Maximilian Kai Reimann, Jutta Kösters, Tautvydas Bieliauskas, Rainer Pöttgen
{"title":"The crystal structures of the ternary intermetallics RE 2Pd2Cd (RE = Nd, Sm, Gd, Dy) and RE 2Ga2Mg (RE = Tb, Er, Tm, Lu) at 90 K","authors":"Maximilian Kai Reimann, Jutta Kösters, Tautvydas Bieliauskas, Rainer Pöttgen","doi":"10.1515/znb-2024-0014","DOIUrl":null,"url":null,"abstract":"The crystal structures of the U<jats:sub>3</jats:sub>Si<jats:sub>2</jats:sub>-related intermetallic compounds <jats:italic>RE</jats:italic> <jats:sub>2</jats:sub>Pd<jats:sub>2</jats:sub>Cd (<jats:italic>RE</jats:italic> = Nd, Sm, Gd, Dy) and <jats:italic>RE</jats:italic> <jats:sub>2</jats:sub>Ga<jats:sub>2</jats:sub>Mg (<jats:italic>RE</jats:italic> = Tb, Er, Tm, Lu) were studied from single crystal X-ray diffraction data at <jats:italic>T</jats:italic> = 90 K in order to understand the slightly enhanced <jats:italic>U</jats:italic> <jats:sub>33</jats:sub> displacements of the 2<jats:italic>a</jats:italic> positions in their room temperature structures. The compounds Sm<jats:sub>2</jats:sub>Pd<jats:sub>2</jats:sub>Cd, Gd<jats:sub>2</jats:sub>Pd<jats:sub>2</jats:sub>Cd and Dy<jats:sub>2</jats:sub>Pd<jats:sub>2</jats:sub>Cd show a decrease of the ratio of <jats:italic>U</jats:italic> <jats:sub>33</jats:sub> to <jats:italic>U</jats:italic> <jats:sub>11</jats:sub> for the cadmium atoms, leading to a more isotropic behavior at low temperature, keeping the <jats:italic>P</jats:italic>4/<jats:italic>mbm</jats:italic> space group symmetry. Nd<jats:sub>2</jats:sub>Pd<jats:sub>2</jats:sub>Cd shows a <jats:italic>translationengleiche</jats:italic> symmetry reduction to space group <jats:italic>P</jats:italic>4<jats:italic>bm</jats:italic> along with a weak puckering effect with shorter (342.7 pm) and longer (345.7 pm) Cd–Nd distances within the Cd@Nd<jats:sub>8</jats:sub> square prisms. This new, non-centrosymmetric superstructure variant was also observed for the magnesium compounds Tb<jats:sub>2</jats:sub>Ga<jats:sub>2.069</jats:sub>Mg<jats:sub>0.931</jats:sub>, Er<jats:sub>2</jats:sub>Ga<jats:sub>2.104</jats:sub>Mg<jats:sub>0.896</jats:sub>, Tm<jats:sub>2</jats:sub>Ga<jats:sub>2.097</jats:sub>Mg<jats:sub>0.903</jats:sub> and Lu<jats:sub>2</jats:sub>Ga<jats:sub>2.173</jats:sub>Mg<jats:sub>0.827</jats:sub>, which show small degrees of Mg/Ga mixing.","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"104 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Zeitschrift für Naturforschung B","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1515/znb-2024-0014","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 crystal structures of the U3Si2-related intermetallic compounds RE2Pd2Cd (RE = Nd, Sm, Gd, Dy) and RE2Ga2Mg (RE = Tb, Er, Tm, Lu) were studied from single crystal X-ray diffraction data at T = 90 K in order to understand the slightly enhanced U33 displacements of the 2a positions in their room temperature structures. The compounds Sm2Pd2Cd, Gd2Pd2Cd and Dy2Pd2Cd show a decrease of the ratio of U33 to U11 for the cadmium atoms, leading to a more isotropic behavior at low temperature, keeping the P4/mbm space group symmetry. Nd2Pd2Cd shows a translationengleiche symmetry reduction to space group P4bm along with a weak puckering effect with shorter (342.7 pm) and longer (345.7 pm) Cd–Nd distances within the Cd@Nd8 square prisms. This new, non-centrosymmetric superstructure variant was also observed for the magnesium compounds Tb2Ga2.069Mg0.931, Er2Ga2.104Mg0.896, Tm2Ga2.097Mg0.903 and Lu2Ga2.173Mg0.827, which show small degrees of Mg/Ga mixing.