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DOE OSTI · 3013557

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

Raines, Morgan E. [Baylor University, Waco, TX (United States)]·McCandless, Gregory T. [Baylor University, Waco, TX (United States)]·Schundelmier, Benny C. [Florida State University, Tallahassee, FL (United States)] (ORCID:0000000273459977)·Cetin, Selin [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0009000284748181)·Spencer, Theodore G. [Baylor University, Waco, TX (United States)]·Scott, Mary C. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]·Wei, Kaya [Florida State University, Tallahassee, FL (United States)]·Chan, Julia Y. [Baylor University, Waco, TX (United States)] (ORCID:0000000344342160)
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Abstract

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.

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36 MATERIALS SCIENCE37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYChemical structureCrystal structureDefects in solidsDiffractionGrowthGrowth of intermetallicsGrowth strategiesPolymorphPolymorphismRare Earth SynthesisTransition metals

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Raines, Morgan E. [Baylor University, Waco, TX (United States)], McCandless, Gregory T. [Baylor University, Waco, TX (United States)], Schundelmier, Benny C. [Florida State University, Tallahassee, FL (United States)] (ORCID:0000000273459977), Cetin, Selin [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0009000284748181), Spencer, Theodore G. [Baylor University, Waco, TX (United States)], Scott, Mary C. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Wei, Kaya [Florida State University, Tallahassee, FL (United States)], Chan, Julia Y. [Baylor University, Waco, TX (United States)] (ORCID:0000000344342160). 2025-10-25. Cooling-Rate-Driven Polymorphism and Vacancy Ordering in Ce 2 MnGe 6 Intergrowth Phases. https://doi.org/10.1021/acs.cgd.5c01182

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36 MATERIALS SCIENCE↗