LiDy(PO3)4

Chehimi-Moumen, F.; Férid, M.

doi:10.1107/S1600536808016875

inorganic compounds

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ISSN: 2056-9890

Volume 64| Part 7| July 2008| Page i45

doi:10.1107/S1600536808016875

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LiDy(PO₃)₄

Fathia Chehimi-Moumen ^a and Mokhtar Férid ^b ^*

^aLaboratoire d'Application de la Chimie aux Ressources et Substances Naturelles et à l'Environnement, Faculté des Sciences de Bizerte, 7021 Zarzouna, Tunisia, and ^bUnité des Matériaux de Terres Rares, Centre National de Recherches en Sciences des Matériaux, BP 95, 2050 Hammam-Lif, Tunisia
^*Correspondence e-mail: mokhtar.ferid@inrst.rnrt.tn

(Received 30 May 2008; accepted 3 June 2008; online 13 June 2008)

Single crystals of lithium dysprosium polyphosphate, LiDy(PO₃)₄, were prepared by the flux method. The atomic arrangement is built up by infinite (PO₃)_n chains extending along the b axis. Dy³⁺ and Li⁺ cations alternate in the middle of four such chains, with Dy⋯Li distances of 3.54 (1) and 3.48 (1) Å. The DyO₈ dodecahedra and LiO₄ tetrahedra deviate significantly from the ideal geometry. Both Dy and Li occupy special positions (Wyckoff position 4e, site symmetry 2).

Related literature

For related literature, see: Averbuch-Pouchot & Bagieu Beucher (1987 ); Ben Zarkouna et al. (2005 ; 2007 ); Ben Zarkouna & Driss (2004 ); Durif (1995 ); Ettis et al. (2006 ); Férid (2006 ); Hashimoto et al. (1991 ); Hong (1975 ); Horchani et al. (2003 ); Liu & Li (1983 ); Chehimi-Moumen & Férid (2007 ); Koizumi (1976 ); Yamada et al. (1974 ).

Experimental

Crystal data

LiDy(PO₃)₄
M_r = 485.32
Monoclinic, C 2/c
a = 16.269 (1) Å
b = 7.0236 (3) Å
c = 9.5781 (8) Å
β = 126.106 (3)°
V = 884.24 (10) Å³
Z = 4
Mo Kα radiation
μ = 9.24 mm⁻¹
T = 295 (2) K
0.10 × 0.09 × 0.08 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: analytical (de Meulenaer & Tompa, 1965 ) T_min = 0.42, T_max = 0.45
3313 measured reflections
1021 independent reflections
858 reflections with I > 2σ(I)
R_int = 0.080

Refinement

R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.087
S = 0.95
1021 reflections
83 parameters
Δρ_max = 2.26 e Å⁻³
Δρ_min = −2.13 e Å⁻³

Data collection: COLLECT (Nonius, 1998 ); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, lidy. DOI: 10.1107/S1600536808016875/fi2064sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808016875/fi2064Isup2.hkl

checkCIF report

Comment top

Condensed phosphates of rare earth and monovalent cations of general formula M^ILn(PO₃)₄ have attracted large interest in the literature of the last three decades due to their possible application as phosphors and laser materials (Yamada et al., 1974; Hashimoto et al., 1991; Horchani et al., 2003).

In order to enrich the chemistry of this compound family, we have successfully synthesized single crystals of lithium dysprosium polyphosphate and investigated its crystal structure.

Structural studies reported for lithium lanthanide polyphosphates LiLn(PO₃)₄, Ln = Nd (Hong, 1975, Koizumi, 1976), Er (Liu et al., 1983, Ben Zarkouna et al., 2005),Yb (Ben Zarkouna et al., 2004), Gd (Ettis et al., 2006), Tb (Ben Zarkouna et al., 2007), showed that all these compounds crystallize in space group C2/c and have similar unit-cell parameters. However, it was reported that the lithium atom is located in the (4a) site in LiNd(PO₃)₄ (Hong, 1975) and LiEr(PO₃)₄ (Liu et al., 1983) and in the (4 e) site in the remaining structures. LiDy(PO₃)₄ is found to be isotypic with the latter group LiLn(PO₃)₄ previously reported. The corresponding asymmetric unit (Fig. 1) is formed by dysprosium and lithium atoms, both located in the (4 e) site, and two PO₄ tetrahedra with all atoms in general positions.

These tetrahedra share common corners yielding infinite chains, of four tetrahedra period, extending along the 2₁ screw axes in the b direction. Four such chains cross the unit cell (Fig. 2).

The polyphosphate chains display two type of distances, P—O terminal ranging from 1.475 (5) to 1.500 (5)Å and P—O bridging, noticeably longer, ranging from 1.573 (5) to 1.619 (5) Å. These distances are comparable with those reported for other condensed phosphates (Durif, 1995; Averbuch-Pouchot & Bagieu Beucher, 1987; Chehimi-Moumen & Férid, 2007; Férid, 2006, Ben Zarkouna et al., 2007).

Dy³⁺ and Li⁺ cations lie alternatingly on the two-fold axis in the middle of four polyphosphate chains, with Dy—Li distances of 3.55 (1) and 3.48 (1) Å. They are coordinated by eight and four external oxygen atoms, respectively. The resulting DyO₈ dodecahedra and LiO₄ tetrahedra are considerably distorted (Figure 3). The Dy—O and Li—O distances range from 2.288 (5) to 2.513 (5)Å and 1.95 (1) to 1.99 (1)Å respectively. The DyO₈ dodecahedra share corners and edges with neighbouring LiO₄ (Fig. 3) and PO₄ tetrahedra building a three dimensional network (Fig. 4). It can be noted that, in the present arrangement, the DyO₈ dodecahedra are isolated from each other, the shortest Dy—Dy distance is 5.563 (5) Å.

Related literature top

For related literature, see: Averbuch-Pouchot & Bagieu Beucher (1987); Ben Zarkouna, Férid & Driss (2005); Ben Zarkouna & Driss (2004), Ben Zarkouna, Horchani-Naifer et al. (2007); Durif (1995); Ettis et al. (2006); Férid (2006); Hashimoto et al. (1991); Hong (1975); Horchani et al. (2003); Liu & Li (1983); Chehimi-Moumen & Férid (2007); Koizumi (1976); Yamada et al. (1974).

Experimental top

A mixture of Li₂CO₃ (2 g), Dy₂O₃ (0.5 g) and H₃PO₄ (85%, 17 ml), were mixed in a vitreous carbon crucible and preheated progressively to 473 K four 2 h. The temperature was then raised and kept at 600 K for 15 days. Colourless single crystals of LiDy(PO₃)₄ were isolated from the reaction mixture by washing with hot water.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. : The asymmetric unit of LiDy(PO₃)₄ with anisotropic displacement parameters drawn at the 50% probability level.Symmetry code: (i)-x + 1, y, -z + 1.5.
	Fig. 2. : Projection of the structure of LiDy(PO₃)₄ along the b axis.
	Fig. 3. : The O-atom coordination around Dy and Li atoms showing the connection of DyO₈ and LiO₄ polyhedra. [Symmetry codes: (i)-x + 1, y, -z + 1.5; (ii)-x + 1, -y + 1, -z + 2; (iii)x, -y + 1, z - 1/2; (iv)x, y + 1, z; (v)-x + 1, y + 1, -z + 1.5.
	Fig. 4. : Structural arrangement of LiDy(PO₃)₄ along the 1 0 1 direction.

lithium dysprosium polyphosphate top

Crystal data top

LiDy(PO₃)₄	F(000) = 900
M_r = 485.32	D_x = 3.646 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1631 reflections
a = 16.269 (1) Å	θ = 0.7–27.9°
b = 7.0236 (3) Å	µ = 9.24 mm⁻¹
c = 9.5781 (8) Å	T = 295 K
β = 126.106 (3)°	Block, colourless
V = 884.24 (10) Å³	0.10 × 0.09 × 0.08 mm
Z = 4

Data collection top

Nonius KappaCCD diffractometer	1021 independent reflections
Radiation source: fine-focus sealed tube	858 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.080
ϕ & ω scans	θ_max = 27.7°, θ_min = 3.6°
Absorption correction: analytical (de Meulenaer & Tompa, 1965)	h = −21→20
T_min = 0.42, T_max = 0.45	k = −9→7
3313 measured reflections	l = −12→9

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F² > 2σ(F²)] = 0.038	Secondary atom site location: difference Fourier map
wR(F²) = 0.087	w = 1/[σ²(F_o²) + (0.0468P)²] where P = (F_o² + 2F_c²)/3
S = 0.95	(Δ/σ)_max < 0.001
1021 reflections	Δρ_max = 2.26 e Å⁻³
83 parameters	Δρ_min = −2.13 e Å⁻³

Crystal data top

LiDy(PO₃)₄	V = 884.24 (10) Å³
M_r = 485.32	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 16.269 (1) Å	µ = 9.24 mm⁻¹
b = 7.0236 (3) Å	T = 295 K
c = 9.5781 (8) Å	0.10 × 0.09 × 0.08 mm
β = 126.106 (3)°

Data collection top

Nonius KappaCCD diffractometer	1021 independent reflections
Absorption correction: analytical (de Meulenaer & Tompa, 1965)	858 reflections with I > 2σ(I)
T_min = 0.42, T_max = 0.45	R_int = 0.080
3313 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	83 parameters
wR(F²) = 0.087	0 restraints
S = 0.95	Δρ_max = 2.26 e Å⁻³
1021 reflections	Δρ_min = −2.13 e Å⁻³

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	U_iso*/U_eq
Dy1	0.5000	0.79714 (6)	0.7500	0.01295 (18)
P1	0.36225 (14)	0.5523 (2)	0.8849 (2)	0.0108 (4)
P2	0.35333 (14)	0.1513 (3)	0.8039 (2)	0.0124 (4)
O1	0.3870 (4)	0.7158 (6)	0.8178 (7)	0.0148 (11)
O2	0.4353 (4)	0.5025 (7)	1.0727 (6)	0.0142 (10)
O3	0.2555 (4)	0.5780 (7)	0.8535 (7)	0.0141 (11)
O4	0.3421 (4)	0.3778 (7)	0.7655 (6)	0.0169 (11)
O5	0.4287 (4)	0.0852 (7)	0.7730 (7)	0.0147 (10)
O6	0.3726 (4)	0.1159 (6)	0.9727 (6)	0.0180 (12)
Li	0.5000	0.292 (2)	0.7500	0.012 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Dy1	0.0130 (3)	0.0101 (3)	0.0150 (3)	0.000	0.0078 (2)	0.000
P1	0.0103 (9)	0.0098 (9)	0.0115 (9)	0.0003 (6)	0.0059 (8)	−0.0008 (6)
P2	0.0106 (10)	0.0115 (9)	0.0123 (9)	−0.0008 (7)	0.0053 (8)	−0.0007 (7)
O1	0.016 (3)	0.013 (3)	0.014 (3)	−0.002 (2)	0.008 (2)	0.0012 (19)
O2	0.008 (3)	0.014 (2)	0.016 (3)	−0.0022 (19)	0.004 (2)	0.001 (2)
O3	0.007 (3)	0.017 (3)	0.018 (3)	0.0056 (19)	0.007 (2)	0.006 (2)
O4	0.023 (3)	0.012 (3)	0.012 (2)	0.004 (2)	0.008 (2)	0.0057 (19)
O5	0.015 (3)	0.016 (2)	0.020 (3)	0.0014 (19)	0.014 (2)	−0.0011 (19)
O6	0.027 (3)	0.008 (2)	0.019 (3)	−0.003 (2)	0.013 (3)	−0.0008 (19)
Li	0.015 (9)	0.004 (8)	0.023 (9)	0.000	0.015 (8)	0.000

Geometric parameters (Å, º) top

Dy1—O6ⁱ	2.288 (5)	P2—O3^vi	1.589 (5)
Dy1—O6ⁱⁱ	2.288 (5)	P2—O4	1.619 (5)
Dy1—O1	2.352 (5)	P2—Li	2.896 (5)
Dy1—O1ⁱⁱⁱ	2.352 (5)	O2—Liⁱ	1.992 (11)
Dy1—O5^iv	2.406 (5)	O2—Dy1ⁱ	2.513 (5)
Dy1—O5^v	2.406 (5)	O3—P2^vii	1.589 (5)
Dy1—O2ⁱⁱ	2.513 (5)	O5—Li	1.951 (11)
Dy1—O2ⁱ	2.513 (5)	O5—Dy1^viii	2.406 (5)
Dy1—Li^v	3.476 (14)	O6—Dy1ⁱ	2.288 (5)
Dy1—Li	3.548 (14)	Li—O5ⁱⁱⁱ	1.951 (11)
P1—O1	1.483 (5)	Li—O2ⁱ	1.992 (11)
P1—O2	1.500 (5)	Li—O2ⁱⁱ	1.992 (11)
P1—O4	1.573 (5)	Li—P2ⁱⁱⁱ	2.896 (5)
P1—O3	1.589 (5)	Li—P1ⁱ	3.035 (5)
P1—Liⁱ	3.035 (5)	Li—P1ⁱⁱ	3.035 (5)
P2—O6	1.475 (5)	Li—Dy1^viii	3.476 (14)
P2—O5	1.495 (5)

O6ⁱ—Dy1—O6ⁱⁱ	149.0 (2)	O3^vi—P2—O4	100.9 (3)
O6ⁱ—Dy1—O1	93.73 (18)	O6—P2—Li	126.0 (2)
O6ⁱⁱ—Dy1—O1	93.71 (19)	O3^vi—P2—Li	121.1 (2)
O6ⁱ—Dy1—O1ⁱⁱⁱ	93.71 (19)	O4—P2—Li	67.6 (3)
O6ⁱⁱ—Dy1—O1ⁱⁱⁱ	93.73 (18)	P1—O1—Dy1	139.8 (3)
O1—Dy1—O1ⁱⁱⁱ	151.9 (2)	P1—O2—Liⁱ	120.0 (4)
O6ⁱ—Dy1—O5^iv	74.10 (17)	P1—O2—Dy1ⁱ	136.6 (3)
O6ⁱⁱ—Dy1—O5^iv	79.93 (18)	Liⁱ—O2—Dy1ⁱ	103.3 (3)
O1—Dy1—O5^iv	136.63 (17)	P1—O3—P2^vii	134.3 (4)
O1ⁱⁱⁱ—Dy1—O5^iv	71.43 (16)	P1—O4—P2	130.8 (3)
O6ⁱ—Dy1—O5^v	79.93 (18)	P2—O5—Li	113.7 (4)
O6ⁱⁱ—Dy1—O5^v	74.10 (17)	P2—O5—Dy1^viii	140.9 (3)
O1—Dy1—O5^v	71.43 (16)	Li—O5—Dy1^viii	105.4 (3)
O1ⁱⁱⁱ—Dy1—O5^v	136.63 (17)	P2—O6—Dy1ⁱ	133.6 (3)
O5^iv—Dy1—O5^v	65.5 (2)	O5—Li—O5ⁱⁱⁱ	83.7 (6)
O6ⁱ—Dy1—O2ⁱⁱ	137.74 (17)	O5—Li—O2ⁱ	119.6 (2)
O6ⁱⁱ—Dy1—O2ⁱⁱ	72.95 (15)	O5ⁱⁱⁱ—Li—O2ⁱ	125.8 (2)
O1—Dy1—O2ⁱⁱ	84.22 (17)	O5—Li—O2ⁱⁱ	125.8 (2)
O1ⁱⁱⁱ—Dy1—O2ⁱⁱ	72.18 (16)	O5ⁱⁱⁱ—Li—O2ⁱⁱ	119.6 (2)
O5^iv—Dy1—O2ⁱⁱ	132.43 (17)	O2ⁱ—Li—O2ⁱⁱ	87.2 (6)
O5^v—Dy1—O2ⁱⁱ	137.20 (17)	O5—Li—P2	28.19 (15)
O6ⁱ—Dy1—O2ⁱ	72.95 (15)	O5ⁱⁱⁱ—Li—P2	111.9 (5)
O6ⁱⁱ—Dy1—O2ⁱ	137.74 (17)	O2ⁱ—Li—P2	99.89 (18)
O1—Dy1—O2ⁱ	72.18 (16)	O2ⁱⁱ—Li—P2	108.8 (2)
O1ⁱⁱⁱ—Dy1—O2ⁱ	84.22 (17)	O5—Li—P2ⁱⁱⁱ	111.9 (5)
O5^iv—Dy1—O2ⁱ	137.20 (17)	O5ⁱⁱⁱ—Li—P2ⁱⁱⁱ	28.19 (15)
O5^v—Dy1—O2ⁱ	132.43 (17)	O2ⁱ—Li—P2ⁱⁱⁱ	108.8 (2)
O2ⁱⁱ—Dy1—O2ⁱ	66.2 (2)	O2ⁱⁱ—Li—P2ⁱⁱⁱ	99.89 (18)
O6ⁱ—Dy1—Li^v	74.52 (12)	P2—Li—P2ⁱⁱⁱ	140.1 (5)
O6ⁱⁱ—Dy1—Li^v	74.52 (12)	O5—Li—P1ⁱ	102.86 (18)
O1—Dy1—Li^v	104.06 (11)	O5ⁱⁱⁱ—Li—P1ⁱ	108.3 (2)
O1ⁱⁱⁱ—Dy1—Li^v	104.06 (11)	O2ⁱ—Li—P1ⁱ	25.34 (15)
O5^iv—Dy1—Li^v	32.77 (12)	O2ⁱⁱ—Li—P1ⁱ	112.5 (5)
O5^v—Dy1—Li^v	32.77 (12)	P2—Li—P1ⁱ	92.53 (5)
O2ⁱⁱ—Dy1—Li^v	146.88 (11)	P2ⁱⁱⁱ—Li—P1ⁱ	101.64 (5)
O2ⁱ—Dy1—Li^v	146.88 (11)	O5—Li—P1ⁱⁱ	108.3 (2)
O6ⁱ—Dy1—Li	105.48 (12)	O5ⁱⁱⁱ—Li—P1ⁱⁱ	102.86 (18)
O6ⁱⁱ—Dy1—Li	105.48 (12)	O2ⁱ—Li—P1ⁱⁱ	112.5 (5)
O1—Dy1—Li	75.94 (11)	O2ⁱⁱ—Li—P1ⁱⁱ	25.34 (15)
O1ⁱⁱⁱ—Dy1—Li	75.94 (11)	P2—Li—P1ⁱⁱ	101.64 (5)
O5^iv—Dy1—Li	147.23 (12)	P2ⁱⁱⁱ—Li—P1ⁱⁱ	92.53 (5)
O5^v—Dy1—Li	147.23 (12)	P1ⁱ—Li—P1ⁱⁱ	137.8 (5)
O2ⁱⁱ—Dy1—Li	33.12 (11)	O5—Li—Dy1^viii	41.9 (3)
O2ⁱ—Dy1—Li	33.12 (11)	O5ⁱⁱⁱ—Li—Dy1^viii	41.9 (3)
Li^v—Dy1—Li	180.000 (5)	O2ⁱ—Li—Dy1^viii	136.4 (3)
O1—P1—O2	118.3 (3)	O2ⁱⁱ—Li—Dy1^viii	136.4 (3)
O1—P1—O4	106.4 (3)	P2—Li—Dy1^viii	70.0 (3)
O2—P1—O4	111.6 (3)	P2ⁱⁱⁱ—Li—Dy1^viii	70.0 (3)
O1—P1—O3	112.1 (3)	P1ⁱ—Li—Dy1^viii	111.1 (2)
O2—P1—O3	105.0 (3)	P1ⁱⁱ—Li—Dy1^viii	111.1 (2)
O4—P1—O3	102.4 (3)	O5—Li—Dy1	138.1 (3)
O1—P1—Liⁱ	90.9 (3)	O5ⁱⁱⁱ—Li—Dy1	138.1 (3)
O4—P1—Liⁱ	144.5 (3)	O2ⁱ—Li—Dy1	43.6 (3)
O3—P1—Liⁱ	99.2 (2)	O2ⁱⁱ—Li—Dy1	43.6 (3)
O6—P2—O5	119.7 (3)	P2—Li—Dy1	110.0 (3)
O6—P2—O3^vi	112.5 (3)	P2ⁱⁱⁱ—Li—Dy1	110.0 (3)
O5—P2—O3^vi	107.3 (3)	P1ⁱ—Li—Dy1	68.9 (2)
O6—P2—O4	109.7 (3)	P1ⁱⁱ—Li—Dy1	68.9 (2)
O5—P2—O4	104.9 (3)	Dy1^viii—Li—Dy1	180.0

Symmetry codes: (i) −x+1, −y+1, −z+2; (ii) x, −y+1, z−1/2; (iii) −x+1, y, −z+3/2; (iv) −x+1, y+1, −z+3/2; (v) x, y+1, z; (vi) −x+1/2, y−1/2, −z+3/2; (vii) −x+1/2, y+1/2, −z+3/2; (viii) x, y−1, z.

Experimental details

Crystal data
Chemical formula	LiDy(PO₃)₄
M_r	485.32
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	295
a, b, c (Å)	16.269 (1), 7.0236 (3), 9.5781 (8)
β (°)	126.106 (3)
V (Å³)	884.24 (10)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	9.24
Crystal size (mm)	0.10 × 0.09 × 0.08

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	Analytical (de Meulenaer & Tompa, 1965)
T_min, T_max	0.42, 0.45
No. of measured, independent and observed [I > 2σ(I)] reflections	3313, 1021, 858
R_int	0.080
(sin θ/λ)_max (Å⁻¹)	0.655

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.087, 0.95
No. of reflections	1021
No. of parameters	83
Δρ_max, Δρ_min (e Å⁻³)	2.26, −2.13

Computer programs: COLLECT (Nonius, 1998), DENZO/SCALEPACK (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999).

Acknowledgements

This work was supported by the Ministry of Higher Education, Scientific Research and Technology of Tunisia.

References

Averbuch-Pouchot, M. T. & Bagieu Beucher, M. (1987). Z. Anorg. Allg. Chem. 552, 171–180. CrossRef CAS Web of Science Google Scholar
Ben Zarkouna, E. & Driss, A. (2004). Acta Cryst. E60, i102–i104. Web of Science CrossRef IUCr Journals Google Scholar
Ben Zarkouna, E., Férid, M. & Driss, A. (2005). Mater. Res. Bull. 40, 198–1992. Web of Science CrossRef Google Scholar
Ben Zarkouna, E., Horchani-Naifer, K., Férid, M. & Driss, A. (2007). Acta Cryst. E63, i1–i2. Web of Science CrossRef IUCr Journals Google Scholar
Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Chehimi-Moumen, F. & Férid, M. (2007). Acta Cryst. E63, i129–i130. Web of Science CrossRef IUCr Journals Google Scholar
Durif, A. (1995). Crystal Chemistry of Condensed Phosphates. New York: Plenum Press. Google Scholar
Ettis, H., Naili, H. & Mhiri, T. (2006). J. Solid State Chem. 179, 3107–3113. Web of Science CrossRef CAS Google Scholar
Férid, M. (2006). Etude des propriétés cristallochimiques et physiques de phosphates condensés de terres rares. Paris: Publibook. Google Scholar
Hashimoto, N., Takada, Y., Sato, K. & Ibuki, S. (1991). J. Lumin. 48–49, 893–897. CrossRef CAS Web of Science Google Scholar
Hong, H. Y. P. (1975). Mater. Res. Bull. 10, 635–640. CrossRef CAS Web of Science Google Scholar
Horchani, K., Gâcon, J. C., Férid, M., Trabelsi-Ayadi, M., Krachni, G. K. & Liu, G. K. (2003). Opt. Mater. 24, 169–174. Web of Science CrossRef CAS Google Scholar
Koizumi, H. (1976). Acta Cryst. B32, 266–268. CrossRef CAS IUCr Journals Web of Science Google Scholar
Liu, J.-C. & Li, D.-Y. (1983). Acta Phys. Sinica, 32, 786–790. CAS Google Scholar
Meulenaer, J. de & Tompa, H. (1965). Acta Cryst. 19, 1014–1018. CrossRef IUCr Journals Web of Science Google Scholar
Nonius (1998). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Yamada, T., Otsuka, K. & Nakano, J. (1974). J. Appl. Phys. 45, 5096–5097. CrossRef CAS Web of Science Google Scholar