Laboratory Soft X-ray XAFS: The Local Structure of K2O-SiO2 Glasses

Abstract

Using the in-laboratory XAFS facility, we have tried to determine the local structure in silicate glasses (K2O•4SiO2, K2O•3SiO2, K2O•2SiO2 and 0.2(Al2O3)0.8(K2O•4SiO2) ) respectively to elucidate the environment of modifying potassium ion which is extremely sensitive to the morphology of the network of the system. The coordination numbers of oxygen around potassium ion in K2O•2SiO2 and K2O•3SiO2 are found to be 4∼5 which is small compared with those of K2O•4SiO2 glass and crystalline nepheline ∼9. The result indicates that the introduction of potassium oxide leads to the disruption of the (SiO4) network and the formation of chain like structure or nonbridging oxygen atoms as increasing the quantity of potassium oxide. The local structures around silicon ion in some potassium silicate glasses are also compared with those of crystalline SiO2 (quartz and cristobalite).