M. Seshasayee

An X-ray RDF study of Li2OP2O5LiCl glasses

An X-ray RDF study has been carried out for the Li ion-conducting glasses, 52%Li2O48%P2O5, 45%Li2O42%P2O513% LiCl and 39%Li2O36%P2O525%LiCl. Short range order in binary Li2O-P2O5 glass is similar to that in crystalline LiPO3. Addition of LiCl leaves the glass matrix unchanged.

Structural studies on superionic glass AgIAg2OV2O5

Abstract An amorphous thin plate with composition (mol%) 50%AgI-30%Ag2O-20%V2O5 was prepared by rapid quenching from the melt. An EXAFS study at the Ag K-edge shows r Ag − I = 2.87 A , nAg−1, where nij is the coordination number, and the difference between two close AgO distances Δr Ag − O = 0.37 A . X-ray RDF studies yield similar values of Ag − I = 2.96 A , nAg−I = 1.3 and Δr Ag −0 = 0.37 A . On theother hand X-ray RDF studies yield two V-O interactions with distances 1.78 and 2.39 A and their coordination numbers are 3.6 and 1.7, respectively. Silver ions form bonds and secondary interactions with the network non-bridging and bridging oxygen atoms and I− ions surround the Ag+ ions. The results favour a model of dispersed Ag+ and I− ions in the glass rather than the presence of clusters of microdomains of AgI in the glass.

Structural study of LiPO3TeO2 glasses

Abstract Short range order of three samples in the mixed glass former system, LiPO 3 TeO 2 , are investigated by X-ray diffraction and FT-Raman spectroscopy. The questions addressed in this study concern the effect of the mixed former on the structure in the presence of a modifier. PO and TeO distances are in the range reported for other phosphate and tellurite glasses. TeTe interaction is the major deformation exhibited by TeO 4 polyhedra in their chains. Mixed glass formation in Li 2 OP 2 O 5 TeO 2 system creates greater stability with higher T g when compared to binary glasses Li 2 OP 2 O 5 and Li 2 OTeO 2 . Higher T g owes its origin to the increased bridging between the PO 4 and TeO 4 chains.

An X-ray RDF study of the glass 30AgI-45Ag2O-25V2O5

Abstract X-ray RDF study of the title glass was taken up to analyse the effect of compositional changes on the basic glass network in comparison to our earlier work on the glass 50AgI-30Ag 2 O-20V 2 O 5 . Results indicate that the V-O coordination remains at five and that the glass network is more closely packed, the V-O distance being 1.72 A. The results also show that the strong Ag-O interaction around 1.9 A. AgI is dispersed in the glassy matrix.

X-ray diffraction studies on AgI-Ag2O-V2O5 glasses

Abstract Results of X-ray diffraction studies on glasses in the AgI-Ag 2 O-V 2 O 5 system are presented. In these glasses, the vanadium atom adopted five-fold coordination of oxygen atoms more frequently than four-fold and six-fold and the V-O distances lay between 1.76 and 1.79 A. The VO x polyhedra in the glasses shared corners, the V-V distances in the glasses lay between 3.30–3.41 A. Short and long Ag-O interactions were observed. An Ag-I interaction between 2.829–2.876 A was observed, which is characteristic of all AgI based glasses. The I-I distance decreased as the iodine content increased, having a value close to that in α-AgI at a high AgI content and approaching the value of β-AgI with decreasing AgI content.

Molecular dynamics study of Li2SiS3 glass

Abstract Molecular dynamics simulation has been carried out for highly conducting Li2SiS3 glass at temperatures ranging from 300–1800 K in order to investigate the glass structure and dynamical behaviour of the mobile ions Li+. The glass transition temperature obtained from the change in energy and diffusion constant D of Li+ as temperature is lowered occurs around 750 K. Silicon is predominantly pentacoordinated to sulphur atoms at an average distance 2.19 A, the geometry around Si being approximately square pyramidal. The glass matrix shows little change with temperature. Room temperature value of diffusion constant (D) of Li+ is 3.53 × 10−10 m2 s−1. Lithium ions are surrounded by four sulphur atoms, LiS distance being 2.61 A.