Publications by authors named "R R Youngman"
The structure of calcium aluminosilicate glasses (CaO)x(Al2O3)y(SiO2)1-x-y with the near tectosilicate compositions x ≃ 0.19 and 1 - x - y ≃ 0.61 or x ≃ 0.
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- Fluorine incorporation in silicate glasses is significant for various applications like geophysics and waste management.
- This study investigated how fluorine influences the structure of alkaline alumino-borosilicate glass with up to 25 mol % fluorine.
- Techniques used included XRD and NMR spectroscopy, revealing that most fluorine remains in the glass, but excess forms crystalline phases at higher concentrations, illustrating complex interactions within the glass structure.
The effect of replacing magnesia by alumina on the pressure-dependent structure of amorphous enstatite was investigated by applying in situ high-pressure neutron diffraction with magnesium isotope substitution to glassy (MgO)0.375(Al2O3)0.125(SiO2)0.
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- The study examines the structure of zinc aluminosilicate glasses with a specific chemical composition, using advanced techniques like neutron diffraction and nuclear magnetic resonance.
- Four-coordinated aluminum atoms are predominantly found, with five-coordinated aluminum atoms being less common, and distinct bond distances for both types were measured.
- The role of zinc in the glass network varies based on composition, affecting its coordination environment and bond properties depending on whether it acts as a network modifier or charge compensator.
The short-range order of binary zinc borate glasses, ZnO-(1-)BO, has been quantitatively described as a function of ZnO content over the entire glass forming range for the first time, to the best of our knowledge. Multiple spectroscopic techniques (B NMR, Raman, infrared) reveal detailed structural information regarding borate speciation and network connectivity, and a new model for quantifying the molar fractions of short-range order units is proposed. A consistent thermal history dependence for the fraction of tetrahedral boron () is well accounted for by the proposed model.
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