Structure of Na 2S–GeS 2 glasses studied by using neutron and X-ray diffraction and reverse Monte Carlo modeling

Abstract

Neutron and X-ray diffraction measurements were performed to investigate the structure of Na 2S–GeS 2 glasses synthesized by mechanical alloying. The Ge–S coordination numbers calculated from the total correlation functions show that GeS 4 tetrahedra form the basic framework structure of Na 2S–GeS 2 glasses. In addition, a three-dimensional structural model of the (Na 2S) 50(GeS 2) 50 glass was obtained by using reverse Monte Carlo (RMC) simulation on neutron and X-ray diffraction data, and it was compared with the RMC model previously obtained for a (Li 2S) 50(GeS 2) 50 glass. The results show that the Ge–S framework structures in the two glasses are almost the same in the short and intermediate ranges; that is, the Ge–S framework structures are formed mainly by the connection of corner-sharing GeS 4 tetrahedra. Many of the Na ions are coordinated by four S atoms, which are non-bridging S atoms and/or bridging S atoms.