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Abstract: This work studies the ion irradiation-induced phase transformations in thin films of yttrium oxide. The films were deposited using an ion beam sputtering technique that allows the control of the order/disorder of the microstructure. As-deposited (disordered) and annealed (ordered) samples were irradiated by xenon ions at different energies and doses. Two different structural phase transformations were observed: cubic/amorphous-like and cubic/monoclinic. In both cases, it is shown that the pristine structure is of prime importance in the transformation process. The phase transformations are analysed in terms of structural extended defect nucleation originating from the oxygen network behaviour, which leads to polygonisation up to a nanocrystallite-like structure, followed by a phase transformation into a monoclinic structure. [Copyright &y& Elsevier]

Abstract: Yttrium oxide (Y2O3) thin films deposited on silicon (Si) by an ion beam sputtering technique have been irradiated by 92MeV xenon ions at room temperature. The microstructure of the irradiated thin film has been studied by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). A complete structural conversion from the cubic C-type to a monoclinic B-type phase is obtained. These results were compared with the phase transformation obtained in Y2O3 thin films by medium energy Xe ion irradiation. In both cases the oxygen network behaviour under irradiation is the key parameter of the phase transformation. [Copyright &y& Elsevier]

3C-SiC single crystals have been initially irradiated in the nuclear energy loss regime with 100keV Fe ions to fluences ranging from 4×1013 to 4×1014 cm− 2 (i.e. 0.07–0.7dpa). RBS/C measurements indicate that SiC rapidly becomes amorphous (at ∼0.4dpa). Two damaged SiC crystals exhibiting a different defective structure have been subsequently irradiated in the electronic energy loss regime with 870MeV swift heavy (Pb) ions (SHIs) up to a fluence of 4×1013 cm− 2. Initially fully amorphous SiC layers showed a decrease in size after SHI irradiation with a recrystallization occurring at the amorphous–crystalline interface. On the contrary, partially amorphous crystals for which onset of amorphization just initiated at the damage peak recovered over the entire damage thickness. Variation of amorphous thickness or disorder level has been monitored as a function of Pb ion fluence, which allowed deriving recrystallization kinetics. Data have been fitted with the direct-impact model and recrystallization cross-sections and threshold values for recovery have been determined for both types of initially defective structures. Differences are qualitatively discussed in terms of nature and density of irradiation defects. All experimental trends have been successfully reproduced by molecular dynamics simulations that mimicked thermal spikes induced by SHIs. [ABSTRACT FROM AUTHOR]