SOFT-X-RAY XAFS STUDIES ON THE LOCAL-STRUCTURE OF K2O-SIO2 GLASSES

Using the laboratory XAFS facility, we have performed to determine the local structure in potassium silicate glasses (K2O . 4SiO(2), K2O . 3 SiO(2), K2O . 2SiO(2) and 0.2(Al2O3). 0.8(K2O . 4SiO(2))) respectively in order to elucidate the environment of modifying potassium ion whic h is extremely sensitive to the morphology of the network structure of glass system. The coordination numbers of oxygen around K+ ion in K2O . 2SiO(2) and K2O . 3SiO(2) glasses are found to be 4-5 which is smal l compared compared with those of K2O . 4SiO(2) glass and crystalline nepheline similar to 9. The result indicates that the introduction of K2O leads to the disruption of SiO4 network structure and the formatio n of SiO32- chain like structure or nonbridging oxygen ions as increas ing quantity of K2O. The local structure around silicon ions in some p otassium silicate glasses are also compared with those of crystalline SiO2 such as quartz and cristobalite.