Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803010122/bt6274sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536803010122/bt6274Isup2.hkl |
Reagent grade CsCl and Ta2O5 chemicals 4.245 g in total, were combined to form 0.1 mol% Cs3Ta5O14 in a 99.9 mol% CsCl flux. In a Pt crucible, the mixture was heated quickly to 1073 K, which was sustained for 2 h and followed by slow cooling at 2.8 K h−1 to 723 K. After rinsing in hot water, the residue contained transparent and colourless crystals of Cs3Ta5O14 with rectangular shapes as well as unidentified crystals with thin hexagonal shapes.
Although minor difficulties were encountered refining the structure because of a tendency toward non-positive definite displacement parameters for two O atoms, the problems were supressed after including all data satisfying F2 ≥ 0 in a refinement on F, in conjunction with a modified weighting scheme. This led to a larger but acceptible R factor wR(F) = 0.032. The refined atomic positions agree with those of Serafin & Hoppe (1982) typically within two of their reported s.u.'s, although the s.u.'s reported here are typically smaller by a factor of about 5. The mean atomic displacement parameters are also comparable in magnitude between the two studies, though herein Ueq for the Ta atoms are about double that reported in the earlier work. In addition, Ueq values for the O atoms reported here have a considerably smaller dynamic range. The anisotropic vibration tensor elements for the Cs atoms are broadly comparable between the experiments, though disparities of up to a factor of 2 on some components are to be found. Ueq values reported here for the Cs atoms are typically half the magnitude of equivalent parameters determined for the four Rb atoms in Rb3Ta5O14 by du Boulay et al. (2002). In particular, the largest vibration tensor component observed herein (U33 = 0.0472 Å2 for Cs3) is less than half that of the largest tensor element reported in the latter [U22 = 0.1057 (11) Å2 for Rb4]. The large Cs atom vibrations are in good accord with the structural geometry because they occupy large structural cavities with asymmetric bonding environments. This is particularly true of Cs3 which has one short Cs3—O6 bond within the plane that appears to act like a hinge on which the Cs3 atom can swing with greater freedom into two adjoining structural cavities.
A relatively large residual Δρ range was observed [−4(1) to 4(1) e Å−3]. The two largest peaks occur 0.7 Å away from Cs1 and 0.8 Å from O4 and both maxima occur on the z=0 mirror plane. The two largest holes were also located on the mirror planes, 1.7 Å from Cs1 and 1.5 Å from Cs2. The positions and magnitudes of the extrema suggest a stochastic measurement noise origin, rather than a deficiency of the harmonic vibration model of the atoms. The experimental electron density does then seem to be in good accord with the Pbam space group symmetry.
As a further check, the data were refined against a lower symmetry Pba2 structural model yielding wR(F) = 0.029 from 199 parameters and 2269 reflections, with 14 of the 23 independent atoms exhibiting non-positive definite atomic displacement parameters and only minor changes in the atomic displacement parameters of the Cs atoms. Comparable results were obtained using P21212 with wR(F) = 0.032 from 200 parameters and 12 atoms non-positive-definite. Although Pba2 symmetry superficially reduces the R factor, it introduces around 25% more atoms and 70% more parameters which do not really improve the structural model. Especially, there was no significant damping effects on the mean squared displacement parameters of the Cs atoms.
We conclude therefore that the adoption of a symmetry lower than Pbam gives no significant improvement over the structural model originally proposed by Seraffin & Hoppe (1982), though the current confirmatory study has modestly improved upon the accuracy of the original and full anisotropic displacement parameters are reported here for all atoms.
Data collection: RAPID-AUTO (Rigaku, 1999); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: Serafin & Hoppe (1982); program(s) used to refine structure: CRYLSQ in Xtal3.7 (Hall et al., 2000); molecular graphics: ATOMS (Dowty, 1999) and ORTEP in Xtal3.7; software used to prepare material for publication: Xtal BONDLA CIFIO in Xtal3.7.
Cs3Ta5O14 | F(000) = 2568 |
Mr = 1527.48 | Dx = 7.048 Mg m−3 |
Orthorhombic, Pbam | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -p 2 2ab | Cell parameters from 20976 reflections |
a = 26.219 (6) Å | θ = 1.6–30.0° |
b = 7.4283 (10) Å | µ = 45.17 mm−1 |
c = 7.3914 (10) Å | T = 295 K |
V = 1439.6 (4) Å3 | Rectangular block, colourless |
Z = 4 | 0.06 × 0.06 × 0.04 mm |
Rigaku Rapid image plate diffractometer | 2269 independent reflections |
Radiation source: Mo Kα tube | 2269 reflections with F > 0 |
Graphite monochromator | Rint = 0.060 |
ω scans | θmax = 30.0°, θmin = 1.6° |
Absorption correction: numerical Gaussian integration on 8× 8× 8 grid | h = 0→36 |
Tmin = 0.113, Tmax = 0.349 | k = −10→0 |
2269 measured reflections | l = 0→10 |
Refinement on F | 0 restraints |
Least-squares matrix: full | 0 constraints |
R[F2 > 2σ(F2)] = 0.044 | w = 1/[σ(F)2 + 0.2 + 10-4F2] |
wR(F2) = 0.032 | (Δ/σ)max = 0.001 |
S = 0.91 | Δρmax = 3.69 e Å−3 |
2269 reflections | Δρmin = −4.25 e Å−3 |
117 parameters |
Cs3Ta5O14 | V = 1439.6 (4) Å3 |
Mr = 1527.48 | Z = 4 |
Orthorhombic, Pbam | Mo Kα radiation |
a = 26.219 (6) Å | µ = 45.17 mm−1 |
b = 7.4283 (10) Å | T = 295 K |
c = 7.3914 (10) Å | 0.06 × 0.06 × 0.04 mm |
Rigaku Rapid image plate diffractometer | 2269 independent reflections |
Absorption correction: numerical Gaussian integration on 8× 8× 8 grid | 2269 reflections with F > 0 |
Tmin = 0.113, Tmax = 0.349 | Rint = 0.060 |
2269 measured reflections |
R[F2 > 2σ(F2)] = 0.044 | 117 parameters |
wR(F2) = 0.032 | 0 restraints |
S = 0.91 | Δρmax = 3.69 e Å−3 |
2269 reflections | Δρmin = −4.25 e Å−3 |
x | y | z | Uiso*/Ueq | ||
Cs1 | 0.29149 (4) | 0.15909 (17) | 0.00000 | 0.0270 (5) | |
Cs2 | 0.02229 (3) | 0.24078 (16) | 0.50000 | 0.0241 (5) | |
Cs3 | 0.38046 (3) | 0.15651 (15) | 0.50000 | 0.0279 (5) | |
Ta1 | 0.054631 (18) | 0.42585 (7) | 0.00000 | 0.0071 (2) | |
Ta2 | 0.442909 (18) | 0.41007 (7) | 0.00000 | 0.0062 (2) | |
Ta3 | 0.25378 (2) | 0.40034 (7) | 0.50000 | 0.0066 (2) | |
Ta4 | 0.151840 (12) | 0.16072 (5) | 0.25490 (4) | 0.00671 (15) | |
O1 | 0.00000 | 0.50000 | 0.1740 (11) | 0.012 (4) | |
O2 | 0.0162 (3) | 0.1597 (14) | 0.00000 | 0.012 (4) | |
O3 | 0.1671 (3) | 0.1326 (14) | 0.00000 | 0.012 (4) | |
O4 | 0.4189 (3) | 0.1719 (15) | 0.00000 | 0.017 (5) | |
O5 | 0.1250 (3) | 0.1554 (14) | 0.50000 | 0.012 (4) | |
O6 | 0.2718 (3) | 0.1448 (14) | 0.50000 | 0.012 (4) | |
O7 | 0.2009 (2) | 0.3374 (9) | 0.3059 (8) | 0.009 (3) | |
O8 | 0.3039 (2) | 0.4561 (9) | 0.6882 (8) | 0.009 (3) | |
O9 | 0.0979 (2) | 0.3408 (9) | 0.1915 (8) | 0.010 (3) | |
O10 | 0.4110 (2) | 0.4733 (9) | 0.2075 (8) | 0.013 (3) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cs1 | 0.0265 (4) | 0.0288 (6) | 0.0256 (4) | −0.0013 (5) | 0.00000 | 0.00000 |
Cs2 | 0.0168 (4) | 0.0293 (6) | 0.0262 (4) | 0.0030 (4) | 0.00000 | 0.00000 |
Cs3 | 0.0132 (4) | 0.0233 (5) | 0.0472 (6) | 0.0018 (4) | 0.00000 | 0.00000 |
Ta1 | 0.0067 (2) | 0.0065 (3) | 0.0080 (2) | 0.0008 (2) | 0.00000 | 0.00000 |
Ta2 | 0.0062 (2) | 0.0061 (2) | 0.0063 (2) | 0.00050 (19) | 0.00000 | 0.00000 |
Ta3 | 0.0079 (2) | 0.0049 (2) | 0.00709 (18) | −0.00035 (19) | 0.00000 | 0.00000 |
Ta4 | 0.00809 (14) | 0.00738 (18) | 0.00465 (14) | −0.00007 (13) | −0.00051 (11) | −0.00051 (15) |
O1 | 0.014 (4) | 0.014 (5) | 0.008 (3) | 0.002 (4) | 0.00000 | 0.00000 |
O2 | 0.009 (3) | 0.009 (5) | 0.017 (4) | −0.001 (4) | 0.00000 | 0.00000 |
O3 | 0.017 (4) | 0.016 (5) | 0.002 (3) | 0.004 (4) | 0.00000 | 0.00000 |
O4 | 0.012 (4) | 0.017 (5) | 0.021 (4) | 0.009 (4) | 0.00000 | 0.00000 |
O5 | 0.008 (4) | 0.013 (5) | 0.015 (4) | 0.001 (4) | 0.00000 | 0.00000 |
O6 | 0.009 (4) | 0.009 (5) | 0.017 (4) | −0.006 (4) | 0.00000 | 0.00000 |
O7 | 0.009 (2) | 0.010 (3) | 0.008 (2) | −0.001 (2) | −0.002 (2) | 0.002 (3) |
O8 | 0.010 (2) | 0.007 (3) | 0.009 (3) | −0.001 (2) | −0.003 (2) | −0.002 (3) |
O9 | 0.008 (2) | 0.014 (3) | 0.009 (3) | 0.002 (2) | −0.007 (2) | −0.002 (3) |
O10 | 0.011 (2) | 0.012 (3) | 0.017 (3) | 0.003 (3) | 0.005 (2) | 0.006 (3) |
Cs1—O8 | 3.207 (6) | Cs3—O9 | 3.320 (6) |
Cs1—O8 | 3.207 (6) | Cs3—O9 | 3.320 (6) |
Cs1—O3 | 3.268 (9) | Ta1—O9iii | 1.920 (6) |
Cs1—O7 | 3.296 (6) | Ta1—O9 | 1.920 (6) |
Cs1—O7 | 3.296 (6) | Ta1—O4i | 1.955 (11) |
Cs1—O4 | 3.342 (9) | Ta1—O1 | 2.002 (5) |
Cs1—Cs1i | 4.3046 (17) | Ta1—O1 | 2.002 (5) |
Cs1—Cs1 | 4.3046 (17) | Ta1—O2 | 2.219 (10) |
Cs1—Cs3 | 4.3704 (9) | Ta2—O10iii | 1.808 (6) |
Cs1—Cs3 | 4.3704 (9) | Ta2—O10 | 1.808 (6) |
Cs2—O5 | 2.767 (8) | Ta2—O4 | 1.878 (11) |
Cs2—O9 | 3.111 (6) | Ta2—O2iv | 1.991 (8) |
Cs2—O9 | 3.111 (6) | Ta2—O2i | 2.141 (10) |
Cs2—O1 | 3.140 (6) | Ta3—O6 | 1.936 (10) |
Cs2—O1 | 3.140 (6) | Ta3—O6 | 1.956 (10) |
Cs2—O10 | 3.417 (6) | Ta3—O8 | 1.959 (6) |
Cs2—O10 | 3.417 (6) | Ta3—O8 | 1.959 (6) |
Cs2—Cs2ii | 3.7634 (18) | Ta3—O7 | 2.050 (6) |
Cs2—Cs3 | 3.7961 (15) | Ta3—O7 | 2.050 (6) |
Cs2—Cs3 | 4.0047 (16) | Ta4—O7 | 1.876 (6) |
Cs2—Cs2 | 4.0247 (18) | Ta4—O3 | 1.937 (2) |
Cs3—O6 | 2.851 (8) | Ta4—O5 | 1.944 (3) |
Cs3—O10 | 3.294 (7) | Ta4—O8 | 1.957 (6) |
Cs3—O10 | 3.294 (7) | Ta4—O9 | 2.003 (6) |
Cs3—O8 | 3.304 (6) | Ta4—O10 | 2.186 (6) |
Cs3—O8 | 3.304 (6) | ||
O8—Cs1—O8 | 91.87 (16) | O10—Cs3—Cs1 | 64.65 (11) |
O8—Cs1—O3 | 98.22 (16) | O8—Cs3—O8 | 49.82 (14) |
O8—Cs1—O7 | 89.98 (15) | O8—Cs3—O9 | 106.89 (15) |
O8—Cs1—O7 | 170.26 (14) | O8—Cs3—O9 | 150.35 (14) |
O8—Cs1—O4 | 83.03 (16) | O8—Cs3—Cs2 | 117.36 (11) |
O8—Cs1—Cs1i | 57.17 (11) | O8—Cs3—Cs2 | 154.98 (10) |
O8—Cs1—Cs1 | 130.17 (11) | O8—Cs3—Cs1 | 91.66 (10) |
O8—Cs1—Cs3 | 123.80 (11) | O8—Cs3—Cs1 | 46.90 (10) |
O8—Cs1—Cs3 | 48.78 (11) | O8—Cs3—O9 | 150.35 (14) |
O8—Cs1—O3 | 98.22 (16) | O8—Cs3—O9 | 106.89 (14) |
O8—Cs1—O7 | 170.26 (14) | O8—Cs3—Cs2 | 117.36 (11) |
O8—Cs1—O7 | 89.98 (15) | O8—Cs3—Cs2 | 154.98 (10) |
O8—Cs1—O4 | 83.03 (16) | O8—Cs3—Cs1 | 46.90 (10) |
O8—Cs1—Cs1i | 57.17 (11) | O8—Cs3—Cs1 | 91.66 (10) |
O8—Cs1—Cs1 | 130.17 (10) | O9—Cs3—O9 | 86.77 (16) |
O8—Cs1—Cs3 | 48.78 (11) | O9—Cs3—Cs2 | 88.53 (10) |
O8—Cs1—Cs3 | 123.80 (11) | O9—Cs3—Cs2 | 49.18 (10) |
O3—Cs1—O7 | 90.97 (16) | O9—Cs3—Cs1 | 132.48 (11) |
O3—Cs1—O7 | 90.97 (16) | O9—Cs3—Cs1 | 60.90 (10) |
O3—Cs1—O4 | 178.2 (3) | O9—Cs3—Cs2 | 88.53 (10) |
O3—Cs1—Cs1i | 63.09 (19) | O9—Cs3—Cs2 | 49.18 (10) |
O3—Cs1—Cs1 | 56.18 (19) | O9—Cs3—Cs1 | 60.90 (10) |
O3—Cs1—Cs3 | 122.177 (18) | O9—Cs3—Cs1 | 132.48 (11) |
O3—Cs1—Cs3 | 122.177 (18) | Cs2—Cs3—Cs2 | 62.05 (3) |
O7—Cs1—O7 | 86.64 (15) | Cs2—Cs3—Cs1 | 121.466 (18) |
O7—Cs1—O4 | 87.70 (16) | Cs2—Cs3—Cs1 | 121.466 (18) |
O7—Cs1—Cs1i | 131.01 (10) | Cs2—Cs3—Cs1 | 110.07 (2) |
O7—Cs1—Cs1 | 53.50 (10) | Cs2—Cs3—Cs1 | 110.07 (2) |
O7—Cs1—Cs3 | 123.00 (11) | Cs1—Cs3—Cs1 | 115.48 (3) |
O7—Cs1—Cs3 | 51.99 (10) | O9iii—Ta1—O9 | 95.0 (2) |
O7—Cs1—O4 | 87.70 (16) | O9iii—Ta1—O4i | 95.6 (3) |
O7—Cs1—Cs1i | 131.01 (10) | O9iii—Ta1—O1 | 92.3 (2) |
O7—Cs1—Cs1 | 53.50 (10) | O9iii—Ta1—O1 | 170.5 (2) |
O7—Cs1—Cs3 | 51.99 (10) | O9iii—Ta1—O2 | 88.5 (2) |
O7—Cs1—Cs3 | 123.00 (11) | O9—Ta1—O4i | 95.6 (3) |
O4—Cs1—Cs1i | 118.73 (19) | O9—Ta1—O1 | 170.5 (2) |
O4—Cs1—Cs1 | 121.99 (19) | O9—Ta1—O1 | 92.3 (2) |
O4—Cs1—Cs3 | 57.763 (17) | O9—Ta1—O2 | 88.5 (2) |
O4—Cs1—Cs3 | 57.763 (17) | O4i—Ta1—O1 | 89.8 (2) |
Cs1i—Cs1—Cs1 | 119.27 (3) | O4i—Ta1—O1 | 89.8 (2) |
Cs1i—Cs1—Cs3 | 105.88 (2) | O4i—Ta1—O2 | 173.8 (4) |
Cs1i—Cs1—Cs3 | 105.88 (2) | O1—Ta1—O1 | 79.9 (3) |
Cs1—Cs1—Cs3 | 105.43 (3) | O1—Ta1—O2 | 85.45 (17) |
Cs1—Cs1—Cs3 | 105.43 (3) | O1—Ta1—O2 | 85.45 (17) |
Cs3—Cs1—Cs3 | 115.48 (3) | O10iii—Ta2—O10 | 116.0 (3) |
O5—Cs2—O9 | 55.59 (14) | O10iii—Ta2—O4 | 95.1 (3) |
O5—Cs2—O9 | 55.59 (14) | O10iii—Ta2—O2iv | 120.9 (2) |
O5—Cs2—O1 | 108.77 (13) | O10iii—Ta2—O2i | 90.4 (2) |
O5—Cs2—O1 | 108.77 (13) | O10—Ta2—O4 | 95.1 (3) |
O5—Cs2—O10 | 50.87 (16) | O10—Ta2—O2iv | 120.9 (2) |
O5—Cs2—O10 | 50.87 (16) | O10—Ta2—O2i | 90.4 (2) |
O5—Cs2—Cs2ii | 94.8 (2) | O4—Ta2—O2iv | 94.5 (4) |
O5—Cs2—Cs3 | 178.3 (2) | O4—Ta2—O2i | 169.6 (4) |
O5—Cs2—Cs3 | 63.7 (2) | O2iv—Ta2—O2i | 75.1 (4) |
O5—Cs2—Cs2 | 120.1 (2) | O6—Ta3—O6 | 173.7 (4) |
O9—Cs2—O9 | 94.29 (15) | O6—Ta3—O8 | 91.9 (3) |
O9—Cs2—O1 | 53.80 (12) | O6—Ta3—O8 | 91.9 (3) |
O9—Cs2—O1 | 122.33 (14) | O6—Ta3—O7 | 88.8 (3) |
O9—Cs2—O10 | 106.08 (15) | O6—Ta3—O7 | 88.8 (3) |
O9—Cs2—O10 | 49.41 (17) | O6—Ta3—O8 | 92.5 (3) |
O9—Cs2—Cs2ii | 115.14 (13) | O6—Ta3—O8 | 92.5 (3) |
O9—Cs2—Cs3 | 125.16 (11) | O6—Ta3—O7 | 86.7 (3) |
O9—Cs2—Cs3 | 53.87 (12) | O6—Ta3—O7 | 86.7 (3) |
O9—Cs2—Cs2 | 87.50 (12) | O8—Ta3—O8 | 90.5 (2) |
O9—Cs2—O1 | 122.33 (14) | O8—Ta3—O7 | 178.8 (3) |
O9—Cs2—O1 | 53.80 (12) | O8—Ta3—O7 | 90.3 (2) |
O9—Cs2—O10 | 49.41 (17) | O8—Ta3—O7 | 90.3 (2) |
O9—Cs2—O10 | 106.08 (15) | O8—Ta3—O7 | 178.8 (3) |
O9—Cs2—Cs2ii | 115.14 (12) | O7—Ta3—O7 | 88.8 (2) |
O9—Cs2—Cs3 | 125.16 (11) | O7—Ta4—O3 | 97.4 (3) |
O9—Cs2—Cs3 | 53.87 (12) | O7—Ta4—O5 | 94.3 (3) |
O9—Cs2—Cs2 | 87.50 (12) | O7—Ta4—O8 | 95.4 (3) |
O1—Cs2—O1 | 100.27 (14) | O7—Ta4—O9 | 93.7 (3) |
O1—Cs2—O10 | 159.63 (11) | O7—Ta4—O10 | 174.2 (2) |
O1—Cs2—O10 | 88.07 (14) | O3—Ta4—O5 | 168.2 (4) |
O1—Cs2—Cs2ii | 121.68 (7) | O3—Ta4—O8 | 90.2 (3) |
O1—Cs2—Cs3 | 72.20 (4) | O3—Ta4—O9 | 89.4 (3) |
O1—Cs2—Cs3 | 69.24 (5) | O3—Ta4—O10 | 86.0 (3) |
O1—Cs2—Cs2 | 50.14 (10) | O5—Ta4—O8 | 89.9 (3) |
O1—Cs2—O10 | 88.07 (14) | O5—Ta4—O9 | 88.6 (3) |
O1—Cs2—O10 | 159.63 (11) | O5—Ta4—O10 | 82.2 (3) |
O1—Cs2—Cs2ii | 121.68 (7) | O8—Ta4—O9 | 170.9 (2) |
O1—Cs2—Cs3 | 72.20 (4) | O8—Ta4—O10 | 89.2 (2) |
O1—Cs2—Cs3 | 69.24 (5) | O9—Ta4—O10 | 81.7 (2) |
O1—Cs2—Cs2 | 50.14 (10) | Ta1—O1—Ta1 | 100.1 (4) |
O10—Cs2—O10 | 78.49 (15) | Ta1—O1—Cs2 | 142.64 (9) |
O10—Cs2—Cs2ii | 66.80 (11) | Ta1—O1—Cs2 | 101.01 (8) |
O10—Cs2—Cs3 | 128.16 (10) | Ta1—O1—Cs2 | 101.01 (8) |
O10—Cs2—Cs3 | 97.05 (11) | Ta1—O1—Cs2 | 142.64 (10) |
O10—Cs2—Cs2 | 134.83 (11) | Cs2—O1—Cs2 | 79.7 (2) |
O10—Cs2—Cs2ii | 66.80 (11) | Ta2—O2—Ta2 | 104.9 (4) |
O10—Cs2—Cs3 | 128.16 (10) | Ta2—O2—Ta1 | 132.1 (5) |
O10—Cs2—Cs3 | 97.05 (11) | Ta2—O2—Ta1 | 123.0 (4) |
O10—Cs2—Cs2 | 134.83 (11) | Ta4iii—O3—Ta4 | 153.1 (5) |
Cs2ii—Cs2—Cs3 | 83.50 (3) | Ta4iii—O3—Cs1 | 101.5 (3) |
Cs2ii—Cs2—Cs3 | 158.56 (3) | Ta4—O3—Cs1 | 101.5 (3) |
Cs2ii—Cs2—Cs2 | 145.02 (3) | Ta2—O4—Ta1 | 139.6 (5) |
Cs3—Cs2—Cs3 | 117.95 (4) | Ta2—O4—Cs1 | 111.2 (4) |
Cs3—Cs2—Cs2 | 61.52 (3) | Ta1—O4—Cs1 | 109.1 (4) |
Cs3—Cs2—Cs2 | 56.43 (3) | Ta4—O5—Ta4 | 137.5 (4) |
O6—Cs3—O10 | 105.37 (18) | Ta4—O5—Cs2 | 110.3 (2) |
O6—Cs3—O10 | 105.37 (18) | Ta4—O5—Cs2 | 110.3 (2) |
O6—Cs3—O8 | 54.1 (2) | Ta3—O6—Ta3 | 145.8 (5) |
O6—Cs3—O8 | 54.1 (2) | Ta3—O6—Cs3 | 112.0 (4) |
O6—Cs3—O9 | 98.60 (17) | Ta3—O6—Cs3 | 102.2 (4) |
O6—Cs3—O9 | 98.60 (17) | Ta4—O7—Ta3 | 139.8 (3) |
O6—Cs3—Cs2 | 170.2 (2) | Ta4—O7—Cs1i | 114.3 (2) |
O6—Cs3—Cs2 | 127.8 (2) | Ta3—O7—Cs1i | 105.9 (2) |
O6—Cs3—Cs1 | 57.766 (17) | Ta4—O8—Ta3 | 135.6 (3) |
O6—Cs3—Cs1 | 57.766 (17) | Ta4—O8—Cs1 | 116.1 (2) |
O10—Cs3—O10 | 82.03 (16) | Ta4—O8—Cs3 | 104.7 (2) |
O10—Cs3—O8 | 86.74 (15) | Ta3—O8—Cs1 | 107.3 (2) |
O10—Cs3—O8 | 52.43 (14) | Ta3—O8—Cs3 | 88.1 (2) |
O10—Cs3—O9 | 156.01 (14) | Cs1—O8—Cs3 | 84.32 (15) |
O10—Cs3—O9 | 90.69 (16) | Ta1—O9—Ta4 | 144.0 (3) |
O10—Cs3—Cs2 | 67.55 (10) | Ta1—O9—Cs2 | 104.1 (2) |
O10—Cs3—Cs2 | 113.32 (11) | Ta1—O9—Cs3 | 112.0 (3) |
O10—Cs3—Cs1 | 64.65 (11) | Ta4—O9—Cs2 | 96.8 (2) |
O10—Cs3—Cs1 | 132.98 (12) | Ta4—O9—Cs3 | 101.0 (2) |
O10—Cs3—O8 | 52.43 (14) | Cs2—O9—Cs3 | 76.95 (14) |
O10—Cs3—O8 | 86.74 (15) | Ta2—O10—Ta4v | 130.5 (3) |
O10—Cs3—O9 | 90.69 (16) | Ta2—O10—Cs3 | 118.9 (3) |
O10—Cs3—O9 | 156.01 (14) | Ta2—O10—Cs2 | 116.8 (3) |
O10—Cs3—Cs2 | 67.55 (10) | Ta4v—O10—Cs3 | 99.6 (2) |
O10—Cs3—Cs2 | 113.32 (11) | Ta4v—O10—Cs2 | 85.1 (2) |
O10—Cs3—Cs1 | 132.98 (12) | Cs3—O10—Cs2 | 97.16 (16) |
Symmetry codes: (i) −x+1/2, y+1/2, −z; (ii) −x, −y, z; (iii) x, y, −z; (iv) x+1/2, −y+1/2, −z; (v) −x+1/2, y+1/2, z. |
Experimental details
Crystal data | |
Chemical formula | Cs3Ta5O14 |
Mr | 1527.48 |
Crystal system, space group | Orthorhombic, Pbam |
Temperature (K) | 295 |
a, b, c (Å) | 26.219 (6), 7.4283 (10), 7.3914 (10) |
V (Å3) | 1439.6 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 45.17 |
Crystal size (mm) | 0.06 × 0.06 × 0.04 |
Data collection | |
Diffractometer | Rigaku Rapid image plate diffractometer |
Absorption correction | Numerical Gaussian integration on 8× 8× 8 grid |
Tmin, Tmax | 0.113, 0.349 |
No. of measured, independent and observed (F > 0) reflections | 2269, 2269, 2269 |
Rint | 0.060 |
(sin θ/λ)max (Å−1) | 0.704 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.044, 0.032, 0.91 |
No. of reflections | 2269 |
No. of parameters | 117 |
Δρmax, Δρmin (e Å−3) | 3.69, −4.25 |
Computer programs: RAPID-AUTO (Rigaku, 1999), RAPID-AUTO, Serafin & Hoppe (1982), CRYLSQ in Xtal3.7 (Hall et al., 2000), ATOMS (Dowty, 1999) and ORTEP in Xtal3.7, Xtal BONDLA CIFIO in Xtal3.7.
In the course of investigation of four layered Rb2Ca2Ta4O13 perovskites a new mesoporous pyrochlore like structural phase, Rb3Ta5O14, was encountered by du Boulay et al. (2002). That phase turned out to be a variant of a Cs3Ta5O14 archetype structure reported previously by Serafin & Hoppe (1982). In reviewing the two structures, the more recent authors were led to suspect some irregularities in the original Cs3Ta5O14 structural model because, with the exception of three independent Cs sites, all atoms were refined with isotropic displacement parameters and of the Cs sites, two exhibited unusually large Uij values. The isotropic displacement parameters of the O atoms also varied considerably over the range 0.001–0.023 Å2. The largest displacement parameter occurred for one atom, Cs3, located on one of two independent Pbam mirror planes which exhibited very large displacements normal to that plane. Consequently du Boulay et al. (2002) speculated that the mirror symmetry could be broken, by analogy with two of the Rb atoms in the Rb3Ta5O14 analogue. This could have led to doubling of the Pbam c axis and a Cs-atom sublattice in closer agreement with the Rb sublattice observed for the latter compound.
To remove any uncertainties the current authors crystalized and reanalysed Cs3Ta5O14 via single-crystal X-ray diffraction. Here we confirm that the structure reported by Serafin & Hoppe (1982) was correct and, in addition, we report marginally more precise structural parameters accompanied by anisotropic displacement parameters determined for all atoms.
X-Ray fluorescence image plate data for Cs3Ta5O14 were measured on a Rigaku R-AXIS RAPID three-circle diffractometer. An Mo Kα X-ray source and a semi-cylindrical fluorescence plate were used to measure the room temperature single-crystal diffraction data. The initial orientation matrix and associated lattice parameters were determined from eight oscillation photos measured at 120 s per ° with Δω = 2°. A single 90 min duration X-ray image was taken while rotating the crystal 30° about its c axis at 180 s per °. That frame failed to reveal superlattice reflections of any kind along the Pbam c axis. The implications being that the originally reported lattice was quite correct, though not necessarily the symmetry.
The data measurement involved 275 image plate frames measured with rotations of Δω = 2° at 500 s per ° from which 20976 reflections were identified out to 2θ ≤ 60.1°. Lattice parameters were refined with other apparatus parameters using all 275 frames and agree with those of Serafin & Hoppe (1982) to about 0.05 Å. The measured intensities were in good accord with the b-glide along a and a-glide along b reported by the previous authors. The uncertainties remaining therefore primarily concern the degree of perfection of the Pbam mirror planes.
Structurally Cs3Ta5O14 consists of four distinct TaO polyhedra, of which three are corner-sharing TaO6 octahedra and one is an edge-sharing TaO5 bicapped trigonal prism, as depicted in Fig. 1. Those TaO polyhedra form the backbone of a network of two symmetry distinct, Cs filled structural cavities, the larger containing four Cs atoms with the smaller cavity containing two. The underlying atomic coordination geometries were well examined by Serafin & Hoppe (1982), and the relationship of Cs3Ta5O14 to the three independent cavity network of mesoporous Rb3Ta5O14 was previously discussed by du Boulay et al. (2002).