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A hitherto unknown phase of sodium titanate, NaTi3O6(OH)·2H2O, was identified as the intermediate species in the synthesis of TiO2 nanorods. This new phase, prepared as nanorods, was investigated by electron diffraction, X-ray powder diffraction, thermogravimetric analysis and high-resolution transmission electron microscopy. The structure was determined ab initio using electron diffraction data collected by the recently developed automated diffraction tomography technique. NaTi3O6(OH)·2H2O crystallizes in the monoclinic space group C2/m. Corrugated layers of corner- and edge-sharing distorted TiO6 octahedra are intercalated with Na+ and water of crystallization. The nanorods are typically affected by pervasive defects, such as mutual layer shifts, that produce diffraction streaks along c*. In addition, edge dislocations were observed in HRTEM images.
Supporting information
Program(s) used to solve structure: Sir2008; program(s) used to refine structure: SHELXL97.
Crystal data top
NaO3Ti1.25 | Z = 8 |
Mr = 130.86 | F(000) = 173 |
Monoclinic, C2/M | Dx = 2.587 Mg m−3 |
a = 21.555 (7) Å | Electron radiation, λ = 0.0197 Å |
b = 3.7583 (9) Å | µ = 0.01 mm−1 |
c = 11.926 (5) Å | T = 295 K |
β = 136.14 (2)° | Elongated wire |
V = 669.5 (4) Å3 | 1.0 × 0.05 × 0.05 mm |
Data collection top
FEI TECNAI F-30 S-TWIN TEM with automated diffraction topography (ADT) and
precession electron diffraction (PED) attachments diffractometer | θmax = 0.7°, θmin = 0.1° |
Not monochromator | h = −26→26 |
1749 measured reflections | k = −4→4 |
628 independent reflections | l = −14→14 |
Rint = 0.158 | |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.267 | Secondary atom site location: difference Fourier map |
wR(F2) = 0.592 | w = 1/[σ2(Fo2) + (0.1P)2] where P = (Fo2 + 2Fc2)/3 |
S = 3.73 | (Δ/σ)max = 0.863 |
628 reflections | Δρmax = 0.73 e Å−3 |
40 parameters | Δρmin = −0.51 e Å−3 |
Crystal data top
NaO3Ti1.25 | V = 669.5 (4) Å3 |
Mr = 130.86 | Z = 8 |
Monoclinic, C2/M | Electron radiation, λ = 0.0197 Å |
a = 21.555 (7) Å | µ = 0.01 mm−1 |
b = 3.7583 (9) Å | T = 295 K |
c = 11.926 (5) Å | 1.0 × 0.05 × 0.05 mm |
β = 136.14 (2)° | |
Data collection top
FEI TECNAI F-30 S-TWIN TEM with automated diffraction topography (ADT) and
precession electron diffraction (PED) attachments diffractometer | 628 independent reflections |
1749 measured reflections | Rint = 0.158 |
Refinement top
R[F2 > 2σ(F2)] = 0.267 | 0 restraints |
wR(F2) = 0.592 | (Δ/σ)max = 0.863 |
S = 3.73 | Δρmax = 0.73 e Å−3 |
628 reflections | Δρmin = −0.51 e Å−3 |
40 parameters | |
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 | x | y | z | Uiso*/Ueq | |
Ti1 | 0.7514 (4) | 0.0000 | 0.3943 (9) | 0.029 (2)* | |
Ti2 | 0.5712 (5) | −0.5000 | 0.5130 (11) | 0.036 (2)* | |
Ti3 | 0.5764 (4) | 0.0000 | 0.3019 (9) | 0.028 (2)* | |
O1 | 0.7286 (9) | 0.0000 | 0.537 (2) | 0.024 (3)* | |
O2 | 0.6272 (13) | 0.0000 | 0.222 (3) | 0.049 (5)* | |
OW1 | 0.3705 (12) | 0.0000 | 0.158 (3) | 0.048 (5)* | |
O3 | 0.7073 (10) | −0.5000 | 0.692 (2) | 0.035 (4)* | |
O4 | 0.6009 (10) | −0.5000 | 0.370 (2) | 0.035 (4)* | |
O5 | 0.5691 (11) | −0.5000 | 0.668 (2) | 0.044 (5)* | |
O6 | 0.5637 (10) | 0.0000 | 0.452 (2) | 0.033 (4)* | |
Na2 | 0.7682 (11) | 0.0000 | 0.916 (3) | 0.052 (4)* | |
OW2 | 0.9124 (14) | 0.0000 | 0.950 (3) | 0.067 (7)* | |
OH | 0.4636 (9) | 0.0000 | 0.119 (2) | 0.031 (4)* | |
Geometric parameters (Å, º) top
Ti1—O3i | 1.775 (19) | Ti3—O6 | 2.00 (2) |
Ti1—O2 | 1.85 (2) | Ti3—O2 | 1.90 (2) |
Ti1—O1ii | 1.983 (5) | O1—Ti1ii | 1.983 (5) |
Ti1—O1i | 1.983 (5) | O1—Ti1i | 1.983 (5) |
Ti1—O1 | 2.086 (18) | OW1—Na2vi | 2.42 (3) |
Ti2—O5 | 1.88 (2) | O3—Ti1i | 1.775 (19) |
Ti2—O5iii | 2.088 (18) | O4—Ti3iv | 1.978 (5) |
Ti2—O6iv | 1.993 (7) | O5—Ti2iii | 2.088 (18) |
Ti2—O6 | 1.993 (7) | O6—Ti2v | 1.993 (7) |
Ti2—O3 | 2.025 (16) | Na2—OW1vi | 2.42 (3) |
Ti3—OH | 1.731 (16) | Na2—Na2vii | 3.23 (3) |
Ti3—O4v | 1.978 (6) | Na2—Na2viii | 3.23 (3) |
Ti3—O4 | 1.978 (5) | | |
| | | |
O3i—Ti1—O2 | 106.4 (10) | O4v—Ti3—O4 | 146.8 (11) |
O3i—Ti1—O1ii | 100.8 (5) | OH—Ti3—O6 | 98.7 (8) |
O2—Ti1—O1ii | 99.6 (4) | O4v—Ti3—O6 | 78.4 (6) |
O3i—Ti1—O1i | 100.8 (5) | O4—Ti3—O6 | 78.4 (6) |
O2—Ti1—O1i | 99.6 (4) | OH—Ti3—O2 | 99.3 (9) |
O1ii—Ti1—O1i | 145.7 (10) | O4v—Ti3—O2 | 97.3 (6) |
O3i—Ti1—O1 | 169.1 (7) | O4—Ti3—O2 | 97.3 (6) |
O2—Ti1—O1 | 84.5 (8) | O6—Ti3—O2 | 162.0 (9) |
O1ii—Ti1—O1 | 76.9 (5) | Ti1ii—O1—Ti1i | 145.7 (10) |
O1i—Ti1—O1 | 76.9 (5) | Ti1ii—O1—Ti1 | 103.1 (5) |
O5—Ti2—O5iii | 88.2 (8) | Ti1i—O1—Ti1 | 103.1 (5) |
O5—Ti2—O6iv | 107.7 (6) | Ti1—O2—Ti3 | 109.6 (12) |
O5iii—Ti2—O6iv | 87.0 (5) | Ti1i—O3—Ti2 | 110.0 (10) |
O5—Ti2—O6 | 107.7 (6) | Ti3—O4—Ti3iv | 146.8 (11) |
O5iii—Ti2—O6 | 87.0 (5) | Ti2—O5—Ti2iii | 91.8 (8) |
O6iv—Ti2—O6 | 143.9 (12) | Ti2v—O6—Ti2 | 143.9 (12) |
O5—Ti2—O3 | 90.7 (8) | Ti2v—O6—Ti3 | 107.3 (6) |
O5iii—Ti2—O3 | 179.0 (9) | Ti2—O6—Ti3 | 107.3 (6) |
O6iv—Ti2—O3 | 93.3 (5) | OW1vi—Na2—Na2vii | 56.0 (6) |
O6—Ti2—O3 | 93.3 (5) | OW1vi—Na2—Na2viii | 56.0 (6) |
OH—Ti3—O4v | 103.4 (5) | Na2vii—Na2—Na2viii | 71.8 (9) |
OH—Ti3—O4 | 103.4 (5) | | |
Symmetry codes: (i) −x+3/2, −y−1/2, −z+1; (ii) −x+3/2, −y+1/2, −z+1; (iii) x+3/2, y−1/2, z+1; (iv) x, y−1, z; (v) x, y+1, z; (vi) x+3/2, y+1/2, z+1; (vii) −x+3/2, −y+1/2, −z+2; (viii) −x+3/2, −y−1/2, −z+2. |
Experimental details
Crystal data |
Chemical formula | NaO3Ti1.25 |
Mr | 130.86 |
Crystal system, space group | Monoclinic, C2/M |
Temperature (K) | 295 |
a, b, c (Å) | 21.555 (7), 3.7583 (9), 11.926 (5) |
β (°) | 136.14 (2) |
V (Å3) | 669.5 (4) |
Z | 8 |
Radiation type | Electron, λ = 0.0197 Å |
µ (mm−1) | 0.01 |
Crystal size (mm) | 1.0 × 0.05 × 0.05 |
|
Data collection |
Diffractometer | FEI TECNAI F-30 S-TWIN TEM with automated diffraction topography (ADT) and
precession electron diffraction (PED) attachments diffractometer |
Absorption correction | – |
No. of measured, independent and observed (?) reflections | 1749, 628, ? |
Rint | 0.158 |
(sin θ/λ)max (Å−1) | 0.620 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.267, 0.592, 3.73 |
No. of reflections | 628 |
No. of parameters | 40 |
(Δ/σ)max | 0.863 |
Δρmax, Δρmin (e Å−3) | 0.73, −0.51 |
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