Jiajie ZHANG PhD defense

Synthèse et caractérisation de verres et de vitrocéramiques à base de soufre pour les applications d'électrolyte solide
Jiajie ZHANG PhD defense

University of Rennes – Beaulieu Campus
Building 10B, Grandjean amphitheater

Thursday December 14, 2023 – 9:30 a.m.



Glass & Ceramics team

 

Abstract

This thesis focuses on the synthesis of glasses in the pseudo-ternary system Na2S–Ga2S3–GeS2. Their thermal, structural, and conductivity properties were studied as a function of Na2S content. We also investigated the synthesis of one crystalline composition in this system, namely NaGaGeS4. First of all, glasses in the system x[Na2S]–(100-x) [0.5GeS2–0.5Ga2S3] were prepared via a two-step synthesis including a melt-quenching synthesis of a Ge-rich precursor, then a mechanical milling step for amorphization. A wide range of composition was obtained (10≤x≤75). Raman spectroscopy was used to study the glass structure as a function of Na2S content. It revealed a steady collapse of Ga(Ge)S4/2  tetrahedron-based medium-range network with the introduction of Na2S, and the formation of non-bridging sulfur in the glass network. The highest room-temperature conductivity is achieved for the sample with x=75 (σ = 1.8 × 10-5 S.cm-1). The highest conductivity is reached for the same sample at 90 °C (σ = 1.0 × 10-3 S.cm-1). An attempt of preparing NaGaGeS4 was carried out. XRD and profile refinement revealed its crystalline structure is similar to Na2Ga2GeS6. An improved ionic conductivity was obtained compared to its glassy counterpart thanks to its structure which promotes the mobility of charge.

 

Jury

  • Marie Guignard, Chargée de recherche CNRS, ICMCB, Bordeaux / Rapporteur
  • Gaëlle Delaizir, Professeur des Universités, IRCER, Université de Limoges / Rapporteur
  • Olivier Hernandez, Professeur des Universités, IMN, Université de Nantes / Examinateur
  • Virginie Nazabal , Directrice de recherche, ISCR, Université de Rennes / Examinateur
  • Xiang-Hua Zhang, Directeur de recherche CNRS, ISCR, Université de Rennes / Directeur de thèse
  • Louisiane Verger, Chargée de recherche CNRS, ISCR, Université de Rennes / Co-encadrante de thèse


Contacts