The intermetallic compound BaAgBi

Barium silver bismuth is isostructural with ZrBeSi. The Ag and Bi atoms form planar honeycomb layers with an Ag-Bi distance of 2.8534 (4) Å. The displacement parameters of Ag and Bi show a strong anisotropy.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Please check) = 0.000 Å
• R factor = 0.038
• wR factor = 0.102
• Data-to-parameter ratio = 16.6

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           29.98
         From the CIF: _reflns_number_total                133
         From the CIF: _diffrn_reflns_limit_ max hkl    6.    3.   12.
         From the CIF: _diffrn_reflns_limit_ min hkl    0.    0.    0.
         TEST1: Expected hkl limits for theta max
         Calculated maximum hkl    6.    6.   12.
         Calculated minimum hkl   -6.   -6.  -12.
          ALERT: Expected hkl max differ from CIF values

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S1. Comment

During studies on the ternary barium–silver–bismuth system, the intermetallic compound BaAgBi was obtained as a side product. Previously, this compound was prepared by stoichiometric reaction of the elements and characterized by X-ray powder diffraction (Merlo et al., 1990).

BaAgBi is isostructural with ZrBeSi (Vogel & Schuster, 1980). The Ag and Bi atoms form planar hexagonal sheets like graphite, with Ag and Bi alternating in the layer. The Ba atoms lie between two layers and are positioned over the centers of the hexagonal rings. The shortest interatomic distance, Ag—Bi, is 2.8534 (4) Å, and each Ba atom is surrounded by six Au and six Sb atoms at distances of 3.6533 (4) Å. The displacement parameters of the Ag and Bi atoms display a strong anisotropy; the U₁₁ values of the Ag and Bi atoms are 0.0120 (11) and 0.0066 (7) Ų while the U₃₃ values are 0.0231 (18) and 0.0140 (10) Ų, respectively. This anisotropy also appears in several ZrBeSi-type compounds, such as EuZnGe (Pöttgen, 1995), CaCuBi (Merlo et al., 1990), and EuAgAs (Tomuschat & Schuster, 1981), suggesting the possibility of interlayer interactions.

S2. Experimental

BaAgBi was obtained as a by-product when Ba [rod, Alfa-Aesar (99.99%)], Ag [powder, -100 mesh, Alfa-Aesar (99.999%)], and Bi [powder, -100 mesh, Alfa-Aesar (99.999%)] were loaded into a tantalum tube (Nobel-Met. Ltd., >99.85%, 0.375 in. OD) in a 1:1:2 molar ratio in an Ar-filled glovebox. The tube was sealed in an arc-melter under argon, placed in a fused-silica jacket, and heated at 973 K for 3 days. The reaction container was cooled slowly to 673 K at 10 K h^-1, and then quenched to room temperature. When the tantalum tube was opened in the Ar-filled glovebox, grey irregular-shaped crystals of BaAgBi were found in the product. Single crystals were mounted in 0.3 mm thin-walled capillaries for diffraction experiments.

S3. Refinement

Space groups P31c, P31c, P6₃mc, P6₃/mmc, and P62c were allowed based on the observed systematic absences. Space group P6₃/mmc was initially selected and confirmed by comparing the refinement results with the other four space groups. The Ba, Ag, and Bi atoms were readily located from the E-map, and refined with anisotropic displacement parameters. The reflection 124 was omitted from the refinement because of possible interference from the beam stop of the X-ray diffractometer. The largest residuals in the final difference map were 2.76 e Å^-3 at a distance of 0.74 Å from Bi, and -3.98 e Å^-3 at a distance of 0.92 Å from Bi.

Computing details

Data collection: TEXSAN (Molecular Structure Corporation, 1990); cell refinement: TEXSAN; data reduction: TEXSAN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

Fig. 1. The layer structure of BaAgBi along the z axis. Displacement ellipsoids are drawn at the 99% probability level. Key: Ba grey, Ag blue, Bi red.

(I)

Crystal data

AgBaBi	Dx = 7.814 Mg m^−3
Mr = 454.19	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63/mmc	Cell parameters from 27 reflections
Hall symbol: -P 6c 2c	θ = 6.5–14.4°
a = 4.9423 (7) Å	µ = 60.31 mm^−1
c = 9.1251 (18) Å	T = 293 K
V = 193.03 (5) Å^3	Irregular, grey
Z = 2	0.09 × 0.03 × 0.03 mm
F(000) = 372

Data collection

Rigaku AFC-6R diffractometer	Rint = 0
2θ/ω scans	θmax = 30.0°, θmin = 4.5°
Absorption correction: ψ scan (North et al., 1968)	h = 0→6
Tmin = 0.132, Tmax = 0.164	k = 0→3
133 measured reflections	l = 0→12
133 independent reflections	3 standard reflections every 100 reflections
89 reflections with I > 2σ(I)	intensity decay: 0.9%

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0405P)^2 + 2.2564P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.038	(Δ/σ)max < 0.001
wR(F^2) = 0.102	Δρmax = 2.76 e Å^−3
S = 1.16	Δρmin = −3.98 e Å^−3
133 reflections	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
8 parameters	Extinction coefficient: 0.011 (2)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Ba	0	0	0	0.0094 (7)
Ag	0.3333	0.6667	0.25	0.0157 (9)
Bi	0.3333	0.6667	0.75	0.0091 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba	0.0113 (10)	0.0113 (10)	0.0057 (12)	0.0057 (5)	0	0
Ag	0.0120 (11)	0.0120 (11)	0.0231 (18)	0.0060 (6)	0	0
Bi	0.0066 (7)	0.0066 (7)	0.0140 (10)	0.0033 (4)	0	0

Geometric parameters (Å, º)

Ba—Bi^i	3.6533 (4)	Ag—Ba^xiii	3.6533 (4)
Ba—Ag	3.6533 (4)	Ag—Ba^xiv	3.6533 (4)
Ba—Bi^ii	3.6533 (4)	Ag—Ba^xv	3.6533 (4)
Ba—Ag^iii	3.6533 (4)	Ag—Ba^xvi	3.6533 (4)
Ba—Bi^iv	3.6533 (4)	Ag—Ba^xvii	3.6533 (4)
Ba—Ag^v	3.6533 (4)	Bi—Ag^xii	2.8534 (4)
Ba—Bi^vi	3.6533 (4)	Bi—Ag^iv	2.8534 (4)
Ba—Ag^vii	3.6533 (4)	Bi—Ag^i	2.8534 (4)
Ba—Ag^viii	3.6533 (4)	Bi—Ba^xviii	3.6533 (4)
Ba—Bi^ix	3.6533 (4)	Bi—Ba^xvi	3.6533 (4)
Ba—Ag^x	3.6533 (4)	Bi—Ba^xv	3.6533 (4)
Ba—Bi^xi	3.6533 (4)	Bi—Ba^xix	3.6533 (4)
Ag—Bi^xii	2.8534 (4)	Bi—Ba^xx	3.6533 (4)
Ag—Bi^iv	2.8534 (4)	Bi—Ba^xiii	3.6533 (4)
Ag—Bi^i	2.8534 (4)
Bi^i—Ba—Ag	45.975 (5)	Bi^xii—Ag—Ba	141.358 (7)
Bi^i—Ba—Bi^ii	180	Bi^iv—Ag—Ba	67.012 (2)
Ag—Ba—Bi^ii	134.025 (5)	Bi^i—Ag—Ba	67.012 (2)
Bi^i—Ba—Ag^iii	134.025 (5)	Bi^xii—Ag—Ba^xiii	67.012 (2)
Ag—Ba—Ag^iii	180	Bi^iv—Ag—Ba^xiii	141.358 (7)
Bi^ii—Ba—Ag^iii	45.975 (5)	Bi^i—Ag—Ba^xiii	67.012 (2)
Bi^i—Ba—Bi^iv	85.129 (10)	Ba—Ag—Ba^xiii	134.025 (5)
Ag—Ba—Bi^iv	45.975 (5)	Bi^xii—Ag—Ba^xiv	67.012 (2)
Bi^ii—Ba—Bi^iv	94.871 (10)	Bi^iv—Ag—Ba^xiv	67.012 (2)
Ag^iii—Ba—Bi^iv	134.025 (5)	Bi^i—Ag—Ba^xiv	141.358 (7)
Bi^i—Ba—Ag^v	45.975 (5)	Ba—Ag—Ba^xiv	85.129 (10)
Ag—Ba—Ag^v	85.129 (10)	Ba^xiii—Ag—Ba^xiv	134.025 (5)
Bi^ii—Ba—Ag^v	134.025 (5)	Bi^xii—Ag—Ba^xv	67.012 (2)
Ag^iii—Ba—Ag^v	94.871 (10)	Bi^iv—Ag—Ba^xv	67.012 (2)
Bi^iv—Ba—Ag^v	102.717 (14)	Bi^i—Ag—Ba^xv	141.358 (7)
Bi^i—Ba—Bi^vi	94.871 (10)	Ba—Ag—Ba^xv	134.025 (5)
Ag—Ba—Bi^vi	134.025 (5)	Ba^xiii—Ag—Ba^xv	85.129 (10)
Bi^ii—Ba—Bi^vi	85.129 (10)	Ba^xiv—Ag—Ba^xv	77.283 (14)
Ag^iii—Ba—Bi^vi	45.975 (5)	Bi^xii—Ag—Ba^xvi	141.358 (7)
Bi^iv—Ba—Bi^vi	180	Bi^iv—Ag—Ba^xvi	67.012 (2)
Ag^v—Ba—Bi^vi	77.283 (14)	Bi^i—Ag—Ba^xvi	67.012 (2)
Bi^i—Ba—Ag^vii	134.025 (5)	Ba—Ag—Ba^xvi	77.283 (14)
Ag—Ba—Ag^vii	94.871 (10)	Ba^xiii—Ag—Ba^xvi	85.129 (10)
Bi^ii—Ba—Ag^vii	45.975 (5)	Ba^xiv—Ag—Ba^xvi	134.025 (5)
Ag^iii—Ba—Ag^vii	85.129 (10)	Ba^xv—Ag—Ba^xvi	85.129 (10)
Bi^iv—Ba—Ag^vii	77.283 (14)	Bi^xii—Ag—Ba^xvii	67.012 (2)
Ag^v—Ba—Ag^vii	180	Bi^iv—Ag—Ba^xvii	141.358 (7)
Bi^vi—Ba—Ag^vii	102.717 (14)	Bi^i—Ag—Ba^xvii	67.012 (2)
Bi^i—Ba—Ag^viii	102.717 (14)	Ba—Ag—Ba^xvii	85.129 (10)
Ag—Ba—Ag^viii	85.129 (10)	Ba^xiii—Ag—Ba^xvii	77.283 (14)
Bi^ii—Ba—Ag^viii	77.283 (14)	Ba^xiv—Ag—Ba^xvii	85.129 (10)
Ag^iii—Ba—Ag^viii	94.871 (10)	Ba^xv—Ag—Ba^xvii	134.025 (5)
Bi^iv—Ba—Ag^viii	45.975 (5)	Ba^xvi—Ag—Ba^xvii	134.025 (5)
Ag^v—Ba—Ag^viii	85.129 (10)	Ag^xii—Bi—Ag^iv	120
Bi^vi—Ba—Ag^viii	134.025 (5)	Ag^xii—Bi—Ag^i	120
Ag^vii—Ba—Ag^viii	94.871 (10)	Ag^iv—Bi—Ag^i	120
Bi^i—Ba—Bi^ix	85.129 (10)	Ag^xii—Bi—Ba^xviii	67.012 (2)
Ag—Ba—Bi^ix	102.717 (14)	Ag^iv—Bi—Ba^xviii	141.358 (7)
Bi^ii—Ba—Bi^ix	94.871 (10)	Ag^i—Bi—Ba^xviii	67.012 (2)
Ag^iii—Ba—Bi^ix	77.283 (14)	Ag^xii—Bi—Ba^xvi	141.358 (7)
Bi^iv—Ba—Bi^ix	85.129 (10)	Ag^iv—Bi—Ba^xvi	67.012 (2)
Ag^v—Ba—Bi^ix	45.975 (5)	Ag^i—Bi—Ba^xvi	67.012 (2)
Bi^vi—Ba—Bi^ix	94.871 (10)	Ba^xviii—Bi—Ba^xvi	134.025 (5)
Ag^vii—Ba—Bi^ix	134.025 (5)	Ag^xii—Bi—Ba^xv	67.012 (2)
Ag^viii—Ba—Bi^ix	45.975 (5)	Ag^iv—Bi—Ba^xv	67.012 (2)
Bi^i—Ba—Ag^x	77.283 (14)	Ag^i—Bi—Ba^xv	141.358 (7)
Ag—Ba—Ag^x	94.871 (10)	Ba^xviii—Bi—Ba^xv	134.025 (5)
Bi^ii—Ba—Ag^x	102.717 (14)	Ba^xvi—Bi—Ba^xv	85.129 (10)
Ag^iii—Ba—Ag^x	85.129 (10)	Ag^xii—Bi—Ba^xix	67.012 (2)
Bi^iv—Ba—Ag^x	134.025 (5)	Ag^iv—Bi—Ba^xix	67.012 (2)
Ag^v—Ba—Ag^x	94.871 (10)	Ag^i—Bi—Ba^xix	141.358 (7)
Bi^vi—Ba—Ag^x	45.975 (5)	Ba^xviii—Bi—Ba^xix	85.129 (10)
Ag^vii—Ba—Ag^x	85.129 (10)	Ba^xvi—Bi—Ba^xix	134.025 (5)
Ag^viii—Ba—Ag^x	180	Ba^xv—Bi—Ba^xix	77.283 (14)
Bi^ix—Ba—Ag^x	134.025 (5)	Ag^xii—Bi—Ba^xx	141.358 (7)
Bi^i—Ba—Bi^xi	94.871 (10)	Ag^iv—Bi—Ba^xx	67.012 (2)
Ag—Ba—Bi^xi	77.283 (14)	Ag^i—Bi—Ba^xx	67.012 (2)
Bi^ii—Ba—Bi^xi	85.129 (10)	Ba^xviii—Bi—Ba^xx	85.129 (10)
Ag^iii—Ba—Bi^xi	102.717 (14)	Ba^xvi—Bi—Ba^xx	77.283 (14)
Bi^iv—Ba—Bi^xi	94.871 (10)	Ba^xv—Bi—Ba^xx	134.025 (5)
Ag^v—Ba—Bi^xi	134.025 (5)	Ba^xix—Bi—Ba^xx	85.129 (10)
Bi^vi—Ba—Bi^xi	85.129 (10)	Ag^xii—Bi—Ba^xiii	67.012 (2)
Ag^vii—Ba—Bi^xi	45.975 (5)	Ag^iv—Bi—Ba^xiii	141.358 (7)
Ag^viii—Ba—Bi^xi	134.025 (5)	Ag^i—Bi—Ba^xiii	67.012 (2)
Bi^ix—Ba—Bi^xi	180	Ba^xviii—Bi—Ba^xiii	77.283 (14)
Ag^x—Ba—Bi^xi	45.975 (5)	Ba^xvi—Bi—Ba^xiii	85.129 (10)
Bi^xii—Ag—Bi^iv	120	Ba^xv—Bi—Ba^xiii	85.129 (10)
Bi^xii—Ag—Bi^i	120	Ba^xix—Bi—Ba^xiii	134.025 (5)
Bi^iv—Ag—Bi^i	120	Ba^xx—Bi—Ba^xiii	134.025 (5)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1, y−1, z−1; (iii) −x, −y, −z; (iv) −x, −y+1, −z+1; (v) x, y−1, z; (vi) x, y−1, z−1; (vii) −x, −y+1, −z; (viii) x−1, y−1, z; (ix) −x, −y, −z+1; (x) −x+1, −y+1, −z; (xi) x, y, z−1; (xii) −x+1, −y+2, −z+1; (xiii) −x+1, −y+1, z+1/2; (xiv) x, y+1, z; (xv) −x, −y+1, z+1/2; (xvi) −x, −y, z+1/2; (xvii) x+1, y+1, z; (xviii) x+1, y+1, z+1; (xix) x, y+1, z+1; (xx) x, y, z+1.