Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides RE12Ge7−xSb21 (RE=La–Pr)

Bie, Haiying; Mar, Arthur

doi:10.1002/asia.200900063

Cited by 4 publications

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References 34 publications

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“…To the best of our knowledge, Ba 4 Ge 2 Sb 2 Te 10 is the first example of a chalcogenide exhibiting bonding between Sb and Ge atoms. There are some examples of lanthanide (Ln)-based germanium antimonides such as Ln 6 Ge 5– x Sb 11+ x and Ln 12 Ge 7– x Sb 21 that show the bonding between Ge and Sb atoms. However, the Ge and Sb atoms are disordered at the same crystallographic site in these structures.…”

Section: Resultsmentioning

confidence: 99%

Germanium Antimony Bonding in Ba₄Ge₂Sb₂Te₁₀ with Low Thermal Conductivity

et al. 2021

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A new quaternary telluride, Ba4Ge2Sb2Te10, was synthesized at high temperature via the reaction of elements. A single-crystal X-ray diffraction study shows that the title compound crystallizes in its own structure type in the monoclinic P21/c space group having cell dimensions of a = 13.984(3) Å, b = 13.472(3) Å, c = 13.569(3) Å, and β = 90.16(3)° with four formula units per unit cell (Z = 4). The pseudo-one-dimensional crystal structure of Ba4Ge2Sb2Te10 consists of infinite 1 ∞[Ge2Sb2Te10]8– stripes, which are separated by Ba2+ cations. Each of the Ge(1) atoms is covalently bonded to four Te atoms, whereas the Ge(2) atom is covalently bonded with one Sb(2) and three Te atoms in a distorted tetrahedral geometry. The title compound is the first example of a chalcogenide that shows Ge–Sb bonding. The Sb(1) atom is present at the center of the seesaw geometry of four Te atoms. In contrast, the Sb(2) atom forms a seesaw geometry by coordinating with one Ge(2) and three Te atoms. Condensation of these Ge and Sb centered polyhedral units lead to the formation of 1 ∞[Ge2Sb2Te10]8– stripes. The temperature-dependent resistivity study suggests the semimetallic/degenerate semiconducting nature of polycrystalline Ba4Ge2Sb2Te10. The positive sign of Seebeck coefficient values indicates that the predominant charge carriers are holes in Ba4Ge2Sb2Te10. An extremely low lattice thermal conductivity of ∼0.34 W/mK at 773 K was observed for polycrystalline Ba4Ge2Sb2Te10, which is presumably due to the lattice anharmonicity induced by the stereochemically active 5s2 lone pair of Sb. The electronic structure of Ba4Ge2Sb2Te10 and the bonding of atom pairs in the structure have been analyzed by means of ELF analysis and crystal orbital Hamilton population (COHP) analysis.

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Section: Resultsmentioning

confidence: 99%

Germanium Antimony Bonding in Ba₄Ge₂Sb₂Te₁₀ with Low Thermal Conductivity

et al. 2021

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“…These fragments could be in the form of two-dimensional slabs, such as the alternation of [ RE As] and [ M 2 As 2 ] layers of varying thicknesses in the two homologous series of arsenides REM 2– x As 2 · n ( RE As) and RE 2– y M 4 As 4 · n ( RE As) (Figure ). ,, Metal-rich pnictides often have structures that can be described in terms of increasingly larger triangular assemblies of pnicogen-centered trigonal prisms. − For many rare-earth transition-metal germanides RE – M –Ge, the structures can be related by focusing on how infinite M Ge ladders (double zigzag chains built of alternating M and Ge atoms propagating in one direction) are connected by Ge n bridges (perpendicular to the ladders) (Figure a) . If n is odd, the M Ge ladders are related by reflection and the structure is orthorhombic; if n is even, they are related by 2-fold rotation and the structure is monoclinic.…”

Section: Traditional Approachesmentioning

confidence: 99%

Discovery of Intermetallic Compounds from Traditional to Machine-Learning Approaches

2017

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Intermetallic compounds are bestowed by diverse compositions, complex structures, and useful properties for many materials applications. How metallic elements react to form these compounds and what structures they adopt remain challenging questions that defy predictability. Traditional approaches offer some rational strategies to prepare specific classes of intermetallics, such as targeting members within a modular homologous series, manipulating building blocks to assemble new structures, and filling interstitial sites to create stuffed variants. Because these strategies rely on precedent, they cannot foresee surprising results, by definition. Exploratory synthesis, whether through systematic phase diagram investigations or serendipity, is still essential for expanding our knowledge base. Eventually, the relationships may become too complex for the pattern recognition skills to be reliably or practically performed by humans. Complementing these traditional approaches, new machine-learning approaches may be a viable alternative for materials discovery, not only among intermetallics but also more generally to other chemical compounds. In this Account, we survey our own efforts to discover new intermetallic compounds, encompassing gallides, germanides, phosphides, arsenides, and others. We apply various machine-learning methods (such as support vector machine and random forest algorithms) to confront two significant questions in solid state chemistry. First, what crystal structures are adopted by a compound given an arbitrary composition? Initial efforts have focused on binary equiatomic phases AB, ternary equiatomic phases ABC, and full Heusler phases ABC. Our analysis emphasizes the use of real experimental data and places special value on confirming predictions through experiment. Chemical descriptors are carefully chosen through a rigorous procedure called cluster resolution feature selection. Predictions for crystal structures are quantified by evaluating probabilities. Major results include the discovery of RhCd, the first new binary AB compound to be found in over 15 years, with a CsCl-type structure; the connection between "ambiguous" prediction probabilities and the phenomenon of polymorphism, as illustrated in the case of TiFeP (with TiNiSi- and ZrNiAl-type structures); and the preparation of new predicted Heusler phases MRuGa and RuMGa (M = first-row transition metal) that are not obvious candidates. Second, how can the search for materials with desired properties be accelerated? One particular application of strong current interest is thermoelectric materials, which present a particular challenge because their optimum performance depends on achieving a balance of many interrelated physical properties. Making use of a recommendation engine developed by Citrine Informatics, we have identified new candidates for thermoelectric materials, including previously unknown compounds (e.g., TiRuGa with Heusler structure; Mn(RuGe) with CsCl-type structure) and previously reported compounds but counterintuitive cand...

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ChemInform Abstract: Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides Ln₁₂Ge_7‐xSb₂₁ (Ln: La—Pr).

Bie

Mar

2009

ChemInform

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are synthesized from the elements (800°C, 12 d) and characterized by single crystal XRD, magnetic measurements, and TB-LMTO band structure calculations. The compounds crystallize with a new structure type in the orthorhombic space group Immm with Z = 2. The three-dimensional polyanionic frameworks consist of Ge pairs and Sb ribbons forming large channels occupied by columns of face-sharing Ln 6 (Ln: La-Pr) trigonal prisms. These trigonal prisms are centered by additional Ge and Sb atoms to form GeSb3 trigonal-planar units. Ce12Ge6.5Sb21 shows antiferromagnetic coupling but no long-range ordering down to 2 K. -(BIE, H.; MAR*, A.; Chem.

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Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides RE₁₂Ge_7−xSb₂₁ (RE=La–Pr)

Cited by 4 publications

References 34 publications

Germanium Antimony Bonding in Ba₄Ge₂Sb₂Te₁₀ with Low Thermal Conductivity

Germanium Antimony Bonding in Ba₄Ge₂Sb₂Te₁₀ with Low Thermal Conductivity

Discovery of Intermetallic Compounds from Traditional to Machine-Learning Approaches

ChemInform Abstract: Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides Ln₁₂Ge_7‐xSb₂₁ (Ln: La—Pr).

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Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides RE12Ge7−xSb21 (RE=La–Pr)

Cited by 4 publications

References 34 publications

Germanium Antimony Bonding in Ba4Ge2Sb2Te10 with Low Thermal Conductivity

Germanium Antimony Bonding in Ba4Ge2Sb2Te10 with Low Thermal Conductivity

Discovery of Intermetallic Compounds from Traditional to Machine-Learning Approaches

ChemInform Abstract: Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides Ln12Ge7‐xSb21 (Ln: La—Pr).

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Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides RE₁₂Ge_7−xSb₂₁ (RE=La–Pr)

Germanium Antimony Bonding in Ba₄Ge₂Sb₂Te₁₀ with Low Thermal Conductivity

Germanium Antimony Bonding in Ba₄Ge₂Sb₂Te₁₀ with Low Thermal Conductivity

ChemInform Abstract: Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides Ln₁₂Ge_7‐xSb₂₁ (Ln: La—Pr).