The effect of pressure on titanium coordination in glasses, with composition K2TiSi4O11, quenched isobarically from liquids equilibrated at high pressure (5, 10, 15, 20, 25, 30 kbar respectively) and T = 1600-degrees-C has been investigated by X-ray absorption spectroscopy (XAS). The XANES spectra collected at the Ti K-edge clearly show a variation with pressure that is related to changes in the geometrical environment around the Ti atoms. By comparison with spectra of standard materials, the XANES spectra of the glasses suggest a relatively low average coordination number (near 5) in samples quenched at low pressure and a higher coordination number (near 6) in samples quenched from the highest pressure. The combination of XANES data with density and compressibility measurements supports the idea that a mixture of 6- and lower coordinated (4- and/or 5-coordinated) Ti geometries are present in the 1 bar glass, and an increasing proportion of 6-coordinated Ti occurs in the glasses synthesized at progressively higher pressures.
Paris, E., SEIFERT F., A., DINGWELL D., B., Romano, C. (1994). Pressure-Induced Coordination Change of Ti in Silicate Glass: a XANES Study. PHYSICS AND CHEMISTRY OF MINERALS, 21, 510-515.
Pressure-Induced Coordination Change of Ti in Silicate Glass: a XANES Study
ROMANO, Claudia
1994-01-01
Abstract
The effect of pressure on titanium coordination in glasses, with composition K2TiSi4O11, quenched isobarically from liquids equilibrated at high pressure (5, 10, 15, 20, 25, 30 kbar respectively) and T = 1600-degrees-C has been investigated by X-ray absorption spectroscopy (XAS). The XANES spectra collected at the Ti K-edge clearly show a variation with pressure that is related to changes in the geometrical environment around the Ti atoms. By comparison with spectra of standard materials, the XANES spectra of the glasses suggest a relatively low average coordination number (near 5) in samples quenched at low pressure and a higher coordination number (near 6) in samples quenched from the highest pressure. The combination of XANES data with density and compressibility measurements supports the idea that a mixture of 6- and lower coordinated (4- and/or 5-coordinated) Ti geometries are present in the 1 bar glass, and an increasing proportion of 6-coordinated Ti occurs in the glasses synthesized at progressively higher pressures.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
