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Title: Rare-earth manganese germanides RE{sub 2+x}MnGe{sub 2+y} (RE=La, Ce) built from four-membered rings and stellae quadrangulae of Mn-centred tetrahedra

Reactions of the elements through arc-melting and annealing at 800 °C have led to the ternary rare-earth manganese germanides RE{sub 2+x}MnGe{sub 2+y} (RE=La, Ce). The approximate composition is RE{sub 2.1}MnGe{sub 2.2}, as determined by single-crystal X-ray diffraction studies on the La member (space group P4/nmm, a=16.0491(4) Å, c=8.1587(2) Å, Z=16). Although this composition is close to other germanides RE{sub 2}MGe{sub 2} (Sc{sub 2}CoSi{sub 2}-type), the structure is completely unrelated. Rather, La{sub 2.1}MnGe{sub 2.2} contains layers built up of Mn-centred tetrahedra in two types of arrangements, four-membered rings and stellae quadrangulae, with La and additional Ge atoms in the intervening spaces. Disorder of La atoms, isolated Ge atoms, and Ge{sub 2} dimers takes place within tunnels in the structure. Electrical and magnetic measurements on La{sub 2.1}MnGe{sub 2.2} indicate metallic behaviour and likely ferromagnetic ordering with a transition temperature above 300 K. - Graphical abstract: MnGe{sub 4} tetrahedra share corners to form four-membered rings and edges to form stellae quandrangulae in the structure of La{sub 2.1}MnGe{sub 2.2}. Display Omitted - Highlights: • RE{sub 2+x}MnGe{sub 2+y} (RE=La, Ce) is unrelated to RE{sub 2}MGe{sub 2} with similar composition. • La{sub 2.1}MnGe{sub 2.2} adopts a new tetragonal structure type. • MnGe{sub 4} tetrahedra are foundmore » in four-membered rings and stellae quadrangulae. • La{sub 2.1}MnGe{sub 2.2} is likely ferromagnetic with a transition temperature above 300 K.« less
Authors:
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Publication Date:
OSTI Identifier:
22274105
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 206; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANNEALING; GERMANIDES; GERMANIUM; MAGNETIC PROPERTIES; MANGANESE; MONOCRYSTALS; SPACE GROUPS; TETRAGONAL LATTICES; TRANSITION TEMPERATURE; X-RAY DIFFRACTION