Variants of the X-phase in the Mn-Co-Ge system

Vitalii Shtender; Simon R Larsen; Martin Sahlberg

doi:10.1107/S2053229621002370

Variants of the X-phase in the Mn-Co-Ge system

Acta Crystallogr C Struct Chem. 2021 Apr 1;77(Pt 4):176-180. doi: 10.1107/S2053229621002370. Epub 2021 Mar 9.

Authors

Vitalii Shtender¹, Simon R Larsen¹, Martin Sahlberg¹

Affiliation

¹ Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, 75121 Uppsala, Sweden.

Abstract

We report two new variants of the X-phase (orthorhombic, space group Pnnm) derived from the Mn-Co-Ge system. Two compositionally related crystals were investigated by means of single-crystal X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The Mn_14.9Co_15.5Ge_6.6 and Mn₁₄Co_16.2Ge_6.8 intermetallic compounds are part of the homogeneity region of the X-phase and adopt the Mn₁₄(Mn_0.11Co_0.64Si_0.25)₂₃ structure type. The composition obtained from refinement of the XRD data is in agreement with the EDS results. In the present study, chemical disorder was only detected on the 8h positions. The ordering is compared with other members of the X-phase family and shows that the degree of disordering depends on the chemical composition. No completely ordered variants of the X-phase have yet been reported.

Keywords: Mn-Co-Ge system; X-phase; cobalt; crystal structure; germanide; intermetallic compound; manganese.

open access.

Grants and funding

EM16-0039/Swedish Foundation for Strategic Research