A comprehensive study of the crystallization of Cu–As–Te glasses: microstructure and thermoelectric properties

J. B. Vaney; G. Delaizir; E. Alleno; O. Rouleau; A. Piarristeguy; J. Monnier; C. Godart; M. Ribes; R. Escalier; A. Pradel; A. P. Gonçalves; E. B. Lopes; G. J. Cuello; P. Ziolkowski; E. Müller; C. Candolfi; A. Dauscher; B. Lenoir

doi:10.1039/C3TA11159H

A comprehensive study of the crystallization of Cu–As–Te glasses: microstructure and thermoelectric properties

J. B. Vaney,^ab G. Delaizir,^c E. Alleno,^d O. Rouleau,^d A. Piarristeguy,^b J. Monnier,^d C. Godart,^d M. Ribes,^b R. Escalier,^b A. Pradel,*^b A. P. Gonçalves,^e E. B. Lopes,^e G. J. Cuello,^f P. Ziolkowski,^g E. Müller,^g C. Candolfi,^a A. Dauscher^a and B. Lenoir^a

Author affiliations

* Corresponding authors

^a Institut Jean Lamour (IJL), UMR 7198 CNRS-Université de Lorraine, France

^b Institut Charles Gerhardt (ICG), UMR 5253 CNRS-Université Montpellier 2, France
E-mail: annie.pradel@univ-montp2.fr

^c Sciences des Procédés Céramique et de Traitement de Surface (SPCTS), UMR CNRS 7315, Centre Européen de la Céramique, Limoges, France

^d Institut de Chimie et des Matériaux de Paris Est (ICMPE), UMR 7182 CNRS, CMTR, Thiais, France

^e ST/ITN Instituto Superior Técnico, Universidade Técnica de Lisboa, P-2686-953 Sacavém, Portugal

^f Institut Laue Langevin, 6 rue Jules Horowitz, B. P. 156, 38042 Grenoble, France

^g Institute of Materials Research, German Aerospace Center (DLR) Linder Hoehe, Cologne, Germany

Abstract

We report a thorough experimental study on the microstructure, thermal behavior and thermoelectric properties of the amorphous composition Cu₁₅As₃₀Te₅₅ and the glass–ceramics related-compounds synthesized by using the Spark Plasma Sintering (SPS) technique. Varying the conditions of the SPS process enables the synthesis of composite glassy-crystalline samples with different crystal/glass ratios. Such treatments result in complex microstructures composed of large glassy domains where nanocrystals of the metastable β-As₂Te₃ phase are embedded. These domains are separated by regions of the dendritic crystalline phase surrounded by a Cu-rich glassy matrix. The presence of β-As₂Te₃, confirmed by both powder X-ray diffraction and scanning electron microscopy, suggests that pressure and/or internal stresses play an important role in stabilizing this phase. This conclusion is further supported by neutron thermodiffraction experiments revealing a sharp crossover from the β-As₂Te₃ to the stable α-As₂Te₃ phase at temperatures below that of the SPS treatment. Transport properties measurements show that the presence of a crystalline fraction significantly lowers the electrical resistivity by four orders of magnitude. However, the probable intrinsic n-type behavior of β-As₂Te₃ has a detrimental influence on the thermopower values. Even though the partial crystallization of the glassy matrix leads to an increase in the thermal conductivity, the measured values remain on the order of 1 W m⁻¹ K⁻¹ at 300 K. Besides an overall increase in the dimensionless figure of merit ZT, our results demonstrate that the partial crystallization of an amorphous matrix is an efficient tool to tune the electrical resistivity over several orders of magnitude while maintaining low thermal conductivity values.

Journal of Materials Chemistry A

A comprehensive study of the crystallization of Cu–As–Te glasses: microstructure and thermoelectric properties

Abstract

Article information

Download Citation

Permissions

A comprehensive study of the crystallization of Cu–As–Te glasses: microstructure and thermoelectric properties

Social activity

Search articles by author

Spotlight

Advertisements