[en] Raman spectroscopy can be a useful tool to determine water content within clays, or even in highly saturated solutions. The following assignment is proposed for the OH region of SAz-2: the two large bands at 3260 and 3475 cm^-1 are assigned to water in pores, the first one to water molecules coordinated to the interlayer cations, and the second one to structural Al-OH groups The band at 3600 cm^-1 is therefore more likely related to adsorbed water on the clay surface. Simple intensity ratios of these different bands give good estimates of water content. (authors)

[en] This book first presents the conventional nucleation theory: vitrification, homogeneous and heterogeneous nucleation, induction time, crystal growth, Oswald law. The second part addresses the evolutions beyond this theory: cluster dynamics, validity of the Stokes-Einstein relationship, non conventional germ system, Gibbs generalized approach, two-stage model. The third part addresses the thermodynamic stability and the global kinetics of transformation: thermodynamic stability and instability of a vitreous system, phenomenological approach to transformation kinetics. The fourth part addresses the de-mixing process on glasses: thermodynamic description of phase separation, de-mixing kinetics, influence of glass structure on de-mixing trend, de-mixing characterisation. The next parts describe the crystal-chemical approach to the main crystalline phases noticed in glass-ceramics (silicate phases and phosphates), the elaboration and control of glass-ceramic microstructure (controllable parameters, elaboration processes, characterization methods, microstructure types, design of glass-ceramics with desired properties by control of crystallisation mechanisms), X ray diffraction in the case of glass-ceramics, calorimetry and differential thermal analysis for the study of glass ceramics, the application of electronic microscopy to the study of nucleation and crystallisation in glasses, small-angle scattering of X rays and neutrons, the use of nuclear magnetic resonance to understand the disorder and crystallisation in vitreous materials, the use of Raman spectrometry to study mechanisms of nucleation and crystal growth, large instruments aimed at an in situ approaches to crystallisation, commercial applications of glass-ceramics, applications of biomaterials in glass and glass-ceramics, the coloration of metal nanoparticles, transparent glass-ceramics, the formation and applications of nanoparticles in silica-based optic fibres, the both-way relationship between non linear optics and glass-ceramics, the laser-oriented micro- and nano-crystallisation to induce non linear optical properties, the case of oxi-fluorinated glass-ceramics, the nucleation, crystallisation and phase separation in chalcogenide glasses, the use of glass-ceramics for waste confinement, and crystalline enamels

[en] Seven magnesium-containing aluminoborosilicate glasses, with three to five oxides, have been studied through comprehensive multinuclear solid-state NMR (¹¹B, ²⁷Al, ²⁹Si, ²³Na, ¹⁷O, and ²⁵Mg) and Raman spectroscopy. The progressive addition of cations and the substitution of sodium and calcium by magnesium illuminate the impact of magnesium on the glass structure. The proportion of tri-coordinated boron drastically increased with magnesium addition, demonstrating the poor charge-compensating capabilities of magnesium in tetrahedral boron units. Oxygen-17 NMR showed the formation of mixing sites containing both Na and Mg near nonbridging oxygen sites. Furthermore, a high magnesium content appears to result in the formation of two sub-networks (boron and silicon rich) with different polymerization degrees as well as to promote the formation of high-coordination aluminum sites (Al[V] and Al[VI]). Finally, magnesium coordination ranging from 4 to 6, with a mean value shifting from 5 to 6 along the series, suggests that magnesium might endorse an intermediate role in these glasses. (authors)

[en] The structure of crystals and melts were obtained at high temperature using X-ray absorption at the Ca K-edge on CaMgSi2O6 (diopside), CaAl2Si2O8 (anorthite), Ca3Al2O6 (C3A) and CaAl2O4 (CA) compositions. Important changes are observed above the liquidus temperature particularly for the C3A composition where all oscillations in the XANES spectra disappear. Important changes in the Ca K-edge XANES are also visible in the pre-edge region, with increasing temperature, for crystalline CaMgSi2O6

[en] Using X-ray absorption at the Al K-edge at high temperature, structural information was determined on Al2O3, CaAl2O4 (CA), Ca3Al2O6 (C3A) and CaAl2Si2O8 (anorthite) in the crystalline and liquid states (2380 K). Important changes are observed for Al2O3 where all oscillation in the XANES spectra disappear above the liquidus temperature. For the three other compositions some modifications of the XANES spectra can be attributed to changes in the Al coordination

[en] The role of lanthanum in the alteration kinetics at different degrees of reaction progress was investigated at 90 C and pH=7 by complementary chemical (SIMS), morphological (SAXS), and structural (NMR, Raman, and EXAFS spectroscopy) approaches. In the first step of alteration, the forward dissolution rate diminishes with the addition of lanthanum, resembling to the behavior previously observed for zirconium. Over longer alteration time, the glasses with the highest lanthanum concentrations reach silicon saturation more slowly, but unlike zirconium, do not result in larger quantities of altered glass. Lanthanum is entirely retained in the alteration layer and is uniformly distributed; it undergoes hydrolysis and recondensation mechanisms, and its coordination number increases from 6 to 9 during leaching. Reconstruction of the alteration layer occurred more slowly at higher REE concentrations, with a slowdown in re-polymerization of the silicate network and structuring of its porosity. (authors)

[en] In this study the correlation between bulk chemistry and optical properties for a set of Eu-bearing phosphate glasses, containing different alkali elements, synthetized in air and under NH₃ flux, was investigated. The chemistry of the glass strongly influences several properties and the effects of bulk chemistry and synthesis conditions on glass structure and on thermal and optical properties are discussed. In alkali-phosphate glasses studied by absorption and photoluminescence spectroscopy we verified that Eu²⁺ emission band shifts toward higher wavelengths by substituting the alkali cation (Na2+ luminescence band. The glass emission tunability is extremely related to the bulk composition and it is possible to adjust the chemistry in order to get the desired lighting in phosphate glasses. - Highlights: • Environmental friendly REE-phosphate glasses were studied. • The effect of substituting alkali elements on the glass structure and Eu thermal/optical properties was investigated. • We studied the effect of synthesis under NH₃-flux on thermal/optical properties. • We verified the chemistry controls on Eu emission tunability.