Crystal structure and high temperature X-ray diffraction study of thermoelectric chimney-ladder FeGeγ (γ ≈ 1.52)

S. Le Tonquesse (1, 2) , C. Hassam (3, 1) , Y. Michiue (1) , Yoshitaka Matsushita (1) , Mathieu Pasturel (4) , T. Mori (1) , Tohru Suzuki (1) , David Berthebaud (1)

1 NIMS - National Institute for Materials Science
2 LINK - Laboratory for Innovative Key Materials and Structures
3 CRISMAT - Laboratoire de cristallographie et sciences des matériaux
4 ISCR - Institut des Sciences Chimiques de Rennes

The crystal structure of Nowotny chimney-ladder phase FeGeγ with γ ≈ 1.52 was studied by X-ray diffractometry from 300 K to 850 K. The diffraction patterns were fitted by Rietveld refinement considering an incommensurate composite crystal structure. The refined crystal structure of FeGeγ is described in details and compared to MnSiγ, a thermoelectric material with γ ≈ 1.74. The lattice parameters a, cFe and cGe were found to increase with the temperature following a polynomial law, while the modulation vector component γ remained constant up to the peritectoid decomposition into FeGe and FeGe2. Within the temperature range considered, the linear and volumetric thermal expansion parameters increased from about 3 × 10−6 K−1 to 10 × 10−6 K−1 and from 9.6 × 10−6 K−1 to 31.5 × 10−6 K−1, respectively.

Mots clés: Crystal structure; Intermetallics; Thermal expansion; Thermoelectic materials; X-ray diffraction

Domaines: Chimie

S. Le Tonquesse, C. Hassam, Y. Michiue, Yoshitaka Matsushita, Mathieu Pasturel, et al.. Crystal structure and high temperature X-ray diffraction study of thermoelectric chimney-ladder FeGeγ (γ ≈ 1.52). Journal of Alloys and Compounds, 2020, 846, pp.155696. ⟨10.1016/j.jallcom.2020.155696⟩. ⟨hal-02932004⟩