The passage of a swift heavy ion through a material can cause columnar, amorphous nano-structures known as ion tracks. Swift heavy ions are present in a number of applications ranging from nuclear reactors to nuclear waste storage and onboard spacecraft. The study of ion tracks has been ongoing since the late 1950s and has led to several technological advancements. In fact, ion beams have been used to enhance material properties and aid in the production of electrical components. Ion beams, and their resultant ion tracks, can therefore be seen as a method to purposefully alter material properties such as thermal diffusivity. One method through which ion tracks can alter material properties is through the alteration of phonon transport. It is expected that phonons are spatially confined between ion tracks.
In this study, Z- and Y-cut α-quartz single crystalline samples were irradiated with 20 MeV nickel 6+ ions. These crystals were irradiated to nominal fluence values of 1.0x109, 1.0x1010, and 1.0x1012 ions cm-2. The crystals were irradiated with varying fluence values in order to understand how the spacing of ion tracks affects phonon transport. An Inelastic Thermal Spike model was also developed to model the track radii. The Thermal Spike model allows for the effects of track size to also be taken in to account. In addition, Raman spectroscopy was performed for each fluence value. The effects of ion tracks on phonon confinement were understood by examining how the peak parameters changed with increasing fluence and comparing the parameters to the phonon dispersion relations for α-quartz --Abstract, page iii
