Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801015094/br6021sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536801015094/br6021Isup2.hkl |
Single crystals of YbMnO3 were obtained using a flux method by weighing appropriate amounts of Yb2O3 and MnO2 with Bi2O3 in a 1:12 ratio (Yakel et al., 1963). The powders were thoroughly mixed and heated for 48 h at 1523 K in a Pt crucible. The crystals were separated from the flux by increasing the temperature to 1723 K and evaporating the Bi2O3 flux (Bertaut et al., 1963).
The space group is determined to be P63cm, taking into consideration the unit-cell parameters, statistical analyses of intensity distributions and, where appropriate, systematic extinctions (h-hl: l ≠ 2n; 00 l: l ≠ 2n). Attempts to fit the data in the space group P63/mcm were unsuccessful with wR2 = 0.45 and R = 0.18. Anisotropic displacement parameters and SHELXL97 (Sheldrick, 1997) indicated that the Yb ions should be shifted away from the mirror plane perpendicular to the c axis. The structure was solved by using initial coordinates which are taken from a previous reported hexagonal manganite, YMnO3 (van Aken et al., 2001a). The positional and anisotropic displacement parameters were refined. The final difference Fourier map showed a peak of 2.5 (10) e Å-3 near the Yb1 position and a hole of 7.3 (10) e Å-3 also near the Yb1 position. No other significant peaks having chemical meaning above the general background 1.0 e Å-3 were observed in the final difference Fourier map. The Flack parameter (Flack, 1983) of an initial refinement indicated that the crystal was twinned. The model without a twin yielded a Flack parameter of x = 0.34 (3) and x = 0.57 (3) for the inverse structure. The R values are wR2 = 0.0789 and R = 0.0305, and wR2 = 0.086 and R = 0.0318, respectively. Therefore an inversion twin was added to the structure model, similar to the one reported for YMnO3 (van Aken et al., 2001a). The final refinement gave a twin fraction near 50%. We expect a 50/50% istribution because this yields no net electrical polarization (Rao & Gopalakrishnan, 1997). Fixing the twin fraction at 50% had no significant influence on any other parameter.
Data collection: CAD-4-UNIX Software (Enraf-Nonius, 1994); cell refinement: SET4 (de Boer & Duisenberg, 1984); data reduction: HELENA (Spek, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 2000); software used to prepare material for publication: PLATON (Spek, 2001).
YbMnO3 | Unit cell parameters (Duisenberg, 1992) and orientation matrix were determined from a least-squares treatment of SET4 (de Boer & Duisenberg, 1984) setting. Reduced cell calculations did not indicate any higher metric lattice symmetry and examination of the final atomic coordinates of the structure did not yield extra symmetry elements (Spek, 1988; Le Page 1987, 1988) |
Mr = 275.88 | Dx = 7.617 Mg m−3 |
Hexagonal, P63cm | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 6c -2 | Cell parameters from 22 reflections |
a = 6.0584 (6) Å | θ = 15.0–27.9° |
c = 11.3561 (7) Å | µ = 43.58 mm−1 |
V = 360.97 (6) Å3 | T = 293 K |
Z = 6 | Platelet, black |
F(000) = 714 | 0.15 × 0.10 × 0.01 mm |
Enraf Nonius CAD-4F diffractometer | 636 reflections with F > 4σ(F) |
Radiation source: fine focus sealed Philips Mo tube | Rint = 0.037 |
Perpendicular mounted graphite monochromator | θmax = 39.9°, θmin = 3.6° |
ω/2θ scans | h = −10→0 |
Absorption correction: gaussian (Spek, 1983) | k = 0→10 |
Tmin = 0.059, Tmax = 0.577 | l = −20→20 |
3264 measured reflections | 3 standard reflections every 180 min |
835 independent reflections | intensity decay: none |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: none |
R[F2 > 2σ(F2)] = 0.030 | w = 1/[σ2(Fo2) + (0.0494P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.072 | (Δ/σ)max < 0.001 |
S = 1.08 | Δρmax = 2.5 (10) e Å−3 |
835 reflections | Δρmin = −7.3 (10) e Å−3 |
32 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0121 (7) |
0 constraints |
YbMnO3 | Z = 6 |
Mr = 275.88 | Mo Kα radiation |
Hexagonal, P63cm | µ = 43.58 mm−1 |
a = 6.0584 (6) Å | T = 293 K |
c = 11.3561 (7) Å | 0.15 × 0.10 × 0.01 mm |
V = 360.97 (6) Å3 |
Enraf Nonius CAD-4F diffractometer | 636 reflections with F > 4σ(F) |
Absorption correction: gaussian (Spek, 1983) | Rint = 0.037 |
Tmin = 0.059, Tmax = 0.577 | 3 standard reflections every 180 min |
3264 measured reflections | intensity decay: none |
835 independent reflections |
R[F2 > 2σ(F2)] = 0.030 | 32 parameters |
wR(F2) = 0.072 | 0 restraints |
S = 1.08 | Δρmax = 2.5 (10) e Å−3 |
835 reflections | Δρmin = −7.3 (10) e Å−3 |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All e.s.d.'s are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
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 > 2σ(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. |
x | y | z | Uiso*/Ueq | ||
Yb1 | 0.00000 | 0.00000 | 0.27336 (5) | 0.00427 (11) | |
Yb2 | 0.33333 | −0.33333 | 0.23061 (3) | 0.00472 (7) | |
Mn | 0.3333 (5) | 0.00000 | −0.00194 (14) | 0.0054 (2) | |
O1 | 0.3030 (12) | 0.00000 | 0.1617 (6) | 0.0039 (10) | |
O2 | 0.3610 (15) | 0.00000 | −0.1658 (6) | 0.0074 (11) | |
O3 | 0.00000 | 0.00000 | −0.0268 (16) | 0.004 (2) | |
O4 | 0.33333 | −0.33333 | 0.0192 (9) | 0.0059 (17) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Yb1 | 0.0047 (2) | 0.0047 (2) | 0.0035 (2) | 0.0023 (1) | 0.0000 | 0.0000 |
Yb2 | 0.0035 (1) | 0.0036 (1) | 0.0071 (2) | 0.0018 (1) | 0.0000 | 0.0000 |
Mn | 0.0069 (4) | 0.0048 (4) | 0.0039 (2) | 0.0024 (6) | 0.0002 (3) | 0.0000 |
O1 | 0.0050 (14) | 0.0017 (18) | 0.0041 (19) | 0.0009 (9) | −0.0019 (15) | 0.0000 |
O2 | 0.014 (2) | 0.0001 (18) | 0.0033 (17) | 0.0000 (9) | 0.0002 (19) | 0.0000 |
O3 | 0.003 (2) | 0.003 (2) | 0.005 (6) | 0.0016 (10) | 0.0000 | 0.0000 |
O4 | 0.009 (3) | 0.009 (3) | 0.000 (3) | 0.0047 (13) | 0.0000 | 0.0000 |
Yb1—Yb2 | 3.5313 (4) | Yb2—O1 | 2.257 (5) |
Yb1—O1 | 2.231 (7) | Yb2—O4 | 2.401 (10) |
Yb1—Yb2i | 3.5313 (4) | Yb2—O4xi | 3.277 (10) |
Yb1—Yb2ii | 3.5313 (4) | Yb2—O2xii | 2.270 (8) |
Yb1—Mniii | 3.254 (3) | Yb2—O1xiii | 2.257 (6) |
Yb1—O2iii | 2.294 (8) | Yb2—O2xiv | 2.270 (5) |
Yb1—O3iii | 2.269 (18) | Yb2—O1xv | 2.257 (8) |
Yb1—O3 | 3.409 (18) | Yb2—O2vii | 2.270 (5) |
Yb1—O1iv | 2.231 (6) | Yb2—Yb2viii | 3.4978 (3) |
Yb1—Mnv | 3.254 (3) | Yb2—Yb2xvi | 3.4978 (3) |
Yb1—O2v | 2.294 (9) | Yb2—Yb2x | 3.4978 (3) |
Yb1—O1vi | 2.231 (7) | Mn—O1 | 1.867 (7) |
Yb1—Mnvii | 3.254 (3) | Mn—O2 | 1.868 (7) |
Yb1—O2vii | 2.294 (7) | Mn—O3 | 2.039 (4) |
Yb1—Yb2viii | 3.5313 (4) | Mn—O4 | 2.034 (4) |
Yb1—Yb2ix | 3.5313 (4) | Mn—O4x | 2.034 (4) |
Yb1—Yb2x | 3.5313 (4) | ||
O1—Yb1—O2iii | 77.2 (2) | O1xiii—Yb2—O2vii | 77.2 (2) |
O1—Yb1—O3iii | 124.64 (18) | O1xv—Yb2—O2xiv | 77.2 (3) |
O1—Yb1—O1iv | 90.89 (18) | O2xiv—Yb2—O2vii | 95.6 (3) |
O1—Yb1—O2v | 162.9 (3) | O1xv—Yb2—O2vii | 169.1 (2) |
O1—Yb1—O1vi | 90.9 (2) | O1—Mn—O2 | 179.5 (4) |
O1—Yb1—O2vii | 77.23 (17) | O1—Mn—O3 | 92.3 (6) |
O2iii—Yb1—O3iii | 72.47 (18) | O1—Mn—O4 | 86.1 (3) |
O1iv—Yb1—O2iii | 77.2 (3) | O1—Mn—O4x | 86.1 (3) |
O2iii—Yb1—O2v | 111.3 (2) | O2—Mn—O3 | 87.2 (6) |
O1vi—Yb1—O2iii | 162.9 (2) | O2—Mn—O4 | 94.2 (3) |
O2iii—Yb1—O2vii | 111.3 (3) | O2—Mn—O4x | 94.2 (3) |
O1iv—Yb1—O3iii | 124.64 (17) | O3—Mn—O4 | 120.54 (8) |
O2v—Yb1—O3iii | 72.47 (18) | O3—Mn—O4x | 120.54 (18) |
O1vi—Yb1—O3iii | 124.64 (18) | O4—Mn—O4x | 118.62 (19) |
O2vii—Yb1—O3iii | 72.47 (17) | Yb1—O1—Yb2 | 103.8 (2) |
O1iv—Yb1—O2v | 77.23 (17) | Yb1—O1—Mn | 130.3 (4) |
O1iv—Yb1—O1vi | 90.9 (2) | Yb1—O1—Yb2x | 103.8 (2) |
O1iv—Yb1—O2vii | 162.9 (2) | Yb2—O1—Mn | 107.0 (3) |
O1vi—Yb1—O2v | 77.2 (2) | Yb2—O1—Yb2x | 101.6 (3) |
O2v—Yb1—O2vii | 111.34 (16) | Yb2x—O1—Mn | 107.0 (3) |
O1vi—Yb1—O2vii | 77.2 (2) | Yb1xvii—O2—Mn | 102.4 (4) |
O1—Yb2—O4 | 69.72 (17) | Yb2xvii—O2—Mn | 123.3 (2) |
O1—Yb2—O2xii | 169.1 (3) | Yb2xviii—O2—Mn | 123.3 (2) |
O1—Yb2—O1xiii | 108.65 (19) | Yb1xvii—O2—Yb2xvii | 101.4 (2) |
O1—Yb2—O2xiv | 77.2 (2) | Yb1xvii—O2—Yb2xvii | 101.4 (2) |
O1—Yb2—O1xv | 108.6 (2) | Yb2xvii—O2—Yb2xviii | 100.8 (3) |
O1—Yb2—O2vii | 77.2 (3) | Yb1xvii—O3—Mn | 98.0 (5) |
O2xii—Yb2—O4 | 121.22 (19) | Mn—O3—Mniv | 118.1 (3) |
O1xiii—Yb2—O4 | 69.72 (17) | Mn—O3—Mnvi | 118.1 (3) |
O2xiv—Yb2—O4 | 121.22 (16) | Yb1xvii—O3—Mniv | 98.0 (5) |
O1xv—Yb2—O4 | 69.72 (18) | Yb1xvii—O3—Mnvi | 98.0 (5) |
O2vii—Yb2—O4 | 121.22 (16) | Mniv—O3—Mnvi | 118.1 (3) |
O1xiii—Yb2—O2xii | 77.2 (3) | Yb2—O4—Mn | 96.8 (3) |
O2xii—Yb2—O2xiv | 95.6 (3) | Yb2—O4—Mnxiii | 96.8 (3) |
O1xv—Yb2—O2xii | 77.2 (3) | Yb2—O4—Mnxv | 96.8 (3) |
O2xii—Yb2—O2vii | 95.6 (3) | Mn—O4—Mnxiii | 118.6 (2) |
O1xiii—Yb2—O2xiv | 169.1 (2) | Mn—O4—Mnxv | 118.63 (17) |
O1xiii—Yb2—O1xv | 108.6 (2) | Mnxiii—O4—Mnxv | 118.63 (19) |
Symmetry codes: (i) x−1, y, z; (ii) x, y+1, z; (iii) x−y, x, z+1/2; (iv) −y, x−y, z; (v) −x, −y, z+1/2; (vi) −x+y, −x, z; (vii) y, −x+y, z+1/2; (viii) y, x−1, z; (ix) y, x, z; (x) y+1, x, z; (xi) −y, −x, z+1/2; (xii) x−y, x−1, z+1/2; (xiii) −y, x−y−1, z; (xiv) −x+1, −y, z+1/2; (xv) −x+y+1, −x, z; (xvi) y+1, x−1, z; (xvii) x−y, x, z−1/2; (xviii) x, x−y−1, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | YbMnO3 |
Mr | 275.88 |
Crystal system, space group | Hexagonal, P63cm |
Temperature (K) | 293 |
a, c (Å) | 6.0584 (6), 11.3561 (7) |
V (Å3) | 360.97 (6) |
Z | 6 |
Radiation type | Mo Kα |
µ (mm−1) | 43.58 |
Crystal size (mm) | 0.15 × 0.10 × 0.01 |
Data collection | |
Diffractometer | Enraf Nonius CAD-4F diffractometer |
Absorption correction | Gaussian (Spek, 1983) |
Tmin, Tmax | 0.059, 0.577 |
No. of measured, independent and observed [F > 4σ(F)] reflections | 3264, 835, 636 |
Rint | 0.037 |
(sin θ/λ)max (Å−1) | 0.903 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.072, 1.08 |
No. of reflections | 835 |
No. of parameters | 32 |
Δρmax, Δρmin (e Å−3) | 2.5 (10), −7.3 (10) |
Computer programs: CAD-4-UNIX Software (Enraf-Nonius, 1994), SET4 (de Boer & Duisenberg, 1984), HELENA (Spek, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 2000), PLATON (Spek, 2001).
Yb1—O1 | 2.231 (7) | Yb2—O4ii | 3.277 (10) |
Yb1—O2i | 2.294 (8) | Yb2—O2iii | 2.270 (8) |
Yb1—O3i | 2.269 (18) | Mn—O1 | 1.867 (7) |
Yb1—O3 | 3.409 (18) | Mn—O2 | 1.868 (7) |
Yb2—O1 | 2.257 (5) | Mn—O3 | 2.039 (4) |
Yb2—O4 | 2.401 (10) | Mn—O4 | 2.034 (4) |
O1—Mn—O2 | 179.5 (4) | O4—Mn—O4iv | 118.62 (19) |
O1—Mn—O3 | 92.3 (6) | Mn—O3—Mnv | 118.1 (3) |
O1—Mn—O4 | 86.1 (3) | Mn—O4—Mnvi | 118.6 (2) |
O3—Mn—O4 | 120.54 (8) |
Symmetry codes: (i) x−y, x, z+1/2; (ii) −y, −x, z+1/2; (iii) x−y, x−1, z+1/2; (iv) y+1, x, z; (v) −y, x−y, z; (vi) −y, x−y−1, z. |
As part of a program to investigate the origin of the ferroelectric behaviour in the hexagonal LnMnO3 family, we have determined accurate structural parameters for several members of this series (van Aken et al., 2001a,b,c). Here we report the structure of YbMnO3. Single-crystal growth of YbMnO3 has frequently been described (Yakel et al., 1963; Bertaut et al., 1963), but the structure was first reported by Isobe et al. (1991). Our refinement shows small but significant differences from the work of Isobe et al. (1991), as discussed below.
The hexagonal LnMnO3 family has been described in great detail previously (van Aken et al., 2001a,b,c). The lattice parameter c of 11.5575 (5) Å reported by Isobe et al. (1991) is exceptionally long when compared with other LnMnO3 compounds. However, the value we measured of 11.3561 (7) Å is likely more reliable, as it lies within the range observed for other isostructural compounds, i.e. 11.36–11.42 Å (Yakel et al., 1963; van Aken et al., 2001a,b,c).
The metal–oxygen bond lengths are given in Table 1. In contrast to the report of Isobe et al. (1991), the equatorial Mn—O distances are the same within the measured s.u.'s. More important, the apical Mn—O distances in our report are also the same within the accuracy. They differ by only 0.001 (7) Å, whereas Isobe reports a difference of 0.058 (10) Å. As a result, the Mn is approximately in the centre of its oxygen environment. Likewise, the differences between the apical bond distances of Yb1 and Yb2, 1.140 (18) and 0.876 (10) Å, respectively, are significantly larger than those reported by Isobe et al. (1991), viz. 1.071 and 0.707 Å.
Isobe et al. (1991) only measured reflections of one asymmetric hkl set and therefore included no Bijvoet pairs, meaning that they could obtain no information about the non-centrosymmetry of their sample. Our experiments included over 90% of the Friedel pairs, allowing us to calculate the Flack (1983) parameter. The refinement indicated that our sample contained roughly equal volumes of inversion twins as was also found for YMnO3 (van Aken et al., 2001a). Our results show the significance of a full data set, for twinned non-centrosymmetric samples.