Ternary rare-earth ruthenium and iridium germanides RE3M2Ge3 (RE=Y, Gd–Tm, Lu; M=Ru, Ir)

doi:10.1016/j.jssc.2013.03.050

Journal of Solid State Chemistry

Volume 202, June 2013, Pages 241-249

https://doi.org/10.1016/j.jssc.2013.03.050 Get rights and content

highlights

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Crystal structures of RE₃Ru₂Ge₃ (RE=Y, Gd–Tm, Lu) and Tb₃Ir₂Ge₃ were determined.
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Strong M–Ge covalent bonds were confirmed by band structure calculations.
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Most RE₃Ru₂Ge₃ members except Y₃Ru₂Ge₃ exhibit metallic behaviour.
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Dy₃Ru₂Ge₃ displays unusual field-dependent magnetic transitions.

Abstract

Through arc-melting reactions of the elements and annealing at 800 °C, the ternary rare-earth germanides RE₃Ru₂Ge₃ and RE₃Ir₂Ge₃ have been prepared for most of the smaller RE components (RE=Y, Gd–Tm, Lu). In the iridium-containing reactions, the new phases RE₂IrGe₂ were also generally formed as by-products. Powder X-ray diffraction revealed orthorhombic Hf₃Ni₂Si₃-type structures (space group Cmcm, Z=4) for RE₃M₂Ge₃ (M=Ru, Ir) and monoclinic Sc₂CoSi₂-type structures (space group C2/m, Z=4) for RE₂IrGe₂. Full crystal structures were determined by single-crystal X-ray diffraction for all members of RE₃Ru₂Ge₃ (a=4.2477(6) Å, b=10.7672(16) Å, c=13.894(2) Å for RE=Y; a=4.2610(3)–4.2045(8) Å, b=10.9103(8)–10.561(2) Å, c=14.0263(10)–13.639(3) Å in the progression of RE from Gd to Lu) and for Tb₃Ir₂Ge₃ (a=4.2937(3) Å, b=10.4868(7) Å, c=14.2373(10) Å). Both structures can be described in terms of CrB- and ThCr₂Si₂-type slabs built from Ge-centred trigonal prisms. However, band structure calculations on Y₃Ru₂Ge₃ support an alternative description for RE₃M₂Ge₃ based on [M₂Ge₃] layers built from linked MGe₄ tetrahedra, which emphasizes the strong M–Ge covalent bonds present. The temperature dependence of the electrical resistivity of RE₃Ru₂Ge₃ generally indicates metallic behaviour but with low-temperature transitions visible for some members (RE=Gd, Tb, Dy) that are probably associated with magnetic ordering of the RE atoms. Anomalously, Y₃Ru₂Ge₃ exhibits semiconductor-like behaviour of uncertain origin. Magnetic measurements on Dy₃Ru₂Ge₃ reveal antiferromagnetic ordering at 3 K and several unusual field-dependent transitions suggestive of complex spin reorientation processes.

Graphical abstract

RE₃M₂Ge₃ (M=Ru, Ir) adopts the Hf₃Ni₂Si₃-type structure containing slabs built up from Ge-centred trigonal prisms.

Introduction

A rich variety of ternary rare-earth transition-metal germanides RE–M–Ge are known. Among systems with M=3d metals, the ones involving the later elements (M=Mn, Fe, Co, Ni, Cu) give rise to numerous phases, in contrast to those containing the earlier elements (M=V, Cr) [1], [2], for which the new compounds REMGe₃ and RECr_xGe₂ have only been identified recently [3], [4], [5]. The same pattern emerges for systems with M=4d and 5d metals, in which the ones containing the precious metals (M=Ru, Os, Rh, Ir, Pd, Pt) promise to show many phases, whereas those containing the earlier elements have barely been explored [1]. Much of the interest in these germanides relates to their diverse physical properties which may prove useful in materials applications. Recent reports of such germanides containing a precious metal have been motivated by the search for new magnetocaloric (e.g., GdRu₂Ge₂) [6], thermoelectric (e.g., RE₃M₄Ge₁₃) [7], [8], and superconducting materials (e.g., RE₂Ir₃Ge₅) [9], [10].

We present here the elucidation of the series RE₃M₂Ge₃ (RE=Y, Gd–Tm, Lu; M=Ru, Ir). Only a few isolated members of these series have been identified previously: Ho₃Ru₂Ge₃ [11], [12], [13], Ho₃Ir₂Ge₃ [14], and Lu₃Ir₂Ge₃ [15]. The crystal structures for all remaining members for the RE₃Ru₂Ge₃ series have now been determined, as well as for Tb₃Ir₂Ge₃. We report electrical resistivity measurements for the RE₃Ru₂Ge₃ series, as well as magnetic susceptibility measurements on Dy₃Ru₂Ge₃. The nature of bonding in these compounds has been examined through band structure calculations.

Section snippets

Synthesis

Stoichiometric mixtures (0.2-g total mass) of freshly filed RE pieces (RE=Y, Gd–Tm, Lu, 99.9%, Hefa), Ru (99.95%, Cerac) or Ir powder (99.9%, Cerac), and Ge powder (99.9999%, Alfa-Aesar) were pressed into pellets, which were arc-melted in a Centorr 5TA tri-arc furnace on a water-cooled copper hearth under an argon atmosphere. To ensure homogeneity, the samples were melted twice, after which the weight loss was found to be less than 1%. The ingots were then sealed within fused-silica tubes and

Results and discussion

The ternary germanides RE₃M₂Ge₃ (RE=Y, Gd–Tm, Lu; M=Ru, Ir) have been obtained by arc-melting reactions and determined by X-ray diffraction studies to adopt the orthorhombic Hf₃Ni₂Si₃-type structure [24]. This structure type is a relative rare one formed mostly by silicides Zr₃M₂Si₃ (M=Fe, Co) [24], Hf₃M₂Si₃ (M=Fe, Co, Ni) [24], RE₃Fe₂Si₃ (RE=Gd–Tm, Lu, Y, Sc) [25], [26], RE₃Co₂Si₃ (RE=Tb–Tm, Lu, Y, Sc) [25], [27], Sc₃Ni₂Si₃ [28], and Y₃M₂Si₃ (M=Rh, Pd) [29]; and germanides Gd₃Mn₂Ge₃ [30], RE₃Fe

Conclusions

Ternary rare-earth germanides RE₃M₂Ge₃ with the Hf₃Ni₂Si₃-type structure have been established for M=Ru, Ir, and it will be worthwhile to attempt the preparation of the analogous series with M=Os, Rh. Although the conventional description in terms of Ge-centred RE₄M₂ and RE₆ trigonal prisms is helpful in clarifying relationships to other structures, the alternative description that emphasizes the presence of [M₂Ge₃] layers is more accurate in portraying the strong covalent M–Ge bonding

Acknowledgments

This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).

References (43)

P.S. Salamakha et al.
P.S. Salamakha
H. Bie et al.
J. Solid State Chem.
(2009)
G. Venturini et al.
Mater. Res. Bull.
(1986)
O.L. Sologub et al.
J. Alloys Compd.
(1994)
O.L. Sologub et al.
J. Alloys Compd.
(1996)
U.Ch. Rodewald et al.
Solid State Sci.
(2003)
P. Boulet et al.
Physica B
(2000)
E. Hovestreydt et al.
J. Less-Common Met.
(1982)
B. Penc et al.
J. Alloys Compd.
(1999)

R. Welter et al.

J. Alloys Compd.

(1997)

B. Chabot et al.

J. Less-Common Met.

(1984)

A.V. Morozkin et al.

Intermetallics

(2012)

A.V. Morozkin

Intermetallics

(2012)

A.V. Morozkin et al.

J. Solid State Chem.

(2012)

G.M. Koterlyn et al.

J. Alloys Compd.

(1999)

W. Choe et al.

J. Alloys Compd.

(2001)

H. Bie et al.

Chem. Mater.

(2007)

H. Bie et al.

J. Mater. Chem.

(2009)

O. Tegus et al.

J. Appl. Phys.

(2002)

H. Kong et al.

J. Appl. Phys.

(2007)

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Ternary rare-earth ruthenium and iridium germanides RE3M2Ge3 (RE=Y, Gd–Tm, Lu; M=Ru, Ir)

highlights

Abstract

Graphical abstract

Introduction

Section snippets

Synthesis

Results and discussion

Conclusions

Acknowledgments

J. Solid State Chem.

Mater. Res. Bull.

J. Alloys Compd.

J. Alloys Compd.

Solid State Sci.

Physica B

J. Less-Common Met.

J. Alloys Compd.

J. Alloys Compd.

J. Less-Common Met.

Intermetallics

Intermetallics

J. Solid State Chem.

J. Alloys Compd.

J. Alloys Compd.

Chem. Mater.

J. Mater. Chem.

J. Appl. Phys.

J. Appl. Phys.

Ternary rare-earth ruthenium and iridium germanides RE₃M₂Ge₃ (RE=Y, Gd–Tm, Lu; M=Ru, Ir)