Thermoelectric properties and stability of glasses in the Cu‐As‐Te system

Abstract

International audienceChalcogenide glasses and more importantly their glass-ceramics counterparts have been an interesting but very peculiar class of thermoelectric materials, with inherently low thermal conductivity (<0.3 W/m.K). In this study, we report on the fabrication of glasses in the ternary system Cu-As-Te (CuxAs55-xTe45 [5≤x≤20], Cu15As85-yTey [45≤y≤70], and Cu20As80-yTey [45≤y≤65]) by melt-quenching and subsequent spark plasma sintering treatment. Their thermal and structural properties have been studied by differential scanning calorimetry and Raman spectroscopy, leading to give insights into the structural evolution of the glassy matrix. Coupling this information with the analysis of their electrical transport properties allowed us to deepen further our understanding of the compositional effect on their thermoelectric properties, and indirectly how the evolution of their electronic band structure is at play. Despite exhibiting low ZT values by themselves, Cu-As-Te glasses may still be interesting candidates for thermoelectricity through partial crystallization for which knowing the relationship between composition and properties remains essential

High-Conductivity Chalcogenide Glasses in Ag–Ga2Te3–SnTe Systems and Their Suitability as Thermoelectric Materials

“…Room-temperature electrical conductivity (σ) as a function of glass transition temperature ( T g ) for Ag–Ga 2 Te 3 –SnTe glasses and typical tellurium-based glasses (refs − , − , − ). The doping concentration is between 5–20% (A) and 5 −35% (B).…”

“…As shown in Figure 7, the κ was <0.21 W m −1 K −1 for all of the Ag−Ga 2 Te 3 −SnTe glassy samples in the investigated temperature interval of 303−463 K, which was lower than the κ values for Cu 30 As 10 Te 54 Se 6 (0.32 W m −1 K −1 ) samples 26 and Cu 22.5 As 17.5 Te 60 (0.35 W m −1 K −1) . 28 Slightly higher κ values were observed for A8 and A10, which clarified the role of the relatively higher densities induced by different Ag doping concentrations. Overall, the κ values of the Ag−Ga 2 Te 3 −SnTe glassy system were not affected by the chemical substitutions, which maintained the typical behavior of semiconducting chalcogenide glasses.…”

“…Moreover, the thermal conductivities of chalcogenide glasses are inversely proportional to their molecular weights owing to their lower speed of phonon transmission; hence, the smaller atomic masses of sulfur and selenium lead to higher thermal conductivities than those of the tellurium-based glasses. Thus, the investigations have focused on tellurium-based glasses, which were found to possess larger atomic masses, relatively low phonon energies, and highly disordered structures, demonstrating their superior TE research prospects. − …”

Theoretical and Experimental Parameters of the Structure and Crystallization Kinetics of Melt-Quenched As30Te64Ga6 Glassy Alloy

“…In order to improve the physical properties of the binary As-Te system, doping with other elements or/and heating treatment are required. For example, the electrical response of the As-Te glassy system reinforces by doping Cu, Ge, Si, or Ga elements, for this reason, the ternary alloys are beneficial in the electrical field not to mention the great benefit of these alloys, whether in the optical or thermal field [9][10][11]. The addition of such elements for forming ternary alloys leads to a change in the characteristic's temperatures such as Tg [12].…”

Short range order of As40-xCuxTe60 glasses

“…In the present case, the most straightforward way of getting element-specific information is to carry out extended X-ray absorption fine structure (EXAFS) measurements. Such information is particularly relevant to better understand the influence of the Cu content on the electrical and thermal transport properties of these glasses [13][14][15][16].…”