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 Mn14.9Co15.5Ge6.6 and Mn14Co16.2Ge6.8 intermetallic compounds are part of the homogeneity region of the X-phase and adopt the Mn14(Mn0.11Co0.64Si0.25)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.
Highlights
Close packed (TCP) phases or Frank–Kasper phases as they are known encompass a large number of intermetallic compounds (Dshemuchadse & Steurer, 2015; Ovchinnikov et al, 2020)
We report two new variants of the X-phase 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)
Summary
Close packed (TCP) phases or Frank–Kasper phases as they are known encompass a large number of intermetallic compounds (Dshemuchadse & Steurer, 2015; Ovchinnikov et al, 2020). The Mn–Co–Si system, from which the base structure is derived, was discovered in the 1970s by two independent groups (Yarmolyuk et al, 1970; Manor et al, 1972) This structure has been reported as Mn15.84Co15.87Si5.29 and Mn44.4Co40.0Si15.1, respectively. Are assigned to the Mn14(Mn0.11Co0.64Si0.25) structure type (Villars & Cenzual, 2016), where seven independent positions relate to Mn and the other nine positions are mixed Co/Mn or Si/Co/Mn. Investigation of the phase diagram of the ternary Mn–Co–Si system at 800 C revealed the formation of Mn16.5Co14.8Si5.7 (Kuz’ma & Gladyshevskii, 1964), while at 1000 C, the authors reported Mn16.5Co14.8Si5.7, as well as Mn3Co3Si (Y-phase) (Bardos et al, 1966). The syntheses and crystal structures of two new Mn–Co–Ge compounds, representatives of the X-phase, will be discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Acta crystallographica. Section C, Structural chemistry
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
