Role of Ag in textured-annealed Bi2Ca2Co1.7Ox thermoelectric ceramic

Delphine Flahaut (1) , Joachim Allouche (1) , A. Sotelo , Sh. Rasekh , M.A. Torres , M.A. Madre , J.C. Diez

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux

Bi2Ca2Co1.7Ox thermoelectric ceramics with small Ag additions (0, 1, 2, 3, 4, and 5 wt.%) have been successfully grown from the melt, using the laser floating zone method and subsequently annealed at 800 °C for 24 h. The microstructure has shown a reduction of the amount of secondary phases for Ag contents up to 4 wt.%. This microstructural evolution leads to a decrease of the electrical resistivity values until an Ag content of 4 wt.%, whereas Seebeck coefficient has been maintained unchanged. This is in agreement with the presence of metallic Ag in all samples, confirmed not only by Energy Dispersive Spectrometry but also by X-ray photoelectron and Auger spectroscopy. These electrical properties lead to maximum power factor values of about 0.30 mW/K2.m at 650 °C for the 4 wt.% Ag containing samples, which is among the best results obtained for this type of materials.

Mots clés: Thermoelectric materials; misfit; X-ray Photoelectron Spectroscopy (XPS); Texture; Auger electron spectroscopies (AES); Thermoelectric materials; X-ray Photoelectron Spectroscopy (XPS); Auger Electron Spectroscopy (AES)

Domaines: Chimie

Delphine Flahaut, Joachim Allouche, A. Sotelo, Sh. Rasekh, M.A. Torres, et al.. Role of Ag in textured-annealed Bi2Ca2Co1.7Ox thermoelectric ceramic. Acta Materialia, 2016, 102, pp.273-283. ⟨10.1016/j.actamat.2015.09.036⟩. ⟨hal-01495408⟩