Kristall- und elektronische Struktur von LaAlSi2 / Crystal and Electronic Structure of LaAlSi2

2001 ◽  
Vol 56 (7) ◽  
pp. 620-625 ◽  
Author(s):  
Christian Kranenberg ◽  
Dirk Johrendt ◽  
Albrecht Mewis ◽  
Winfried Kockelmann

Abstract LaAlSi2 (a = 4.196(2), c = 11.437(7) Å; P3̄ml; Z = 2) was synthesized by arc-melting of preheated mixtures of the elements. The compound was investigated by means of X-ray methods and by neutron diffraction. The crystal structure can be described as a stacking variant of two different segments. The first one corresponds to the CaAl2Si2 structure type (LaAl2Si2), the second one with the A1B2 structure type (LaSi2). The segments are stacked along [001]. The electronic structure of the compound is discussed on the basis of LMTO band structure calculations.

2020 ◽  
Vol 75 (1-2) ◽  
pp. 217-223
Author(s):  
Volodymyr Babizhetskyy ◽  
Jürgen Köhler ◽  
Yuriy Tyvanchuk ◽  
Chong Zheng

AbstractThe title compound was prepared from the elements by arc-melting. The crystal structure was investigated by means of single-crystal X-ray diffraction. It crystallizes in the TbFeSi2 structure type, orthorhombic space group Cmmm, a = 4.0496(8), b = 16.416(2), c = 3.9527(6) Å, Z = 4, R1 = 0.041, wR2 = 0.11 for 207 unique reflections with Io > 2 σ(Io) and 19 refined parameters. The Fe position is not fully occupied and the refinement results in a composition GdFe0.68Si2 in agreement with a chemical analysis. The structure consists of zig-zag chains of Si(1) atoms which are terminally bound to additional Si(2) atoms. For an ordered variant GdFe0.5Si2 the Zintl concept can be applied which results in formal oxidation states Gd3+(Fe2+)0.5Si(1)1−Si(2)3−. The electronic structure of this variant GdFe0.5Si2 was analyzed using the tight-binding LMTO method and the results confirm the simple bonding picture.


2019 ◽  
Vol 234 (1) ◽  
pp. 19-32 ◽  
Author(s):  
Vitalii V. Shtender ◽  
Volodymyr V. Pavlyuk ◽  
Grygoriy S. Dmytriv ◽  
Wojciech Nitek ◽  
Wiesław Łasocha ◽  
...  

Abstract The synthesis, structural characterization, and chemical bonding peculiarities of new intermetallic compounds from Y–Mg–Ni ternary system are reported herein. The crystal structures of these compounds were determined by single-crystal and X-ray powder diffraction analysis. Three ternary compounds were studied: Y2Mg11Ni2 [own structure type, monoclinic, Pearson Symbol mS30, Space Group C2/m, a=18.969(4), b=3.6582(7), c=11.845(2) Å, β=125.07(3)°], Y4Mg3Ni2 [Ru4Al3B2 structure type, tetragonal, P4/mmm, tP18, a=10.8668(2), c=3.59781(12) Å] and YMgNi [MoAlB structure type, orthorhombic, Cmcm, a=3.6713(4), b=17.708(3), c=3.9583(5) Å]. New compositions of Y1−xMgxNi4 and Y5−xMg24+x solid solutions were detected: YMg0.86(1)Ni4.14(1) [SnMgCu4 structure type, cubic, F4̅3m, cF24, a=7.0747(6) Å] and Y4.28(1)Mg24.72(1) [Ti5Re24 structure type, cubic, I4̅3m, cI58, a=11.2655(11) Å]. The crystal structure peculiarities of these compounds are discussed. A particular attention has been given to Y2Mg11Ni2 and its relations with other Mg-containing compounds. Crystallographic analysis together with linear muffin-tin orbital band structure calculations reveals the presence of [Y2Ni4@Mg20] and [Y4Ni2@Mg18] clusters in Y2Mg11Ni2 phase. For Y4Mg3Ni2 the formation of the Ni–Mg nets was observed, while the Y atoms form a monolayer.


Author(s):  
Nazar Zaremba ◽  
Ihor Muts ◽  
Volodymyr Pavlyuk ◽  
Viktor Hlukhyy ◽  
Rainer Pöttgen ◽  
...  

Abstract Single crystals of a new samarium platinum indide have been synthesized in a high-frequency furnace under flowing argon atmosphere. The crystal structure of SmPt2In2 was determined from single-crystal X-ray data (R1 = 0.0416 for 1049 F values and 63 variables). It belongs to the CePt2In2 structure type with the following crystallographic parameters: P21/m, mP20, Z = 4, a = 10.0561(8), b = 4.4214(2), c = 10.1946(8) Å, β = 116.492(5)°, V = 405.68(5) Å3. Physical properties were studied and the crystal chemical discussion is supported by electronic structure calculations.


Author(s):  
Rongqing Shang ◽  
An T. Nguyen ◽  
Allan He ◽  
Susan M. Kauzlarich

A rare-earth-containing compound, ytterbium aluminium antimonide, Yb3AlSb3 (Ca3AlAs3-type structure), has been successfully synthesized within the Yb–Al–Sb system through flux methods. According to the Zintl formalism, this structure is nominally made up of (Yb2+)3[(Al1−)(1b – Sb2−)2(2b – Sb1−)], where 1b and 2b indicate 1-bonded and 2-bonded, respectively, and Al is treated as part of the covalent anionic network. The crystal structure features infinite corner-sharing AlSb4 tetrahedra, [AlSb2Sb2/2]6−, with Yb2+ cations residing between the tetrahedra to provide charge balance. Herein, the synthetic conditions, the crystal structure determined from single-crystal X-ray diffraction data, and electronic structure calculations are reported.


1994 ◽  
Vol 49 (6) ◽  
pp. 721-728 ◽  
Author(s):  
Gerhard Cordier ◽  
Volker Müller

Na17Ga29ln12 (a = 2178.5(5) pm, Fd3m, Z = 8, R = 0.081) and K17In41 (a = 2424.1(5) pm, Fd3m, Z = 8, R = 0.060) have been prepared from the elements and characterized by single crystal X -ray methods. Na17Ga29ln12 is a ternary variant of K17In41. The crystal structure of Na17Ga29ln12 contains Ga12 icosahedra (In 12 icosahedra in K17In41) and truncated In12 tetrahedra which are four-capped and centred by additional Ga atoms (In atoms in K17In41). The packing of icosahedra and truncated tetrahedra leads to interpenetrating Samson polyhedra. The Ga12 icosahedra (In12 icosahedra in K17In41) take the Cu positions of the MgCu2 type, the In12 clusters take the positions of the Mg atoms of this structure type. The alkali atoms in Na17Ga29In12 and K17In41 occupy the deltahedral faces of the icosahedra and form pentagonal dodecahedra


2008 ◽  
Vol 78 (23) ◽  
Author(s):  
Catherine Guillot-Deudon ◽  
Sylvie Harel ◽  
Arezki Mokrani ◽  
Alain Lafond ◽  
Nicolas Barreau ◽  
...  

1980 ◽  
Vol 35 (12) ◽  
pp. 1518-1524 ◽  
Author(s):  
Hadi Limartha ◽  
Brigitte Eisenmann ◽  
Herbert Schäfer ◽  
Hans A. Graf

Abstract The formerly described compound Ca2Sb is to be corrected to Ca4Sb2O as shown by X-ray diffractometer data of single crystals and neutron diffraction diagramms of powders. The compound crystallizes in the K2NiF4 structure type.


2000 ◽  
Vol 14 (2) ◽  
pp. 281-286 ◽  
Author(s):  
V.R. Galakhov ◽  
M.A. Korotin ◽  
N.A. Ovechkina ◽  
E.Z. Kurmaev ◽  
V.S. Gorshkov ◽  
...  

2001 ◽  
Vol 79 (9) ◽  
pp. 1338-1343
Author(s):  
Holger Kleinke

Ti5SixSb3–x can be prepared by melting mixtures of Ti, Si, and TiSb2. The ternary phase with x = 1.32(5) crystallizes in the W5Si3 type (space group I4/mcm, Z = 8, for x = 1.32(5): a = 1034.6(2), c = 515.2(1) pm), while Ti5Sb3 and Ti5Si3 adopt the Yb5Sb3 type and the Mn5Si3 type, respectively. The Si and Sb atoms share two sites in Ti5Si1.32(5)Sb1.68: one site is located within a linear chain with short interatomic bonds, which is almost exclusively occupied by Si (i.e., 92(1)% Si and 8% Sb), whereas the second site, being occupied by 80(2)% Sb and 20% Si, shows no significant interactions between the main group elements. Band structure calculations reveal the new silicide antimonide being metallic as a consequence of partly filled Ti d states. The structure is mainly stabilized by bonding Ti—Sb, Ti—Si, and Si—Si interactions.Key words: titanium, silicide, antimonide, crystal structure, electronic structure, structure and bonding.


1994 ◽  
Vol 50 (24) ◽  
pp. 18330-18340 ◽  
Author(s):  
S. Eisebitt ◽  
J.-E. Rubensson ◽  
M. Nicodemus ◽  
T. Böske ◽  
S. Blügel ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document