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The temperature and chemical dependence of the melt viscosity are ubiquitous in the model development of the volcanic dynamics, as well as in the glass production and design. We focussed on the yet-explored relationship between the bulk and shear moduli ratio and boson peak with the melt fragility of their parental glasses. Here, we explored the extension of the observed trend by testing the conventional binary system Na2O-SiO2, thus providing new evidence supporting the link between the flow of melts and supercooled liquids and the vibrational dynamics of their parental glasses. This was accomplished by integrating new low-frequency Raman measurements and integrating data from the literature on Brillouin light scattering and viscometry. This approach allows us to feed the MYEGA equation with reliable input parameters to quantitatively predict the viscosity of the Na2O-SiO2 system from the liquid up to the glass transition. [ABSTRACT FROM AUTHOR]

Basalts are among the most abundant igneous rocks on Earth. Originated from the rapid cooling of magma erupted by volcanoes, they are increasingly used as raw materials in glass and ceramic technology due to their unique physico‐chemical properties. The characteristics of basalts, like the glass transition temperature, are strongly controlled by their structure, which is a function of composition. Therefore, the investigation of the interplay between the intimate structure and the mechanical and physical properties of basalt glasses is of paramount importance in view of their industrial exploitation. Here, we present a Raman study of a set of synthetic‐basalt glasses in which the occurrence of small chemical variations appreciably affects their glass transition temperature. We analyzed the Raman spectra focusing on both the spectral regions of the so‐called nonbridging oxygens and of the boson peak. We show the existence of a scaling law for the boson peak of four synthetic‐basalt glasses, and we infer from its breakdown the occurrence of a deep reorganization of the glass structure resulting from the Na–K replacement in the network, despite small variations of the other major elements. [ABSTRACT FROM AUTHOR]

The vibrational dynamics of a new class of cross-linked polymers obtained from both native and modified cyclodextrin, referred to as cyclodextrin nanosponges, is here investigated. The main purpose is to spot the structure of these materials at molecular level unlikely to be characterized by diffraction methods due to the low or null degree of crystallinity. The analysis of the spectral features of the vibrational bands observed between 1650 and 1800 cm−1 in both Raman and infrared spectra, and assigned to the carbonyl stretching modes of the polymeric network, is performed by using band deconvolution procedures. At the same time, a detailed inspection of the low-wavenumber vibrational dynamics of these polymers is carried out, focusing on the modifications occurring on the so-called boson peak. The simultaneous analysis of different wavenumber ranges in Raman and infrared spectra of cyclodextrin nanosponges allows us to develop a reliable strategy for exploring both the cross-linking degree and the elastic properties of these innovative materials. The overall results give a complete characterization of the structural and dynamical properties of the system, in turn strictly connected to the entrapment/transport ability of these polymeric matrices. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

[Display omitted] Volcanic eruptions generate huge amounts of material with a wide range of compositions and therefore different physicochemical properties. We present a combined Raman and calorimetric study carried out on four synthetic basaltic glasses with different alkali vs iron ratio which spans the typical compositions of basalts on Earth. Differential scanning calorimetry shows that changes of this ratio modify the glass transition interval whereas Raman spectra allow to gain insight about the structure of the glass in the microscopic and macroscopic range. Indeed, our Raman analysis is extended from the high frequency region, characterized by the molecular peaks, to the very low frequency region where glasses exhibit the boson peak. Spectra show a variation of the non-bridging oxygens number that affects the medium range order of the glass and the network interconnections. In the considered substitution interval, the boson peak shape is conserved while its position shift upwards. This means that increasing the alkali vs iron content, the elastic medium hardens but it does not change nature. This study emphasizes the importance of considering the full-range spectra when analysing multicomponent or natural systems with small chemical variations. [ABSTRACT FROM AUTHOR]