Mixed valent stannide EuRuSnb>3b> – Structure, magnetic properties, and Mössbauer spectroscopic investigation

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• 作者：Thomas Harmening ; Wilfried Hermes ; Matthias Eul ; Rainer P&#xf6 ; ttgen
• 关键词：Intermetallic compounds ; Crystal chemistry ; EuRuSnb>3b> ; Magnetic properties ; M&#xf6 ; ssbauer spectroscopy
• 刊名：Solid State Sciences
• 出版年：2010
• 出版时间：February 2010
• 年：2010
• 卷：12
• 期：2
• 页码：284-290
• 全文大小：1065 K

文摘

The stannide EuRuSnb>3b> was synthesized by induction melting of the elements in a sealed tantalum tube in a water-cooled quartz glass sample chamber. The structure was refined on the basis of single crystal X-ray diffractometer data (LaRuSnb>3b> type, Pmn, a = 976.0(1) pm, wR2 = 0.0399, 317 F² values, and 13 variables). EuRuSnb>3b> shows modified Curie–Weiss behaviour in the temperature range 50–305 K with an experimental magnetic moment of 7.34(1) bc;b>Bb> per formula unit. Thus, the europium atoms are not in a purely divalent state. Low field susceptibility measurement indicates a ferro- or ferrimagnetic ordering at Tb>Cb> = 11.2(2) K and magnetization measurements indicate EuRuSnb>3b> as a non-collinear ferro- or ferrimagnet. ¹⁵¹Eu Mössbauer spectroscopic measurements suggested one europium site to be static mixed valent with a Eu²⁺/Eu³⁺ ratio close to one and the other site purely divalent. This was supported by substituting the Eu³⁺ atoms with Y³⁺ in a sample with a composition of Eub>0.7b>Yb>0.3b>RuSnb>3b> (a = 971.24(8) pm, wR2 = 0.0485, 313 F² values, 14 variables). The ¹¹⁹Sn Mössbauer spectra show a pronounced Gol'danskii–Karyagin effect in the paramagnetic range and a magnetic hyperfine field distribution at 4.2 K, due to the complex magnetic structure. The influence of the valence electron concentration on the europium valence was tested via Ru/Pd substitution. A EuRub>0.8b>Pdb>0.2b>Snb>3b> sample shows almost purely divalent europium.