Synthesis, structural characterization and magnetic properties of RE{sub 2}MgGe{sub 2} (RE=rare-earth metal)

Journal Article · Tue Nov 15 00:00:00 EST 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.09.003· OSTI ID:21580060

Suen, Nian-Tzu; Tobash, Paul H ^[1]; Bobev, Svilen ^[1]

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1. Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States)

A series of rare-earth metal-magnesium-germanides RE{sub 2}MgGe{sub 2} (RE=Y, Nd, Sm, Gd-Tm, Lu) has been synthesized by reactions of the corresponding elements at high temperature. Their structures have been established by single-crystal and powder X-ray diffraction and belong to the Mo{sub 2}FeB{sub 2} structure type (space group P4/mbm (No. 127), Z=2; Pearson symbol tP10). Temperature dependent DC magnetization measurements indicate Curie-Weiss paramagnetism in the high-temperature regime for all members of the family, excluding Y{sub 2}MgGe{sub 2}, Sm{sub 2}MgGe{sub 2}, and Lu{sub 2}MgGe{sub 2}. At cryogenic temperatures (ca. 60 K and below), most RE{sub 2}MgGe{sub 2} phases enter into an antiferromagnetic ground-state, except for Er{sub 2}MgGe{sub 2} and Tm{sub 2}MgGe{sub 2}, which do not undergo magnetic ordering down to 5 K. The structural variations as a function of the decreasing size of the rare-earth metals, following the lanthanide contraction, and the changes in the magnetic properties across the series are discussed as well. - Graphical Abstract: The structure of RE{sub 2}MgGe{sub 2} (RE=Y, Nd, Sm, Gd-Tm, Lu) can be best viewed as 2-dimensional slabs of Mg and Ge atoms (anionic sub-lattice), and layers of rare-earth metal atoms (cationic sub-lattice) between them. Within this description, one should consider the Ge-Ge dumbbells (formally Ge{sup 6-}{sub 2}), interconnected with square-planar Mg atom as forming flat [MgGe{sub 2}] layers (z=0), stacked along the c-axis with the layers at z=1/2, made of rare-earth metal cations (formally RE{sup 3+}). Highlights: > RE{sub 2}MgGe{sub 2} (RE=Y, Nd, Sm, Gd-Tm, Lu) are new ternary germanides. > Their structures can be recognized as a 1:1 intergrowth of CsCl- and AlB{sub 2}-like slabs. > Ge atoms are covalently bound into Ge{sub 2} dumbbells. > Most RE{sub 2}MgGe{sub 2} phases are antiferromagnetically ordered at cryogenic temperatures.

• OSTI ID: 21580060
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 11; Other Information: DOI: 10.1016/j.jssc.2011.09.003; PII: S0022-4596(11)00485-3; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
GERMANIDES
INTERMETALLIC COMPOUNDS
MAGNESIUM
MAGNETIC PROPERTIES
MAGNETIZATION
MONOCRYSTALS
PARAMAGNETISM
RARE EARTHS
RHENIUM IONS
SPACE GROUPS
SYNTHESIS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
TETRAGONAL LATTICES
X-RAY DIFFRACTION
ALKALINE EARTH METALS
ALLOYS
CHARGED PARTICLES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DIFFRACTION
ELEMENTS
GERMANIUM COMPOUNDS
IONS
MAGNETISM
METALS
PHYSICAL PROPERTIES
SCATTERING
SYMMETRY GROUPS
TEMPERATURE RANGE