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β-Al2TiO5 (dialuminium titanium pentaoxide), grown by rapid cooling of a melt of equimolar amounts of Al2O3 and TiO2, adopts the same overall structure as that crystallized by more conventional methods, such as sintering. Nevertheless, reinvestigation of this structure has resulted in an improved structure model with previously unknown site preferences determined. Ti prefers the slightly more regular 4c octahedral site, leaving more room for Al at the 8f octahedral site. The formula has been determined as [4c][Al0.626 (7)Ti0.374 (7)][8f][Al0.687 (3)Ti0.313 (3)]2O5.
Supporting information
Key indicators
- Single-crystal X-ray study
- T = 297 K
- Mean () = 0.000 Å
- Disorder in main residue
- R factor = 0.028
- wR factor = 0.028
- Data-to-parameter ratio = 10.3
checkCIF/PLATON results
No syntax errors found
Alert level B
PLAT301_ALERT_3_B Main Residue Disorder ......................... 26.00 Perc.
0 ALERT level A = In general: serious problem
1 ALERT level B = Potentially serious problem
0 ALERT level C = Check and explain
0 ALERT level G = General alerts; check
0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
0 ALERT type 2 Indicator that the structure model may be wrong or deficient
1 ALERT type 3 Indicator that the structure quality may be low
0 ALERT type 4 Improvement, methodology, query or suggestion
Data collection: RAPID-AUTO (Rigaku, 2003); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO (Rigaku 2003), and DIFDAT, SORTRF and ADDREF in Xtal3.7 (Hall
et al., 2000); program(s) used to solve structure: atomic positions from Morosin & Lynch (1972); program(s) used to refine structure: CRYLSQ in Xtal3.7; molecular graphics: DIAMOND (Brandenburg, 2001), and FOURR, SLANT and CONTRS in Xtal3.7; software used to prepare material for publication: BONDLA, ATABLE and CIFIO in Xtal3.7.
Crystal data top
Al2TiO5 | F(000) = 352 |
Mr = 181.84 | Dx = 3.675 Mg m−3 |
Orthorhombic, Cmcm | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2c 2 | Cell parameters from 8632 reflections |
a = 3.605 (2) Å | θ = 3.0–30.5° |
b = 9.445 (4) Å | µ = 3.02 mm−1 |
c = 9.653 (4) Å | T = 297 K |
V = 328.7 (3) Å3 | Block, blue |
Z = 4 | 0.09 × 0.07 × 0.06 mm |
Data collection top
Rigaku R-AXIS RAPID diffractometer | 304 independent reflections |
Radiation source: normal-focus sealed tube | 288 reflections with F > 2σ(F) |
Graphite monochromator | Rint = 0.025 |
ω scans | θmax = 30.5°, θmin = 4.2° |
Absorption correction: gaussian (RAPID-AUTO; Rigaku, 2003) | h = −5→5 |
Tmin = 0.827, Tmax = 0.880 | k = −13→13 |
1774 measured reflections | l = −13→13 |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | 21 constraints |
R[F2 > 2σ(F2)] = 0.028 | w = 1/[σ2(F) + 0.015(F)] |
wR(F2) = 0.028 | (Δ/σ)max = 0.00019 |
S = 1.09 | Δρmax = 0.91 e Å−3 |
288 reflections | Δρmin = −0.73 e Å−3 |
28 parameters | |
Special details top
Refinement. The following constraints were used during refinement: H-atom parameters constrained x(Al1)=0.0 + 1.0*x(Ti1) H-atom
parameters constrained y(Al1)=0.0 + 1.0*y(Ti1) H-atom parameters
constrained z(Al1)=0.0 + 1.0*z(Ti1) H-atom parameters
constrained u11(Al1)=0.0 + 1.0*u11(Ti1) H-atom parameters constrained
u22(Al1)=0.0 + 1.0*u22(Ti1) H-atom parameters constrained u33(Al1)=0.0 +
1.0*u33(Ti1) H-atom parameters constrained u12(Al1)=0.0 + 1.0*u12(Ti1) H-atom
parameters constrained u13(Al1)=0.0 + 1.0*u13(Ti1) H-atom parameters
constrained u23(Al1)=0.0 + 1.0*u23(Ti1) H-atom parameters constrained
pop(Al1)=1.0–1.0*pop(Ti1) H-atom parameters constrained pop(Ti2)=0.5–0.5*pop(Ti1) H-atom parameters
constrained pop(Al2)=0.5 + 0.5*pop(Ti1) H-atom parameters constrained x(Al2)=0.0 + 1.0*x(Ti2) H-atom
parameters constrained y(Al2)=0.0 + 1.0*y(Ti2) H-atom parameters
constrained z(Al2)=0.0 + 1.0*z(Ti2) H-atom parameters
constrained u11(Al2)=0.0 + 1.0*u11(Ti2) H-atom parameters constrained
u22(Al2)=0.0 + 1.0*u22(Ti2) H-atom parameters constrained u33(Al2)=0.0 +
1.0*u33(Ti2) H-atom parameters constrained u12(Al2)=0.0 + 1.0*u12(Ti2) H-atom
parameters constrained u13(Al2)=0.0 + 1.0*u13(Ti2) H-atom parameters
constrained u23(Al2)=0.0 + 1.0*u23(Ti2) i.e., basically placing Ti and Al together at same site as Al3+ and Ti4+
have similar ionic radii, so no hope of distinguish them from each other
during refinement. And the residual electron density does not contradict this
approach··· |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Ti1 | 0 | 0.18547 (10) | 0.25000 | 0.0073 (4) | 0.374 (7) |
Al1 | 0 | 0.18547 (10) | 0.25000 | 0.0073 (4) | 0.626 (7) |
Ti2 | 0 | 0.13551 (7) | 0.56186 (7) | 0.0089 (3) | 0.313 (3) |
Al2 | 0 | 0.13551 (7) | 0.56186 (7) | 0.0089 (3) | 0.687 (3) |
O1 | 0 | 0.7572 (3) | 0.25000 | 0.0084 (12) | |
O2 | 0 | 0.0485 (2) | 0.1165 (2) | 0.0089 (9) | |
O3 | 0 | 0.3125 (2) | 0.0724 (2) | 0.0091 (9) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ti1 | 0.0064 (5) | 0.0088 (5) | 0.0069 (4) | 0 | 0 | 0 |
Al1 | 0.0064 (5) | 0.0088 (5) | 0.0069 (4) | 0 | 0 | 0 |
Ti2 | 0.0062 (3) | 0.0102 (4) | 0.0102 (3) | 0 | 0 | −0.0001 (2) |
Al2 | 0.0062 (3) | 0.0102 (4) | 0.0102 (3) | 0 | 0 | −0.0001 (2) |
O1 | 0.0069 (12) | 0.0101 (12) | 0.0082 (12) | 0 | 0 | 0 |
O2 | 0.0120 (10) | 0.0068 (8) | 0.0080 (9) | 0 | 0 | −0.0013 (7) |
O3 | 0.0059 (8) | 0.0082 (8) | 0.0134 (10) | 0 | 0 | 0.0020 (7) |
Geometric parameters (Å, º) top
Ti1—O2 | 1.826 (2) | Ti2—O2ii | 1.816 (2) |
Ti1—O2i | 1.826 (2) | Ti2—O3iii | 1.8708 (11) |
Ti1—O1 | 1.9253 (14) | Ti2—O3 | 1.8708 (11) |
Ti1—O1 | 1.9253 (14) | Ti2—O2i | 1.907 (2) |
Ti1—O3 | 2.093 (2) | Ti2—O1 | 2.0799 (17) |
Ti1—O3i | 2.093 (2) | Ti2—O3i | 2.115 (2) |
Al1—O2 | 1.826 (2) | Al2—O2ii | 1.816 (2) |
Al1—O2i | 1.826 (2) | Al2—O3iii | 1.8708 (11) |
Al1—O1 | 1.9253 (14) | Al2—O3 | 1.8708 (11) |
Al1—O1 | 1.9253 (14) | Al2—O2i | 1.907 (2) |
Al1—O3 | 2.093 (2) | Al2—O1 | 2.0799 (17) |
Al1—O3i | 2.093 (2) | Al2—O3i | 2.115 (2) |
| | | |
O2—Ti1—O3 | 80.09 (9) | O2ii—Ti2—O1 | 102.30 (10) |
O2—Ti1—O2i | 89.80 (10) | O2ii—Ti2—O2i | 81.35 (9) |
O2—Ti1—O3i | 169.89 (9) | O2ii—Ti2—O3i | 159.08 (9) |
O2—Ti1—O1 | 104.42 (6) | O2ii—Ti2—O3 | 103.61 (6) |
O2—Ti1—O1 | 104.42 (6) | O2ii—Ti2—O3iii | 103.61 (6) |
O3—Ti1—O2i | 169.89 (9) | O1—Ti2—O2i | 176.35 (10) |
O3—Ti1—O3i | 110.03 (9) | O1—Ti2—O3i | 98.62 (10) |
O3—Ti1—O1 | 78.37 (5) | O1—Ti2—O3 | 79.90 (6) |
O3—Ti1—O1 | 78.37 (5) | O1—Ti2—O3iii | 79.90 (6) |
O2i—Ti1—O3i | 80.09 (9) | O2i—Ti2—O3i | 77.73 (9) |
O2i—Ti1—O1 | 104.42 (6) | O2i—Ti2—O3 | 99.33 (7) |
O2i—Ti1—O1 | 104.42 (6) | O2i—Ti2—O3iii | 99.33 (7) |
O3i—Ti1—O1 | 78.37 (5) | O3i—Ti2—O3 | 79.98 (6) |
O3i—Ti1—O1 | 78.37 (5) | O3i—Ti2—O3iii | 79.98 (6) |
O1—Ti1—O1 | 138.82 (13) | O3—Ti2—O3iii | 148.91 (9) |
O2—Al1—O3 | 80.09 (9) | O2ii—Al2—O1 | 102.30 (10) |
O2—Al1—O2i | 89.80 (10) | O2ii—Al2—O2i | 81.35 (9) |
O2—Al1—O3i | 169.89 (9) | O2ii—Al2—O3i | 159.08 (9) |
O2—Al1—O1 | 104.42 (6) | O2ii—Al2—O3 | 103.61 (6) |
O2—Al1—O1 | 104.42 (6) | O2ii—Al2—O3iii | 103.61 (6) |
O3—Al1—O2i | 169.89 (9) | O1—Al2—O2i | 176.35 (10) |
O3—Al1—O3i | 110.03 (9) | O1—Al2—O3i | 98.62 (10) |
O3—Al1—O1 | 78.37 (5) | O1—Al2—O3 | 79.90 (6) |
O3—Al1—O1 | 78.37 (5) | O1—Al2—O3iii | 79.90 (6) |
O2i—Al1—O3i | 80.09 (9) | O2i—Al2—O3i | 77.73 (9) |
O2i—Al1—O1 | 104.42 (6) | O2i—Al2—O3 | 99.33 (7) |
O2i—Al1—O1 | 104.42 (6) | O2i—Al2—O3iii | 99.33 (7) |
O3i—Al1—O1 | 78.37 (5) | O3i—Al2—O3 | 79.98 (6) |
O3i—Al1—O1 | 78.37 (5) | O3i—Al2—O3iii | 79.98 (6) |
O1—Al1—O1 | 138.82 (13) | O3—Al2—O3iii | 148.91 (9) |
Symmetry codes: (i) −x, y, −z+1/2; (ii) −x, −y, z+1/2; (iii) −x+1/2, −y+1/2, z+1/2. |
Comparison of M—O bond lengths (Å) as determined in this report with those
determined by Morosin & Lynch (1972) top | This report | Previous report |
M1—O2i | 1.826 (2) × 2 | 1.823 (4) × 2 |
M1—O1ii, iii | 1.9253 (14) × 2 | 1.920 (2) × 2 |
M1—O3i | 2.093 (2) × 2 | 2.087 (4) × 2 |
M2—O2iv | 1.816 (2) | 1.814 (4) |
M2—O3v, vi | 1.8708 (11) × 2 | 1.864 (1) × 2 |
M2—O2i | 1.907 (2) | 1.900 (4) |
M2—O1vii | 2.0799 (17) | 2.076 (3) |
M2—O3i | 2.115 (2) | 2.114 (4) |
[Symmetry codes: (i) -x, y, 1/2-z; (ii) x-1/2, y-1/2, z; (iii) 1/2+x, y-1/2, z;
(iv) -x, -y, 1/2+z; (v) 1/2-x, 1/2-y, 1/2+z; (vi) -1/2-x, 1/2-y, 1/2+z; (vii)
-x, 1-y, 1/2+z. |
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