Glasses Tech – Prescription Glasses, Prescription Eyeglasses

March 8, 2010

Cationic ordering in oxide glasses: the example of transition elements

Filed under: Glasses 2000 — admin @ 2:35 am

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Structural data have been obtained on the cation surroundings in multi-component silicate and borosilicate glasses using chemically selective spectroscopic and scattering methods, such as extended X-ray absorption and neutron scattering with isotope substitution (NSIS). Transition elements such as Ni or Ti may occur in unusual 5-coordinated sites which coexist with other coordination numbers, depending on glass composition. Distribution of cationic sites in the glassy structure is responsible for unusual spectroscopic properties, as shown by Fe2+ Mössbauer spectroscopy. The environment of cations such as Zn, Zr or Mo, has been determined by EXAFS and discussed using the bond valence theory, which predicts the way to charge compensate the oxygen neighbours and which indicates the linkage of cationic sites with the silicate framework. (more…)

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Glasses Tech – Prescription Glasses, Prescription Eyeglasses