The structure of tellurite glass: a combined NMR, neutron diffraction, and X-ray diffraction study

Models are presented of sodium tellurite glasses in the composition range (Na2O)x–(TeO2)1−x, 0.1<x<0.3. The models combine self-consistently data from three different and complementary sources: sodium-23 nuclear magnetic resonance (NMR), neutron diffraction, and X-ray diffraction. The models were generated using the Reverse Monte Carlo algorithm, modified to include NMR data in addition to diffraction data. The presence in the models of all five tellurite polyhedra consistent with the Te4+ oxidation state were found to be necessary to achieve agreement with the data. The distribution of polyhedra among these types varied from a dominance of bridged species at lower sodium contents, to polyhedra with one or zero bridging oxygen at larger sodium contents. The models indicate that the sodium cations themselves form sodium oxide clusters particularly at the x=0.2 composition.