K7B7Si39, ein Borosilicid mit Clathrat‐I‐Struktur

Jung, Walter; Lörincz, Josef; Ramlau, R.; Borrmann, Horst; Prots, Yurii; Haarmann, Frank; Schnelle, Walter; Burkhardt, Ulrich; Baitinger, Michael; Grin, Yuri

doi:10.1002/ange.200701028

Cited by 22 publications

(17 citation statements)

References 18 publications

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“…Boron atoms occupy some of the positions of silicon atoms in the clathrate framework, as determined by EELS and other methods. [348] Borosilicides with clathrate frameworks are promising candidates for good thermoelectric properties.…”

Section: Other Boron Compounds Of Main Group Elementsmentioning

confidence: 99%

Boron: Elementary Challenge for Experimenters and Theoreticians

Albert¹,

Hillebrecht²

2009

Angew Chem Int Ed

567

436

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Many of the fundamental questions regarding the solid-state chemistry of boron are still unsolved, more than 200 years after its discovery. Recently, theoretical work on the existence and stability of known and new modifications of the element combined with high-pressure and high-temperature experiments have revealed new aspects. A lot has also happened over the last few years in the field of reactions between boron and main group elements. Binary compounds such as B(6)O, MgB(2), LiB(1-x), Na(3)B(20), and CaB(6) have caused much excitement, but the electron-precise, colorless boride carbides Li(2)B(12)C(2), LiB(13)C(2), and MgB(12)C(2) as well as the graphite analogue BeB(2)C(2) also deserve special attention. Physical properties such as hardness, superconductivity, neutron scattering length, and thermoelectricity have also made boron-rich compounds attractive to materials research and for applications. The greatest challenges to boron chemistry, however, are still the synthesis of monophasic products in macroscopic quantities and in the form of single crystals, the unequivocal identification and determination of crystal structures, and a thorough understanding of their electronic situation. Linked polyhedra are the dominating structural elements of the boron-rich compounds of the main group elements. In many cases, their structures can be derived from those that have been assigned to modifications of the element. Again, even these require a critical revision and discussion.

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Section: Other Boron Compounds Of Main Group Elementsmentioning

confidence: 99%

Boron: Elementary Challenge for Experimenters and Theoreticians

Albert¹,

Hillebrecht²

2009

Angew Chem Int Ed

567

436

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“…[347] Aufsehen erregte das kürzlich beschriebene erste Borsilicid mit Clathrat-I-Struktur, K 7 B 7 Si 39 , in dem Boratome die Positionen von Siliciumatomen im Clathratgerüst teilweise besetzen, wie unter anderem durch EELS bewiesen werden konnte. [348] Von Borsiliciden mit Clathratgerüsten erhofft man sich gute thermoelektrische Eigenschaften.…”

Section: Andere Borverbindungen Der Hauptgruppenelementeunclassified

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

Albert

Hillebrecht

2009

Angewandte Chemie

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Auch mehr als zweihundert Jahre nach der Entdeckung des Elementes Bor gibt es auf viele grundlegende Fragen in der Festkörperchemie von Bor noch keine eindeutigen Antworten. In jüngster Zeit zeigten theoretische Arbeiten zur Stabilität und Existenz bekannter und neuer Modifikationen des Elements in Verbindung mit Hochdruck‐ und Hochtemperaturexperimenten neue Aspekte. Auch auf dem Gebiet der Reaktionen von Bor mit Hauptgruppenelementen hat sich in den letzten Jahren viel getan. Aufsehen haben binäre Verbindungen wie B6O, MgB2, LiB1−x, Na3B20 oder CaB6 erregt, aber auch die elektronenpräzisen, farblosen Boridcarbide Li2B12C2, LiB13C2 und MgB12C2 sowie Graphit‐analoges BeB2C2 verdienen besonderes Augenmerk. Physikalische Eigenschaften wie Härte, Supraleitfähigkeit, Neutroneneinfangquerschnitt und Thermoelektrizität machen borreiche Verbindungen auch für Materialforschung und Anwendung attraktiv. Die größten wissenschaftlichen Herausforderungen bestehen jedoch weiterhin in der Synthese einphasiger Produkte in makroskopischen Mengen und in Form von Einkristallen, in der zweifelsfreien Identifizierung und Bestimmung von Zusammensetzung und Kristallstruktur sowie im Verständnis der elektronischen Situation. Verknüpfte Polyeder sind das dominierende Strukturelement in borreichen Verbindungen der Hauptgruppenelemente. In vielen Fällen leiten sich deren Strukturen von denen ab, die den Elementmodifikationen zugeschrieben werden. Auch diese bedürfen allerdings einer neuen, kritischen Durchsicht und Diskussion.

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“…[9] Other methods include preceding arc melting and annealing, as described for K 7 B 7 Si 39 . [10] In some cases, crystalline products can be obtained directly from the arc-melting procedure, as shown for Ba 8 Cu 4 Si 42 . [11] Other routes apply heating of the sample to rather high temperatures (up to 1700 K) by using high-frequency furnaces, as employed for the transition-metal-containing clathrates Ba 8 M x Si 46Àx .…”

Section: Introductionmentioning

confidence: 99%

A Combined Metal–Halide/Metal Flux Synthetic Route towards Type‐I Clathrates: Crystal Structures and Thermoelectric Properties of A₈Al₈Si₃₈ (A=K, Rb, and Cs)

Baran

Senyshyn

Karttunen

et al. 2014

Chemistry A European J

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Single‐phase samples of the compounds K8Al8Si38 (1), Rb8Al8Si38 (2), and Cs7.9Al7.9Si38.1 (3) were obtained with high crystallinity and in good quantities by using a novel flux method with two different flux materials, such as Al and the respective alkali‐metal halide salt (KBr, RbCl, and CsCl). This approach facilitates the removal of the product mixture from the container and also allows convenient extraction of the flux media due to the good solubility of the halide salts in water. The products were analyzed by means of single‐crystal X‐ray structure determination, powder X‐ray and neutron diffraction experiments, 27Al‐MAS NMR spectroscopy measurements, quantum chemical calculations, as well as magnetic and transport measurements (thermal conductivity, electrical resistivity, and Seebeck coefficient). Due to the excellent quality of the neutron diffraction data, the difference between the nuclear scattering factors of silicon and aluminum atoms was sufficient to refine their mixed occupancy at specific sites. The role of variable‐range hopping for the interpretation of the resistivity and the Seebeck coefficient is discussed.

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K₇B₇Si₃₉, ein Borosilicid mit Clathrat‐I‐Struktur

Cited by 22 publications

References 18 publications

Boron: Elementary Challenge for Experimenters and Theoreticians

Boron: Elementary Challenge for Experimenters and Theoreticians

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

A Combined Metal–Halide/Metal Flux Synthetic Route towards Type‐I Clathrates: Crystal Structures and Thermoelectric Properties of A₈Al₈Si₃₈ (A=K, Rb, and Cs)

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K7B7Si39, ein Borosilicid mit Clathrat‐I‐Struktur

Cited by 22 publications

References 18 publications

Boron: Elementary Challenge for Experimenters and Theoreticians

Boron: Elementary Challenge for Experimenters and Theoreticians

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

A Combined Metal–Halide/Metal Flux Synthetic Route towards Type‐I Clathrates: Crystal Structures and Thermoelectric Properties of A8Al8Si38 (A=K, Rb, and Cs)

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K₇B₇Si₃₉, ein Borosilicid mit Clathrat‐I‐Struktur

A Combined Metal–Halide/Metal Flux Synthetic Route towards Type‐I Clathrates: Crystal Structures and Thermoelectric Properties of A₈Al₈Si₃₈ (A=K, Rb, and Cs)