Aylin Koldemir, Josef Maximilian Gerdes, Maximilian Kai Reimann, Michael Ryan Hansen, Rainer Pöttgen
{"title":"The HfFe2Si2 type silicides ScT 2Si2 (T = Ru, Rh, Os) – structure and solid-state 29Si/45Sc NMR spectroscopy","authors":"Aylin Koldemir, Josef Maximilian Gerdes, Maximilian Kai Reimann, Michael Ryan Hansen, Rainer Pöttgen","doi":"10.1515/zkri-2023-0048","DOIUrl":null,"url":null,"abstract":"The silicides Sc<jats:italic>T</jats:italic> <jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub> (<jats:italic>T</jats:italic> = Ru, Rh, Os) were synthesized by arc-melting of the elements and subsequent annealing in sealed silica ampoules. They crystallize with the rarely observed HfFe<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub> type structure, space group <jats:italic>Pbcm</jats:italic>. The structures of ScRu<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub> (<jats:italic>a</jats:italic> = 761.64(4), <jats:italic>b</jats:italic> = 730.70(6), <jats:italic>c</jats:italic> = 521.07(6) pm, w<jats:italic>R</jats:italic> = 0.0314, 633 <jats:italic>F</jats:italic> <jats:sup>2</jats:sup> values, 31 variables) and ScOs<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub> (<jats:italic>a</jats:italic> = 771.10(8), <jats:italic>b</jats:italic> = 736.68(7), <jats:italic>c</jats:italic> = 521.88(5) pm, w<jats:italic>R</jats:italic> = 0.0479, 623 <jats:italic>F</jats:italic> <jats:sup>2</jats:sup> values, 31 variables) were refined from single crystal X-ray diffractometer data. The refinements showed small degrees of Ru/Si respectively Os/Si mixing on one 4<jats:italic>c</jats:italic> site, leading to the refined compositions ScRu<jats:sub>1.96(1)</jats:sub>Si<jats:sub>2.04(1)</jats:sub> and ScOs<jats:sub>1.91(1)</jats:sub>Si<jats:sub>2.09(1)</jats:sub>. The monomeric building units in both structures are two slightly distorted, crystallographically independent RuSi<jats:sub>5</jats:sub> respectively OsSi<jats:sub>5</jats:sub> square pyramids, which are condensed via common edges. The resulting densely packed [Ru<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub>] and [Os<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub>] networks leave voids for the scandium atoms with coordination number 18: Sc@Si<jats:sub>8</jats:sub>Ru<jats:sub>8</jats:sub>Sc<jats:sub>2</jats:sub> and Sc@Si<jats:sub>8</jats:sub>Os<jats:sub>8</jats:sub>Sc<jats:sub>2</jats:sub>. Temperature dependent magnetic susceptibility measurements of ScRu<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub> and ScOs<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub> indicate Pauli paramagnetism. Solid-state <jats:sup>29</jats:sup>Si and <jats:sup>45</jats:sup>Sc static and MAS NMR spectroscopy reveal significant Knight shifts and a strong influence of the <jats:italic>T</jats:italic>/Si mixing on the experimental NMR line shapes. A larger overall <jats:sup>29</jats:sup>Si magnetic shift for ScRu<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub> compared to ScOs<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub>, although with a negative sign for one of the <jats:sup>29</jats:sup>Si resonances, suggests stronger paramagnetic effects for ScRu<jats:sub>2</jats:sub>Si<jats:sub>2</jats:sub>, in agreement with the magnetic susceptibility measurements.","PeriodicalId":23855,"journal":{"name":"Zeitschrift für Kristallographie - Crystalline Materials","volume":"29 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Zeitschrift für Kristallographie - Crystalline Materials","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1515/zkri-2023-0048","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The silicides ScT2Si2 (T = Ru, Rh, Os) were synthesized by arc-melting of the elements and subsequent annealing in sealed silica ampoules. They crystallize with the rarely observed HfFe2Si2 type structure, space group Pbcm. The structures of ScRu2Si2 (a = 761.64(4), b = 730.70(6), c = 521.07(6) pm, wR = 0.0314, 633 F2 values, 31 variables) and ScOs2Si2 (a = 771.10(8), b = 736.68(7), c = 521.88(5) pm, wR = 0.0479, 623 F2 values, 31 variables) were refined from single crystal X-ray diffractometer data. The refinements showed small degrees of Ru/Si respectively Os/Si mixing on one 4c site, leading to the refined compositions ScRu1.96(1)Si2.04(1) and ScOs1.91(1)Si2.09(1). The monomeric building units in both structures are two slightly distorted, crystallographically independent RuSi5 respectively OsSi5 square pyramids, which are condensed via common edges. The resulting densely packed [Ru2Si2] and [Os2Si2] networks leave voids for the scandium atoms with coordination number 18: Sc@Si8Ru8Sc2 and Sc@Si8Os8Sc2. Temperature dependent magnetic susceptibility measurements of ScRu2Si2 and ScOs2Si2 indicate Pauli paramagnetism. Solid-state 29Si and 45Sc static and MAS NMR spectroscopy reveal significant Knight shifts and a strong influence of the T/Si mixing on the experimental NMR line shapes. A larger overall 29Si magnetic shift for ScRu2Si2 compared to ScOs2Si2, although with a negative sign for one of the 29Si resonances, suggests stronger paramagnetic effects for ScRu2Si2, in agreement with the magnetic susceptibility measurements.
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