Structural effects in UO₂ thin films irradiated with U ions

AbstractThis work presents the results of a detailed structural characterisation of irradiated and unirradiated single crystal thin films of UO2. Thin films of UO2 were produced by reactive magnetron sputtering onto (001), (110) and (111) single crystal yttria-stabilised zirconia (YSZ) substrates. Half of the samples were irradiated with 110MeV 238U31+ ions to fluences of 5×1010, 5×1011 and 5×1012ions/cm2 to induce radiation damage, with the remainder kept for reference measurements. It was observed that as-produced UO2 films adopted the crystallographic orientation of their YSZ substrates. The irradiation fluences used in this study however, were not sufficient to cause any permanent change in the crystalline nature of UO2. It has been demonstrated that the effect of epitaxial re-crystallisation of the induced radiation damage can be quantified in terms of kernel average misorientation (KAM) and different crystallographic orientations of UO2 respond differently to ion irradiation

From isomorphous to "anisomorphous" ionic co-crystals of barbituric acid upon dehydration and return

The isomorphous hydrated ionic co-crystals (ICCs) of barbituric acid (BA) of the formula BA\ub7MBr\ub72H2O (M = Na, K, Rb) can be easily dehydrated to the corresponding anhydrous ICCs BA\ub7MBr (M = Na, K, Rb). The three anhydrous crystals possess different structures that revert to the isomorphous crystals upon hydration. Only BA\ub7RbBr is stable in air, making it possible to determine its crystal structure from single-crystal X-ray diffraction. BA\ub7NaBr and BA\ub7KBr rapidly absorb water from air and convert to the hydrated form. The crystal structures of BA\ub7NaBr and BA\ub7KBr have been determined by X-ray powder diffraction in sealed capillaries. Solid-state NMR spectroscopy was fundamental in determining the number of independent molecules in the asymmetric unit for the structural determination of the ICC BA\ub7NaBr. The dehydration process was characterized by variable temperature X-ray powder diffraction, DSC and TGA