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Our investigations into the ZnO-TeO2 system have produced a new phase, zinc(II) hexa­tellurium(IV) trideca­oxide, ZnTe6O13, with trigonal (R\overline{3}) symmetry, synthesized by repeated heating and cooling to a maximum temperature of 1053 K. The asymmetric unit consists of a Zn atom coordinated in a distorted octa­hedral fashion by two unique tellurium(IV) oxide units that form trigonal-bipyramidal TeO4 and TeO3+1 corner- and edge-shared polyhedra. Except for the Zn and an O atom, which occupy 6c positions, all atoms occupy 18f general positions.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107027412/iz3022sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107027412/iz3022Isup2.hkl
Contains datablock I

Comment top

The established phase diagram of the ZnO–TeO2 system has three crystalline compositions, viz. ZnTeO3 (Hanke, 1967), at low TeO2 mole percent, Zn2Te3O8 (Hanke, 1966), at higher TeO2 mole percent, and the recently reported Zn3TeO6 (Weil, 2006). Glassy compositions are current electronic and photonic research interests (e.g. Nukui, 2001; Bürger et al., 1992; Öveçoğlu et al., 2004). The title compound, (I), was obtained unexpectedly by repeated melting and cooling of the 21:79 mol percent ZnO:TeO2 mixture, normally used to produce the mixed-phase TeO2 and Zn2Te3O8. This mole percent is used to achieve the lowest melting mixture at the eutectic point and reduces the evaporation of TeO2 during the melt. The additional melting cycles (the last at very high heat) as well as the additional cooling under an O2 flow may have contributed to the formation of the new ZnTe6O13 phase.

The space group of (I), according to systematic absences, may be R3, R3, R32, R3m or R3m; however, subsequent structure and least-squares refinement indicated that the correct space group is R3. Fig. 1 shows the full coordination environment around each metal centre. There are two unique TeIV atoms in the asymmetric unit and the complete coordination environment around each is generated by symmetry [Te1, symmetry code: (i) -x + 2/3, -y + 1/3, -z + 1/3, O2; Te2, symmetry code: (ii) -y + 1, x - y + 1, z, O4; see Table 1]. Both are four-coordinate trigonal–bipyramidal (tbp), i.e. TeO4, with a stereochemically active lone pair of electrons, a common motif in tellurate(IV) structures. The environment around Te1 (see Table 1), although compressed, is similar to that in α-TeO2 (Leciejewicz, 1961; Te—O = 1.919 and 2.087 Å, apical O—Te—O = 163.9°; Lindqvist, 1968; Te—O = 1.903 (20) and 2.082 (23) Å, apical O—Te—O = 168.5 (13)°]. However, the coordination around Te2 is similar to the TeO3 + 1 coordination found in ZnTe3O8, CuTe2O5 (Hanke et al., 1973) and CuTe3O8 (Feger et al., 1999), with three similar Te—O distances and the fourth significantly longer (see Table 1). In (I), the tbp TeO4 polyhedra are both corner linked equatorial to apical for both Te1–Te2 and Te2–Te2 polyhedra, and edged shared for Te1–Te1 polyhedra. Corner-sharing TeO4 polyhedra are seen in α-TeO2 but both corner- and edged-shared TeO4 polyhedra are seen in ZnTeO3 and ZnTe3O8.

The coordination environment around the unique Zn atom after symmetry generation (see Table 1) is a highly distorted octahedron with trans O—Zn—O angles of ca 163°. Three of the O atoms are corner linked to Te1 polyhedra and the other three are corner linked to Te2 polyhedra, all to equatorial O atoms. Three Te2 units and atom Zn1 form an adamantyl-type substructure. Three Te1 units and atom Zn1 form a `paddle wheel' arrangement with oxygen-bridged O2—Te1—O2 atoms (see Fig. 2). The complete packing superstructure consists of a bilayer of tellurium oxide linked by the Te1—O2 bridging units. These bilayers are connected via the Zn atoms.

The bulk material was examined by powder X-ray diffraction. The pattern, shown in Fig. 3, indicates that there is a mixture of phases compared with the calculated pure phase, ZnTe6O13, which is shown as an overlay. A simulated powder pattern using CrystalDiffract 1.3 (reference?) shows that the bulk composition consists of 54:46% ZnTe6O13/Zn2Te3O8, with no occurance of α-TeO2. The composition of the new phase was also confirmed using a Camebax MBX electron probe microanalyser with wavelength dispersive spectroscopy (WDS) on polished sections. Compositional distribution between (I) and Zn2Te3O8 is shown in a backscattered electron image in Fig. 4.

Related literature top

For related literature, see: Bürger et al. (1992); Feger et al. (1999); Hanke (1966, 1967); Hanke et al. (1973); King et al. (1996); Leciejewicz (1961); Lindqvist (1968); Nukui (2001); Rajendran & Mellen (1987); Stockbarger (1936); Weil (2006); Öveçoğlu et al. (2004).

Experimental top

ZnO and TeO2 powders (Alpha Aesar, 99.999% purity) were mixed in a ZnO:TeO2 mole percentage of 21:79% using a jar mill with a total average mixing time of 15 h. The mixed powder was placed in a platinum crucible and calcined. The calcined powder was melted and frozen in a radiofrequency furnace several times with (a) a maximum temperature of 939 K and a cooling rate of 7 K h-1 in air with an O2 flow, (b) a maxmimum temperature of 958 K and a cooling rate of 12 K h-1, air only, (c) a maximum temperature of 923 K and a cooling rate of 30 K h-1 in air, and (d) a maximum temperature of 1053 K and a cooling rate of 48 K h-1 in air, and finally cooled at 2 K h-1 with an axial temperature gradient of 60 K cm-1 (Bridgman technique; Stockbarger, 1936; King et al., 1996; Rajendran & Mellen, 1987) to room temperature.

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT-Plus (Bruker, 2003); data reduction: SAINT-Plus; program(s) used to solve structure: XS in SHELXTL (Bruker, 2003); program(s) used to refine structure: XL in SHELXTL; molecular graphics: DIAMOND (Brandenburg, 1998); software used to prepare material for publication: publCIF (Westrip, 2007).

Figures top
[Figure 1] Fig. 1. The full coordination environment around each unique metal center in the asymmetric unit. The atom legend and coordinate system are shown, and symmetry-generated atom operations are given in Table 1.
[Figure 2] Fig. 2. The partial unit cell (coordination completed) drawn parallel to the hexagonal axis [001], showing the arrangement of the tbp TeO4 units. The atom legend and coordinate system are shown.
[Figure 3] Fig. 3. Powder X-ray diffraction overlay pattern for (bottom line) bulk composition, (middle line) calculated mixed composition and (top line) calculated pure ZnTe6O13 phase using Cu Kα radiation.
[Figure 4] Fig. 4. A representative back scattered electron image. The pale-gray (yellow in the online version of the journal) area is ZnTe6O13 and the mid-gray (brown) area is Zn2Te3O8 (composition confirmed by wavelength dispersive spectroscopy). The black background is the glass substrate.
zinc(II) hexatellurium(IV) tridecaoxide top
Crystal data top
ZnTe6O13Dx = 6.149 Mg m3
Mr = 1038.97Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3Cell parameters from 5081 reflections
Hall symbol: -R 3θ = 4.8–30.0°
a = 10.1283 (9) ŵ = 17.55 mm1
c = 18.948 (3) ÅT = 86 K
V = 1683.3 (3) Å3Fragment, yellow
Z = 60.13 × 0.06 × 0.02 mm
F(000) = 2676
Data collection top
Bruker/Siemens SMART APEX
diffractometer
679 independent reflections
Radiation source: normal-focus sealed tube659 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.033
Detector resolution: 8.3 pixels mm-1θmax = 25.2°, θmin = 2.6°
ω scansh = 1212
Absorption correction: multi-scan
(SADABS; Bruker, 2002)
k = 1212
Tmin = 0.204, Tmax = 0.705l = 2222
8273 measured reflections
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)] = 0.020 w = 1/[σ2(Fo2) + (0.0343P)2 + 33.5991P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.060(Δ/σ)max < 0.001
S = 1.12Δρmax = 0.73 e Å3
679 reflectionsΔρmin = 0.69 e Å3
62 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
6 restraintsExtinction coefficient: 0.00040 (3)
Crystal data top
ZnTe6O13Z = 6
Mr = 1038.97Mo Kα radiation
Trigonal, R3µ = 17.55 mm1
a = 10.1283 (9) ÅT = 86 K
c = 18.948 (3) Å0.13 × 0.06 × 0.02 mm
V = 1683.3 (3) Å3
Data collection top
Bruker/Siemens SMART APEX
diffractometer
679 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2002)
659 reflections with I > 2σ(I)
Tmin = 0.204, Tmax = 0.705Rint = 0.033
8273 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0206 restraints
wR(F2) = 0.060 w = 1/[σ2(Fo2) + (0.0343P)2 + 33.5991P]
where P = (Fo2 + 2Fc2)/3
S = 1.12Δρmax = 0.73 e Å3
679 reflectionsΔρmin = 0.69 e Å3
62 parameters
Special details top

Experimental. A standard resevoir mount was used for powder XRD on a Siemens D500, with Cu Kα radiation. Data were collected using a 0.02° step at room temperature.

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
O10.00000.00000.0868 (3)0.0037 (14)
O20.2038 (5)0.1155 (5)0.1926 (2)0.0071 (9)
O30.2515 (5)0.2509 (5)0.0511 (2)0.0074 (9)
O40.2037 (5)0.4826 (5)0.0977 (2)0.0058 (9)
O50.3843 (5)0.5229 (5)0.0201 (2)0.0050 (9)
Te10.23760 (4)0.08143 (5)0.09533 (2)0.0048 (2)
Te20.39512 (5)0.49509 (5)0.07609 (2)0.00422 (19)
Zn10.33330.66670.07580 (6)0.0048 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.004 (2)0.004 (2)0.003 (3)0.0022 (11)0.0000.000
O20.005 (2)0.010 (2)0.006 (2)0.0032 (18)0.0028 (17)0.0012 (16)
O30.011 (2)0.007 (2)0.005 (2)0.0053 (17)0.0017 (17)0.0002 (17)
O40.005 (2)0.008 (2)0.006 (2)0.0040 (18)0.0019 (16)0.0027 (17)
O50.008 (2)0.005 (2)0.004 (2)0.0053 (19)0.0016 (16)0.0013 (16)
Te10.0063 (3)0.0041 (3)0.0047 (3)0.00296 (18)0.00013 (14)0.00013 (15)
Te20.0043 (3)0.0043 (3)0.0043 (3)0.00235 (17)0.00005 (14)0.00019 (14)
Zn10.0048 (4)0.0048 (4)0.0049 (6)0.0024 (2)0.0000.000
Geometric parameters (Å, º) top
O1—Te1i2.1244 (7)O5—Te21.857 (4)
O1—Te12.1244 (7)Te2—O4vi2.026 (4)
O1—Te1ii2.1244 (7)O5—Zn12.061 (4)
O2—Te11.936 (4)Te1—O2iii2.168 (4)
O2—Te1iii2.168 (4)Zn1—O5vi2.061 (4)
O2—Zn1iv2.175 (4)Zn1—O5v2.061 (4)
O3—Te11.851 (4)Zn1—O2vii2.175 (4)
O3—Te22.204 (4)Zn1—O2viii2.175 (4)
O4—Te21.922 (4)Zn1—O2ix2.175 (4)
O4—Te2v2.026 (4)
Te1i—O1—Te1119.43 (5)O5—Te2—O384.47 (16)
Te1i—O1—Te1ii119.43 (5)O4—Te2—O383.91 (17)
Te1—O1—Te1ii119.43 (5)O4vi—Te2—O3176.87 (16)
Te1—O2—Te1iii105.55 (18)O5vi—Zn1—O5v96.17 (15)
Te1—O2—Zn1iv130.4 (2)O5vi—Zn1—O596.17 (15)
Te1iii—O2—Zn1iv122.09 (19)O5v—Zn1—O596.17 (15)
Te1—O3—Te2130.2 (2)O5vi—Zn1—O2vii99.42 (17)
Te2—O4—Te2v137.0 (2)O5v—Zn1—O2vii75.45 (17)
Te2—O5—Zn1131.6 (2)O5—Zn1—O2vii162.97 (17)
O3—Te1—O2101.77 (18)O5vi—Zn1—O2viii75.45 (17)
O3—Te1—O182.64 (16)O5v—Zn1—O2viii162.97 (17)
O2—Te1—O182.8 (2)O5—Zn1—O2viii99.42 (17)
O3—Te1—O2iii91.17 (18)O2vii—Zn1—O2viii91.12 (16)
O2—Te1—O2iii74.45 (18)O5vi—Zn1—O2ix162.97 (17)
O1—Te1—O2iii154.71 (18)O5v—Zn1—O2ix99.42 (17)
O5—Te2—O494.86 (17)O5—Zn1—O2ix75.45 (17)
O5—Te2—O4vi94.34 (17)O2vii—Zn1—O2ix91.12 (16)
O4—Te2—O4vi93.3 (2)O2viii—Zn1—O2ix91.12 (16)
Symmetry codes: (i) x+y, x, z; (ii) y, xy, z; (iii) x+2/3, y+1/3, z+1/3; (iv) x1/3, y2/3, z+1/3; (v) x+y, x+1, z; (vi) y+1, xy+1, z; (vii) y+1/3, xy+2/3, z1/3; (viii) x+1/3, y+2/3, z1/3; (ix) x+y+1/3, x+2/3, z1/3.

Experimental details

Crystal data
Chemical formulaZnTe6O13
Mr1038.97
Crystal system, space groupTrigonal, R3
Temperature (K)86
a, c (Å)10.1283 (9), 18.948 (3)
V3)1683.3 (3)
Z6
Radiation typeMo Kα
µ (mm1)17.55
Crystal size (mm)0.13 × 0.06 × 0.02
Data collection
DiffractometerBruker/Siemens SMART APEX
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2002)
Tmin, Tmax0.204, 0.705
No. of measured, independent and
observed [I > 2σ(I)] reflections
8273, 679, 659
Rint0.033
(sin θ/λ)max1)0.600
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.020, 0.060, 1.12
No. of reflections679
No. of parameters62
No. of restraints6
w = 1/[σ2(Fo2) + (0.0343P)2 + 33.5991P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å3)0.73, 0.69

Computer programs: SMART (Bruker, 2003), SAINT-Plus (Bruker, 2003), SAINT-Plus, XS in SHELXTL (Bruker, 2003), XL in SHELXTL, DIAMOND (Brandenburg, 1998), publCIF (Westrip, 2007).

Selected geometric parameters (Å, º) top
O1—Te12.1244 (7)Te2—O4ii2.026 (4)
O2—Te11.936 (4)O5—Zn12.061 (4)
O2—Te1i2.168 (4)Zn1—O5ii2.061 (4)
O3—Te11.851 (4)Zn1—O5iii2.061 (4)
O3—Te22.204 (4)Zn1—O2iv2.175 (4)
O4—Te21.922 (4)Zn1—O2v2.175 (4)
O5—Te21.857 (4)Zn1—O2vi2.175 (4)
O3—Te1—O2101.77 (18)O5ii—Zn1—O2iv99.42 (17)
O1—Te1—O2i154.71 (18)O5iii—Zn1—O2iv75.45 (17)
O5—Te2—O4ii94.34 (17)O5—Zn1—O2iv162.97 (17)
O4ii—Te2—O3176.87 (16)O5iii—Zn1—O2v162.97 (17)
O5ii—Zn1—O596.17 (15)O5ii—Zn1—O2vi162.97 (17)
O5iii—Zn1—O596.17 (15)
Symmetry codes: (i) x+2/3, y+1/3, z+1/3; (ii) y+1, xy+1, z; (iii) x+y, x+1, z; (iv) y+1/3, xy+2/3, z1/3; (v) x+1/3, y+2/3, z1/3; (vi) x+y+1/3, x+2/3, z1/3.
 

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