Materials parameters and ion-induced track formation

The role of various materials parameters in track formation is discussed. Experimental information is utilized showing a direct quantitative relationship in different solids between the melting points T-m and the ion-induced track radii R-e without involving other materials parameters. It is shown for Theta = T-m - T-ir (T-ir - irradiation temperature) that Theta similar to exp{-R-e(2)/w(2)} for S-e/N = constant, where S-e and N are the electronic stopping power and the number density of atoms and w = 4.5 nm. The validity of this universal-type relation is demonstrated for 14 different insulators including LiNbO3 and BaFe12O19. It is shown that the thermal diffusivity D, the heat of fusion L the band gap energy E-g and the absorption radius alpha(e) of the electron distribution must not affect the track sizes as this would not be coherent with this identical behavior. Original reports on LiNbO3 and BaFe12O19 with opposite conclusions are critically analyzed. It is shown that an arbitrary value of the ion energy was used in the analysis that modified substantially the results leading to an undue justification of the contribution of L and E-g in apparent agreement with the experimental data.