X-ray diffraction study of MO-TeO₂ (M=Zn and Ba) glasses

Structures of MO-TeO₂ (M=Zn and Ba) glasses have been investigated by x-ray diffraction analysis. Local environments around Zn and Ba atoms were examined in terms of the difference RDF curve, ΔRDF, which was obtained by subtracting the RDF curve of ZnO-TeO₂ glass from that of BaO-TeO₂ glass at the same composition. Coordination numbers of Zn and Ba were estimated by the pair function curve fitting with the ΔRDF curves. The coordination number of Zn atoms (N_Zn-O) decreased from 5·3 to 3·9 as ZnO content increased from 10 to 40 mol%. Coordination numbers of Ba atoms (N_Ba-O) up to 35 mol% BaO were 6·1-6·4 independent of BaO content. N_Ba-O decreased over 35 mol% BaO and was 5·6 at 40 mol% BaO. On the basis of the local structures around Zn and Ba atoms revealed in this work and the one around Te atoms derived from the previous ¹²⁵Te static NMR study, the detailed structure models of MO-TeO₂ (M=Zn and Ba) glasses were proposed.