Synthesis, structure, and magnetic properties of LaTMg and CeTMg (T = Pd, Pt, Au)

• Published in: Journal of physics. Condensed matter Vol. 14; no. 20; pp. 5173 - 5186
• Main Authors: Gibson, B J, Das, A, Kremer, R K, Hoffmann, R-D, Pöttgen, R
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 27.05.2002; Institute of Physics
• Subjects: Alloys; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Physics; Saturation moments and magnetic susceptibilities; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Lanthanum alloys; Metallic conduction; Space groups; Gold alloys; Magnesium alloys; Cerium alloys; Curie-Weiss law; Long-range order; Platinum alloys; Refinement; Ternary alloys; XRD; Experimental study; Magnetic susceptibility; Specific heat; Valence; Palladium alloys; Crystallographic site; Rare earth alloys; Transition element alloys; Crystal structure
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/14/20/312

The title compounds were prepared from the elements by reactions in sealed tantalum tubes in a water-cooled sample chamber of a high-frequency furnace. They crystallize with the ZrNiAl-type structure, space group P62m. The structures of the cerium compounds were refined from single-crystal x-ray diffraction data: a = 767.3(1)pm, c = 410.37(4) pm, wR2 = 0.0324,521 F exp 2 -values for CePdMg; a = 755.02(7) pm, c = 413.82(4) pm, wR2 = 0.0393, 514 F exp 2 -values for CePtMg; and a = 774.1(3) pm, c = 421.6(1) pm, wR2 = 0.0355, 395 F exp 2 -values for CeAuMg, with 14 variables for each refinement. The palladium compound shows a small homogeneity range: CePd sub 1+x Mg sub 1-x . The structures contain two crystallographically different transition metal sites T1 and T2 which are located in tri-capped trigonal prisms: [T1Mg sub 6 Ce sub 3 ] and [T2Ce sub 6 Mg sub 3 ]. Magnetic susceptibility and heat capacity measurements reveal long-range magnetic ordering at 2.1(2) K for CePdMg, 3.6(2) K for CePtMg, and 2.0(2) K for CeAuMg. Curie-Weiss behaviour at higher temperatures shows that the cerium ions are in the 3+ oxidation state. The isotypic LaTMg compounds are Pauli paramagnetic down to lowest temperatures (T = 0.3 K). All the compounds, RETMg (RE = La, Ce; T = Pd, Pt, Au) show metallic-behaviour.