Ion dynamics in superionic chalcogenide glasses:: Complete conductivity spectra

Gallium sulphide forms stable glasses with GeS2 over a wide range of composition, and in the same system complex materials are obtained by dissolving silver sulphide. In such glasses Ga2S3 acts as a co-former with GeS2 whereas Ag2S plays the role of modifier. Raman scattering and infrared absorption measurements have been carried out on the Ge2S4Ga2S3Ag2S glass system. The structural arrangement of these glasses is studied as a function of the composition in the ternary glass-forming region. The vibrational assignment is made mainly in terms of bridging and non-bridging sulphur in the vitreous network. The tendency of gallium atoms to form GaS4 tetrahedra forces germanium atoms to induce the formation of S3GeGeS3 structural groups due to the shortage of sulphur atoms. When Ag2S is associated with Ge2S4Ga2S3 glasses, its defavors the edge-shared GeS4 tetrahedra and contributes to the cohesion of corner-shared tetrahedra. When Ag2S content increases, we observe a band located at low frequency that we have attributed to charge-coupled silver cation motion. A slight distortion of the tetrahedral groups is also seen from the vibrational features.

Raman and infrared spectroscopic studies of GeGaAg sulphide glasses

Critical review is given on the recent progress in superionic conducting glasses. The ion species of Ag + , Cu + , Li + , Na + , and F − are separately treated since the level of progress is different in glasses of each ion species. The development of glasses as active cathode materials in the rechargeable secondary cells is also mentioned.

Recent progress in superionic conducting glasses

The different glass compositions which exhibit ionic transport properties in the oxide, sulfide and fluoride systems, are presented. The main data concerning the conductivities and activation energies for conduction are given and compared to those of the best superionic conductors. The available models on ion transport in glasses are briefly discussed and the applicability of the weak electrolyte theory emphasized. Future development concerns protonic conduction in glasses and “soft” methods for synthesis of new glass compositions.

Ionic transport properties in glasses

Photoinduced optical phenomena in amorphous Sb2Se3–BaCl2–PbCl2 glasses are studied using experimental spectroscopic and theoretical quantum chemical methods. Photoinduced two-photon absorption (TPA) (for λ=10.6 μm) and second harmonic generation (SHG) (for the output wavelengths 5.3 μm) were measured. CO laser (λ=5.5 μm) was used as a source of photoinducing light. We have found that with an increasing CO-laser exposure the SHG maximum output signal increases and achieves its maximum value at CO photon fluence 18×1013 phot./cm2 per pulse after two hours of illumination. The output SHG signal was more than one order less comparing with ZnS crystals in case of its third rank nonlinear optical susceptibility tensor components χ222 (λ=10.6 μm). With decreasing temperature the SHG signal strongly increases within the 26–32 K temperature range. Time-dependent probe-pump measurements show an existence of SHG maximum at time delay about 45 ps. Good correlation between SHG and TPA was observed. Spectral positions ...

Photoinduced effects in the Sb2Se3–BaCl2–PbCl2 glasses

Ag2S forms with GeS2 stable glasses over a wide range of compositions (0–55% Ag2S mol%) In the same system, more complex glasses obtained by dissolving silver iodide have been synthesized with up to 50 mol% AgI Raman spectra are presented and a vibrational assignment in terms of bridging and non-bridging sulfur has been made The electrical conductivity of these glasses has been measured over a temperature range (−50°C− + 50°C) and for various compositions by the complex impedance diagram method At 25°C, the conductivity reached a maximum value of 6 × 10−3 Ω−1 cm−1 Whatever the glass used, the same limit value of conductivity (σ − 10 su−2 Ω −1 cm −1 ) and activation energy ( E σ ⋍ 025 eV ) are obtained for the highest content of silver iodide A conduction mechanism is proposed

Evelyne Robinel

Papers

Silver sulfide based glasses (I). Glass forming regions, structure and ionic conduction of glasses in GeS2Ag2S and GeS2Ag2SAgI systems