Results for “Ca(MnGe)2” | Engineering Papers

DOE OSTI2020

Materials Data on Ca(MnGe)2 by Materials Project

CaMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ca is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Ca–Ge bond lengths are 3.14 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.44 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Ca, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.73 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Cooling-Rate-Driven Polymorphism and Vacancy Ordering in Ce 2 MnGe 6 Intergrowth Phases

Intergrowth phases in intermetallic systems provide a compelling framework for investigating structure–property relationships as a function of crystallographic subunit stacking. In this study, we examine the influence of Mn vacancy ordering on subunit stacking and reassign the structure of Ce 2 MnGe 6 to a monoclinic C2/m space group (a = 8.3486(17) Å, b = 8.6181(18) Å, c = 10.778(2) Å, β = 101.17(2)°). Additionally, we report a monoclinic polymorph of the Ln 2 MGe 6 family characterized as a tripled c-axis supercell derivative of monoclinic Ce 2 MnGe 6 , 3×c-Ce 2 MnGe 6 (a = 8.3482(16) Å, b = 8.6179(18) Å, c = 31.813(6) Å, β = 93.763(7)°). This polymorph emerges under rapid cooling conditions during the synthesis and offers insight into the structural relationship between the orthorhombic and monoclinic variants of the Ln 2 MGe 6 phases. Notably, the supercell form of Ce 2 MnGe 6 (3×c-Ce 2 MnGe 6 ) exhibits increased electrical resistivity and suggests enhanced Zintl-like behavior, potentially indicating greater thermodynamic stability relative to the parent monoclinic phase.

36 MATERIALS SCIENCE↗