Synthesis and crystal structure of MgB12

Adasch, Volker; Hess, Kai‐Uwe; Ludwig, Thilo; Vojteer, Natascha; Hillebrecht, Harald

doi:10.1016/j.jssc.2006.03.045

Cited by 25 publications

(72 citation statements)

References 23 publications

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“…Blue-black crystals of the compound MgB 12 were recently obtained in a Mg/Cu melt at 1823 K. [136] Even though the dimensions of the unit cell of this compound are nearly identical with those of "g-AlB 12 " (MgB 12 : a = 1663.2 pm, b = 1780.3 pm, c = 1039.6 pm), it is not isotypic with the aluminum compound described above. MgB 12 crystallizes in space group Pnma (no.…”

Section: Boron Compounds With a T-imentioning

confidence: 99%

“…Despite this, this synthesis route has proved itself: Li 2 B 12 C 2 , MgB 12 , Li 2 B 12 Si 2 , MgB 12 Si 2 , and MgB 12 C 2 are some examples of single-phase, highly pure, single-crystal boron compounds which have recently been obtained in this way. [136][137][138][139][140] There have been occasional reports of the use of chemical transport reactions and chemical vapor deposition (CVD) techniques to synthesize boron and borides. [141] These methods, however, have not so far proved themselves for boronrich compounds to the extent that it seems necessary to discuss them here in detail.…”

Section: Synthesismentioning

confidence: 99%

“…The example of the alkaline-earth hexaborides has shown that quite a precise determination of the composition of boron-rich borides is possible. [142] Energyand wavelength-dispersive X-ray spectroscopy (EDS, WDS) have also been employed [136][137][138][139][140]143] to quantify the components of borides. Careful handling and preparation of the samples as well as the employment of suitable, well-defined standards are essential.…”

Section: Characterization and Analysismentioning

confidence: 99%

See 2 more Smart Citations

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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Section: Boron Compounds With a T-imentioning

confidence: 99%

Section: Synthesismentioning

confidence: 99%

Section: Characterization and Analysismentioning

confidence: 99%

See 1 more Smart Citation

Boron: Elementary Challenge for Experimenters and Theoreticians

Albert¹,

Hillebrecht²

2009

Angew Chem Int Ed

Self Cite

580

436

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“…It seems that the strong anisotropy of this structure has a considerable effect on the phonon spectrum. only (for more details, see [104][105][106]). The close relationship between these two structures is demonstrated by describing α-AlB 12 in the pseudo-orthorhombic presentation.…”

Section: Tetragonal Boron Structuresmentioning

confidence: 99%

Raman effect in icosahedral boron-rich solids

Werheit¹,

Филипов

Kuhlmann

et al. 2010

Science and Technology of Advanced Materials

133

116

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We present Raman spectra of numerous icosahedral boron-rich solids having the structure of α-rhombohedral, β-rhombohedral, α-tetragonal, β-tetragonal, YB 66 , orthorhombic or amorphous boron. The spectra were newly measured and, in some cases, compared with reported data and discussed. We emphasize the importance of a high signal-to-noise ratio in the Raman spectra for detecting weak effects evoked by the modification of compounds, accommodation of interstitial atoms and other structural defects. Vibrations of the icosahedra, occurring in all the spectra, are interpreted using the description of modes in α-rhombohedral boron by Beckel et al. The Raman spectrum of boron carbide is largely clarified. Relative intra-and inter-icosahedral bonding forces are estimated for the different structural groups and for vanadium-doped β-rhombohedral boron. The validity of Badger's rule is demonstrated for the force constants of inter-icosahedral B-B bonds, whereas the agreement is less satisfactory for the intra-icosahedral B-B bonds.

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“…[136] Auch wenn die Abmessungen der Elementarzelle dieser Verbindung nahezu identisch mit denen von "g-AlB 12 " sind (MgB 12 19 -, B 20 -oder B 21 -Einheiten, die in den t-I-und t-II-Strukturen sowie den Strukturen von a-und g-AlB 12 und MgB 12 gefunden wurden, kann man die mno-Regeln für kondensierte, unvollständige oder über-dachte bzw. überbrückte Cluster nach Jemmis anwenden.…”

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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Synthesis and crystal structure of MgB12

Cited by 25 publications

References 23 publications

Boron: Elementary Challenge for Experimenters and Theoreticians

Boron: Elementary Challenge for Experimenters and Theoreticians

Raman effect in icosahedral boron-rich solids

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

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