UNSPECIFIED (2000) X-ray photoelectron spectroscopy study of the germanate anomaly in the Na2O-GeO2 system. PHYSICS AND CHEMISTRY OF GLASSES, 41 (4). pp. 175-181. ISSN 0031-9090

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Abstract

Photoelectron spectra of the O 1s and Ge 3d levels have been obtained from a series of Na2O-GeO2 glasses of general formula xNa(2)O.(1-x)GeO2 (x=0.125, 0.175, 0.2 and 0.3) and from powders of quartz-like GeO2 and rutile-like GeO2. The O 1s binding energy is unchanged in both crystalline polymorphs bur the binding energies of Ge 3d differ by 0.7+/-0.1 eV. Symmetric O 1s peaks from samples with x less than or equal to 0.2 are assigned to bridging oxygens connecting combinations of 4 and 6 coordinated Ge. The O 1s spectrum from the x=0.3 sample contains contributions from bridging and nonbridging oxygens. Ge 3d spectra from the glasses have been fitted to contributions from 4 and 6 coordinated Ge giving values for N-6 (the fraction of 6 coordinated Ge) consistent with the theoretical relationship N-6=x(1-x)(-1) for x less than or equal to 0.2. For the x=0.3 sample N-6 is lower than predicted due to replacement of 6 coordinated Ge by 4 coordinated Ge plus nonbridging oxygens This lower value of N-6 would require there to be 20+/-3% nonbridging oxygens present and this is reasonably consistent with the value of 25+/-2% obtained by fitting the O 1s spectrum.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry T Technology > TP Chemical technology
Journal or Publication Title:	PHYSICS AND CHEMISTRY OF GLASSES
Publisher:	SOC GLASS TECHNOLOGY
ISSN:	0031-9090
Date:	August 2000
Volume:	41
Number:	4
Number of Pages:	7
Page Range:	pp. 175-181
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/13062

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