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Lithium barium antimony, LiBaSb, crystallizes in the centrosymmetric hexagonal space group P63/mmc. Ba atoms sit on positions with \overline 3m symmetry, while the Sb and Li atoms occupy sites of \overline 62m symmetry. The structure of LiBaSb contains alternate hexagonal layers of (LiSb) and Ba. In this compound, antimony is present as isolated Sb3- species. The Ba atom lies inside a hexagonal prism (6 × Li and 6 × Sb).

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S160053680100201X/br6002sup1.cif
Contains datablocks LiBaSb, LIBASB

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S160053680100201X/br6002Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • R factor = 0.022
  • wR factor = 0.055
  • Data-to-parameter ratio = 16.0

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry
Red Alert Alert Level A:
GEOM_005 Alert A _geom_angle_atom_site_label_1 is missing Label identifying the atom site 1. GEOM_006 Alert A _geom_angle_atom_site_label_2 is missing Label identifying the atom site 2. GEOM_007 Alert A _geom_angle_atom_site_label_3 is missing Label identifying the atom site 3. GEOM_008 Alert A _geom_angle is missing Angle between atom sites 1, 2 and 3.
Yellow Alert Alert Level C:
ABSTY_02 Alert C An _exptl_absorpt_correction_type has been given without a literature citation. This should be contained in the _exptl_absorpt_process_details field. Absorption correction given as numerical CRYSR_01 Alert C _exptl_crystal_size_rad not in the CIF when expected. General Notes
ABSTM_02 The ratio of expected to reported Tmax/Tmin(RR) is > 1.10 Tmin and Tmax reported: 0.439 0.541 Tmin and Tmax expected: 0.310 0.458 RR = 1.200 Please check that your absorption correction is appropriate.
4 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
2 Alert Level C = Please check

Comment top

The structure of LiBaSb has been determined in the centrosymmetric space group P63/mmc (No. 194). Ba and Sb atoms were refined anisotropically, and an attempt to refine the Li atom anisotropically resulted in an uncertainties/Uij ratio that was too large. This compound is isostructural with KZnSb (Savelsberg & Schaefer, 1986) and NaBeSb (Tiburtius & Schuster, 1977), but the atomic positions of the monovalent and divalent cations are exchanged. In the LiBaSb structure, Li occupies the 6m2 site and Ba the 3 m site, while in KZnSb (or NaBeSb), K (or Na) sits at 3 m and Zn (or Be) at 6m2. The ionic radius of Li+ (0.90 Å) is closer to that of Zn2+ (0.88 Å) (or Be2+ 0.60 Å) than to that of K+ (1.52 Å) [or Na+ (1.20 Å)]. This favors exchange of monovalent/divalent atom positions. This structure can be considered as a filled NiAs-type structure or is better described as a substituted Li3Sb structure; one Ba2+ substitutes two Li+ cations. The LiBaSb structure adopts the same space group as Li3Sb. Owing to the largest size of the barium cations (Ba2+ 1.49 Å) compared with Li+ (0.9 Å), the cell parameters of the ternary phase are expanded (a = 4.701 Å and c = 8.309 Å in Li3Sb). Atomic positions are different from those in the binary phase. The structure of LiBaSb may be described with hexagonal prisms Ba(Li3Sb3)2 fused along the c axis. The barium cations are surrounded by 6 Li and 6 Sb atoms at 3.616 (1) Å. The Sb atoms are coordinated to three Li cations at 2.828 Å, close to the Li—Sb distance in Li3Sb (2.71 and 2.77 Å), and to six Ba cations at 3.616 (1) Å.

Unlike the parent Li4Ba3As4 compound (Monconduit & Belin, 1999), which contains two anionic moieties, namely As24- dumbbells and isolated As3- anions, and was characterized as a large band semi-conductor, the LiBaSb (Li+Ba2+Sb3-) compound contains only isolated Sb3- anions in association with Li+ and Ba2+ cations and is an insulator.

Experimental top

In the aim of obtaining the ternary compound Li4Ba3Sb4, amounts of Li, Ba and Sb (in proportion 4/3/4) were inserted in a niobium reactor, then weld-sealed under argon·The niobium reactor was protected against oxidation inside an evacuated silica tube. Single crystals of LiBaSb were obtained as side products by heating the initial mixture at 780 K for 10 h, maintaining at 580 K for 3 days and quenching in air. Elemental analyses (SEM) of crystals confirmed the presence of barium and antimony nearly in the ratio 1:1. The air-sensitive crystals were inserted into Lindemann glass capillaries for X-ray data investigations. Parameters and crystallographic space group were initially determined by oscillation and Weissenberg techniques. The best diffracting crystal was used for accurate intensity measurements on a CAD-4 Nonius diffractometer. Space group was found to be P63/mmc (n° 194) (observation conditions: 00 (0) l for l = 2n and hh(-2 h)l for l=2n).

Refinement top

All computations were carried out on a Pentium II 266 computer. The structure representation has been drawn with the program ORTEP-3 for Windows (Farrugia, 1997) which is a MS-Windows version of the current release of ORTEP-III (Burnett & Johnson).

Computing details top

Figures top
[Figure 1] Fig. 1. Representation of the hexagonal unit cell of LiBaSb. Barium cations are shown inside the hexagonal Li6Sb6 prism. Li atoms are represented by blue circles, Ba atoms by green circles and Sb atoms by red circles. Displacement ellipsoids are drawn at the 90% probability level.
(LiBaSb) top
Crystal data top
?β = ?°
Mr = ?γ = ?°
?, ?V = ? Å3
a = ? ÅZ = ?
b = ? Å? radiation, λ = ? Å
c = ? Å × × mm
α = ?°
Data collection top
h = ??l = ??
k = ??
Refinement top
Crystal data top
?β = ?°
Mr = ?γ = ?°
?, ?V = ? Å3
a = ? ÅZ = ?
b = ? Å? radiation, λ = ? Å
c = ? Å × × mm
α = ?°
Data collection top
Refinement top

Experimental details

Crystal data
Chemical formula?
Mr?
Crystal system, space group?, ?
Temperature (K)?
a, b, c (Å)?, ?, ?
α, β, γ (°)?, ?, ?
V3)?
Z?
Radiation type?, λ = ? Å
µ (mm1)?
Crystal size (mm) × ×
Data collection
Diffractometer?
Absorption correction?
the absorption effects have been corrected using the numerical procedure provided by SHELX 76 program (Sheldrick, 1976)
No. of measured, independent and
observed (?) reflections
?, ?, ?
Rint?
Refinement
R[F2 > 2σ(F2)], wR(F2), S ?, ?, ?
No. of reflections?
No. of parameters?
No. of restraints?
Δρmax, Δρmin (e Å3)?, ?

 

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