Local structure around Ge in lithium germanate glasses analyzed by AXS and EXAFS techniques

Abstract

The local structure around Ge in xLi 2 O-(1 - x)GeO 2 (x = 0, 0.17, 0.20, 0.24) glasses was investigated using AXS and EXAFS measurements. The averaged coordination number of the first nearest Ge-O pair increased with increasing Li 2 O content up to 24 mol% and the amount of six-coordinated Ge was proportional to Li 2 O content. The introduction of a GeO 6 unit is suggested to be one of the most fundamental structural changes accompanying the so-called germanate anomaly detected in density measurements of alkali-germanate glasses.