Structure, Magnetic Properties and 151Eu, 119Sn Moessbauer Spectroscopy of Eu5Sn3S12 and Eu4LuSn3S12.

Jakubcová, Petra; Johrendt, Dirk; Sebastian, C. Peter; Rayaprol, Sudhindra; Poettgen, Rainer

doi:10.1002/chin.200716009

Cited by 2 publications

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“…In contrast to Eu 14 Cl 33 50 no temperature-dependent change in the Eu 2+ /Eu 3+ ratio could be observed in the Mo ¨ssbauer spectra, probably due to the more rigid lattice of the nitridosilicate compound. 51 The valence behavior of Eu 2 SiN 3 is similar to other static intermediate valence compounds such as Eu 2 CuS 3 , 52 Eu 3 F 4 S 2 , 53 Eu 5 Sn 3 S 12 , 54 or Eu 5 Zr 3 S 12 . 55 The Eu 2 SiN 3 sample has also been measured at 4.2 K, well below the magnetic ordering temperature of T C ) 24 K. The divalent europium site magnetic hyperfine field splitting; however, although the total counting time was 5 days, the resulting spectrum had a poor signal-to-background ratio.…”

Section: Resultsmentioning

confidence: 76%

Mixed Valence Europium Nitridosilicate Eu₂SiN₃

et al. 2009

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Abstract:The mixed valence europium nitridosilicate Eu 2 SiN 3 has been synthesized at 900°C in welded tantalum ampules starting from europium and silicon diimide Si(NH) 2 in a lithium flux. The structure of the black material has been determined by single-crystal X-ray diffraction analysis (Cmca (no. 64), a ) 542.3(11) pm, b ) 1061.0(2) pm, c ) 1162.9(2) pm, Z ) 8, 767 independent reflections, 37 parameters, R1 ) 0.017, wR2 ) 0.032). Eu 2 SiN 3 is a chain-type silicate comprising one-dimensional infinite nonbranched zweier chains of corner-sharing SiN 4 tetrahedra running parallel [100] with a maximum stretching factor f s ) 1.0. The compound is isostructural with Ca 2 PN 3 and Rb 2 TiO 3 , and it represents the first example of a nonbranched chain silicate in the class of nitridosilicates. There are two crystallographically distinct europium sites (at two different Wyckoff positions 8f) being occupied with Eu 2+ and Eu 3+ , respectively. 151 Eu Mö ssbauer spectroscopy of Eu 2 SiN 3 differentiates unequivocally these two europium atoms and confirms their equiatomic multiplicity, showing static mixed valence with a constant ratio of the Eu 2+ and Eu 3+ signals over the whole temperature range. The Eu 2+ site shows magnetic hyperfine field splitting at 4.2 K. Magnetic susceptibility measurements exhibit Curie-Weiss behavior above 24 K with an effective magnetic moment of 7.5 µ B /f.u. and a small contribution of Eu 3+ , in accordance with Eu 2+ and Eu 3+ in equiatomic ratio. Ferromagnetic ordering at unusually high temperature is detected at T C ) 24 K. DFT calculations of Eu 2 SiN 3 reveal a band gap of ∼0.2 eV, which is in agreement with the black color of the compound. Both DFT calculations and lattice energetic calculations (MAPLE) corroborate the assignment of two crystallographically independent Eu sites to Eu 2+ and Eu 3+ .

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Section: Resultsmentioning

confidence: 76%

Mixed Valence Europium Nitridosilicate Eu₂SiN₃

et al. 2009

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“…Eu 5 Zr 3 S 12 is a Curie paramagnet with an effective magnetic moment of μ eff ϭ 13.37(1) μ B per formula unit (fu), in agreement with three Eu 2ϩ /fu. 151 Recently, we reported on the ternary thiostannate Eu 5 Sn 3 S 12 , a mixed-valent compound with three Eu 2ϩ and two Eu 3ϩ ions occupying five different crystallographic sites [6]. The static nature of the valence mixture was verified by 151 Eu Moessbauer spectra showing two separate absorptions with almost temperature-independent chemical shifts.…”

Section: Introductionmentioning

confidence: 94%

“…Mixed-valence compounds have been a matter of interest for decades [1]. In solids, europium can be divalent (Eu 2ϩ , 4f 7 ) or trivalent (Eu 3ϩ , 4f 6 ), and fluctuations between these configurations frequently occur. In structures with one crystallographic europium site and high fluctuation frequencies, Eu 2ϩ and Eu 3ϩ are not observable separately and thus homogeneously mixed (intermediate) valence results.…”

Section: Introductionmentioning

confidence: 99%

“…Homogeneous mixed valence is known from metallic compounds like EuCu 2 Si 2 [2] and EuNi 2 P 2 [3]. The nonmetallic compounds Eu 3 O 4 [4], Eu 2 CuS 3 [5], and Eu 5 Sn 3 S 12 [6] are examples of static mixed valence with different europium sites. Inhomogeneous mixed valence associated with Verwey transitions has been observed in Eu 3 S 4 [7], Eu 4 As 3 [8], and in the metallic compounds EuPtP [9,10], EuPdAs [11], and EuNiP [12,13].…”

Section: Introductionmentioning

confidence: 99%

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