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Titanium germanium anti­monide, TiGeSb

aDepartment of Chemistry, University of Alberta, Edmonton, AB, Canada T6G 2G2
*Correspondence e-mail: arthur.mar@ualberta.ca

(Received 5 August 2009; accepted 10 August 2009; online 15 August 2009)

TiGeSb adopts the PbFCl- or ZrSiS-type structure, with Ti atoms (4mm symmetry) centred within monocapped square anti­prisms generated by the stacking of denser square nets of Ge atoms ([\overline{4}]m2 symmetry) alternating with less dense square nets of Sb atoms (4mm symmetry).

Related literature

For PbFCl- or ZrSiS-type structures, see: Tremel & Hoffmann (1987[Tremel, W. & Hoffmann, M. (1987). J. Am. Chem. Soc. 109, 124-140.]). For a previous report on TiGeSb, see: Dashjav & Kleinke (2002[Dashjav, E. & Kleinke, H. (2002). Z. Anorg. Allg. Chem. 628, 2176.]). The Ti—Ge—Sb phase diagram at 670 K was reported by Kozlov & Pavlyuk (2004[Kozlov, A. Yu. & Pavlyuk, V. V. (2004). J. Alloys Compd, 367, 76-79.]). For the related ZrGeSb, see: Lam & Mar (1997[Lam, R. & Mar, A. (1997). J. Solid State Chem. 134, 388-394.]). For background to solid solutions in this class of compounds, see: Soheilnia et al. (2003[Soheilnia, N., Assoud, A. & Kleinke, H. (2003). Inorg. Chem. 42, 7319-7325.]); Kozlov & Pavlyuk (2004[Kozlov, A. Yu. & Pavlyuk, V. V. (2004). J. Alloys Compd, 367, 76-79.]). Metallic radii were taken from Pauling (1960[Pauling, L. (1960). The Nature of the Chemical Bond, 3rd ed. Ithaca, NY: Cornell University Press.]).

Experimental

Crystal data
  • TiGeSb

  • Mr = 242.24

  • Tetragonal, P 4/n m m

  • a = 3.7022 (5) Å

  • c = 8.2137 (12) Å

  • V = 112.58 (3) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 28.18 mm−1

  • T = 295 K

  • 0.12 × 0.11 × 0.01 mm

Data collection
  • Enraf–Nonius CAD-4 diffractometer

  • Absorption correction: numerical (SHELXTL; Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) Tmin = 0.117, Tmax = 0.718

  • 1906 measured reflections

  • 181 independent reflections

  • 178 reflections with I > 2σ(I)

  • Rint = 0.125

  • 3 standard reflections frequency: 120 min intensity decay: none

Refinement
  • R[F2 > 2σ(F2)] = 0.032

  • wR(F2) = 0.081

  • S = 1.17

  • 181 reflections

  • 10 parameters

  • Δρmax = 1.95 e Å−3

  • Δρmin = −2.53 e Å−3

Table 1
Selected bond lengths (Å)

Ti—Ge 2.7570 (10)
Ti—Sbi 2.8452 (7)
Ti—Sb 3.0129 (14)
Ge—Geii 2.6179 (4)
Symmetry codes: (i) -x, -y, -z+1; (ii) -x+1, -y, -z.

Data collection: CAD-4-PC (Enraf–Nonius, 1993[Enraf-Nonius (1993). CAD-4-PC. Enraf-Nonius, Delft, The Netherlands.]); cell refinement: CAD-4-PC; data reduction: XCAD4 (Harms & Wocadlo, 1995[Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.]); program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: ATOMS (Dowty, 1999[Dowty, E. (1999). ATOMS. Shape Software, Kingsport, Tennessee, USA.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

After a report of the ternary antimonide ZrGeSb (Lam & Mar, 1997), the corresponding Ti and Hf analogues were later described in a conference proceeding, but full crystallographic details have not been forthcoming (Dashjav & Kleinke, 2002). The complete structure of TiGeSb, which is absent in the Ti—Ge—Sb phase diagram at 670 K (Kozlov & Pavlyuk, 2004) but was prepared here at 1273 K, is presented. Common to many equiatomic compounds of the formulation MAB (M = large transition-metal atom; A, B = main group atoms), TiGeSb adopts the PbFCl- or ZrSiS-type structure, among other names (Tremel & Hoffmann, 1987). Square nets of each type of atom, with the Ge net being twice as dense as the other two, are stacked along the c axis (Fig. 1). The Zr atoms are nine-coordinate, centred within monocapped square antiprisms. The Ge–Ge distances are 0.13 Å longer than the sum of the Pauling metallic radii (2.48 Å; Pauling, 1960), indicative of weak polyanionic bonding. The solid solutions ZrGexSb1-x and HfGexSb1-x (up to x = 0.2) form related orthorhombic PbCl2-type structures (Soheilnia et al., 2003), whereas TiGexSb1-x adopts a NiAs-type structure (Kozlov & Pavlyuk, 2004).

Related literature top

For PbFCl- or ZrSiS-type structures, see: Tremel & Hoffmann (1987). For a previous report on TiGeSb, see: Dashjav & Kleinke (2002). The Ti—Ge—Sb phase diagram at 670 K was reported by Kozlov & Pavlyuk (2004). For the related ZrGeSb, see: Lam & Mar (1997). For background to solid solutions in this class of compounds, see: Soheilnia et al. (2003); Kozlov & Pavlyuk (2004). Metallic radii were taken from Pauling (1960).

Experimental top

A 0.25 g mixture of Ti (99.98%, Cerac), Ge (99.999%, Cerac), and Sb (99.995%, Aldrich) powders in a 1:1:3 molar ratio was placed in an evacuated fused-silica tube. The tube was heated at 873 K for 2 d and 1273 K for 2 d. Silver plate-shaped crystals were obtained, which were found by semiquantitative energy-dispersive X-ray (EDX) analysis to have a composition (at%) of 32 (2)% Ti, 35 (2)% Ge, and 33 (2)% Sb, in good agreement with the formula TiGeSb.

Refinement top

Analysis of Weissenberg photographs on a plate-shaped crystal, subsequently transferred to the four-circle diffractometer, established Laue symmetry 4/mmm and provided approximate cell parameters of a = 3.71 Å and c = 8.22 Å. In the final Fourier map based on origin choice 2 of space group P4/nmm the maximum peak and deepest hole are located 0.67 Å and 0.02 Å, respectively, from the Sb atom.

Computing details top

Data collection: CAD-4-PC (Enraf–Nonius, 1993); cell refinement: CAD-4-PC (Enraf–Nonius, 1993); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: ATOMS (Dowty, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Projection of the TiGeSb structure approximately along the a axis. Displacement ellipsoids are drawn at the 90% probability level.
titanium germanium antimonide top
Crystal data top
TiGeSbDx = 7.146 Mg m3
Mr = 242.24Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P4/nmmCell parameters from 24 reflections
Hall symbol: -P 4a 2aθ = 11.0–23.3°
a = 3.7022 (5) ŵ = 28.18 mm1
c = 8.2137 (12) ÅT = 295 K
V = 112.58 (3) Å3Plate, silver
Z = 20.12 × 0.11 × 0.01 mm
F(000) = 210
Data collection top
Enraf–Nonius CAD-4
diffractometer
178 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.125
Graphite monochromatorθmax = 34.8°, θmin = 2.5°
θ/2θ scansh = 55
Absorption correction: numerical
(SHELXTL; Sheldrick, 2008)
k = 55
Tmin = 0.117, Tmax = 0.718l = 1313
1906 measured reflections3 standard reflections every 120 min
181 independent reflections intensity decay: none
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.032 w = 1/[σ2(Fo2) + (0.044P)2 + 0.3679P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.081(Δ/σ)max < 0.001
S = 1.17Δρmax = 1.95 e Å3
181 reflectionsΔρmin = 2.53 e Å3
10 parametersExtinction correction: SHELXTL (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.038 (9)
Crystal data top
TiGeSbZ = 2
Mr = 242.24Mo Kα radiation
Tetragonal, P4/nmmµ = 28.18 mm1
a = 3.7022 (5) ÅT = 295 K
c = 8.2137 (12) Å0.12 × 0.11 × 0.01 mm
V = 112.58 (3) Å3
Data collection top
Enraf–Nonius CAD-4
diffractometer
178 reflections with I > 2σ(I)
Absorption correction: numerical
(SHELXTL; Sheldrick, 2008)
Rint = 0.125
Tmin = 0.117, Tmax = 0.7183 standard reflections every 120 min
1906 measured reflections intensity decay: none
181 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03210 parameters
wR(F2) = 0.0810 restraints
S = 1.17Δρmax = 1.95 e Å3
181 reflectionsΔρmin = 2.53 e Å3
Special details top

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.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Ti0.25000.25000.24875 (16)0.0054 (3)
Ge0.75000.25000.00000.0063 (3)
Sb0.25000.25000.61556 (6)0.0063 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ti0.0060 (4)0.0060 (4)0.0043 (6)0.0000.0000.000
Ge0.0065 (4)0.0065 (4)0.0059 (4)0.0000.0000.000
Sb0.0056 (3)0.0056 (3)0.0076 (4)0.0000.0000.000
Geometric parameters (Å, º) top
Ti—Gei2.7570 (10)Ge—Geix2.6179 (3)
Ti—Geii2.7570 (10)Ge—Tii2.7570 (10)
Ti—Geiii2.7570 (10)Ge—Tix2.7570 (10)
Ti—Ge2.7570 (10)Ge—Tiiii2.7570 (10)
Ti—Sbiv2.8452 (7)Sb—Tiiv2.8452 (7)
Ti—Sbv2.8452 (7)Sb—Tiv2.8452 (7)
Ti—Sbvi2.8452 (7)Sb—Tivi2.8452 (7)
Ti—Sbvii2.8452 (7)Sb—Tivii2.8452 (7)
Ti—Sb3.0129 (14)Sb—Sbv3.2337 (7)
Ge—Geviii2.6179 (4)Sb—Sbiv3.2337 (7)
Ge—Gei2.6179 (4)Sb—Sbvii3.2337 (7)
Ge—Geiii2.6179 (4)Sb—Sbvi3.2337 (7)
Gei—Ti—Geii56.69 (2)Tii—Ge—Tix123.31 (2)
Gei—Ti—Geiii84.35 (4)Geviii—Ge—Ti118.344 (11)
Geii—Ti—Geiii56.69 (2)Gei—Ge—Ti61.656 (11)
Gei—Ti—Ge56.69 (2)Geiii—Ge—Ti61.656 (11)
Geii—Ti—Ge84.35 (4)Geix—Ge—Ti118.344 (11)
Geiii—Ti—Ge56.69 (2)Tii—Ge—Ti123.31 (2)
Gei—Ti—Sbiv136.65 (2)Tix—Ge—Ti84.35 (4)
Geii—Ti—Sbiv136.65 (2)Geviii—Ge—Tiiii61.656 (11)
Geiii—Ti—Sbiv81.574 (14)Gei—Ge—Tiiii118.344 (11)
Ge—Ti—Sbiv81.574 (14)Geiii—Ge—Tiiii61.656 (11)
Gei—Ti—Sbv81.574 (14)Geix—Ge—Tiiii118.344 (11)
Geii—Ti—Sbv81.574 (14)Tii—Ge—Tiiii84.35 (4)
Geiii—Ti—Sbv136.65 (2)Tix—Ge—Tiiii123.31 (2)
Ge—Ti—Sbv136.65 (2)Ti—Ge—Tiiii123.31 (2)
Sbiv—Ti—Sbv133.88 (5)Tiiv—Sb—Tiv133.88 (5)
Gei—Ti—Sbvi136.65 (2)Tiiv—Sb—Tivi81.17 (2)
Geii—Ti—Sbvi81.574 (14)Tiv—Sb—Tivi81.17 (2)
Geiii—Ti—Sbvi81.574 (14)Tiiv—Sb—Tivii81.17 (2)
Ge—Ti—Sbvi136.65 (2)Tiv—Sb—Tivii81.17 (2)
Sbiv—Ti—Sbvi81.17 (2)Tivi—Sb—Tivii133.88 (5)
Sbv—Ti—Sbvi81.17 (2)Tiiv—Sb—Ti113.06 (3)
Gei—Ti—Sbvii81.574 (14)Tiv—Sb—Ti113.06 (3)
Geii—Ti—Sbvii136.65 (2)Tivi—Sb—Ti113.06 (3)
Geiii—Ti—Sbvii136.65 (2)Tivii—Sb—Ti113.06 (3)
Ge—Ti—Sbvii81.574 (14)Tiiv—Sb—Sbv167.11 (4)
Sbiv—Ti—Sbvii81.17 (2)Tiv—Sb—Sbv59.01 (3)
Sbv—Ti—Sbvii81.17 (2)Tivi—Sb—Sbv103.295 (14)
Sbvi—Ti—Sbvii133.88 (5)Tivii—Sb—Sbv103.295 (14)
Gei—Ti—Sb137.823 (19)Ti—Sb—Sbv54.051 (16)
Geii—Ti—Sb137.823 (19)Tiiv—Sb—Sbiv59.01 (3)
Geiii—Ti—Sb137.823 (19)Tiv—Sb—Sbiv167.11 (4)
Ge—Ti—Sb137.823 (19)Tivi—Sb—Sbiv103.295 (14)
Sbiv—Ti—Sb66.94 (3)Tivii—Sb—Sbiv103.295 (14)
Sbv—Ti—Sb66.94 (3)Ti—Sb—Sbiv54.051 (16)
Sbvi—Ti—Sb66.94 (3)Sbv—Sb—Sbiv108.10 (3)
Sbvii—Ti—Sb66.94 (3)Tiiv—Sb—Sbvii103.295 (14)
Geviii—Ge—Gei180.0Tiv—Sb—Sbvii103.295 (14)
Geviii—Ge—Geiii90.0Tivi—Sb—Sbvii167.11 (4)
Gei—Ge—Geiii90.0Tivii—Sb—Sbvii59.01 (3)
Geviii—Ge—Geix90.0Ti—Sb—Sbvii54.051 (16)
Gei—Ge—Geix90.0Sbv—Sb—Sbvii69.840 (16)
Geiii—Ge—Geix180.0Sbiv—Sb—Sbvii69.840 (16)
Geviii—Ge—Tii118.344 (11)Tiiv—Sb—Sbvi103.295 (14)
Gei—Ge—Tii61.656 (11)Tiv—Sb—Sbvi103.295 (14)
Geiii—Ge—Tii118.344 (11)Tivi—Sb—Sbvi59.01 (3)
Geix—Ge—Tii61.656 (11)Tivii—Sb—Sbvi167.11 (4)
Geviii—Ge—Tix61.656 (11)Ti—Sb—Sbvi54.051 (16)
Gei—Ge—Tix118.344 (11)Sbv—Sb—Sbvi69.840 (16)
Geiii—Ge—Tix118.344 (11)Sbiv—Sb—Sbvi69.840 (16)
Geix—Ge—Tix61.656 (11)Sbvii—Sb—Sbvi108.10 (3)
Symmetry codes: (i) x+1, y, z; (ii) x1, y, z; (iii) x+1, y+1, z; (iv) x+1, y+1, z+1; (v) x, y, z+1; (vi) x, y+1, z+1; (vii) x+1, y, z+1; (viii) x+2, y+1, z; (ix) x+2, y, z; (x) x+1, y, z.

Experimental details

Crystal data
Chemical formulaTiGeSb
Mr242.24
Crystal system, space groupTetragonal, P4/nmm
Temperature (K)295
a, c (Å)3.7022 (5), 8.2137 (12)
V3)112.58 (3)
Z2
Radiation typeMo Kα
µ (mm1)28.18
Crystal size (mm)0.12 × 0.11 × 0.01
Data collection
DiffractometerEnraf–Nonius CAD-4
diffractometer
Absorption correctionNumerical
(SHELXTL; Sheldrick, 2008)
Tmin, Tmax0.117, 0.718
No. of measured, independent and
observed [I > 2σ(I)] reflections
1906, 181, 178
Rint0.125
(sin θ/λ)max1)0.803
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.081, 1.17
No. of reflections181
No. of parameters10
Δρmax, Δρmin (e Å3)1.95, 2.53

Computer programs: CAD-4-PC (Enraf–Nonius, 1993), XCAD4 (Harms & Wocadlo, 1995), SHELXTL (Sheldrick, 2008), ATOMS (Dowty, 1999).

Selected bond lengths (Å) top
Ti—Ge2.7570 (10)Ti—Sb3.0129 (14)
Ti—Sbi2.8452 (7)Ge—Geii2.6179 (4)
Symmetry codes: (i) x, y, z+1; (ii) x+1, y, z.
 

Acknowledgements

The Natural Sciences and Engineering Research Council of Canada supported this work.

References

First citationDashjav, E. & Kleinke, H. (2002). Z. Anorg. Allg. Chem. 628, 2176.  CrossRef Google Scholar
First citationDowty, E. (1999). ATOMS. Shape Software, Kingsport, Tennessee, USA.  Google Scholar
First citationEnraf–Nonius (1993). CAD-4-PC. Enraf–Nonius, Delft, The Netherlands.  Google Scholar
First citationHarms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.  Google Scholar
First citationKozlov, A. Yu. & Pavlyuk, V. V. (2004). J. Alloys Compd, 367, 76–79.  Web of Science CrossRef CAS Google Scholar
First citationLam, R. & Mar, A. (1997). J. Solid State Chem. 134, 388–394.  Web of Science CrossRef CAS Google Scholar
First citationPauling, L. (1960). The Nature of the Chemical Bond, 3rd ed. Ithaca, NY: Cornell University Press.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSoheilnia, N., Assoud, A. & Kleinke, H. (2003). Inorg. Chem. 42, 7319–7325.  Web of Science CrossRef PubMed CAS Google Scholar
First citationTremel, W. & Hoffmann, M. (1987). J. Am. Chem. Soc. 109, 124–140.  CrossRef CAS Web of Science Google Scholar

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