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

Abstract

The local structure around Ge in xLi₂O–(1 － x)GeO₂ (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 Li₂O content up to 24 mol% and the amount of six–coordinated Ge was proportional to Li₂O content. The introduction of a GeO₆ 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.