Aluminium cyclo­hexa­phosphate

Oudahmane, A.; Mbarek, A.; El-Ghozzi, M.; Avignant, D.

doi:10.1107/S1600536810005374

inorganic compounds

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ISSN: 2056-9890

Volume 66| Part 3| March 2010| Page i17

doi:10.1107/S1600536810005374

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Aluminium cyclohexaphosphate

Abdelghani Oudahmane,^a Aïcha Mbarek,^b Malika El-Ghozzi ^c and Daniel Avignant ^c ^*

^aLaboratoire de Chimie du Solide Minéral, Département de Chimie, Faculté des Sciences Semlalia, Université Cadi Ayyad, Marrakech, Morocco, ^bLaboratoire de Chimie Industrielle, Département de Génie des Matériaux, Ecole Nationale d'Ingénieurs de Sfax, Université de Sfax, BP W 3038, Sfax, Tunisia, and ^cLaboratoire des Matériaux Inorganiques, UMR CNRS 6002, Université Blaise Pascal, 24 Avenue des Landais, 63177 Aubière, France
^*Correspondence e-mail: Daniel.avignant@univ-bpclermont.fr

(Received 27 January 2010; accepted 9 February 2010; online 13 February 2010)

Single crystals of the title compound, Al₂P₆O₁₈, were obtained by solid-state reaction. The monoclinic structure is isotypic with its Cr^III, Ga^III and Ru^III analogues and is built up of six-membered phosphate ring anions, P₆O₁₈⁶⁻, isolated from each other and further linked by isolated AlO₆ octahedra by sharing corners. Each AlO₆ octahedron is linked to four P₆O₁₈⁶⁻ rings. More accurately, two rings are linked through bidentate diphosphate groups attached in the cis-positions to the AlO₆ octahedron. The other two rings are linked to the two remaining corners, also in cis-positions of the AlO₆ octahedron.

Related literature

The title compound was first synthesized by Kanene et al. (1985 ) and its unit cell determined from Weissenberg photographs. Isotypic compounds have been reported: Ga₂P₆O₁₈ (Chudinova et al., 1987 ); Cr₂P₆O₁₈ (Bagieu-Beucher & Guitel, 1977 ) and Ru₂P₆O₁₈ (Fukuoka et al., 1995 ). For a review of the crystal chemistry of cyclohexaphosphates, see: Durif (1995 , 2005 ). For applications of aluminium phosphate, see: Vippola et al. (2000 ). For the structures of other cyclohexaphosphates with the P₆O₁₈⁶⁻ anion, see: Averbuch-Pouchot & Durif (1991a ,b ,c ).

Experimental

Crystal data

Al₂P₆O₁₈
M_r = 527.79
Monoclinic, P 2₁ /c
a = 6.0931 (2) Å
b = 15.0676 (4) Å
c = 8.2016 (3) Å
β = 105.166 (1)°
V = 726.75 (4) Å³
Z = 2
Mo Kα radiation
μ = 0.96 mm⁻¹
T = 296 K
0.16 × 0.07 × 0.06 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ) T_min = 0.860, T_max = 0.945
6548 measured reflections
1674 independent reflections
1398 reflections with I > 2σ(I)
R_int = 0.035

Refinement

R[F² > 2σ(F²)] = 0.032
wR(F²) = 0.130
S = 1.16
1674 reflections
118 parameters
Δρ_max = 0.56 e Å⁻³
Δρ_min = −0.71 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

P1—O3	1.471 (2)
P1—O5	1.478 (2)
P1—O7	1.587 (2)
P1—O9	1.594 (3)
P2—O4	1.482 (2)
P2—O6	1.487 (2)
P2—O7ⁱ	1.579 (2)
P2—O8	1.593 (2)
P3—O1	1.476 (2)
P3—O2	1.479 (3)
P3—O9ⁱⁱ	1.594 (2)
P3—O8ⁱⁱⁱ	1.597 (2)
Al—O3	1.852 (2)
Al—O2^iv	1.873 (3)
Al—O1	1.877 (3)
Al—O4	1.887 (3)
Al—O5^v	1.889 (3)
Al—O6ⁱⁱⁱ	1.904 (2)

P2^v—O7—P1	139.91 (16)
P2—O8—P3ⁱⁱⁱ	130.56 (16)
P1—O9—P3^vi	129.42 (16)
Symmetry codes: (i) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[x-1, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) -x+1, -y, -z; (iv) x+1, y, z; (v) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (vi) $[x+1, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CaRine (Boudias & Monceau, 1998 ) and ORTEP-3 (Farrugia, 1997 ); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810005374/wm2303sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810005374/wm2303Isup2.hkl

checkCIF report

Comment top

Although the Al₂P₆0₁₈ cyclohexaphosphate is known since twenty five years (Kanene et al., 1985), its crystal structure has never been refined from single crystal X-ray diffraction data. This paper deals with this purpose.

The crystal structure of Al₂P₆0₁₈ is isotypic with Cr₂P₆O₁₈ (Bagieu-Beucher & Guitel, 1977), Ga₂P₆O₁₈ (Chudinova et al., 1987) and Ru₂P₆O₁₈ (Fukuoka et al., 1995). It is built up of six-membered phosphate ring anions (P₆O₁₈)^6- isolated from each others and further linked by AlO₆ octahedra by sharing corners. These centrosymmetric ring anions (P₆O₁₈)^6- are located around inversion centers at 0 0 1/2 and 0 1/2 0 (Fig. 1a). Their mean planes are parallel to either (121) or (121 ) planes (Fig. 1 b). Each AlO₆ octahedron is linked to four P₆O₁₈ rings. More accurately, two rings are linked through bidentate diphosphate groups attached in cis-positions to the AlO₆ octahedron. The two other rings are linked to the two remaining corners of the AlO₆ octahedron (Fig. 2). Each (P₆O₁₈)^6- ring anion is connected to eight AlO₆ octahedra by corner-sharing. Four diphosphate groups of the ring anion including P(3)O₄ and either P(1)O₄ or P(2)O₄ tetrahedra are bidentate whereas the P(1)O₄—P(2)O₄ couple does not bind in a bidentate fashion. This may be correlated with the value of the P(1)—O—P(2) angle (139.91 (16)°) which is greater than P(2)—O—P(3) (130.56 (16)°) and P(1)—O—P(3) (129.42 (16) °) ones and also to the P(1)—P(2) distance (2.9741 (12) Å) slightly greater than P(2)—P(3) = 2.8970 (11) Å and P(1)—P(3) = 2.8826 (12) Å ones.

A survey of the internal symmetry of the (P₆O₁₈)^6- ring anions shows that most of them are centrosymmetric with P—P—P angles spreading from 87.8° to 142.8° (Averbuch-Pouchot & Durif, 1991a), i.e. with large deviations from the ideal value of 120°. When the (P₆O₁₈)^6- ring anion has internal 1 symmetry, it is built up of three independent P atoms and hence there are three characteristic α_i = P—P—P angles in the ring (α₁ = P₁—P₂—P₃, α₂ = P₂—P₃—P₁, α₃ = P₃—P₁—P₂). When taking the δ = Σ_i|120-α_i| parameter as a rough measure of the ring distorsion, Al₂P₆O₁₈ exhibits the third lowest δ = 15.28° value after its homologous congeners Ru₂P₆O₁₈ (δ = 13.78°) and Cr₂P₆O₁₈ (δ = 14.39°). It should be noted that the characteristic P—P—P angles for both isotypic Ga₂P₆O₁₈ and Fe₂P₆O₁₈ structures have not been reported. The highest δ values calculated from data for other cyclohexaphosphates reported up to date are related to Cu₂(NH₄)₂P₆O₁₈^.8H₂O (δ = 65.98°) (Averbuch-Pouchot & Durif, 1991b) and Ag₄Li₂P₆O₁₈.2H₂O (δ = 67.29°) (Averbuch-Pouchot & Durif, 1991c).

For applications of aluminium phosphate, see: Vippola et al. (2000). For general reviews on the crystal chemistry of cyclohexaphosphates, see: Durif (1995) and Durif (2005).

Related literature top

The title compound was first synthesized by Kanene et al. (1985) and its unit cell determined from Weissenberg photographs. Isotypic compounds have been reported: Ga₂P₆O₁₈ (Chudinova et al., 1987); Cr₂P₆O₁₈ (Bagieu-Beucher et al., 1977) and Ru₂P₆O₁₈ (Fukuoka et al., 1995). For a review of the crystal chemistry of cyclohexaphosphates, see: Durif (1995, 2005). For applications of aluminium phosphate, see: Vippola et al. (2000). For the structures of other cyclohexaphosphates with the P₆O₁₈^6- anion, see: Averbuch-Pouchot & Durif (1991a,b,c).

Experimental top

Single crystals of the title compound have been obtained by reacting Al₂O₃ with (NH₄)H₂PO₄ in an alumina boat. A mixture of these reagents in the molar ratio 1:6 was used for the synthesis. The mixture was first heated at 473 K for 24 h. Afterwards the temperature was successively raised to 573 K for 12 h, then to 673 K for 12 additional hours and finally to 923 K. After a heating period of 48 h at this temperature, the sample was cooled to room temperature by switching the furnace off. Translucent rhombs of Al₂P₆O₁₈ were extracted from the batch.

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CaRine (Boudias & Monceau, 1998) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

Fig. 1. (a) ORTEP-3 view of the centrosymmetric (P₆O₁₈)^6- ring anion. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes: (iii) 2 - x, 1/2 + y, 1/2 - z; (iv) 1 - x, 1 - y, -z; (v) 2 - x, 1 - y, 1 - z; (vi) x, 1 + y, z; (vii) 1 + x, 1 + y, 1 + z; (viii) x, 3/2 - y, 1/2 + z. (b) Partial projection along [101] showing the orientation of the mean planes of the (P₆O₁₈)^6- ring anions.

Fig. 2. Partial projection showing the connection between the (P₆O₁₈)^6- ring anion and the AlO₆ octahedra.

Aluminium hexacyclophosphate top

Crystal data top

Al₂P₆O₁₈	F(000) = 520
M_r = 527.79	D_x = 2.412 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2041 reflections
a = 6.0931 (2) Å	θ = 3.5–27.5°
b = 15.0676 (4) Å	µ = 0.96 mm⁻¹
c = 8.2016 (3) Å	T = 296 K
β = 105.166 (1)°	Rhombic, colourless
V = 726.75 (4) Å³	0.16 × 0.07 × 0.06 mm
Z = 2

Data collection top

Bruker APEXII CCD diffractometer	1674 independent reflections
Radiation source: fine-focus sealed tube	1398 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.035
Detector resolution: 8.3333 pixels mm^-1	θ_max = 27.5°, θ_min = 2.7°
ϕ and ω scans	h = −7→7
Absorption correction: multi-scan (SADABS; Bruker, 2008)	k = −11→19
T_min = 0.860, T_max = 0.945	l = −10→10
6548 measured reflections

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F² > 2σ(F²)] = 0.032	Secondary atom site location: difference Fourier map
wR(F²) = 0.130	w = 1/[σ²(F_o²) + (0.0787P)² + 0.2264P] where P = (F_o² + 2F_c²)/3
S = 1.16	(Δ/σ)_max < 0.001
1674 reflections	Δρ_max = 0.56 e Å⁻³
118 parameters	Δρ_min = −0.71 e Å⁻³

Crystal data top

Al₂P₆O₁₈	V = 726.75 (4) Å³
M_r = 527.79	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 6.0931 (2) Å	µ = 0.96 mm⁻¹
b = 15.0676 (4) Å	T = 296 K
c = 8.2016 (3) Å	0.16 × 0.07 × 0.06 mm
β = 105.166 (1)°

Data collection top

Bruker APEXII CCD diffractometer	1674 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2008)	1398 reflections with I > 2σ(I)
T_min = 0.860, T_max = 0.945	R_int = 0.035
6548 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.032	118 parameters
wR(F²) = 0.130	0 restraints
S = 1.16	Δρ_max = 0.56 e Å⁻³
1674 reflections	Δρ_min = −0.71 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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	U_iso*/U_eq
P1	0.70149 (15)	0.33738 (5)	0.01706 (11)	0.0049 (2)
P2	0.64525 (14)	0.04431 (5)	0.21869 (11)	0.0050 (2)
P3	0.08497 (14)	0.11301 (5)	−0.20937 (11)	0.0054 (2)
Al	0.61549 (17)	0.13831 (6)	−0.12313 (13)	0.0046 (3)
O1	0.3051 (4)	0.15855 (15)	−0.1454 (3)	0.0082 (5)
O2	−0.0766 (4)	0.11484 (16)	−0.1026 (3)	0.0090 (5)
O3	0.6755 (4)	0.25850 (15)	−0.0920 (3)	0.0078 (5)
O4	0.6653 (4)	0.12162 (15)	0.1117 (3)	0.0076 (5)
O5	0.5656 (4)	0.34555 (16)	0.1415 (3)	0.0084 (5)
O6	0.4448 (4)	−0.01495 (15)	0.1608 (3)	0.0073 (5)
O7	0.6509 (5)	0.42395 (15)	−0.0967 (3)	0.0109 (5)
O8	0.8737 (4)	−0.01227 (15)	0.2539 (3)	0.0110 (5)
O9	0.9653 (4)	0.34779 (16)	0.1085 (3)	0.0107 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
P1	0.0052 (5)	0.0050 (4)	0.0042 (5)	−0.0007 (3)	0.0008 (3)	0.0001 (3)
P2	0.0060 (5)	0.0041 (4)	0.0050 (5)	−0.0003 (3)	0.0014 (3)	−0.0009 (3)
P3	0.0036 (5)	0.0058 (4)	0.0069 (5)	0.0007 (3)	0.0015 (3)	0.0002 (3)
Al	0.0034 (5)	0.0055 (5)	0.0052 (5)	−0.0006 (4)	0.0015 (4)	−0.0003 (3)
O1	0.0045 (12)	0.0065 (12)	0.0136 (13)	−0.0012 (9)	0.0025 (10)	−0.0021 (9)
O2	0.0050 (12)	0.0127 (12)	0.0094 (13)	−0.0002 (9)	0.0024 (10)	0.0014 (10)
O3	0.0110 (13)	0.0045 (11)	0.0077 (12)	−0.0028 (9)	0.0020 (10)	−0.0015 (9)
O4	0.0119 (13)	0.0059 (11)	0.0053 (12)	−0.0022 (9)	0.0025 (10)	−0.0007 (9)
O5	0.0066 (13)	0.0132 (12)	0.0057 (12)	0.0000 (9)	0.0020 (10)	0.0003 (9)
O6	0.0060 (12)	0.0063 (12)	0.0098 (12)	0.0002 (9)	0.0025 (10)	−0.0012 (9)
O7	0.0221 (15)	0.0059 (12)	0.0053 (12)	0.0033 (9)	0.0045 (11)	0.0022 (9)
O8	0.0061 (12)	0.0073 (12)	0.0175 (14)	−0.0004 (9)	−0.0007 (10)	−0.0038 (9)
O9	0.0052 (13)	0.0186 (13)	0.0084 (13)	−0.0021 (10)	0.0019 (10)	−0.0062 (10)

Geometric parameters (Å, º) top

P1—O3	1.471 (2)	Al—O3	1.852 (2)
P1—O5	1.478 (2)	Al—O2^iv	1.873 (3)
P1—O7	1.587 (2)	Al—O1	1.877 (3)
P1—O9	1.594 (3)	Al—O4	1.887 (3)
P2—O4	1.482 (2)	Al—O5^v	1.889 (3)
P2—O6	1.487 (2)	Al—O6ⁱⁱⁱ	1.904 (2)
P2—O7ⁱ	1.579 (2)	O2—Al^vi	1.873 (3)
P2—O8	1.593 (2)	O5—Alⁱ	1.889 (3)
P3—O1	1.476 (2)	O6—Alⁱⁱⁱ	1.904 (2)
P3—O2	1.479 (3)	O7—P2^v	1.579 (2)
P3—O9ⁱⁱ	1.594 (2)	O8—P3ⁱⁱⁱ	1.597 (2)
P3—O8ⁱⁱⁱ	1.597 (2)	O9—P3^vii	1.594 (3)

O3—P1—O5	119.77 (14)	O3—Al—O4	90.93 (11)
O3—P1—O7	109.47 (14)	O2^iv—Al—O4	89.61 (11)
O5—P1—O7	106.27 (14)	O1—Al—O4	90.56 (12)
O3—P1—O9	107.50 (14)	O3—Al—O5^v	89.33 (11)
O5—P1—O9	110.17 (14)	O2^iv—Al—O5^v	90.32 (11)
O7—P1—O9	102.27 (14)	O1—Al—O5^v	89.50 (11)
O4—P2—O6	118.09 (14)	O4—Al—O5^v	179.74 (12)
O4—P2—O7ⁱ	110.17 (13)	O3—Al—O6ⁱⁱⁱ	178.54 (12)
O6—P2—O7ⁱ	107.36 (14)	O2^iv—Al—O6ⁱⁱⁱ	88.66 (11)
O4—P2—O8	108.93 (14)	O1—Al—O6ⁱⁱⁱ	89.77 (11)
O6—P2—O8	110.01 (13)	O4—Al—O6ⁱⁱⁱ	90.46 (11)
O7ⁱ—P2—O8	100.91 (14)	O5^v—Al—O6ⁱⁱⁱ	89.29 (11)
O1—P3—O2	117.68 (15)	P3—O1—Al	139.30 (16)
O1—P3—O9ⁱⁱ	108.14 (14)	P3—O2—Al^vi	139.15 (17)
O2—P3—O9ⁱⁱ	109.62 (14)	P1—O3—Al	149.33 (16)
O1—P3—O8ⁱⁱⁱ	109.89 (14)	P2—O4—Al	133.84 (15)
O2—P3—O8ⁱⁱⁱ	108.82 (14)	P1—O5—Alⁱ	138.32 (16)
O9ⁱⁱ—P3—O8ⁱⁱⁱ	101.47 (14)	P2—O6—Alⁱⁱⁱ	138.20 (15)
O3—Al—O2^iv	90.88 (11)	P2^v—O7—P1	139.91 (16)
O3—Al—O1	90.69 (11)	P2—O8—P3ⁱⁱⁱ	130.56 (16)
O2^iv—Al—O1	178.43 (11)	P1—O9—P3^vii	129.42 (16)

Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) x−1, −y+1/2, z−1/2; (iii) −x+1, −y, −z; (iv) x+1, y, z; (v) x, −y+1/2, z−1/2; (vi) x−1, y, z; (vii) x+1, −y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formula	Al₂P₆O₁₈
M_r	527.79
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	6.0931 (2), 15.0676 (4), 8.2016 (3)
β (°)	105.166 (1)
V (Å³)	726.75 (4)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.96
Crystal size (mm)	0.16 × 0.07 × 0.06

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2008)
T_min, T_max	0.860, 0.945
No. of measured, independent and observed [I > 2σ(I)] reflections	6548, 1674, 1398
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.032, 0.130, 1.16
No. of reflections	1674
No. of parameters	118
Δρ_max, Δρ_min (e Å⁻³)	0.56, −0.71

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), CaRine (Boudias & Monceau, 1998) and ORTEP-3 (Farrugia, 1997), SHELXTL (Sheldrick, 2008).

Selected geometric parameters (Å, º) top

P1—O3	1.471 (2)	P3—O2	1.479 (3)
P1—O5	1.478 (2)	P3—O9ⁱⁱ	1.594 (2)
P1—O7	1.587 (2)	P3—O8ⁱⁱⁱ	1.597 (2)
P1—O9	1.594 (3)	Al—O3	1.852 (2)
P2—O4	1.482 (2)	Al—O2^iv	1.873 (3)
P2—O6	1.487 (2)	Al—O1	1.877 (3)
P2—O7ⁱ	1.579 (2)	Al—O4	1.887 (3)
P2—O8	1.593 (2)	Al—O5^v	1.889 (3)
P3—O1	1.476 (2)	Al—O6ⁱⁱⁱ	1.904 (2)

P2^v—O7—P1	139.91 (16)	P1—O9—P3^vi	129.42 (16)
P2—O8—P3ⁱⁱⁱ	130.56 (16)

Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) x−1, −y+1/2, z−1/2; (iii) −x+1, −y, −z; (iv) x+1, y, z; (v) x, −y+1/2, z−1/2; (vi) x+1, −y+1/2, z+1/2.

References

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