"Nanoscale manipulation of the properties of solids at high pressure with relativistic heavy ions"
Maik Lang, Fuxiang Zhang, Jiaming Zhang, Jianwei Wang, Beatrice Schuster, Christina Trautmann, Reinhard Neumann, U do Becker, Rodney Ewing,
Nature Materials
Vol. 8
2009
793-797
Link
High-pressure and high-temperature phases show unusual physical and chemical properties, but they are often difficult to ‘quench’ to ambient conditions1. Here, we present a new approach, using bombardment with very high-energy, heavy ions accelerated to relativistic velocities, to stabilize a high-pressure phase. In this case, Gd2Zr2O7, pressurized in a diamond-anvil cell up to 40?GPa, was irradiated with 20?GeV xenon or 45?GeV uranium ions, and the (previously unquenchable) cubic high-pressure phase was recovered after release of pressure. Transmission electron microscopy revealed a radiation-induced, nanocrystalline texture. Quantum-mechanical calculations confirm that the surface energy at the nanoscale is the cause of the remarkable stabilization of the high-pressure phase. The combined use of high pressure and high-energy ion irradiation2,3 provides a new means for manipulating and stabilizing new materials to ambient conditions that otherwise could not be recovered.
"Swift heavy ion track formation in Gd2Zr2-xTixO7 pyrochlore: Effect of electronic energy loss"
Maik Lang, Marcel Toulemonde, Jiaming Zhang, Fuxiang Zhang, Cameron Tracy, Jie Lian, Zhongwu Wang, William Weber, Daniel Severin, Markus Bender, Christina Trautmann, Rodney Ewing,
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Vol. 336
2014
102-115
Link
The morphology of swift heavy ion tracks in the Gd2Zr2-xTixO7 pyrochlore system has been investigated as a function of the variation in chemical composition and electronic energy loss, dE/dx, over a range of energetic ions: 58Ni, 101Ru, 129Xe, 181Ta, 197Au, 208Pb, and 238U of 11.1 MeV/u specific energy. Bright-field transmission electron microscopy, synchrotron X-ray diffraction, and Raman spectroscopy reveal an increasing degree of amorphization with increasing Ti-content and dE/dx. The size and morphology of individual ion tracks in Gd2Ti2O7 were characterized by high-resolution transmission electron microscopy revealing a core–shell structure with an outer defect-fluorite dominated shell at low dE/dx to predominantly amorphous tracks at high dE/dx. Inelastic thermal-spike calculations have been used together with atomic-scale characterization of ion tracks in Gd2Ti2O7 by high resolution transmission electron microscopy to deduce critical energy densities for the complex core–shell morphologies induced by ions of different dE/dx.
