Trilling Formation in the EuAuGe type Gallides REAuGa with RE = La, Ce, Pr, Nd, and Sm

The equiatomic gallides REAuGa (RE = La, Ce, Pr, Nd, Sm) were synthesized from the elements by arc‐melting. Small single crystals were grown by slowly cooling the samples from 1073 K to room temperature at a rate of 3 K·h–1. The REAuGa structures were reinvestigated from single‐crystal X‐ray diffrac...

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Published inZeitschrift für anorganische und allgemeine Chemie (1950) Vol. 644; no. 24; pp. 1741 - 1748
Main Authors Schubert, Lea, Hoffmann, Rolf‐Dieter, Heletta, Lukas, Pöttgen, Rainer
Format Journal Article
LanguageEnglish
Published Weinheim Wiley Subscription Services, Inc 31.12.2018
Subjects
Antiferromagnetism
Bonding strength
Cerium
Cooling rate
Crystal growth
Crystal structure
Crystals
Curie temperature
Electric arc melting
Gallide
Gallium intermetallics
Interlayers
Lanthanum
Magnetic permeability
Magnetic properties
Paramagnetism
Praseodymium
Rare earth compounds
Single crystals
Structure elucidation
Superstructures
Temperature dependence
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Summary:The equiatomic gallides REAuGa (RE = La, Ce, Pr, Nd, Sm) were synthesized from the elements by arc‐melting. Small single crystals were grown by slowly cooling the samples from 1073 K to room temperature at a rate of 3 K·h–1. The REAuGa structures were reinvestigated from single‐crystal X‐ray diffractometer data. The five gallides adopt the non‐centrosymmetric EuAuGe type structure, space group Imm2, a superstructure variant of KHg2. The symmetry reductions lead to the formation of trillings and inversion twins. The domain ratios were precisely determined from the single crystal data. The striking structural motifs of the REAuGa structures are slightly puckered Au3Ga3 layers with strong covalent Au–Ga bonding. Stacking of these layers in AA′ sequence (A and A′ are related by mirror planes) leads to weak Au–Au (aurophilic bonding) and Ga–Ga interlayer interactions (319 and 283 pm in SmAuGa). Temperature dependent magnetic susceptibility measurements revealed Curie–Weiss behavior for CeAuGa and NdAuGa, whereas SmAuGa exhibits the typical van Vleck paramagnetism caused by contributions of the excited states. Antiferromagnetic ground states were observed for CeAuGa, NdAuGa, and SmAuGa below the respective Néel temperatures of 2.8, 9.5 and 24.1 K. LaAuGa is Pauli paramagnetic.
ISSN:0044-2313
1521-3749
DOI:10.1002/zaac.201800319