New Boron-Rich Materials:  Cubic Carbaborides of Sodium and Potassium

Albert, Barbara; Schmitt, Konny

doi:10.1021/cm991130d

Cited by 29 publications

(32 citation statements)

References 33 publications

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“…These compositional forms are more likely to stabilize with, for example, carbon substitution within the boron framework. This possibility is analogous to the existence of symmetrically equivalent, isotypic and isoelectronic compounds NaB 5 C and KB 5 C [48].…”

Section: Band Structure Calculationsmentioning

confidence: 90%

Metal Hexaborides with Sc, Ti or Mn

Alarco¹,

Talbot²

2013

MNSMS

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Comparison of well-determined single crystal data for stoichiometric, or near-stoichiometric, metal hexaborides confirms previously identified lattice parameter trends using powder diffraction. Trends for both divalent and trivalent forms suggest that potential new forms for synthesis include Sc and Mn hexaborides. Density Functional Theory (DFT) calculations for KB 6 , CaB 6 , YB 6 , LaB 6 , boron octahedral clusters and Sc and Mn forms show that the shapes of bonding orbitals are defined by the boron framework. Inclusion of metal into the boron framework induces a reduction in energy ranging from 1 eV to 6 eV increasing with ionic charge. For metals with d 1 character, such a shift in energy brings a doubly degenerate band section along with the G-M reciprocal space direction within the conduction bands tangential to the Fermi surface. ScB 6 band structure and density of states calculations show directions and gap characteristics similar to those of YB 6 and LaB 6 . These calculations for ScB 6 suggest that it may be possible to realize superconductivity in this compound if synthesized.

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Section: Band Structure Calculationsmentioning

confidence: 90%

Metal Hexaborides with Sc, Ti or Mn

Alarco¹,

Talbot²

2013

MNSMS

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“…[125]. The structure of the metal carbapentaborides MB 5 C (M = Na, K), in which one of the six boron atoms is substituted by a carbon atom, [265,266] is derived from this, as is the structure of Li 2 B 6 , in which two metal ions occupy the cuboctahedral gap.…”

Section: 2mentioning

confidence: 99%

Boron: Elementary Challenge for Experimenters and Theoreticians

Albert¹,

Hillebrecht²

2009

Angew Chem Int Ed

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580

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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“…[125] referiert. Von ihm ableitbar ist die Struktur der Metallcarbapentaboride MB 5 C (M = Na, K), in denen eines der sechs Boratome durch ein Kohlenstoffatom ersetzt ist, [265,266] sowie die Struktur von Li 2 B 6 , in der zwei Metallionen gemeinsam die kuboktaedrische Lücke besetzen. [267] SiB 6 mit CaB 6 -Struktur, wie ursprünglich postuliert, existiert nicht.…”

Section: Borverbindungen Mit T-i-unclassified

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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New Boron-Rich Materials: Cubic Carbaborides of Sodium and Potassium

Cited by 29 publications

References 33 publications

Metal Hexaborides with Sc, Ti or Mn

Metal Hexaborides with Sc, Ti or Mn

Boron: Elementary Challenge for Experimenters and Theoreticians

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

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