New representatives of the linear structure series containing empty Ga/Ge cubes in the Sm–Ga–Ge system

Tokaychuk, Ya.; Filinchuk, Yaroslav; Fedorchuk, A.O.; Kozlov, Artem; Mokra, I. R.

doi:10.1016/j.jssc.2006.01.041

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…They both consist of geometrically equivalent layers of defective BaAl 4 (of R □ MGe 2 composition), AlB 2 and α-Po type slabs stacked linearly along the c direction. 2,41 These layers are also energetically equivalent, and consequently no strong preference for one of the polytypes can be envisaged. Frequently, the structure of such compounds is sensitive to the crystallization conditions and small fluctuations of these may reverse the energetic preferences and at the same time give origin to stacking faults, twinnings or non-periodic structures; as an example the families of SiC, ZnS, CdI 2 , micas, etc.…”

Section: From R 2 Pdge 6 To R 2 Mge 6 Compounds: Crystallochemical Anmentioning

confidence: 99%

A new glance on R₂MGe₆(R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R₂PdGe₆germanides

et al. 2017

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The RPdGe series (R = rare earth metal) was structurally characterized, and the results achieved were extended for a comprehensive study on RMGe (M = another metal) compounds, employing symmetry-based structural rationalization and energy calculations. Directly synthesized RPdGe exists for almost all R-components (R = Y, La-Nd, Sm and Gd-Lu) and even if with La is probably metastable. Several single crystal X-ray analyses (R = Y, Ce, Pr, Nd, Er and Lu) indicated oS72-Ce(GaGe) as the correct structure. The alternative In-flux method, once optimized, produced three good quality RPdGe single crystals: LaPdGe and PrPdGe turned out to be mS36-LaAlGe-type non-merohedrally twinned crystals and YbPdGe is of oS72-Ce(GaGe)-type. The vacancy ordering phenomenon was considered as a possible cause of the symmetry reduction relations connecting the most frequently reported 2 : 1 : 6 structural models (oS18, oS72 and mS36) with the oS20-SmNiGe aristotype. The detected twin formation is consistent with the symmetry relations, which are discussed even considering the validity of the different structural models. DFT total energy calculations were performed for RPdGe (R = Y and La) in the three abovementioned structural models, and for LaMGe (M = Pt, Cu, Ag and Au) in the oS18 and oS72 modifications. The results indicate that the oS18-CeCuGe structure, prevalently proposed in the literature, is associated with the highest energy and thus it is not likely to be realized in these series. The oS72 and mS36 polytypes are energetically equivalent, and small changes in the synthetic conditions could easily stabilize any of them, in agreement with experimental results obtained by direct and flux syntheses.

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Section: From R 2 Pdge 6 To R 2 Mge 6 Compounds: Crystallochemical Anmentioning

confidence: 99%

A new glance on R₂MGe₆(R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R₂PdGe₆germanides

et al. 2017

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“…x $2.2) [29], e-SmGa 6 [43], Sm 2 Ga 1.8 Ge 5.2 [44], Sm 4 Ga 5.24 Ge 5.76 [44] Ca 3 Au 6.61 Ga 4.39 [45], and YbGa 3.34 [46]. In addition to Ln:Ga (Ln ¼lanthanide) binary and Ln:Ag:Ga (Ln¼ lanthanide) ternary phases, complex GaGe-containing networks including YbGaGe Fig.…”

Section: Structurementioning

confidence: 99%

Crystal growth and properties of Ln2Ag1−xGa10−y (Ln=La, Ce), a disordered variant of the Ce2NiGa10-structure type

Menard

Xiong

Karki

et al. 2010

Journal of Solid State Chemistry

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“…The two models oS 72 and mS 36 are also intimately related. In fact, they can be described as belonging to a homological series constructed by linear intergrowth of inhomogeneous segments of the defective BaAl 4 , AlB 2 , and α-Po structure types. , An alternative description was given by Grin, based on only two types of segments, AlB 2 and defective CeRe 4 Si 2 .…”

Section: Introductionmentioning

confidence: 99%

“…In these cases the total number of atoms per unit cell is coincident with the stoichiometric model, but a more correct general formula should be R 2 M 1– x Ge 6+ x , where x could be positive or negative. For R = Y, M = Ga both possibilities are realized; in fact, two compounds have been reported with these elements, a Ge-rich phase (Y 2 Ga 0.34 Ge 6.66 , oS 72, x = 0.66) and a Ge-poor one (Y 2 Ga 3 Ge 4 , mS 36, x = −2).…”

Section: Introductionmentioning

confidence: 99%

Vacancy Ordering as a Driving Factor for Structural Changes in Ternary Germanides: The New R₂Zn_1–xGe₆Series of Polar Intermetallics (R = Rare-Earth Metal)

et al. 2015

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Synthesis and structural characterization of the new compounds R2Zn1-xGe6 (R = La-Nd, Sm, Gd-Ho) is reported. A structural change was revealed along this series by careful analysis of single-crystal X-ray diffraction data. For light rare earths up to Tb the orthorhombic oS72-Ce2(Ga0.1Ge0.9)7 model was established; instead, the Dy compound represents a new structure type (P21/m, mP34, Z = 4, a = 7.9613(3) Å, b = 8.2480(4) Å, c = 10.5309(5) Å, β = 100.861(1)°) being a superstructure of the mS36-La2AlGe6 prototype. The established structural models support the increase of Zn deficiency along the series, suggested by microprobe analysis, and its key role in governing structural changes. The vacancy ordering criterion was applied as a successful approach to find a general scheme including the structures of the ∼R2MGe6 compounds known up to now (R = rare-earth metal, M = transition metal, Mg, Al, Ga) and highlighting the subtle structural differences within this family. According to this scheme, these structures are obtained from a common aristotype (oS20-SmNiGe3) via symmetry reduction based on group-subgroup relations accompanied by ordering of vacancies. This approach was optimized with the help of the ToposPro software and extended to the R2Zn3Ge6 series, enriched with new members (R = Sm, Gd-Ho) during this work. Electronic structure calculations on La2ZnGe6 confirm the presence of infinite covalent germanium zigzag chains and three-bonded corrugated layers connected via Zn atoms to form a polyanionic network stabilized by La atoms.

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New representatives of the linear structure series containing empty Ga/Ge cubes in the Sm–Ga–Ge system

Cited by 6 publications

References 13 publications

A new glance on R₂MGe₆(R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R₂PdGe₆germanides

A new glance on R₂MGe₆(R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R₂PdGe₆germanides

Crystal growth and properties of Ln2Ag1−xGa10−y (Ln=La, Ce), a disordered variant of the Ce2NiGa10-structure type

Vacancy Ordering as a Driving Factor for Structural Changes in Ternary Germanides: The New R₂Zn_1–xGe₆Series of Polar Intermetallics (R = Rare-Earth Metal)

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New representatives of the linear structure series containing empty Ga/Ge cubes in the Sm–Ga–Ge system

Cited by 6 publications

References 13 publications

A new glance on R2MGe6(R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R2PdGe6germanides

A new glance on R2MGe6(R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R2PdGe6germanides

Crystal growth and properties of Ln2Ag1−xGa10−y (Ln=La, Ce), a disordered variant of the Ce2NiGa10-structure type

Vacancy Ordering as a Driving Factor for Structural Changes in Ternary Germanides: The New R2Zn1–xGe6Series of Polar Intermetallics (R = Rare-Earth Metal)

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A new glance on R₂MGe₆(R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R₂PdGe₆germanides

A new glance on R₂MGe₆(R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R₂PdGe₆germanides

Vacancy Ordering as a Driving Factor for Structural Changes in Ternary Germanides: The New R₂Zn_1–xGe₆Series of Polar Intermetallics (R = Rare-Earth Metal)