The Preparation and Structure of Magnesium Boride, MgB<sub>2</sub>

Jones, Morton E.; Marsh, Richard E.

doi:10.1021/ja01634a089

Cited by 257 publications

(161 citation statements)

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“…The lattice parameters and the ADP's of our single crystals are consistent with established values: [33][34][35][36] It is evident that the a and c lattice parameters strongly shrink when going from MgB 2 to Mg 0.8 Al 0.2 B 2 and AlB 2 . Moreover, our multipole refinement of MgB 2 is in agreement with published results.…”

Section: Resultssupporting

confidence: 89%

Electronic Structure of Single-Crystalline Mg_xAl₁₋_xB₂ Probed by X-ray Diffraction Multipole Refinements and Polarization-Dependent X-ray Absorption Spectroscopy

et al. 2014

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X-ray diffraction multipole refinements of single-crystalline MgxAl1−xB2 and polarizationdependent near-edge x-ray absorption fine structure at the B 1s edge reveal a strongly anisotropic electronic structure. Comparing the data for superconducting compounds (x = 0.8, 1.0) with those for the non-superconductor (x = 0) gives direct evidence for a rearrangement of the hybridizations of the boron pz bonds and underline the importance of holes in the σ-bonded covalent sp 2 states for the superconducting properties of the diborides. The data indicate that Mg is approximately divalent in MgB2 and suggest predominantly ionic bonds between the Mg ions and the two-dimensional B rings. For AlB2 (x = 0), on the other hand, about 1.5 electrons per Al atom are transferred to the B sheets while the residual 1.5 electrons remain at the Al site which suggests significant covalent bonding between the Al ions and the B sheets. This finding together with the static electron deformation density points to almost equivalent electron counts on B sheets of MgB2 and AlB2, yet with a completely different electron/hole distribution between the σ and π bonds.

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Section: Resultssupporting

confidence: 89%

Electronic Structure of Single-Crystalline Mg_xAl₁₋_xB₂ Probed by X-ray Diffraction Multipole Refinements and Polarization-Dependent X-ray Absorption Spectroscopy

et al. 2014

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“…3, at ≥ 0 25 the reaction products contain a new hexagonal phase for which the unit cell parameter is equal to the arithmetic mean of the parameters of MgB 2 and "AlB 2 " (0.3086 and 0.3004 nm, respectively [13,14]) and is equal to the sum of the values for these diborides (0.3522 and 0.3251 nm). In this composition range the plot of T as a function of the Al amount, shows a kink indicating the onset of a sharp decrease in T [10].…”

Section: Resultsmentioning

confidence: 99%

Structure and properties of solid solutions in the Mg-Al-B system

et al. 2011

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Ê Ú ¿½ Å Ý ¾¼½¼ ÔØ ¾ Â ÒÙ ÖÝ ¾¼½½ ×ØÖ ØCompounds with the general formula Mg 1− Al B 2 were obtained by two-step ceramic synthesis. All compounds were characterized by X-ray diffraction, NMR spectroscopy, and by four point probe resistivity measurements in various magnetic fields method. The diborides unit cell parameters were determined as a function of the Al mole fraction. With the vaues of up to 0.40 (where is the composition of the stock prepared for sintering), the unit cell parameters of Mg 1− Al B 2 are similar to those of pure MgB 2 and the superconducting transition temperature was lowered. For stock compositions of 0 25 ≤ ≤ 0 60, the products contain a superstructure, also superconducting phase, which becomes the only product at = 0 50, and at > 0 60 this phase is replaced by AlB 2 -based solid solutions.

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“…Furthermore, the chloride hydrides of rareearth metals LnXH and LnXH x also have the same stacking sequence as hydrogen occupies the respective nitride site [87,[89][90][91]. Another related compound is TaS 2 in its 2H-structure (hexagonal, P6 3 /mmc), in which the van-derWaals gap is located between sulfide anions [92,93] [95][96][97], but those are not separated by van-der-Waals gaps. As nitride contain- …”

Section: Compounds With Structures Related To B-mnxmentioning

confidence: 99%

Superconducting nitride halides MNX (M = Ti, Zr, Hf; X = Cl, Br, I)

Schurz

Shlyk

Schleid

et al. 2011

Zeitschrift Für Kristallographie

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Abstract. Two different polymorphs of the metal nitride halides MNX (M ¼ Ti, Zr, Hf; X ¼ Cl, Br, I) are known to crystallize in layered structures. The two crystal structures differ in the way 2 1 {X[M 2 N 2 ]X} slabs are stacked along the c-axes. Metal atoms and/or organic molecules can be intercalated into the van-der-Waals gap between these layers. After such an electron-doping via intercalation the prototypic band insulators change into superconductors with moderate high critical temperatures T c up to 25.5 K. This review gathers information on synthesis routes, structural characteristics and properties of the prototypic nitride halides and the derivatives after electron-doping with a focus on superconductivity.

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The Preparation and Structure of Magnesium Boride, MgB₂

Cited by 257 publications

References 0 publications

Electronic Structure of Single-Crystalline Mg_xAl₁₋_xB₂ Probed by X-ray Diffraction Multipole Refinements and Polarization-Dependent X-ray Absorption Spectroscopy

Electronic Structure of Single-Crystalline Mg_xAl₁₋_xB₂ Probed by X-ray Diffraction Multipole Refinements and Polarization-Dependent X-ray Absorption Spectroscopy

Structure and properties of solid solutions in the Mg-Al-B system

Superconducting nitride halides MNX (M = Ti, Zr, Hf; X = Cl, Br, I)

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The Preparation and Structure of Magnesium Boride, MgB2

Cited by 257 publications

References 0 publications

Electronic Structure of Single-Crystalline MgxAl1−xB2 Probed by X-ray Diffraction Multipole Refinements and Polarization-Dependent X-ray Absorption Spectroscopy

Electronic Structure of Single-Crystalline MgxAl1−xB2 Probed by X-ray Diffraction Multipole Refinements and Polarization-Dependent X-ray Absorption Spectroscopy

Structure and properties of solid solutions in the Mg-Al-B system

Superconducting nitride halides MNX (M = Ti, Zr, Hf; X = Cl, Br, I)

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The Preparation and Structure of Magnesium Boride, MgB₂

Electronic Structure of Single-Crystalline Mg_xAl₁₋_xB₂ Probed by X-ray Diffraction Multipole Refinements and Polarization-Dependent X-ray Absorption Spectroscopy

Electronic Structure of Single-Crystalline Mg_xAl₁₋_xB₂ Probed by X-ray Diffraction Multipole Refinements and Polarization-Dependent X-ray Absorption Spectroscopy