research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

Ca2Te3O8, a new phase in the CaO–TeO2 system

CROSSMARK_Color_square_no_text.svg

aInstitute for Chemical Technologies and Analytics, Division of Structural Chemistry, TU Wien, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria
*Correspondence e-mail: matthias.weil@tuwien.ac.at

Edited by S. Parkin, University of Kentucky, USA (Received 3 December 2018; accepted 5 December 2018; online 1 January 2019)

Single crystals of dicalcium octa­oxidotritellurate(IV), Ca2Te3O8, were obtained from a CsCl/NaCl melt with CaO and TeO2 as educts in the molar ratio of 1:2. Ca2Te3O8 crystallizes isotypically with Pb3Te2O8 and is comprised of two unique Ca, four Te and eight O sites. One calcium cation has eight and the other nine coordination partners. Both coordination polyhedra are considerably distorted. Two kinds of oxotellurate(IV) anions with the same formula [Te3O8]4− are present. One is an infinite zigzag chain anion consisting of pairs of [TeO4] bis­phenoids linked to a trigonal–pyramidal [TeO3] group with a connectivity of [(TeO1/1O2/2)(TeO2/1O2/2)2]n, while the other is a finite anion made up of one central [TeO4] bis­phenoid linked to two [TeO3] trigonal pyramids and has a connectivity of [(TeO2/1O1/2)2(TeO2/2O2/1)]. In the crystal, the anions are organized in layers extending parallel to (100). Adjacent layers are held together by the calcium cations to define a three-dimensional framework structure.

1. Chemical context

A partial phase diagram for the pseudo-binary system CaO–TeO2 has been determined for the composition range 50–100 mol% TeO2 to contain the 1:1 phase CaTeO3 and the 1:2 phase CaTe2O5 (Mishra et al., 1998[Mishra, R., Namboodiri, P. N., Tripathi, S. N. & Dharwadkar, S. R. (1998). J. Alloys Compd. 280, 56-64.]). Another phase not reported during the original study of Mishra et al. (1998[Mishra, R., Namboodiri, P. N., Tripathi, S. N. & Dharwadkar, S. R. (1998). J. Alloys Compd. 280, 56-64.]) is the 4:5 phase Ca4Te5O14, for which full structural details were determined for the normal-pressure and high-pressure forms (Weil, 2004[Weil, M. (2004). Solid State Sci. 6, 29-37.]; Weil et al., 2016[Weil, M., Heymann, G. & Huppertz, H. (2016). Eur. J. Inorg. Chem. pp. 2374-3579.]). For compositions CaTeO3 and CaTe2O5, polymorphism was reported on the basis of differential thermal analysis and temperature-dependent X-ray diffracion (Mishra et al., 1998[Mishra, R., Namboodiri, P. N., Tripathi, S. N. & Dharwadkar, S. R. (1998). J. Alloys Compd. 280, 56-64.]; Tripathi et al., 2001[Tripathi, S. N., Mishra, R., Mathews, M. D. & Namboodiri, P. N. (2001). Powder Diffr. 16, 205-211.]), however, without structural details of the corresponding phases. Whereas crystal structure determinations were subsequently performed for four polymorphic forms of CaTeO3 (Stöger et al., 2009[Stöger, B., Weil, M., Zobetz, E. & Giester, G. (2009). Acta Cryst. B65, 167-181.]; Poupon et al., 2015[Poupon, M., Barrier, N., Petit, S., Clevers, S. & Dupray, V. (2015). Inorg. Chem. 54, 5660-5670.]), our present knowledge of the CaTe2O5 structures is restricted to only one form (Weil & Stöger, 2008[Weil, M. & Stöger, B. (2008). Acta Cryst. C64, i79-i81.]; Barrier et al., 2009[Barrier, N., Rueff, J. M., Lepetit, M. B., Contreras-Garcia, J., Malo, S. & Raveau, B. (2009). Solid State Sci. 11, 289-293.]) that is not related to the mica-like CaTe2O5 phase reported nearly 50 years ago (Redman et al., 1970[Redman, M. J., Chen, J. H., Binnie, W. P. & Mallo, W. J. (1970). J. Am. Chem. Soc. 53, 645-648.]). In an attempt to grow single crystals of the latter from a salt melt at comparatively low temperatures, a heretofore unknown phase in the CaO–TeO2 system was obtained, viz. the 2:3 phase Ca2Te3O8.

In this article, preparation conditions, crystal structure and the relation to the isotypic lead(II) analogue Pb2Te3O8 (Champarnaud-Mesjard et al., 2001[Champarnaud-Mesjard, J. C., Thomas, P., Colas-Dutreilh, M. & Oufkir, A. (2001). Z. Kristallogr. New Cryst. Struct. 216, 185-186.]) are reported.

2. Structural commentary

The asymmetric unit of Ca2Te3O8 comprises two Ca sites, four Te sites and eight O sites. One Ca site (Ca2) is located on Wyckoff position 8g (site symmetry ..m), sites Te1 on 4c (m2m), Te2 on 8f (m..), Te4 on 8g, O1 on 8f, O2 on 8e (2..) and O7 and O8 both on 8g; all other sites are on general positions 16h.

The two Ca2+ cations are surrounded by eight (Ca1) and nine (Ca2) O atoms, considering a cut-off value of 3.1 Å for relevant Ca—O distances (Table 1[link]). The bond valence sums (Brown, 2002[Brown, I. D. (2002). In The Chemical Bond in Inorganic Chemistry: The Bond Valence Model. Oxford University Press.]) computed with the parameters of Brown & Altermatt (1985[Brown, I. D. & Altermatt, D. (1985). Acta Cryst. B41, 244-247.]) are 1.89 valence units (v.u.) for Ca1 and 2.02 v.u. for Ca2, in good agreement with the expected value of 2. Likewise, the mean Ca—O bond length of 2.55 Å for Ca1 and 2.57 Å for Ca2 are in accord with the values for eight- and nine-coordinate Ca of 2.50 (15) and 2.56 (20) Å, respectively (Gagné & Hawthorne, 2016[Gagné, O. C. & Hawthorne, F. C. (2016). Acta Cryst. B72, 602-625.]). Whereas the [Ca1O8] polyhedron is difficult to derive from a simple geometric figure, [Ca2O9] can be best described as a monocapped square anti­prism (Fig. 1[link]).

Table 1
Comparison of bond lengths (Å) in Ca2Te3O8 and isotypic Pb2Te3O8

  Ca2Te3O8a Pb2Te3O8b
M1—O3i 2.3198 (11) 2.372 (8)
M1—O6ii 2.3903 (13) 2.440 (8)
M1—O5 2.3924 (11) 2.470 (6)
M1—O3 2.4691 (12) 2.636 (8)
M1—O5iii 2.4712 (11) 2.934 (8)
M1—O3iv 2.6212 (12) 3.032 (8)
M1—O4 2.7186 (13)  
M1—O8 3.0360 (4) 3.069 (2)
M2—O8v 2.3089 (18) 2.439 (9)
M2—O7vi 2.3660 (17) 2.374 (10)
M2—O5v 2.4497 (11) 2.556 (6)
M2—O5iii 2.4497 (11) 2.556 (6)
M2—O8 2.4749 (19) 3.080 (11)
M2—O4vi 2.6335 (13) 2.732 (6)
M2—O4iv 2.6335 (13) 2.732 (6)
M2—O4 2.9154 (13) 3.342 (7)
M2—O4ii 2.9154 (13) 3.342 (7)
Te1—O7vii 1.8369 (17) 1.852 (10)
Te1—O7viii 1.8369 (17) 1.852 (10)
Te1—O1 2.1608 (17) 2.160 (9)
Te1—O1ii 2.1608 (17) 2.160 (9)
Te2—O6ix 1.8522 (12) 1.859 (8)
Te2—O6 1.8522 (12) 1.859 (8)
Te2—O1 1.8902 (17) 1.883 (10)
Te3—O3 1.8602 (11) 1.868 (8)
Te3—O5x 1.8743 (10) 1.856 (7)
Te3—O2x 2.0123 (5) 2.008 (3)
Te3—O4 2.3222 (12) 2.338 (6)
Te4—O8 1.8694 (17) 1.857 (10)
Te4—O4 1.8994 (11) 1.900 (7)
Te4—O4ii 1.8994 (11) 1.900 (7)
Notes: (a) this study; (b) Champarnaud-Mesjard et al. (2001[Champarnaud-Mesjard, J. C., Thomas, P., Colas-Dutreilh, M. & Oufkir, A. (2001). Z. Kristallogr. New Cryst. Struct. 216, 185-186.]); single-crystal data with a = 19.522 (4), b = 7.121 (1) and c = 18.813 (4) Å. Symmetry codes: (i) x, −y + 1, −z + 1; (ii) x, y, −z + [{1\over 2}]; (iii) −x + [{1\over 2}], y + [{1\over 2}], z; (iv) −x + [{1\over 2}], y − [{1\over 2}], z; (v) −x + [{1\over 2}], y + [{1\over 2}], −z + [{1\over 2}]; (vi) −x + [{1\over 2}], y − [{1\over 2}], −z + [{1\over 2}]; (vii) x, y − 1, z; (viii) −x + 1, y − 1, −z + [{1\over 2}]; (ix) −x + 1, y, z; (x) x, y + 1, z.
[Figure 1]
Figure 1
(a) The [Ca1O8] and (b) the [Ca1O9] polyhedra in the crystal structure of Ca2Te3O8. Displacement ellipsoids are drawn at the 90% probability level. Symmetry codes refer to Table 1[link].

All four Te atoms have an oxidation state of +IV and can be divided into two pairs with the most commonly observed three-coordination in the form of a trigonal pyramid (Te2 and Te4) and four-coordination in the form of a bis­phenoid (Te1 and Te3). The Te—O bond lengths within the [TeO3] trigonal pyramids are only slightly spread, ranging from 1.8522 (12) to 1.8994 (11) Å. The two [TeO4] bis­phenoids are characterised by two short bonds of < 2 Å and two longer bonds of > 2 Å, with the maximum at 2.3222 (12) Å for Te3. All Te—O bond lengths (Table 1[link]) are in characteristic ranges for oxotellurates(IV) with three- and four-coordinate tellurium, as reviewed recently by Christy et al. (2016[Christy, A. G., Mills, S. J. & Kampf, A. R. (2016). Mineral. Mag. 80, 415-545.]).

Bond valence sums for the four Te atoms computed with the parameters of Brese and O'Keeffe (1991[Brese, N. E. & O'Keeffe, M. (1991). Acta Cryst. B47, 192-197.]) are 4.14, 4.07, 3.99 and 3.81 v.u., but are considerably lower when the revised parameters of Mills & Christy (2013[Mills, S. J. & Christy, A. G. (2013). Acta Cryst. B69, 145-149.]) are used, i.e. 3.93, 3.80, 3.81 and 3.57 v.u.

The oxotellurium(IV) network is built up from two different anions, both with composition [Te3O8]4−. One anion is made up from an infinite zigzag chain that extends parallel to [001] and consists of a pair of corner-sharing [Te3O4] bis­phenoids linked alternately to a [Te4O3] trigonal pyramid {= [(Te4O1/1O2/2)(Te3O2/1O2/2)2]n} (Fig. 2[link]a). The second oxotellurate(IV) anion is finite and is situated between neighbouring chain anions. It is comprised of a curved [Te3O8]4− unit with a central Te1O4 bis­phenoid linked to two [Te2O3] trigonal pyramids {= [(Te1O2/1O1/2)2(Te2O2/2O2/1)]} (Fig. 2[link]b).

[Figure 2]
Figure 2
(a) The chain [Te3O8]4− anion and (b) the finite [Te3O8]4− anion in the crystal structure of Ca2Te3O8. Displacement ellipsoids are drawn at the 90% probability level. Symmetry codes refer to Table 1[link].

In the crystal, the two types of [Te3O8]4− anions are arranged in layers parallel to (100). Approximately at x ≃ 1/4 and 3/4, the calcium cations link adjacent layers into the three-dimensional framework (Fig. 3[link]).

[Figure 3]
Figure 3
The crystal structure of Ca2Te3O8 in a projection along [0[\overline{1}]0]. Displacement ellipsoids and colour code as in Figs. 1[link] and 2[link].

Ca2Te3O8 is isotypic with Pb2Te3O8 (Champarnaud-Mesjard et al., 2001[Champarnaud-Mesjard, J. C., Thomas, P., Colas-Dutreilh, M. & Oufkir, A. (2001). Z. Kristallogr. New Cryst. Struct. 216, 185-186.]), but not with its higher alkaline earth homologue Sr2Te3O8, which is reported to have a different ortho­rhom­bic cell, with details of the structure not known (Elerman & Koçak, 1986[Elerman, Y. & Koçak, M. (1986). J. Appl. Cryst. 19, 410.]). Comparison of the bond lengths of the [MOx] (M = Ca, Pb) polyhedra and the [TeO3] and [TeO4] units in the isotypic structures of Ca2Te3O8 and Pb2Te3O8 (Table 1[link]) reveals nearly identical values for the individual oxotellurate(IV) units, but differences up to 0.6 Å for the metal–oxygen polyhedra. On one hand, this behaviour is ascribed to the different ionic radii for eight-coordinate CaII and PbII of 1.12 and 1.29 Å, respectively (Shannon, 1976[Shannon, R. D. (1976). Acta Cryst. A32, 751-767.]), and, on the other hand, to the stereochemical activity (Galy et al., 1975[Galy, J., Meunier, G., Anderson, S. & Åström, A. (1975). J. Solid State Chem. 13, 142-159.]) of the 6s2 free-electron lone pair located at PbII that is responsible for the formation of off-centred lead–oxygen polyhedra with either holo- or hemidirected oxygen ligands (Shimoni-Livny et al., 1998[Shimoni-Livny, L., Glusker, J. P. & Bock, C. W. (1998). Inorg. Chem. 37, 1853-1867.]).

For a qu­anti­tative structural comparison of the isotypic M2Te3O8 (M = Ca, Pb) structures, the program compstru (de la Flor et al., 2016[Flor, G. de la, Orobengoa, D., Tasci, E., Perez-Mato, J. M. & Aroyo, M. I. (2016). J. Appl. Cryst. 49, 653-664.]), available at the Bilbao Crystallographic Server (Aroyo et al., 2006[Aroyo, M. I., Perez-Mato, J. M., Capillas, C., Kroumova, E., Ivantchev, S., Madariaga, G., Kirov, A. & Wondratschek, H. (2006). Z. Kristallogr. 221, 15-27.]), was used. The degree of lattice distortion is 0.0205, the maximum distance between the atomic positions of paired atoms is 0.403 Å for pair O8, the arithmetic mean of all distances is 0.195 Å and the measure of similarity is 0.05.

3. Synthesis and crystallization

Crystals of Ca2Te3O8 were obtained as one of the products from a flux synthesis using a CsCl/NaCl salt mixture (molar ratio 0.65/0.35). To 1.5 g of the salt mixture were added CaO (0.075 g; freshly prepared by heating CaCO3 at 1473 K for 1 d) and TeO2 (0.425 g) according to a molar ratio of 1:2. The reaction mixture was placed in a silica ampoule that was subsequently evacuated and sealed. The ampoule was placed vertically in a furnace and heated from room temperature within 3 h to 793 K, kept at that temperature for 90 h and cooled within 10 h to room temperature. The silica ampoule was broken and the solidified melt leached out with water for two h. The colourless product was filtered off, washed with water and was dried in a stream of air. The title compound was present in the form of a few crystals that were distinguishable from the other crystals due to their characteristic square form (maximum edge length 1.5 mm). Other phases identified by single-crystal X-ray diffraction measurements of selected crystals and by powder X-ray diffraction measurements of the bulk were CaTe2O5 in the mica-like modification reported by Redman et al. (1970[Redman, M. J., Chen, J. H., Binnie, W. P. & Mallo, W. J. (1970). J. Am. Chem. Soc. 53, 645-648.]) as the main phase (tiny colourless plates) and Ca4Te5O14 (small colourless pinacoids; Weil, 2004[Weil, M. (2004). Solid State Sci. 6, 29-37.]).

4. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link]. Starting coordinates for the refinement were taken from isotypic Pb2Te3O8 (Champarnaud-Mesjard et al., 2001[Champarnaud-Mesjard, J. C., Thomas, P., Colas-Dutreilh, M. & Oufkir, A. (2001). Z. Kristallogr. New Cryst. Struct. 216, 185-186.]). Both remaining maximum and minimum electron-density peaks are located 0.64 and 0.30 Å from the Te2 site.

Table 2
Experimental details

Crystal data
Chemical formula Ca2Te3O8
Mr 590.95
Crystal system, space group Orthorhombic, Cmcm
Temperature (K) 297
a, b, c (Å) 18.7368 (15), 6.8399 (6), 18.5652 (15)
V3) 2379.3 (3)
Z 12
Radiation type Mo Kα
μ (mm−1) 12.27
Crystal size (mm) 0.25 × 0.15 × 0.10
 
Data collection
Diffractometer Bruker APEXII CCD
Absorption correction Multi-scan (SADABS; Krause et al., 2015[Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3-10.])
Tmin, Tmax 0.472, 0.750
No. of measured, independent and observed [I > 2σ(I)] reflections 47523, 6097, 5325
Rint 0.043
(sin θ/λ)max−1) 1.057
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.023, 0.043, 1.12
No. of reflections 6097
No. of parameters 101
Δρmax, Δρmin (e Å−3) 4.13, −2.08
Computer programs: APEX3 and SAINT (Bruker, 2016[Bruker (2016). APEX3 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXL2017 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. A71, 3-8.]), ATOMS (Dowty, 2006[Dowty, E. (2006). ATOMS for Windows. Shape Software, 521 Hidden Valley Road, Kingsport, TN 37663, USA.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]). Starting coordinates taken from an isotypic compound.

Supporting information


Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: coordinates from isotypic compound; program(s) used to refine structure: SHELXL2017 (Sheldrick, 2015); molecular graphics: ATOMS (Dowty, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Dicalcium octaoxidotritellurate(IV) top
Crystal data top
Ca2Te3O8Dx = 4.949 Mg m3
Mr = 590.95Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, CmcmCell parameters from 9248 reflections
a = 18.7368 (15) Åθ = 3.2–48.6°
b = 6.8399 (6) ŵ = 12.27 mm1
c = 18.5652 (15) ÅT = 297 K
V = 2379.3 (3) Å3Plate, colourless
Z = 120.25 × 0.15 × 0.10 mm
F(000) = 3120
Data collection top
Bruker APEXII CCD
diffractometer
5325 reflections with I > 2σ(I)
ω scansRint = 0.043
Absorption correction: multi-scan
(SADABS; Krause et al., 2015)
θmax = 48.7°, θmin = 2.2°
Tmin = 0.472, Tmax = 0.750h = 3739
47523 measured reflectionsk = 1414
6097 independent reflectionsl = 3639
Refinement top
Refinement on F2Primary atom site location: isomorphous structure methods
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.0102P)2 + 6.3377P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.023(Δ/σ)max = 0.002
wR(F2) = 0.043Δρmax = 4.13 e Å3
S = 1.12Δρmin = 2.08 e Å3
6097 reflectionsExtinction correction: SHELXL2017 (Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
101 parametersExtinction coefficient: 0.00143 (3)
0 restraints
Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Ca10.29994 (2)0.36584 (4)0.41210 (2)0.00884 (4)
Ca20.19996 (2)0.49754 (6)0.2500000.00819 (5)
Te10.5000000.08952 (3)0.2500000.00866 (3)
Te20.5000000.29743 (2)0.07448 (2)0.00865 (2)
Te30.37898 (2)0.84140 (2)0.41362 (2)0.00685 (2)
Te40.37986 (2)0.54478 (2)0.2500000.00616 (2)
O10.5000000.0728 (2)0.13377 (9)0.0150 (3)
O20.40826 (9)0.0000000.5000000.0146 (3)
O30.31332 (6)0.69421 (16)0.46567 (6)0.01057 (16)
O40.32340 (7)0.67071 (18)0.32118 (6)0.01226 (17)
O50.31362 (6)0.02866 (15)0.38074 (6)0.00918 (15)
O60.42263 (7)0.42092 (19)0.11674 (8)0.0165 (2)
O70.42329 (9)0.9223 (3)0.2500000.0135 (3)
O80.31736 (10)0.3318 (3)0.2500000.0209 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ca10.00841 (9)0.00807 (9)0.01005 (9)0.00102 (7)0.00031 (7)0.00024 (7)
Ca20.00857 (13)0.00778 (12)0.00821 (12)0.00113 (10)0.0000.000
Te10.00648 (6)0.00643 (6)0.01305 (7)0.0000.0000.000
Te20.00773 (4)0.00848 (4)0.00974 (4)0.0000.0000.00001 (3)
Te30.00550 (3)0.00710 (3)0.00794 (3)0.00067 (2)0.00072 (2)0.00095 (2)
Te40.00569 (4)0.00572 (4)0.00706 (4)0.00012 (3)0.0000.000
O10.0227 (8)0.0108 (6)0.0116 (6)0.0000.0000.0018 (5)
O20.0110 (6)0.0209 (7)0.0119 (6)0.0000.0000.0089 (5)
O30.0123 (4)0.0103 (4)0.0091 (4)0.0023 (3)0.0028 (3)0.0010 (3)
O40.0122 (4)0.0157 (4)0.0088 (4)0.0031 (3)0.0022 (3)0.0022 (3)
O50.0096 (4)0.0072 (3)0.0107 (4)0.0021 (3)0.0006 (3)0.0000 (3)
O60.0091 (4)0.0175 (5)0.0228 (6)0.0037 (4)0.0000 (4)0.0049 (4)
O70.0072 (5)0.0142 (6)0.0193 (7)0.0022 (5)0.0000.000
O80.0099 (7)0.0077 (6)0.0451 (12)0.0030 (5)0.0000.000
Geometric parameters (Å, º) top
Ca1—O3i2.3198 (11)Ca2—O42.9154 (13)
Ca1—O6ii2.3903 (13)Ca2—O4ii2.9154 (13)
Ca1—O52.3924 (11)Ca2—Te43.3863 (5)
Ca1—O32.4691 (12)Ca2—Te4vi3.4390 (5)
Ca1—O5iii2.4712 (11)Ca2—Te3vi3.5434 (3)
Ca1—O3iv2.6212 (12)Te1—O7vii1.8369 (17)
Ca1—O42.7186 (13)Te1—O7viii1.8369 (17)
Ca1—O83.0360 (4)Te1—O12.1608 (17)
Ca1—Te3iv3.3567 (4)Te1—O1ii2.1609 (17)
Ca1—Te33.5742 (4)Te2—O6ix1.8522 (12)
Ca1—Te43.5773 (4)Te2—O61.8522 (12)
Ca1—Ca23.6575 (4)Te2—O11.8902 (17)
Ca2—O8v2.3089 (18)Te3—O31.8602 (11)
Ca2—O7vi2.3660 (17)Te3—O5x1.8743 (10)
Ca2—O5v2.4497 (11)Te3—O2x2.0123 (5)
Ca2—O5iii2.4497 (11)Te3—O42.3222 (12)
Ca2—O82.4749 (19)Te4—O81.8694 (17)
Ca2—O4vi2.6335 (13)Te4—O41.8994 (11)
Ca2—O4iv2.6335 (13)Te4—O4ii1.8994 (11)
O3i—Ca1—O6ii98.22 (5)O8v—Ca2—Te3vi103.87 (2)
O3i—Ca1—O593.20 (4)O7vi—Ca2—Te3vi61.771 (12)
O6ii—Ca1—O589.68 (4)O5v—Ca2—Te3vi29.94 (2)
O3i—Ca1—O375.88 (4)O5iii—Ca2—Te3vi146.33 (3)
O6ii—Ca1—O381.32 (4)O8—Ca2—Te3vi103.47 (2)
O5—Ca1—O3164.59 (4)O4vi—Ca2—Te3vi40.94 (3)
O3i—Ca1—O5iii113.79 (4)O4iv—Ca2—Te3vi96.03 (3)
O6ii—Ca1—O5iii134.77 (4)O4—Ca2—Te3vi147.38 (2)
O5—Ca1—O5iii117.99 (4)O4ii—Ca2—Te3vi93.73 (2)
O3—Ca1—O5iii76.84 (4)Te4—Ca2—Te3vi116.377 (7)
O3i—Ca1—O3iv68.72 (4)Te4vi—Ca2—Te3vi63.068 (6)
O6ii—Ca1—O3iv159.11 (4)O7vii—Te1—O7viii102.97 (11)
O5—Ca1—O3iv75.37 (4)O7vii—Te1—O188.11 (3)
O3—Ca1—O3iv109.69 (4)O7viii—Te1—O188.11 (3)
O5iii—Ca1—O3iv66.05 (4)O7vii—Te1—O1ii88.11 (3)
O3i—Ca1—O4136.52 (4)O7viii—Te1—O1ii88.11 (3)
O6ii—Ca1—O465.45 (4)O1—Te1—O1ii173.92 (9)
O5—Ca1—O4124.82 (4)O7vii—Te1—Ca2vi28.98 (5)
O3—Ca1—O462.35 (4)O7viii—Te1—Ca2vi131.95 (6)
O5iii—Ca1—O469.34 (4)O1—Te1—Ca2vi89.497 (8)
O3iv—Ca1—O4135.24 (4)O1ii—Te1—Ca2vi89.497 (8)
O3i—Ca1—O8160.81 (5)O7vii—Te1—Ca2xi131.95 (6)
O6ii—Ca1—O871.74 (5)O7viii—Te1—Ca2xi28.98 (5)
O5—Ca1—O870.93 (4)O1—Te1—Ca2xi89.497 (8)
O3—Ca1—O8117.27 (4)O1ii—Te1—Ca2xi89.497 (8)
O5iii—Ca1—O883.89 (4)Ca2vi—Te1—Ca2xi160.934 (13)
O3iv—Ca1—O8115.39 (4)O6ix—Te2—O6103.01 (8)
O4—Ca1—O854.98 (4)O6ix—Te2—O197.12 (6)
O3i—Ca1—Te3iv95.22 (3)O6—Te2—O197.12 (6)
O6ii—Ca1—Te3iv165.99 (3)O6ix—Te2—Ca1xii30.77 (4)
O5—Ca1—Te3iv93.50 (3)O6—Te2—Ca1xii133.69 (4)
O3—Ca1—Te3iv98.24 (3)O1—Te2—Ca1xii93.563 (8)
O5iii—Ca1—Te3iv33.33 (2)O6ix—Te2—Ca1ii133.69 (4)
O3iv—Ca1—Te3iv33.48 (2)O6—Te2—Ca1ii30.77 (4)
O4—Ca1—Te3iv101.83 (3)O1—Te2—Ca1ii93.563 (8)
O8—Ca1—Te3iv96.42 (4)Ca1xii—Te2—Ca1ii163.902 (10)
O3i—Ca1—Te396.23 (3)O3—Te3—O5x96.14 (5)
O6ii—Ca1—Te357.30 (3)O3—Te3—O2x93.33 (5)
O5—Ca1—Te3146.60 (3)O5x—Te3—O2x93.97 (5)
O3—Ca1—Te329.18 (3)O3—Te3—O479.35 (5)
O5iii—Ca1—Te387.05 (3)O5x—Te3—O479.04 (5)
O3iv—Ca1—Te3137.74 (3)O2x—Te3—O4169.18 (6)
O4—Ca1—Te340.52 (3)O3—Te3—Ca1iii51.01 (4)
O8—Ca1—Te391.90 (3)O5x—Te3—Ca1iii46.42 (3)
Te3iv—Ca1—Te3117.328 (9)O2x—Te3—Ca1iii104.60 (5)
O3i—Ca1—Te4146.96 (3)O4—Te3—Ca1iii64.59 (3)
O6ii—Ca1—Te449.84 (3)O3—Te3—Ca2v109.41 (4)
O5—Ca1—Te494.60 (3)O5x—Te3—Ca2v40.72 (3)
O3—Ca1—Te489.14 (3)O2x—Te3—Ca2v129.382 (18)
O5iii—Ca1—Te490.46 (3)O4—Te3—Ca2v47.99 (3)
O3iv—Ca1—Te4144.22 (3)Ca1iii—Te3—Ca2v63.955 (8)
O4—Ca1—Te431.52 (2)O3—Te3—Ca140.32 (4)
O8—Ca1—Te431.50 (3)O5x—Te3—Ca1110.40 (3)
Te3iv—Ca1—Te4116.244 (9)O2x—Te3—Ca1127.580 (17)
Te3—Ca1—Te461.433 (6)O4—Te3—Ca149.52 (3)
O3i—Ca1—Ca2154.68 (3)Ca1iii—Te3—Ca168.372 (6)
O6ii—Ca1—Ca2105.63 (3)Ca2v—Te3—Ca195.427 (9)
O5—Ca1—Ca295.28 (3)O3—Te3—Ca1i26.53 (4)
O3—Ca1—Ca299.17 (3)O5x—Te3—Ca1i105.99 (3)
O5iii—Ca1—Ca241.77 (3)O2x—Te3—Ca1i68.39 (3)
O3iv—Ca1—Ca290.45 (3)O4—Te3—Ca1i105.36 (3)
O4—Ca1—Ca251.91 (3)Ca1iii—Te3—Ca1i68.861 (8)
O8—Ca1—Ca242.13 (4)Ca2v—Te3—Ca1i132.402 (9)
Te3iv—Ca1—Ca260.505 (8)Ca1—Te3—Ca1i60.638 (8)
Te3—Ca1—Ca289.690 (9)O8—Te4—O490.26 (6)
Te4—Ca1—Ca255.803 (9)O8—Te4—O4ii90.26 (6)
O8v—Ca2—O7vi94.49 (6)O4—Te4—O4ii88.18 (7)
O8v—Ca2—O5v84.22 (3)O8—Te4—Ca245.74 (6)
O7vi—Ca2—O5v85.27 (3)O4—Te4—Ca259.26 (4)
O8v—Ca2—O5iii84.22 (3)O4ii—Te4—Ca259.26 (4)
O7vi—Ca2—O5iii85.27 (3)O8—Te4—Ca2v115.43 (6)
O5v—Ca2—O5iii164.44 (5)O4—Te4—Ca2v49.41 (4)
O8v—Ca2—O8125.35 (5)O4ii—Te4—Ca2v49.42 (4)
O7vi—Ca2—O8140.16 (6)Ca2—Te4—Ca2v69.699 (8)
O5v—Ca2—O897.59 (3)O8—Te4—Ca158.067 (9)
O5iii—Ca2—O897.59 (3)O4—Te4—Ca148.45 (4)
O8v—Ca2—O4vi144.79 (4)O4ii—Te4—Ca1120.49 (4)
O7vi—Ca2—O4vi69.70 (5)Ca2—Te4—Ca163.297 (6)
O5v—Ca2—O4vi63.85 (3)Ca2v—Te4—Ca197.242 (7)
O5iii—Ca2—O4vi123.62 (4)O8—Te4—Ca1ii58.067 (9)
O8—Ca2—O4vi76.04 (5)O4—Te4—Ca1ii120.49 (4)
O8v—Ca2—O4iv144.79 (4)O4ii—Te4—Ca1ii48.45 (4)
O7vi—Ca2—O4iv69.70 (5)Ca2—Te4—Ca1ii63.299 (6)
O5v—Ca2—O4iv123.62 (4)Ca2v—Te4—Ca1ii97.242 (7)
O5iii—Ca2—O4iv63.85 (3)Ca1—Te4—Ca1ii114.545 (11)
O8—Ca2—O4iv76.04 (5)Te2—O1—Te1122.58 (9)
O4vi—Ca2—O4iv60.24 (5)Te3vii—O2—Te3i148.36 (9)
O8v—Ca2—O473.10 (5)Te3—O3—Ca1i132.49 (6)
O7vi—Ca2—O4149.63 (3)Te3—O3—Ca1110.51 (5)
O5v—Ca2—O4119.75 (4)Ca1i—O3—Ca1102.82 (4)
O5iii—Ca2—O466.29 (3)Te3—O3—Ca1iii95.51 (5)
O8—Ca2—O458.73 (4)Ca1i—O3—Ca1iii111.28 (4)
O4vi—Ca2—O4134.77 (3)Ca1—O3—Ca1iii99.92 (4)
O4iv—Ca2—O4104.43 (4)Te4—O4—Te3119.50 (6)
O8v—Ca2—O4ii73.10 (5)Te4—O4—Ca2v97.37 (5)
O7vi—Ca2—O4ii149.63 (3)Te3—O4—Ca2v91.07 (4)
O5v—Ca2—O4ii66.29 (3)Te4—O4—Ca1100.03 (5)
O5iii—Ca2—O4ii119.75 (4)Te3—O4—Ca189.96 (4)
O8—Ca2—O4ii58.73 (4)Ca2v—O4—Ca1159.36 (5)
O4vi—Ca2—O4ii104.43 (4)Te4—O4—Ca286.69 (4)
O4iv—Ca2—O4ii134.77 (3)Te3—O4—Ca2153.51 (5)
O4—Ca2—O4ii53.91 (5)Ca2v—O4—Ca289.17 (4)
O8v—Ca2—Te492.60 (5)Ca1—O4—Ca280.88 (3)
O7vi—Ca2—Te4172.91 (4)Te3vii—O5—Ca1130.51 (5)
O5v—Ca2—Te495.46 (3)Te3vii—O5—Ca2vi109.34 (5)
O5iii—Ca2—Te495.46 (3)Ca1—O5—Ca2vi108.29 (4)
O8—Ca2—Te432.75 (4)Te3vii—O5—Ca1iv100.25 (5)
O4vi—Ca2—Te4104.27 (3)Ca1—O5—Ca1iv106.55 (4)
O4iv—Ca2—Te4104.27 (3)Ca2vi—O5—Ca1iv96.02 (4)
O4—Ca2—Te434.05 (2)Te2—O6—Ca1ii125.87 (7)
O4ii—Ca2—Te434.05 (2)Te1x—O7—Ca2v128.92 (9)
O8v—Ca2—Te4vi146.15 (5)Te4—O8—Ca2vi149.29 (10)
O7vi—Ca2—Te4vi51.66 (4)Te4—O8—Ca2101.52 (8)
O5v—Ca2—Te4vi91.90 (3)Ca2vi—O8—Ca2109.19 (7)
O5iii—Ca2—Te4vi91.90 (3)Te4—O8—Ca190.43 (3)
O8—Ca2—Te4vi88.51 (4)Ca2vi—O8—Ca193.49 (3)
O4vi—Ca2—Te4vi33.21 (2)Ca2—O8—Ca182.49 (4)
O4iv—Ca2—Te4vi33.21 (2)Te4—O8—Ca1ii90.43 (3)
O4—Ca2—Te4vi135.31 (3)Ca2vi—O8—Ca1ii93.49 (3)
O4ii—Ca2—Te4vi135.31 (3)Ca2—O8—Ca1ii82.49 (4)
Te4—Ca2—Te4vi121.252 (12)Ca1—O8—Ca1ii164.82 (7)
Symmetry codes: (i) x, y+1, z+1; (ii) x, y, z+1/2; (iii) x+1/2, y+1/2, z; (iv) x+1/2, y1/2, z; (v) x+1/2, y+1/2, z+1/2; (vi) x+1/2, y1/2, z+1/2; (vii) x, y1, z; (viii) x+1, y1, z+1/2; (ix) x+1, y, z; (x) x, y+1, z; (xi) x+1/2, y1/2, z; (xii) x+1, y, z+1/2.
Comparison of bond lengths (Å) in Ca2Te3O8 and isotypic Pb2Te3O8 top
Ca2Te3O8(a)Pb2Te3O8(b)
M1—O3i2.3198 (11)2.372 (8)
M1—O6ii2.3903 (13)2.440 (8)
M1—O52.3924 (11)2.470 (6)
M1—O32.4691 (12)2.636 (8)
M1—O5iii2.4712 (11)2.934 (8)
M1—O3iv2.6212 (12)3.032 (8)
M1—O42.7186 (13)
M1—O83.0360 (4)3.069 (2)
M2—O8v2.3089 (18)2.439 (9)
M2—O7vi2.3660 (17)2.374 (10)
M2—O5v2.4497 (11)2.556 (6)
M2—O5iii2.4497 (11)2.556 (6)
M2—O82.4749 (19)3.080 (11)
M2—O4vi2.6335 (13)2.732 (6)
M2—O4iv2.6335 (13)2.732 (6)
M2—O42.9154 (13)3.342 (7)
M2—O4ii2.9154 (13)3.342 (7)
Te1—O7vii1.8369 (17)1.852 (10)
Te1—O7viii1.8369 (17)1.852 (10)
Te1—O12.1608 (17)2.160 (9)
Te1—O1ii2.1608 (17)2.160 (9)
Te2—O6ix1.8522 (12)1.859 (8)
Te2—O61.8522 (12)1.859 (8)
Te2—O11.8902 (17)1.883 (10)
Te3—O31.8602 (11)1.868 (8)
Te3—O5x1.8743 (10)1.856 (7)
Te3—O2x2.0123 (5)2.008 (3)
Te3—O42.3222 (12)2.338 (6)
Te4—O81.8694 (17)1.857 (10)
Te4—O41.8994 (11)1.900 (7)
Te4—O4ii1.8994 (11)1.900 (7)
Notes: (a) this study; (b) Champarnaud-Mesjard et al. (2001); single-crystal data with a = 19.522 (4), b = 7.121 (1) and c = 18.813 (4) Å.

Symmetry codes: (i) x, -y+1, -z+1; (ii) x, y, -z+1/2; (iii) -x+1/2, y+1/2, z; (iv) -x+1/2, y-1/2, z; (v) -x+1/2, y+1/2, -z+1/2; (vi) -x+1/2, y-1/2, -z+1/2; (vii) x, y-1, z; (viii) -x+1, y-1, -z+1/2; (ix) -x+1, y, z; (x) x, y+1, z.
 

Acknowledgements

The X-ray centre of the TU Wien is acknowledged for financial support and for providing access to the single-crystal and powder X-ray diffractometers.

References

First citationAroyo, M. I., Perez-Mato, J. M., Capillas, C., Kroumova, E., Ivantchev, S., Madariaga, G., Kirov, A. & Wondratschek, H. (2006). Z. Kristallogr. 221, 15–27.  Web of Science CrossRef CAS Google Scholar
First citationBarrier, N., Rueff, J. M., Lepetit, M. B., Contreras-Garcia, J., Malo, S. & Raveau, B. (2009). Solid State Sci. 11, 289–293.  CrossRef Google Scholar
First citationBrese, N. E. & O'Keeffe, M. (1991). Acta Cryst. B47, 192–197.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationBrown, I. D. (2002). In The Chemical Bond in Inorganic Chemistry: The Bond Valence Model. Oxford University Press.  Google Scholar
First citationBrown, I. D. & Altermatt, D. (1985). Acta Cryst. B41, 244–247.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationBruker (2016). APEX3 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationChamparnaud-Mesjard, J. C., Thomas, P., Colas-Dutreilh, M. & Oufkir, A. (2001). Z. Kristallogr. New Cryst. Struct. 216, 185–186.  Google Scholar
First citationChristy, A. G., Mills, S. J. & Kampf, A. R. (2016). Mineral. Mag. 80, 415–545.  Web of Science CrossRef CAS Google Scholar
First citationDowty, E. (2006). ATOMS for Windows. Shape Software, 521 Hidden Valley Road, Kingsport, TN 37663, USA.  Google Scholar
First citationElerman, Y. & Koçak, M. (1986). J. Appl. Cryst. 19, 410.  CrossRef Web of Science IUCr Journals Google Scholar
First citationFlor, G. de la, Orobengoa, D., Tasci, E., Perez-Mato, J. M. & Aroyo, M. I. (2016). J. Appl. Cryst. 49, 653–664.  Web of Science CrossRef IUCr Journals Google Scholar
First citationGagné, O. C. & Hawthorne, F. C. (2016). Acta Cryst. B72, 602–625.  Web of Science CrossRef IUCr Journals Google Scholar
First citationGaly, J., Meunier, G., Anderson, S. & Åström, A. (1975). J. Solid State Chem. 13, 142–159.  CrossRef Google Scholar
First citationKrause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3–10.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationMills, S. J. & Christy, A. G. (2013). Acta Cryst. B69, 145–149.  CrossRef CAS IUCr Journals Google Scholar
First citationMishra, R., Namboodiri, P. N., Tripathi, S. N. & Dharwadkar, S. R. (1998). J. Alloys Compd. 280, 56–64.  CrossRef Google Scholar
First citationPoupon, M., Barrier, N., Petit, S., Clevers, S. & Dupray, V. (2015). Inorg. Chem. 54, 5660–5670.  CrossRef Google Scholar
First citationRedman, M. J., Chen, J. H., Binnie, W. P. & Mallo, W. J. (1970). J. Am. Chem. Soc. 53, 645–648.  CAS Google Scholar
First citationShannon, R. D. (1976). Acta Cryst. A32, 751–767.  CrossRef CAS IUCr Journals Web of Science Google Scholar
First citationSheldrick, G. M. (2015). Acta Cryst. A71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationShimoni-Livny, L., Glusker, J. P. & Bock, C. W. (1998). Inorg. Chem. 37, 1853–1867.  Web of Science CrossRef CAS Google Scholar
First citationStöger, B., Weil, M., Zobetz, E. & Giester, G. (2009). Acta Cryst. B65, 167–181.  Web of Science CrossRef IUCr Journals Google Scholar
First citationTripathi, S. N., Mishra, R., Mathews, M. D. & Namboodiri, P. N. (2001). Powder Diffr. 16, 205–211.  Web of Science CrossRef CAS Google Scholar
First citationWeil, M. (2004). Solid State Sci. 6, 29–37.  Web of Science CrossRef CAS Google Scholar
First citationWeil, M., Heymann, G. & Huppertz, H. (2016). Eur. J. Inorg. Chem. pp. 2374–3579.  Google Scholar
First citationWeil, M. & Stöger, B. (2008). Acta Cryst. C64, i79–i81.  Web of Science CrossRef IUCr Journals Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds