a solid can lead to the formation of long columnar defects along the ion trajectories. Such ion tracks have been observed in numerous insulators and a number of semiconductors. Metallic materials are in general less sensitive to SHI irradiation except a few selected metals (e.g. Bi, Fe, Zr, Ti) and various amorphous metallic alloys. In these amorphous metals overlapping tracks produce macroscopic anisotropic growth phenomena [1]. Characterization and imaging of single ion tracks, however, is challenging and has been successful only in a few cases using chemical track etching [2] and scanning probe [3] and transmission electron microscopy [4].

Small-angle x-ray scattering (SAXS) provides a powerful tool for measuring ion track properties and has previously been successfully used to resolve the radial density structure of tracks in amorphous SiO₂ [5]. Here, we report on SAXS measurements in amorphous metallic alloys (Fe₈₀B₂₀, Fe₈₅B₁₅, Fe₈₁B_13.5Si_3.5C₂, and Fe₄₀Ni₄₀B₂₀) irradiated with Xe and Au ions of 11.1 MeV/u energy. We demonstrate that SAXS is capable of providing evidence for ion track formation and retrieving the track radii in amorphous metallic alloys. The measurements indicate a cylindrical track structure with high aspect ratio, as expected for ion tracks, with a relatively sharp transition to the undamaged material. Despite the similar energy loss in all analysed samples, considerable differences in the track radii are observed for the different alloys. For example, in the case of Fe₈₀B₂₀ and Fe₈₅B₁₅, track radii differ by approximately 20%. Results are compared to previous data [6] and with calculations using an inelastic thermal spike model [7].

[1]   M.-D. Hou, S. Klaumünzer, G. Schumacher, Phys. Rev. B 41 (1990) 1144

[2]   C. Trautmann et al., Nucl. Instr. and Meth. In Phys. Res. B 107 (1996) 397

[3]   A. Audouard, R. Mamy, M. Toulemonde, G. Szenes , L. Thomé, Europhys. Lett. 40 (1997) 527

[4]   G. Rizza, A. Dunlop, G. Jaskierowicz, M. Kopcewicz, J. Phys: Cond. Matter 16 (2004) 1547

[5]   P. Kluth et al., Phys. Rev.  Lett. 101 (2008) 175503

[6]   A. Audouard, M. Toulemonde, G. Szenes and L. Thomé Nucl. Instr. Meth. in Phys. Res. B 146 (1998) 233

[7]   M. Toulemonde, C. Dufour and E. Paumier Phys. Rev. B 46 (1992) 14362

 

Matias Daniel Rodriguez*, Research School of Physics and Engineering, Australian National University, Australia
Boshra Afra, Research School of Physics and Engineering, Australian National University, Australia
Raquel Giulian, Research School of Physics and Engineering, Australian National University, Australia
James Leslie, Research School of Physics and Engineering, Australian National University, Australia
Christina Trautmann, GSI Helmholtz Center for Heavy Ion Research, Germany
Marcel Toulemonde, Centre interdisciplinaire de recherche sur les Ions, les Matériaux et la Photonique, France
Nigel Kirby, Australian Synchrotron, Australia
Patrick Kluth, Research School of Physics and Engineering, Australian National University, Australia
Mark Cameron Ridgway, Research School of Physics and Engineering, Australian National University, Australia

*presenting author