Structure of lithium germanate glasses by neutron diffraction with isotopic substitution
Alex C. Hannon*
ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
The thermophysical properties of germanate glasses show a minimum or maximum as increasing amounts of modifier are added to the glass, and this behaviour is known as the germanate anomaly. One of the factors involved in the germanate anomaly is the Ge-O coordination number, which initially increases above a value of 4 for pure GeO2
, and then decreases back towards 4 for high modifier contents. A report is given of a high resolution neutron diffraction study of lithium germanate glasses, with the use of lithium isotopic substitution. The use of lithium isotopes enables the Ge-O coordination number to be determined without interference from the Li-O bonds in the glass. Furthermore, the Li-O coordination number is also determined due to the use of lithium isotopes.