Nd{sub 8}Co{sub 4−x}Al{sub x}Ge{sub 2}C{sub 3}: A case study in flux growth of lanthanide-rich intermetallics

• Published in: Journal of solid state chemistry Vol. 236
• Main Authors: Zhou, Sixuan, Latturner, Susan E.
• Format: Journal Article
• Language: English
• Published: United States 15-04-2016
• Subjects: ALUMINIUM OXIDES; ANISOTROPY; CARBON; COBALT; DENSITY; DENSITY OF STATES; EUTECTICS; GERMANIUM; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; INTERMETALLIC COMPOUNDS; MAGNETIC MOMENTS; MAGNETIC SUSCEPTIBILITY; MAGNETIZATION; MONOCRYSTALS; NEODYMIUM; NEODYMIUM IONS; ORTHORHOMBIC LATTICES; SPACE GROUPS
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/J.JSSC.2015.08.029

The intermetallic Nd{sub 8}Co{sub 4−x}Al{sub x}Ge{sub 2}C{sub 3} (x≈0.65) was prepared from reaction of germanium and carbon in Nd/Co eutectic flux in an alumina crucible. This phase exhibits a new structure type in orthorhombic space group Pbcm, with unit cell parameters a=8.001(1) Å, b=11.696(2) Å, c=15.020(3) Å (Z=4; R{sub 1}=0.0234). The structure features germanium-centered neodymium clusters Ge@Nd{sub 9} which share faces to form layers separated by zigzag chains of cobalt atoms capped by carbon. Density of states calculations confirm that this compound is metallic, and indicate that the cobalt should not have a magnetic moment. This is supported by magnetic susceptibility measurements which show a low temperature ferromagnetic ordering at T{sub C}=50 K due to the Nd{sup 3+} ions. Magnetization field dependence studies on single crystals indicate this compound is a strong ferromagnet with large anisotropy; the Nd{sup 3+} magnetic moments align along the a-axis. - Graphical abstract: Nd{sub 8}Co{sub 4−x}Al{sub x}Ge{sub 2}C{sub 3} (x≈0.65) contains germanium-centered neodymium clusters Ge@Nd{sub 9} which share faces to form layers separated by zigzag chains of cobalt atoms capped by carbon. - Highlights: • Nd{sub 8}Ge{sub 2}Co{sub 3.35}Al{sub 0.65}C{sub 3} grows as large crystals from reactions in Nd/Co eutectic flux. • Structure features Ge@Nd{sub 9} clusters and zigzag cobalt chains capped by carbon. • Cobalt has no magnetic moment; Nd{sup 3+} ion moments order ferromagnetically. • Hard ferromagnet with strong anisotropy below T{sub C} of 50 K. • Flux growth and structural trends of lanthanide-rich intermetallics are reviewed.