EVIDENCE FOR THE COORDINATION-NUMBER CHANGE OF RARE-EARTH IONS IN RARE-EARTH PHOSPHATE-GLASSES

Rare earth phosphate glasses of the composition Ln(PO3)(3) . KPO3 (Ln : rare earth ion) were prepared and their glass transition temperature s (T-g's) were measured. From the T-g variation across the series, it is shown that the coordination number of rare earth ions changes, prob ably from nine to eight, in the middle of the series.