Composition dependent thermal annealing behaviour of ion tracks in apatite

Abstract

Natural apatite samples with different F/Cl content from a variety of geological locations (Durango, Mexico; Mud Tank, Australia; and Snarum, Norway) were irradiated with swift heavy ions to simulate fission tracks. The annealing kinetics of the resulting ion tracks was investigated using synchrotron-based small-angle x-ray scattering (SAXS) combined with ex situ annealing. The activation energies for track recrystallization were extracted and consistent with previous studies using track-etching, tracks in the chlorine-rich Snarum apatite are more resistant to annealing than in the other compositions.

SAXS data modelling for the characterisation of ion tracks in polymers

“…For inorganic insulators, the thermal-spike model suggests melting can occur inside the track core, [82][83][84] and the track boundary can be very sharp, for example when the track remains as an amorphous inclusion in a crystalline matrix as observed for quartz and mineral apatite. 64,65,85,86 In these cases, the transition region is insignificant, hence one would expect that the Core Transition Model is unnecessary. On the other hand, a 'Core Shell Model' has been successfully applied to show the finer structure of ion tracks in amorphous insulators like silicon dioxide, silicon nitride and silicon oxynitrides.…”

Long-term reactivation and morphotectonic history of the Zambezi Belt, northern Zimbabwe, revealed by multi-method thermochronometry

“…Although the final track length is primarily a function of the maximum temperature to which an apatite was subjected, the rate of annealing is also affected by individual grain compositions with the Cl/F ratio thought to exert the greatest influence such that Cl-rich apatites are more resistant to annealing (Barbarand et al, 2003;Burtner et al, 1994). Additionally, the crystallographic orientation of a track also affects its annealing rate, with tracks oriented parallel to the crystallographic c-axis being more resistant to annealing than those perpendicular to the c-axis (Green and Durrani, 1977;Nadzri et al, 2017). Compositional effects and anisotropic annealing will be accounted for during the inverse thermal history modelling process (see Section 5.1 for more details).…”

Quantitative Identification of the Annealing Degree of Apatite Fission Tracks Using Terahertz Time Domain Spectroscopy (THz-TDS)

“…The number of confined tracks is far lower than that of surface tracks, and thus can be ignored when calculating the total track volume. The volume of the surface track is actually only part of its original track volume, and therefore should be multiplied by a geometric factor η 35,36 when calculating the total track volume ( V t ). Consequently, in which N is the number of apatite particles in the test point, ρ is the fission-track density, and S is the mean particle surface area within the test point.…”

“…The difference in the diameters of latent tracks (only a few nanometers 7,36 ) can be negligible because the diameters of etched tracks are approximately 0.89 µm (Fig. 3).…”

“…The number of confined tracks is far lower than that of surface tracks, and thus can be ignored when calculating the total track volume. The volume of the surface track is actually only part of its original track volume, and therefore should be multiplied by a geometric factor Z 35,36 when calculating the total track volume (…”