Structure and properties of lead silicate glasses
Résumé
Given their specific properties, glasses containing lead oxide have a very broad field of application. This extends from crystal glasses, enamels and glazes, to optical glasses with high refractive index, passing through glasses absorbing ionizing radiation and glasses for low-temperature welding of metals, ceramics or glasses. This chapter focuses first of all on the chemistry of lead, and more specifically on the properties and stereochemistry of the Pb$^{2+}$ ion (species under which lead is present in oxide glasses), the nature of the Pb-O chemical bond and the crystalline structure of pure PbO oxide (stereochemistry and mode of connection of the polyhedrons). Then, since the lead-based oxide glasses of interest are overwhelmingly silicate glasses, the focus is on how the Pb$^{2+}$ ions get inserted in the glassy network of silica and modify its structure, first of all in the case of the simple binary SiO2-PbO system (for which the evolution of the structure of the binary crystalline phases will also be approached depending on their PbO content compared to glasses), then in the case of more complex systems such as the ternary SiO$_2$-PbO-R$_2$O (R: alkaline) and SiO$_2$-PbO-Al$_2$O$_3$ systems.
Domaines
Chimie
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