Soft X-ray XAFS Studies on the Local Structure of K<SUB>2</SUB>O-SiO<SUB>2</SUB> Glasses

Abstract

Using the laboratory XAFS facility, we have performed to determine the local structure in potassium silicate glasses (K2O·4SiO2, K2O·3SiO2, K2O·2SiO2 and 0.2(Al2O3)·0.8(K2O·4SiO2)) respectively in order to clucidate the environment of modifying potassium ion which is extremely sensitive to the morphology of the network structure of glass system. The coordination numbers of oxygen around K+ ion in K2O·2SiO2 and K2O·3SiO2 glasses 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 K2O leads to the disruption of SiO4 network structure and the formation of SiO32− chain like structure or nonbridging oxygen ions as increasing quantity of K2O. The local structure around silicon ions in some potassium silicate glasses are also compared with those of crystalline SiO2 such as quartz and cristobalite.