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Title: The RELi{sub x}Sn{sub 2} (RE=La–Nd, Sm, and Gd; 0≤x<1) series revisited. Synthesis, crystal chemistry, and magnetic susceptibilities

Abstract

This study is concerned with the ternary compounds RELi{sub x}Sn{sub 2} (RE=La–Nd, Sm, and Gd; 0≤x<1), which have been previously thought to be the stoichiometric RELiSn{sub 2} phases. These materials crystallize with the base-centered orthorhombic space group Cmcm (No. 63), and can be formally assigned with the CeNiSi{sub 2} structure type (Pearson symbol oC16). Our systematic single-crystal X-ray diffraction studies revealed substantial Li-deficiencies in all cases, with SmSn{sub 2} (space group Cmmm, ZrGa{sub 2} structure type, Pearson symbol oC12) and GdSn{sub 2} (space group Cmcm, ZrSi{sub 2} structure type, Pearson symbol oC12) being completely lithium-free. The structure refinements also uncovered positional disorder on the Sn site neighboring the vacancies. The Sn-disorder and the Li-deficiency correlate, and vary monotonically with the decreased size of the rare-earth atoms in the order RE=La–Nd. The SmSn{sub 2} and GdSn{sub 2} structures are devoid of any disorder. Temperature-dependent studies of the magnetic response of the title compounds are also presented and discussed. -- Graphical abstract: RELi{sub x}Sn{sub 2} (RE=La–Nd, 0≤x<1) crystallize in a defect variants of the CeNiSi{sub 2} structure type (a). The Sn-disorder and the Li-deficiency correlate, and vary monotonically with the decreased size of the rare-earth atoms in the order RE=La–Nd. The SmSn{submore » 2} (b) and GdSn{sub 2} (c) structures are devoid of any disorder. Highlights: • The crystal structures of the RELi{sub x}Sn{sub 2} (RE=La–Nd, 0≤x<1) compounds are revised using single-crystal X-ray diffraction data. • The structure is a filled derivative of the ZrSi{sub 2} structure type or defect variant of the CeNiSi{sub 2} structure type. • SmSn{sub 2} is isotypic with the ZrGa{sub 2} structure, while RESn{sub 2} (RE=Gd–Lu) are isotypic with the ZrSi{sub 2} structure.« less

Authors:
; ;  [1]; ; ;  [2];  [1]
  1. Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716 (United States)
  2. Department of Physics, University of Maryland, College Park, MD 20742 (United States)
Publication Date:
OSTI Identifier:
22275852
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 211; Journal Issue: Complete; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DEFECTS; ELECTRONIC STRUCTURE; MAGNETIC SUSCEPTIBILITY; MONOCRYSTALS; ORTHORHOMBIC LATTICES; SPACE GROUPS; SYNTHESIS; TEMPERATURE DEPENDENCE; X-RAY DIFFRACTION; ZIRCONIUM SILICIDES

Citation Formats

Makongo, Julien P.A., Suen, Nian-Tzu, Guo, Shengping, Saha, Shanta, Greene, Richard, Paglione, Johnpierre, and Bobev, Svilen, E-mail: bobev@udel.edu. The RELi{sub x}Sn{sub 2} (RE=La–Nd, Sm, and Gd; 0≤x<1) series revisited. Synthesis, crystal chemistry, and magnetic susceptibilities. United States: N. p., 2014. Web. doi:10.1016/J.JSSC.2013.12.010.
Makongo, Julien P.A., Suen, Nian-Tzu, Guo, Shengping, Saha, Shanta, Greene, Richard, Paglione, Johnpierre, & Bobev, Svilen, E-mail: bobev@udel.edu. The RELi{sub x}Sn{sub 2} (RE=La–Nd, Sm, and Gd; 0≤x<1) series revisited. Synthesis, crystal chemistry, and magnetic susceptibilities. United States. doi:10.1016/J.JSSC.2013.12.010.
Makongo, Julien P.A., Suen, Nian-Tzu, Guo, Shengping, Saha, Shanta, Greene, Richard, Paglione, Johnpierre, and Bobev, Svilen, E-mail: bobev@udel.edu. Sat . "The RELi{sub x}Sn{sub 2} (RE=La–Nd, Sm, and Gd; 0≤x<1) series revisited. Synthesis, crystal chemistry, and magnetic susceptibilities". United States. doi:10.1016/J.JSSC.2013.12.010.
@article{osti_22275852,
title = {The RELi{sub x}Sn{sub 2} (RE=La–Nd, Sm, and Gd; 0≤x<1) series revisited. Synthesis, crystal chemistry, and magnetic susceptibilities},
author = {Makongo, Julien P.A. and Suen, Nian-Tzu and Guo, Shengping and Saha, Shanta and Greene, Richard and Paglione, Johnpierre and Bobev, Svilen, E-mail: bobev@udel.edu},
abstractNote = {This study is concerned with the ternary compounds RELi{sub x}Sn{sub 2} (RE=La–Nd, Sm, and Gd; 0≤x<1), which have been previously thought to be the stoichiometric RELiSn{sub 2} phases. These materials crystallize with the base-centered orthorhombic space group Cmcm (No. 63), and can be formally assigned with the CeNiSi{sub 2} structure type (Pearson symbol oC16). Our systematic single-crystal X-ray diffraction studies revealed substantial Li-deficiencies in all cases, with SmSn{sub 2} (space group Cmmm, ZrGa{sub 2} structure type, Pearson symbol oC12) and GdSn{sub 2} (space group Cmcm, ZrSi{sub 2} structure type, Pearson symbol oC12) being completely lithium-free. The structure refinements also uncovered positional disorder on the Sn site neighboring the vacancies. The Sn-disorder and the Li-deficiency correlate, and vary monotonically with the decreased size of the rare-earth atoms in the order RE=La–Nd. The SmSn{sub 2} and GdSn{sub 2} structures are devoid of any disorder. Temperature-dependent studies of the magnetic response of the title compounds are also presented and discussed. -- Graphical abstract: RELi{sub x}Sn{sub 2} (RE=La–Nd, 0≤x<1) crystallize in a defect variants of the CeNiSi{sub 2} structure type (a). The Sn-disorder and the Li-deficiency correlate, and vary monotonically with the decreased size of the rare-earth atoms in the order RE=La–Nd. The SmSn{sub 2} (b) and GdSn{sub 2} (c) structures are devoid of any disorder. Highlights: • The crystal structures of the RELi{sub x}Sn{sub 2} (RE=La–Nd, 0≤x<1) compounds are revised using single-crystal X-ray diffraction data. • The structure is a filled derivative of the ZrSi{sub 2} structure type or defect variant of the CeNiSi{sub 2} structure type. • SmSn{sub 2} is isotypic with the ZrGa{sub 2} structure, while RESn{sub 2} (RE=Gd–Lu) are isotypic with the ZrSi{sub 2} structure.},
doi = {10.1016/J.JSSC.2013.12.010},
journal = {Journal of Solid State Chemistry},
number = Complete,
volume = 211,
place = {United States},
year = {Sat Mar 15 00:00:00 EDT 2014},
month = {Sat Mar 15 00:00:00 EDT 2014}
}
  • Investigations on phase relationships and crystal structures have been conducted on several ternary rare-earth titanium antimonide systems. The isothermal cross-sections of the ternary RE-Ti-Sb systems containing a representative early (RE=La) and late rare-earth element (RE=Er) have been constructed at 800 deg. C. In the La-Ti-Sb system, the previously known compound La{sub 3}TiSb{sub 5} was confirmed and the new compound La{sub 2}Ti{sub 7}Sb{sub 12} (own type, Cmmm, Z=2, a=10.5446(10) A, b=20.768(2) A, and c=4.4344(4) A) was discovered. In the Er-Ti-Sb system, no ternary compounds were found. The structure of La{sub 2}Ti{sub 7}Sb{sub 12} consists of a complex arrangement of TiSb{sub 6}more » octahedra and disordered fragments of homoatomic Sb assemblies, generating a three-dimensional framework in which La atoms reside. Other early rare-earth elements (RE=Ce, Pr, Nd) can be substituted in this structure type. Attempts to prepare crystals in these systems through use of a tin flux resulted in the discovery of a new Sn-containing pseudoternary phase RETi{sub 3}(Sn{sub x}Sb{sub 1-x}){sub 4} for RE=Nd, Sm (own type, Fmmm, Z=8; a=5.7806(4) A, b=10.0846(7) A, and c=24.2260(16) A for NdTi{sub 3}(Sn{sub 0.1}Sb{sub 0.9}){sub 4}; a=5.7590(4) A, b=10.0686(6) A, and c=24.1167(14) A for SmTi{sub 3}(Sn{sub 0.1}Sb{sub 0.9}){sub 4}). Its structure consists of double-layer slabs of Ti-centred octahedra stacked alternately with nets of the RE atoms; the Ti atoms are arranged in kagome nets. - Graphical abstract: La{sub 2}Ti{sub 7}Sb{sub 12} contains sectioned layers consisting of Ti-centred octahedra linked by corner- and face-sharing.« less
  • Fifteen ternary rare-earth metal gallium silicides have been synthesized using molten Ga as a molten flux. They have been structurally characterized by single-crystal and powder X-ray diffraction to form with three different structures—the early to mid-late rare-earth metals RE=La–Nd, Sm, Gd–Ho, Yb and Y form compounds with empirical formulae RE(Ga xSi 1–x)₂ (0.38≤x≤0.63), which crystallize with the tetragonal α-ThSi₂ structure type (space group I4₁/amd, No. 141; Pearson symbol tI12). The compounds of the late rare-earth crystallize with the orthorhombic α-GdSi₂ structure type (space group Imma, No. 74; Pearson symbol oI12), with refined empirical formula REGa xSi 2–x–y (RE=Ho, Er, Tm;more » 0.33≤x≤0.40, 0.10≤y≤0.18). LuGa₀.₃₂₍₁₎Si₁.₄₃₍₁₎ crystallizes with the orthorhombic YbMn₀.₁₇Si₁.₈₃ structure type (space group Cmcm, No. 63; Pearson symbol oC24). Structural trends are reviewed and analyzed; the magnetic susceptibilities of the grown single-crystals are presented. - Graphical abstract: This article details the exploration of the RE–Ga–Si ternary system with the aim to systematically investigate the structural “boundaries” between the α-ThSi₂ and α-GdSi₂-type structures, and studies of the magnetic properties of the newly synthesized single-crystalline materials. Highlights: • Light rare-earth gallium silicides crystallize in α-ThSi₂ structure type. • Heavy rare-earth gallium silicides crystallize in α-GdSi₂ structure type. • LuGaSi crystallizes in a defect variant of the YbMn₀.₁₇Si₁.₈₃ structure type.« less
  • A large new family of rare-earth metal-cadmium-germanides RE{sub 2}CdGe{sub 2} (RE=Y, Pr, Nd, Sm, Gd-Yb) has been synthesized and structurally characterized. All eleven structures have been established from single-crystal X-ray diffraction data and have been found to belong to the tetragonal Mo{sub 2}FeB{sub 2} structure type (ordered ternary variant of the U{sub 3}Si{sub 2} structure type-space group P4/mbm (No. 127), Z=2; Pearson symbol tP10). The structural variations among the three series of isostructural RE{sub 2}MgGe{sub 2}, RE{sub 2}InGe{sub 2}, and RE{sub 2}CdGe{sub 2} compounds are discussed, as well as the crystal chemistry changes as a function of the decreasing sizemore » of the rare-earth metals (lattice constants a=7.176(2)-7.4589(12) A and c=4.1273(14)-4.4356(13) A). The experimental results have been complemented by tight-binding linear muffin-tin orbital (TB-LMTO) electronic structure calculations. - Graphical abstract: More than 300 compounds have been reported to crystallize with the tetragonal U{sub 3}Si{sub 2} structure type, or the Mo{sub 2}FeB{sub 2} structure type, which is its ordered ternary variant. Among them, there are several large RE{sub 2}CdX{sub 2} classes, where the X-elements are typically late transition metals such as Cu, Ni, Au, Pd, Pt, and Rh. The new RE{sub 2}CdGe{sub 2} phases (RE=Y, Pr, Nd, Sm, Gd-Yb) increase the diversity and represent the first cadmium germanides. Highlights: Black-Right-Pointing-Pointer RE{sub 2}CdGe{sub 2} (RE=Y, Pr, Nd, Sm, Gd-Yb) are new ternary germanides. Black-Right-Pointing-Pointer Their structures can be recognized as a 1:1 intergrowth of CsCl- and AlB{sub 2}-like slabs. Black-Right-Pointing-Pointer The Ge atoms are covalently bound into Ge{sub 2} dumbbells. Black-Right-Pointing-Pointer Almost all RE{sub 2}CdGe{sub 2} phases are the first structurally characterized phases in the respective ternary RE-Cd-Ge systems.« less
  • The existence of ternary compounds according to the formula REFe{sub 12{minus}{ital x}} Ga{sub {ital x}} which for {ital x} {approximately}6 represents the iron-rich end of a homogeneous range has been confirmed. X-ray powder analysis of alloys annealed at 800 {degree}C or above generally reveal isotypism with the body- centered tetragonal ThMn{sub 12} -type structure. For the alloys with heavier rare-earth elements from Gd to Lu a phase transition to a body-centered orthorhombic structure type (ScFe{sub 6} Ga{sub 6} type) is observed, which has not been reported before. The transition corresponds to a crystallographic group-subgroup relation ({ital I}4/{ital mmm}{r arrow}{ital t}{submore » 2} {r arrow}{ital Immm}), and the transition temperature increases with the ordinal number of the rare earth, indicating the higher the stability of the ScFe{sub 6} Ga{sub 6} -type structure, the smaller the radius of the rare-earth element. Accordingly, the ThMn{sub 12} -type structure is stable for the early rare-earth members and no transition was observed as low as 400 {degree}C. From magnetization curves it is shown that for REFe{sub 12{minus}{ital x}} Ga{sub {ital x}} (RE=rare earth, Y) all magnetic sublattices order simultaneously at temperatures above {Tc} {approximately}400 K. For Y, Lu, and light rare-earth-containing alloys collinear or canted ferromagnetism is observed. The vector of magnetization was found to be close to the {ital a},{ital b} plane. Strong hysteresis effects are revealed in all alloys. Energy products are highest for (Pr,Sm)Fe{sub {approximately}6}Ga{sub {approximately}6}. For the compounds with the heavy rare-earth elements a ferrimagnetic behavior is encountered. Both magnetic sublattices, i.e., Fe and RE, couple antiparallel, exhibiting easy plane anisotropy. The crystallographic transformation, tetragonal-orthorhombic, has little effect on the magnetic behavior of these alloys.« less