Glass, nanocomposites, immobilisation

Subtopics

• (i) Loading of CeO2 into simulated nuclear glasses.
  In a nutshell: Cerium is a good simulant for actinide behaviour in glass. Speciation of cerium in borosilicate glasses is examined at rather high loadings, and various shapes of nanoscale precipitates found (round/ dendritic/ amorphous/ crystalline). Various Ce loadings, various co-doping levels (especially redox-active elements like Cr, Ag) and various matrix compositions, mainly alkali-boro-silicate, but also including Si-free glasses are examined. For nanotomography on glass composites see the respective pages
  
  See: Crystal Growth and Design 8 , 1102 (2008); J Europ Ceram Soc 30 (4) 831-838 (2010)

• (ii) Nanopatterning of glasses and Nanocomposite Glasses
  In a nutshell: Thin samples of various borosilicate glass compositions are irradiated by TEM to locally pattern or precipitate particles in an otherwise homogeneous glass matrix. Zn, Cu, and Ag loaded borosilicate glasses are found to precipitate metallic nanoparticles localised to a sub-100 nm electron beam irradiated region. Line patterns can be generated by scanning the beam across a sample. Complex behaviour between competing effects of particle precipitation, amorphous phase separation, and glass matrix ablation/ hole drilling, are found.
  Electron irradiation is also demonstrated to promote “quasi-melting” or “radiation-induced-fluidity” behaviour at near room-temperature as evidenced by surface rounding, glass bead formation, low-T particle sintering, and rapid radiolytic materials flow.
  
  See: J Materials Research 30 1914-1924 (2015),
  Journal of Nuclear Materials 396 (2-3) 264-271 (2010).

• (iii) Atomic scale spectroscopy of glasses and nanocomposites
  In a nutshell: Glasses and glass composite materials are analysed by electron energy loss spectroscopy (EELS) and its fine structure (ELNES) in TEM. Local oxidation states (+III vs +IV) of e.g. Ce ions are measured with sub-10nm resolution in both glass matrix and in various Ce-rich precipitates. In separate experiments, the boron coordination (3-fold vs 4-fold) is quantified as a function of both irradiation duration and of alkali-modifier element (Li, Na, K, Cs series).
  
  See: Phys Chem Glass - Europ J of Glass Sc and Techn, B 50 378-383 (2010)
  Solid State Sciences 10 , 1194-1199 (2008)
  Micron, 37 , 433-441, (2006); Phys Chem Glass, 47, (2006)