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A Quintupled Superstructure of the KHg2 Type Realized for the New Stannide EuAuSn (1997)

Pöttgen, Rainer ; Hoffmann, Rolf-Dieter ; Müllmann, Ralf ; [et al.]

Weinheim : Wiley-Blackwell

Chemistry - A European Journal 3 (1997), S. 1852-1859

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ISSN: 0947-6539

Keywords: conductivity ; europium ; gold ; magnetic properties ; superstructures ; tin ; Chemistry ; General Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The title compound was prepared from the elements by reaction in a sealed tantalum tube at 1320 K followed by slow cooling to 970 K. EuAuSn crystallizes with a pronounced subcell of space group Imma (KHg2 type). Additional very weak reflections required a quintupled b axis. The superstructure was refined from single-crystal four-circle diffractometer data (Imm 2, a = 479.1(1) pm, b = 3833.6(5) pm, c = 820.1(1) pm, Z = 20, wR2 = 0.0834, 3675 F2 values and 94 variables). Six crystallographically different europium sites occur in the superstructure. Each europium site has an ordered near-neighbour environment of six gold and six tin atoms in the form of two tilted hexagons. Magnetic susceptibility measurements show Curie-Weiss behaviour above 50 K with an experimental magnetic moment of 7.6(1) μB/Eu, indicating divalent europium. EuAuSn orders antiferromagnetically at about 12 K and undergoes a metamagnetic transition at a critical field of 2.0(2) T. Electrical conductivity measurements show metallic behaviour with a room temperature value of 260 μΩcm. 151Eu and 119Sn Mössbauer spectroscopic experiments are compatible with divalent europium and show complex magnetic hyperfine field splitting at low temperature.

Additional Material: 8 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/chem.19970031118

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151Eu Mössbauer spectroscopic, electric, and magnetic measurements of EuAgGe and EuAuGe (1997)

Müllmann, Ralf ; Mosel, Bernd D. ; Eckert, Hellmut ; [et al.]

Springer

Hyperfine interactions 108 (1997), S. 389-400

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ISSN: 1572-9540

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract The physical properties of EuAgGe and EuAuGe, the structures of which are derived from the CeCu2 type, have been investigated in detail by means of magnetic susceptibility, electrical conductivity and 151Eu Mössbauer measurements. Above 50 K both germanides show Curie--Weiss behavior with experimental magnetic moments of \mu exp=7.70(5) \mu B (EuAgGe) and \mu exp=7.40(5) \mu B (EuAuGe) and Weiss constants of -2(1) K (EuAgGe) and 33(1) K (EuAuGe). For EuAgGe, a magnetic phase transition is observed below 18(1) K. Zero-field cooling and field cooling measurements indicate cluster glass behavior (weak ferromagnetism, mictomagnetism). Magnetization measurements at 5 K show a saturation magnetic moment of 3.3(2) \mu B/Eu at 5.5 T. 151Eu Mössbauer measurements show a Eu(II) valence state (\delta =-10.4 mm/s). While magnetic hyperfine splitting appears in the spectra at temperatures as high as 15 K, complete magnetic ordering is not reached at temperatures down to 4.2 K. EuAuGe orders ferromagnetically at 32.9(2) K. Magnetization measurements at 2 K show a saturation magnetic moment of 6.2(1) \mu B/Eu at 5.5 T, respectively, indicating that all spins are ordered ferromagnetically at low temperatures. 151Eu Mössbauer measurements show a Eu(II) valence state (\delta =-10.6 mm/s) and two spectral components in an approximate 1:1 ratio, subjected to magnetic hyperfine splitting effects at T1=32(2) and T2=18(4) K, respectively. Thus, the transition temperature of 32.9 K observed in the susceptibility measurements appears to be associated with ordering of only one of the two crystallographically distinct europium sites in this compound. Electrical conductivity measurements indicate metallic behavior for both germanides.