Synchrotron x-ray diffraction analysis of gadolinium and lanthanum titanate oxides irradiated by xenon and tantalum swif
- PDF / 3,928,365 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 83 Downloads / 160 Views
Synchrotron x-ray diffraction analysis of gadolinium and lanthanum titanate oxides irradiated by xenon and tantalum swift heavy ions Sulgiye Park1, Maik Lang2, Cameron L. Tracy3, Fuxiang Zhang4, Christina Trautmann5,6,Zhongwu Wang7, Rodney C. Ewing1 1
Department of Geological and Environmental Sciences, Stanford University, Stanford, CA, 94305, USA Department of Nuclear Engineering, University of Tennessee, TN, 37996, USA 3 Department of Materials Science & Engineering, University of Michigan, Ann Arbor, MI 48109, USA 4 Department of Earth & Environmental Sciences, University of Michigan, Ann Arbor, MI 48109, USA 5 GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany 6 Technische Universität Darmstadt, 64287 Darmstadt, Germany 7 Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY 14853, USA 2
ABSTRACT A synthetic cubic pyrochlore, Gd2Ti2O7 (Fd m) irradiated with swift heavy ions is compared with a compositionally-related composition La2Ti2O7 (P21), which has a monoclinic, layered, perovskite-type structure. Irradiation experiments were performed at the GSI Helmholtz Center with 181Ta ions and 129Xe ions at specific energies of 11MeV/amu. At these energies the ions pass entirely through the sample thickness of ~ 40 μm. Angle-dispersive synchrotron powder xray diffraction (XRD) measurements were completed and an increasing ion-induced amorphization with increasing ion fluence was for both phases. The ion track cross-sections for the radiation-induced crystalline-to-amorphous transformation, as determined from the evolution of the integrated peak intensities as a function of fluence, reveal that La2Ti2O7 (track diameter, d ~ 7.2 nm with 181Ta and 5.1 nm with 129Xe) is more susceptible to amorphization than Gd2Ti2O7 (d ~ 6.2 nm with 181Ta and 4.6 nm with 129Xe). The radiation response of the two titanate compounds can be understood in the context of their different structures and cation ionic radius ratios rA/rB, where the susceptibility of radiation of titanate pyrochlores is proportionate with this radius ratio. The higher electronic linear energy loss of the 181Ta ions as compared with 129Xe ions leads to a consistent increase of volume amorphized per ion in both materials, which manifests as a larger track diameter. INTRODUCTION The highly localized energy deposition caused by swift heavy ions with has been used to study the radiation response of two compositionally-related complex oxides. Such energetic ions transfer their energy to the electrons along the ion path via electronic excitation and ionization (electronic energy loss). The deposited energy is subsequently transferred to atoms in the target material through electron-phonon coupling associated with non-radiative decay of electrons from the conduction band, driving the material close to the ion path to far-from-equilibrium states. The energy density produced in many materials near the ion trajectory exceeds the binding energy, leading to complex structural modifications [1]. In many insulators, cylindrical damage zon
Data Loading...
