inorganic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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Al0.5Nb1.5(PO4)3

aDepartment of Physics and Chemistry, Henan Polytechnic University, Jiaozuo, Henan 454000, People's Republic of China
*Correspondence e-mail: iamzd@hpu.edu.cn

(Received 9 January 2011; accepted 31 January 2011; online 12 February 2011)

Single crystals of the title compound, aluminium niobium triphosphate, Al0.5Nb1.5(PO4)3, have been synthesized by a high-temperature reaction in a platinium crucible. The AlIII and NbV atoms occupy the same site on the [\overline{3}] axis, with disorder in the ratio of 1:3. The fundamental building units of the title structure are isolated Al/NbO6 octa­hedra and PO4 tetra­hedra (. 2 symmetry), which are further inter­locked by corner-sharing O atoms, leading to a three-dimensional framework structure with infinite channels along the a axis.

Related literature

For related structures, see: Aatiq & Bakri, (2007[Aatiq, A. & Bakri, R. (2007). Powder Diffr. 22, 47-54.]); Boilot et al. (1987[Boilot, J. P., Collin, G. & Colomban, Ph. (1987). Mater. Res. Bull. 22, 669-676.]); Chakir et al. (2006)[Chakir, M., El Jazouli, A. & de Waal, D. (2006). J. Solid State Chem. 179, 1883-1891.]; Hong (1976[Hong, H. Y. P. (1976). Mater. Res. Bull. 11, 173-182.]); Masquelier et al. (2000[Masquelier, C., Wurm, C., Rodriguez-Carvajal, J., Gaubicher, J. & Nazar, L. (2000). Chem. Mater. 12, 525-532.]); Trubach et al. (2004[Trubach, I. G., Orlova, A. I., Beskrovnyi, A. I., Koryttseva, A. K., Zharinova, M. V., Kurazhkovskaya, V. S. & Lipatova, E. V. (2004). Crystallogr. Rep. 49, 396-400.]); Rodrigo et al. (1989[Rodrigo, J. L., Carrasco, M. P. & Alamo, J. (1989). Mater. Res. Bull. 24, 611-618.]); Zatovskii et al. (2006[Zatovskii, I. V., Ushchapovskaya, T. I., Slobodyanik, N. S. & Ogorodnik, I. V. (2006). Zh. Neorg. Khim. 51, 41-46.]); Zhao et al. (2009[Zhao, D., Xie, Z., Hu, J. M., Zhang, H., Zhang, W. L., Yang, S. L. & Cheng, W. D. (2009). J. Mol. Struct. 922, 127-134.]). For compounds with the same structure type, see: Benmokhtar et al. (2007[Benmokhtar, S., El Jazouli, A., Aatiq, A., Chaminade, J. P., Gravereau, P., Wattiaux, A., Fournes, L. & Grenier, J. C. (2007). J. Solid State Chem. 180, 2004-2012.]); Leclaire et al. (1989[Leclaire, A., Borel, M.-M., Grandin, A. & Raveau, B. (1989). Acta Cryst. C45, 699-701.]). For related structures, see: Brochu et al. (1997[Brochu, R., Louer, M., Alami, M., Alqaraoui, M. & Louer, D. (1997). Mater. Res. Bull. 32, 113-122.]).

Experimental

Crystal data
  • Al0.5Nb1.5(PO4)3

  • Mr = 437.76

  • Trigonal, [R \overline 3c ]

  • a = 8.5679 (6) Å

  • c = 21.898 (2) Å

  • V = 1392.14 (19) Å3

  • Z = 6

  • Mo Kα radiation

  • μ = 2.51 mm−1

  • T = 293 K

  • 0.15 × 0.05 × 0.05 mm

Data collection
  • Bruker SMART 1K CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 1997[Bruker (1997). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.704, Tmax = 0.885

  • 2295 measured reflections

  • 302 independent reflections

  • 298 reflections with I > 2σ(I)

  • Rint = 0.029

Refinement
  • R[F2 > 2σ(F2)] = 0.027

  • wR(F2) = 0.064

  • S = 1.39

  • 302 reflections

  • 27 parameters

  • Δρmax = 0.45 e Å−3

  • Δρmin = −0.39 e Å−3

Data collection: SMART (Bruker, 1997[Bruker (1997). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1997[Bruker (1997). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: DIAMOND (Brandenburg, 2004[Brandenburg, K. (2004). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]).

Supporting information


Comment top

The mixed phosphates AM2(PO4)3 family (A = alkali metals; M = Ti, Zr, Ge, Sn) which usually belong to the NASICON (Na3Zr2Si2PO12: Boilot, et al., 1987) or the NZP (NaZr2(PO4)3: Hong, 1976) structure-type have been extensively investigated for the low thermal expansion behavior of some members. The crystal structure that features a flexible three-dimensional framework of PO4 tetrahedra sharing comers with MO6 octahedra, is amenable to a wide variety of chemical substitutions at the various crystallographic positions, thus yielding a large number of closely related compounds, such as Na3MgZr(PO4)3 (Chakir, et al., 2006), Na3Fe2(PO4)3 (Masquelier, et al., 2000), NaFeNb(PO4)3 (Zatovskii, et al., 2006), NaTi2(PO4)3 (Rodrigo, et al., 1989) and NaGe2P3O12 (Zhao et al., 2009). The three-dimensional network consisting of PO4 and MO6 octahedra delimit two different types of channels in which the A atoms are usually located to compensate the negative charges. It is reported that the A atoms can completely empty in some areas, such as Fe0.5Nb1.5(PO4)3 (Trubach, et al., 2004) and Fe0.5Sb1.5(PO4)3 (Aatiq & Bakri, 2007), Nb2(PO4)3(Leclaire, et al.,1989) and Fe0.5Ti2(PO4)3(Benmokhtar, et al., 2007), etc. In order to inrich this type of compounds, we synthesis the compound Al0.5Nb1.5(PO4)3 by a high-temperature reaction and determine the crystal structure from single-crystal X-ray diffraction analysis.

As shown in Fig. 1, the asymmetric unit of Al0.5Nb1.5(PO4)3 contains a single P and Al/Nb atoms. The P atom is four coordinated by four oxygen atoms, forming isolated PO4 tetrahedron. Al and Nb atoms are in mixed occupancy disorder locating at the 3 axes with the moral ratio of 1: 3, being coordinated by six oxygen atoms to form Al/NbO6 octahedra. Al/NbO6 octahedra and PO4 tetrahedra are further interconnected via corner-sharing O atoms to form the three-dimensional framework of Al0.5Nb1.5(PO4)3, as shown in Fig. 2. The Al/Nb—O bonds have two groups of different distances, that is, 1.913 (3) and 1.949 (3) Å. The PO4 tetrahedra are regular with two groups of P–O bond distances of 1.521 (3) and 1.529 (3) Å, and O–P–O bond angles weak dispersion from 107.91 (16) to 111.3 (2)o, which is about the ideal value of 109.48°. On the other hand, this structure can be viewed as a NZP structure, in which the Na atom sites empty and the Zr atoms site are replaced by Al and Nb atoms in disordered manner on the principle of aliovalent pair combination Zr4+ 0.25 A l3+ + 0.73 N b5+.

Related literature top

For related structures, see: Aatiq & Bakri, (2007); Boilot et al. (1987); Chakir et al. (2006); Hong (1976); Masquelier et al. (2000); Trubach et al. (2004); Rodrigo et al. (1989); Zatovskii et al. (2006); Zhao et al. (2009). For compounds with the same structure type, see: Benmokhtar et al. (2007); Leclaire et al. (1989). For related structures, see: Brochu et al. (1997).

Experimental top

The finely ground reagents K2CO3, Al2O3, Nb2O5 and NH4H2PO4 were mixed in the molar ratio K: Al: Nb: P = 1: 3: 10: 20, were placed in a Pt crucible, and heated at 573 K for 4 h. The mixture was then re-ground and heated at 1473 K for 20 h, then cooled to 973 K at a rate of 3 K h-1, and finally quenched to room temperature. A few colorless crystals of the title compound with prismatic shape were obtained.

Refinement top

The structure contains substitutional disorder in which Al1 and Nb1 occupy the same position. The atomic positional and anisotropic displacement parameters of Al1 and Nb1 atoms were constrained to be identical by using EADP and EXYZ constraint instructions (SHELXL97; Sheldrick, 2008). The ratio of Al1 and Nb1 was fixed to 1: 3 to achieve charge balance.

Computing details top

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2004); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The expanded asymmetric unit of Al0.5Nb1.5(PO4)3 showing the coordination environments of the P and Al/Nb atoms. The displacement ellipsoids are drawn at the 50% probability level.[Symmetry codes: (i) x, y, z; (ii) -x + y, -x, z; (iii) -y, x-y, z; (iv) 0.66667 - x, 0.33333 - x + y, 0.83333 - z; (v) 0.66667 - y, 0.33333 - x, -0.16667 + z; (vi) -1/3 + x, 1/3 + x-y, -0.16667 + z; (vii) -0.33333 - x + y, -2/3 + y, -0.16667 + z.]
[Figure 2] Fig. 2. View of the crystal structure of Al0.5Nb1.5(PO4)3 along [010]. PO4 and Al/NbO6 units are given in the polyhedral representation.
aluminium(III) triniobium(V) phosphate(V) top
Crystal data top
Al0.5Nb1.5(PO4)3Dx = 3.133 Mg m3
Mr = 437.76Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3cCell parameters from 247 reflections
Hall symbol: -R 3 2"cθ = 2.6–25.0°
a = 8.5679 (6) ŵ = 2.51 mm1
c = 21.898 (2) ÅT = 293 K
V = 1392.14 (19) Å3Prism, colourless
Z = 60.15 × 0.05 × 0.05 mm
F(000) = 1254
Data collection top
Bruker SMART 1K CCD area-detector
diffractometer
302 independent reflections
Radiation source: fine-focus sealed tube298 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.029
ω scansθmax = 25.7°, θmin = 3.3°
Absorption correction: multi-scan
(SADABS; Bruker, 1997)
h = 710
Tmin = 0.704, Tmax = 0.885k = 108
2295 measured reflectionsl = 2621
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.027Secondary atom site location: difference Fourier map
wR(F2) = 0.064 w = 1/[σ2(Fo2) + (0.0163P)2 + 17.3988P]
where P = (Fo2 + 2Fc2)/3
S = 1.39(Δ/σ)max < 0.001
302 reflectionsΔρmax = 0.45 e Å3
27 parametersΔρmin = 0.39 e Å3
Crystal data top
Al0.5Nb1.5(PO4)3Z = 6
Mr = 437.76Mo Kα radiation
Trigonal, R3cµ = 2.51 mm1
a = 8.5679 (6) ÅT = 293 K
c = 21.898 (2) Å0.15 × 0.05 × 0.05 mm
V = 1392.14 (19) Å3
Data collection top
Bruker SMART 1K CCD area-detector
diffractometer
302 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1997)
298 reflections with I > 2σ(I)
Tmin = 0.704, Tmax = 0.885Rint = 0.029
2295 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0270 restraints
wR(F2) = 0.064 w = 1/[σ2(Fo2) + (0.0163P)2 + 17.3988P]
where P = (Fo2 + 2Fc2)/3
S = 1.39Δρmax = 0.45 e Å3
302 reflectionsΔρmin = 0.39 e Å3
27 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
xyzUiso*/UeqOcc. (<1)
Nb10.00000.00000.35896 (3)0.0091 (2)0.75
Al10.00000.00000.35896 (3)0.0091 (2)0.25
P10.33330.38482 (17)0.41670.0143 (4)
O10.1675 (4)0.1984 (4)0.40796 (12)0.0173 (6)
O20.3025 (4)0.4696 (4)0.47305 (12)0.0194 (7)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Nb10.0092 (3)0.0092 (3)0.0090 (4)0.00460 (14)0.0000.000
Al10.0092 (3)0.0092 (3)0.0090 (4)0.00460 (14)0.0000.000
P10.0179 (8)0.0126 (5)0.0141 (7)0.0089 (4)0.0043 (6)0.0022 (3)
O10.0172 (15)0.0132 (14)0.0183 (14)0.0053 (13)0.0039 (12)0.0051 (11)
O20.0253 (16)0.0164 (15)0.0162 (14)0.0102 (14)0.0008 (12)0.0052 (11)
Geometric parameters (Å, º) top
Nb1—O11.913 (3)P1—O21.521 (3)
Nb1—O1i1.913 (3)P1—O2vi1.521 (3)
Nb1—O1ii1.913 (3)P1—O1vi1.529 (3)
Nb1—O2iii1.949 (3)P1—O11.529 (3)
Nb1—O2iv1.949 (3)O2—Al1vii1.949 (3)
Nb1—O2v1.949 (3)O2—Nb1vii1.949 (3)
O1—Nb1—O1i91.63 (12)O1ii—Nb1—O2v89.81 (12)
O1—Nb1—O1ii91.63 (12)O2iii—Nb1—O2v88.66 (12)
O1i—Nb1—O1ii91.63 (12)O2iv—Nb1—O2v88.66 (12)
O1—Nb1—O2iii89.81 (12)O2—P1—O2vi111.3 (2)
O1i—Nb1—O2iii89.86 (12)O2—P1—O1vi110.32 (15)
O1ii—Nb1—O2iii177.90 (12)O2vi—P1—O1vi107.91 (16)
O1—Nb1—O2iv177.90 (12)O2—P1—O1107.91 (16)
O1i—Nb1—O2iv89.81 (12)O2vi—P1—O1110.32 (15)
O1ii—Nb1—O2iv89.86 (12)O1vi—P1—O1109.1 (2)
O2iii—Nb1—O2iv88.66 (12)P1—O1—Nb1152.96 (18)
O1—Nb1—O2v89.86 (12)P1—O2—Al1vii155.8 (2)
O1i—Nb1—O2v177.90 (12)P1—O2—Nb1vii155.8 (2)
Symmetry codes: (i) x+y, x, z; (ii) y, xy, z; (iii) y+2/3, x+1/3, z1/6; (iv) x+y1/3, y2/3, z1/6; (v) x1/3, xy+1/3, z1/6; (vi) x+2/3, x+y+1/3, z+5/6; (vii) x+y+1/3, y+2/3, z+1/6.

Experimental details

Crystal data
Chemical formulaAl0.5Nb1.5(PO4)3
Mr437.76
Crystal system, space groupTrigonal, R3c
Temperature (K)293
a, c (Å)8.5679 (6), 21.898 (2)
V3)1392.14 (19)
Z6
Radiation typeMo Kα
µ (mm1)2.51
Crystal size (mm)0.15 × 0.05 × 0.05
Data collection
DiffractometerBruker SMART 1K CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 1997)
Tmin, Tmax0.704, 0.885
No. of measured, independent and
observed [I > 2σ(I)] reflections
2295, 302, 298
Rint0.029
(sin θ/λ)max1)0.610
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.027, 0.064, 1.39
No. of reflections302
No. of parameters27
w = 1/[σ2(Fo2) + (0.0163P)2 + 17.3988P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å3)0.45, 0.39

Computer programs: SMART (Bruker, 1997), SAINT (Bruker, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2004), SHELXTL (Sheldrick, 2008).

 

Acknowledgements

The authors acknowledge the Doctoral Foundation of Henan Polytechnic University (B2010–92, 648483).

References

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First citationBenmokhtar, S., El Jazouli, A., Aatiq, A., Chaminade, J. P., Gravereau, P., Wattiaux, A., Fournes, L. & Grenier, J. C. (2007). J. Solid State Chem. 180, 2004–2012.  Web of Science CrossRef CAS Google Scholar
First citationBoilot, J. P., Collin, G. & Colomban, Ph. (1987). Mater. Res. Bull. 22, 669–676.  CrossRef CAS Google Scholar
First citationBrandenburg, K. (2004). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBrochu, R., Louer, M., Alami, M., Alqaraoui, M. & Louer, D. (1997). Mater. Res. Bull. 32, 113–122.  CrossRef CAS Web of Science Google Scholar
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First citationChakir, M., El Jazouli, A. & de Waal, D. (2006). J. Solid State Chem. 179, 1883–1891.  Web of Science CrossRef CAS Google Scholar
First citationHong, H. Y. P. (1976). Mater. Res. Bull. 11, 173–182.  CrossRef CAS Web of Science Google Scholar
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First citationMasquelier, C., Wurm, C., Rodriguez-Carvajal, J., Gaubicher, J. & Nazar, L. (2000). Chem. Mater. 12, 525–532.  Web of Science CrossRef CAS Google Scholar
First citationRodrigo, J. L., Carrasco, M. P. & Alamo, J. (1989). Mater. Res. Bull. 24, 611–618.  CrossRef CAS Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationTrubach, I. G., Orlova, A. I., Beskrovnyi, A. I., Koryttseva, A. K., Zharinova, M. V., Kurazhkovskaya, V. S. & Lipatova, E. V. (2004). Crystallogr. Rep. 49, 396–400.  Web of Science CrossRef CAS Google Scholar
First citationZatovskii, I. V., Ushchapovskaya, T. I., Slobodyanik, N. S. & Ogorodnik, I. V. (2006). Zh. Neorg. Khim. 51, 41–46.  CAS Google Scholar
First citationZhao, D., Xie, Z., Hu, J. M., Zhang, H., Zhang, W. L., Yang, S. L. & Cheng, W. D. (2009). J. Mol. Struct. 922, 127–134.  Web of Science CrossRef CAS Google Scholar

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