Silver europium(III) polyphosphate

Ayadi, M.; Férid, M.; Moine, B.

doi:10.1107/S1600536809004085

inorganic compounds

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ISSN: 2056-9890

Volume 65| Part 3| March 2009| Page i13

doi:10.1107/S1600536809004085

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Silver europium(III) polyphosphate

Mounir Ayadi,^a ^* Mokhtar Férid ^b and Bernard Moine ^c

^aLaboratoire d'Application de la Chimie aux Ressources et, Substances Naturelles et á l'Environnement, Faculté des Sciences de Bizerte, 7021 Zarzouna Bizerte, Tunisia, ^bUnité de Recherches de Matériaux de Terres Rares, Centre National de Recherches en Sciences des Matériaux, BP 95 Hammam-Lif 2050, Tunisia, and ^cLPCML–UMR 5620 CNRS/UCBL, Domaine Scientifique de la Doua, Université Claude Bernard Lyon 1 Batiment Alfred Kastler, 10 rue André-Marie Ampére, 69622 Villeurbanne Cedex, France
^*Correspondence e-mail: Mounir.Ayadi@fsm.rnu.tn

(Received 14 December 2008; accepted 3 February 2009; online 11 February 2009)

Europium(III) silver polyphosphate, AgEu(PO₃)₄, was prepared by the flux method. The atomic arrangement is built up by infinite (PO₃)_n chains (periodicity of 4) extending along the c axis. These chains are joined to each other by EuO₈ dodecahedra. The Ag⁺ cations are located in the voids of this arrangement and are surrounded by five oxygen atoms in a distorted [4+1] coordination.

Related literature

For isotypic AgNd(PO₃)₄, see: Trunov et al. (1990 ). For related structures, see: Yamada et al. (1974 ); Hashimoto et al. (1991 ); Horchani et al. (2003 ); Durif (1995 ); Averbuch-Pouchot & Bagieu-Beucher (1987 ); Férid (2006 ).

Experimental

Crystal data

AgEu(PO₃)₄
M_r = 575.72
Monoclinic, P 2₁ /n
a = 9.9654 (3) Å
b = 13.1445 (7) Å
c = 7.2321 (3) Å
β = 90.42 (1)°
V = 947.31 (7) Å³
Z = 4
Mo Kα radiation
μ = 9.37 mm⁻¹
T = 298 (2) K
0.19 × 0.18 × 0.17 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.167, T_max = 0.201
3371 measured reflections
2019 independent reflections
1704 reflections with I > 2σ(I)
R_int = 0.042

Refinement

R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.109
S = 1.03
2019 reflections
164 parameters
Δρ_max = 2.43 e Å⁻³
Δρ_min = −2.06 e Å⁻³

Data collection: COLLECT (Nonius, 2001 ); 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, 1998 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809004085/br2089sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809004085/br2089Isup2.hkl

checkCIF report

Comment top

In the last decades, investigation of the synthesis and characterization of rare earth polyphosphates has gained much attention due to their potential applications in diverse areas such as phosphors and laser materials (Yamada et al., 1974; Hashimoto et al., 1991; Horchani et al., 2003). In aim to study the condensed phosphates of rare earth and monovalent cations of general formula MILn(PO₃)₄ (with MI = monovalent cation)(Durif, 1995), (Ln = Eu, Er, Yb), we have synthesized single crystals of silver europium polyphosphate and investigated its crystalline structure. The atomic arrangement of this structure is characterized by a three-dimensional framework built of (PO₃)_n chains that are formed by corner-sharing of PO₄ tetrahedra. Eu3+ and Ag+ cations alternate in the middle of four such chains with Eu—Ag distances of 3.64 (7) Å (figures 1,3). The EuO₈ dodecahedra are isolated from each other and the distances Eu—O are arranged in interval 2.355 (5)- 2.508 (5)Å (figure 2). The polyphosphate chains display two types of distances, P—O terminal ranging from 1.479 (5) to 1.505 (5)Å and P—O bridging, ranging from 1.585 (5)to 1.609 (5)Å. These distances are comparable with those repoted for other condensed phosphates (Durif, 1995; Averbuch-Pouchot & Bagieu Beucher, 1987; Férid (2006). The structural study reported for silver neodymium polyphosphate AgNd(PO₃)₄ (Trunov et al., 1990) showed that the compound crystallize in the P2₁/n space group and has similar unit cell prameters compared to AgEu(PO₃)₄.

Related literature top

For isotypic AgNd(PO₃)₄, see: Trunov et al. (1990). For related structures, see: Yamada et al. (1974); Hashimoto et al. (1991); Horchani et al. (2003); Durif (1995); Averbuch-Pouchot & Bagieu Beucher (1987); Férid (2006).

Experimental top

Single crystals of AgEu(PO₃)₄ were prepared by flux method. A mixture of Ag₂CO₃ (3 g), EuCl_3.6H₂O (0.5 g) and H₃PO₄(85%, 17 ml), was progressively heated in a vitreous carbon crucible to 473 K for 12 h. The temperature was then raised and kept at 600 K for 16 days after that, the furnance was slowly cooled until the room temperature. The product was washed with boiling water to separate colorless single crystals from phosphoric acid.

Computing details top

Data collection: COLLECT (Nonius, 2001); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS08 (Sheldrick, 2008); program(s) used to refine structure: SHELXL08 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL08 (Sheldrick, 2008).

Figures top

	Fig. 1. : The structural arrangement of AgEu(PO₃)₄ along a axis.
	Fig. 2. : Projection of EuO₈ dodecahedra viewed along [0 0 1] direction.
	Fig. 3. : The sequence of PO₄ tetrahedra in AgEu(PO₃₎4, with displacement ellipsoids drawn at the 50% probability level. [Symmetry codes: (i) 1-x, 2-y, 2-z; (ii) 1-x/2, 2-y, 3-z]

Europium(III) silver polyphosphate top

Crystal data top

AgEu(PO₃)₄	F(000) = 1064
M_r = 575.72	D_x = 4.037 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 25 reflections
a = 9.9654 (3) Å	θ = 2.4–30.1°
b = 13.1445 (7) Å	µ = 9.37 mm⁻¹
c = 7.2321 (3) Å	T = 298 K
β = 90.42 (1)°	Prism, colorless
V = 947.31 (7) Å³	0.19 × 0.18 × 0.17 mm
Z = 4

Data collection top

Nonius KappaCCD diffractometer	2019 independent reflections
Radiation source: fine-focus sealed tube	1704 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.042
ϕ and ω scans	θ_max = 27.5°, θ_min = 3.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −12→12
T_min = 0.167, T_max = 0.201	k = −16→15
3371 measured reflections	l = −9→9

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.042	w = 1/[σ²(F_o²) + (0.0685P)² + 1.0941P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.109	(Δ/σ)_max < 0.001
S = 1.03	Δρ_max = 2.43 e Å⁻³
2019 reflections	Δρ_min = −2.06 e Å⁻³
164 parameters	Extinction correction: SHELXL08 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00014 (2)

Crystal data top

AgEu(PO₃)₄	V = 947.31 (7) Å³
M_r = 575.72	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 9.9654 (3) Å	µ = 9.37 mm⁻¹
b = 13.1445 (7) Å	T = 298 K
c = 7.2321 (3) Å	0.19 × 0.18 × 0.17 mm
β = 90.42 (1)°

Data collection top

Nonius KappaCCD diffractometer	2019 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1704 reflections with I > 2σ(I)
T_min = 0.167, T_max = 0.201	R_int = 0.042
3371 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	164 parameters
wR(F²) = 0.109	0 restraints
S = 1.03	Δρ_max = 2.43 e Å⁻³
2019 reflections	Δρ_min = −2.06 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
Eu	0.52254 (4)	0.78212 (2)	0.51227 (4)	0.01862 (19)
Ag	0.43355 (7)	0.77670 (5)	1.00017 (8)	0.0322 (2)
P1	0.25190 (18)	0.90008 (12)	1.2536 (2)	0.0168 (4)
P2	0.19511 (18)	0.87338 (12)	1.6486 (2)	0.0167 (4)
P3	0.79921 (18)	0.90983 (12)	1.2635 (2)	0.0172 (4)
P4	0.73739 (18)	0.88594 (12)	0.8738 (2)	0.0162 (4)
O1	0.1995 (5)	0.8356 (3)	1.1018 (6)	0.0241 (11)
O2	0.3997 (5)	0.8951 (4)	1.2904 (7)	0.0243 (11)
O3	0.2039 (5)	1.0133 (3)	1.2168 (7)	0.0240 (11)
O4	0.1629 (5)	0.8769 (3)	1.4335 (6)	0.0198 (10)
O5	0.3444 (5)	0.8678 (4)	1.6767 (7)	0.0218 (10)
O6	0.1062 (6)	0.7906 (3)	1.7231 (6)	0.0228 (11)
O7	0.8644 (5)	1.0214 (3)	1.2777 (7)	0.0193 (10)
O8	0.9144 (5)	0.8395 (3)	1.2329 (6)	0.0236 (10)
O9	0.7055 (5)	0.8919 (3)	1.4217 (6)	0.0218 (10)
O10	0.7085 (5)	0.9202 (3)	1.0822 (6)	0.0203 (10)
O11	0.8483 (5)	0.8097 (3)	0.8671 (7)	0.0218 (10)
O12	0.6047 (5)	0.8557 (3)	0.7933 (6)	0.0198 (10)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Eu	0.0183 (3)	0.0189 (2)	0.0186 (2)	−0.00063 (12)	−0.00048 (15)	−0.00108 (12)
Ag	0.0262 (4)	0.0456 (4)	0.0249 (3)	0.0034 (2)	0.0008 (2)	−0.0088 (2)
P1	0.0201 (9)	0.0138 (7)	0.0165 (7)	−0.0001 (6)	0.0005 (6)	0.0001 (6)
P2	0.0173 (9)	0.0155 (8)	0.0173 (8)	0.0007 (6)	−0.0001 (6)	−0.0002 (6)
P3	0.0206 (9)	0.0143 (7)	0.0168 (8)	0.0004 (6)	−0.0017 (6)	−0.0002 (6)
P4	0.0162 (9)	0.0160 (8)	0.0165 (8)	−0.0001 (6)	−0.0020 (6)	−0.0012 (6)
O1	0.034 (3)	0.019 (2)	0.019 (2)	0.004 (2)	−0.002 (2)	−0.0060 (19)
O2	0.023 (3)	0.026 (2)	0.023 (2)	0.000 (2)	−0.002 (2)	−0.002 (2)
O3	0.028 (3)	0.016 (2)	0.028 (3)	0.007 (2)	−0.004 (2)	0.0052 (19)
O4	0.019 (3)	0.025 (2)	0.016 (2)	0.0000 (19)	−0.0004 (18)	0.0039 (18)
O5	0.017 (3)	0.024 (2)	0.025 (2)	0.0021 (19)	−0.003 (2)	−0.007 (2)
O6	0.029 (3)	0.021 (2)	0.018 (2)	−0.005 (2)	0.000 (2)	0.0038 (18)
O7	0.013 (2)	0.014 (2)	0.031 (3)	−0.0005 (18)	0.0063 (19)	−0.003 (2)
O8	0.027 (3)	0.018 (2)	0.026 (2)	0.003 (2)	−0.001 (2)	−0.002 (2)
O9	0.027 (3)	0.023 (2)	0.016 (2)	−0.004 (2)	0.0040 (19)	−0.0026 (18)
O10	0.017 (2)	0.020 (2)	0.024 (2)	0.0009 (19)	−0.0016 (18)	−0.0023 (19)
O11	0.022 (3)	0.018 (2)	0.025 (2)	0.007 (2)	−0.001 (2)	0.002 (2)
O12	0.023 (3)	0.021 (2)	0.015 (2)	0.005 (2)	−0.0053 (19)	−0.0005 (18)

Geometric parameters (Å, º) top

Eu—O11ⁱ	2.355 (5)	P2—O4	1.587 (5)
Eu—O12	2.390 (4)	P2—O7^vi	1.598 (5)
Eu—O9ⁱⁱ	2.420 (5)	P3—O8	1.492 (5)
Eu—O5ⁱⁱ	2.422 (5)	P3—O9	1.500 (5)
Eu—O1ⁱⁱⁱ	2.430 (5)	P3—O10	1.593 (5)
Eu—O6^iv	2.451 (5)	P3—O7	1.607 (5)
Eu—O2ⁱⁱ	2.500 (5)	P4—O11	1.493 (5)
Eu—O8ⁱ	2.508 (5)	P4—O12	1.495 (5)
Eu—Ag	3.6453 (7)	P4—O3^vii	1.592 (5)
Eu—Agⁱⁱ	3.8025 (7)	P4—O10	1.602 (5)
Ag—O8ⁱ	2.470 (5)	O1—Eu^viii	2.430 (5)
Ag—O12	2.503 (5)	O2—Eu^v	2.500 (5)
Ag—O6ⁱⁱⁱ	2.511 (5)	O3—P4^vii	1.592 (5)
Ag—O1	2.570 (5)	O5—Eu^v	2.422 (5)
Ag—Eu^v	3.8025 (7)	O6—Eu^ix	2.451 (5)
P1—O1	1.479 (5)	O6—Ag^viii	2.511 (5)
P1—O2	1.496 (6)	O7—P2^vi	1.598 (5)
P1—O3	1.585 (5)	O8—Ag^x	2.470 (5)
P1—O4	1.609 (5)	O8—Eu^x	2.508 (5)
P2—O5	1.502 (5)	O9—Eu^v	2.420 (5)
P2—O6	1.505 (5)	O11—Eu^x	2.355 (5)

O11ⁱ—Eu—O12	146.43 (17)	O12—Ag—Eu	40.66 (10)
O11ⁱ—Eu—O9ⁱⁱ	137.70 (16)	O6ⁱⁱⁱ—Ag—Eu	117.27 (12)
O12—Eu—O9ⁱⁱ	74.62 (16)	O1—Ag—Eu	119.92 (10)
O11ⁱ—Eu—O5ⁱⁱ	85.21 (16)	O8ⁱ—Ag—Eu^v	142.17 (11)
O12—Eu—O5ⁱⁱ	69.01 (16)	O12—Ag—Eu^v	114.81 (10)
O9ⁱⁱ—Eu—O5ⁱⁱ	114.34 (16)	O6ⁱⁱⁱ—Ag—Eu^v	39.40 (11)
O11ⁱ—Eu—O1ⁱⁱⁱ	108.89 (17)	O1—Ag—Eu^v	85.49 (10)
O12—Eu—O1ⁱⁱⁱ	77.74 (15)	Eu—Ag—Eu^v	152.34 (2)
O9ⁱⁱ—Eu—O1ⁱⁱⁱ	84.55 (16)	O1—P1—O2	116.6 (3)
O5ⁱⁱ—Eu—O1ⁱⁱⁱ	134.29 (16)	O1—P1—O3	108.0 (3)
O11ⁱ—Eu—O6^iv	70.99 (18)	O2—P1—O3	111.5 (3)
O12—Eu—O6^iv	140.07 (18)	O1—P1—O4	107.3 (3)
O9ⁱⁱ—Eu—O6^iv	74.93 (16)	O2—P1—O4	113.3 (3)
O5ⁱⁱ—Eu—O6^iv	148.82 (17)	O3—P1—O4	98.4 (3)
O1ⁱⁱⁱ—Eu—O6^iv	74.24 (16)	O5—P2—O6	120.1 (3)
O11ⁱ—Eu—O2ⁱⁱ	70.26 (16)	O5—P2—O4	109.1 (3)
O12—Eu—O2ⁱⁱ	117.94 (15)	O6—P2—O4	104.9 (3)
O9ⁱⁱ—Eu—O2ⁱⁱ	80.70 (17)	O5—P2—O7^vi	111.5 (3)
O5ⁱⁱ—Eu—O2ⁱⁱ	71.45 (17)	O6—P2—O7^vi	106.6 (3)
O1ⁱⁱⁱ—Eu—O2ⁱⁱ	154.17 (16)	O4—P2—O7^vi	103.2 (3)
O6^iv—Eu—O2ⁱⁱ	81.49 (16)	O8—P3—O9	120.0 (3)
O11ⁱ—Eu—O8ⁱ	68.78 (16)	O8—P3—O10	111.3 (3)
O12—Eu—O8ⁱ	82.12 (15)	O9—P3—O10	106.8 (3)
O9ⁱⁱ—Eu—O8ⁱ	151.72 (16)	O8—P3—O7	105.3 (3)
O5ⁱⁱ—Eu—O8ⁱ	70.38 (16)	O9—P3—O7	110.4 (3)
O1ⁱⁱⁱ—Eu—O8ⁱ	74.87 (16)	O10—P3—O7	101.6 (3)
O6^iv—Eu—O8ⁱ	116.40 (15)	O11—P4—O12	117.5 (3)
O2ⁱⁱ—Eu—O8ⁱ	125.20 (17)	O11—P4—O3^vii	105.7 (3)
O11ⁱ—Eu—Ag	103.74 (12)	O12—P4—O3^vii	112.8 (3)
O12—Eu—Ag	43.03 (12)	O11—P4—O10	111.0 (3)
O9ⁱⁱ—Eu—Ag	117.57 (11)	O12—P4—O10	106.1 (3)
O5ⁱⁱ—Eu—Ag	49.41 (11)	O3^vii—P4—O10	102.9 (3)
O1ⁱⁱⁱ—Eu—Ag	84.88 (11)	P1—O1—Eu^viii	144.5 (3)
O6^iv—Eu—Ag	154.81 (10)	P1—O1—Ag	93.9 (3)
O2ⁱⁱ—Eu—Ag	120.77 (12)	Eu^viii—O1—Ag	112.98 (17)
O8ⁱ—Eu—Ag	42.51 (10)	P1—O2—Eu^v	128.1 (3)
O11ⁱ—Eu—Agⁱⁱ	52.44 (12)	P1—O3—P4^vii	137.7 (4)
O12—Eu—Agⁱⁱ	155.75 (11)	P2—O4—P1	133.6 (3)
O9ⁱⁱ—Eu—Agⁱⁱ	85.32 (11)	P2—O5—Eu^v	133.2 (3)
O5ⁱⁱ—Eu—Agⁱⁱ	108.69 (11)	P2—O6—Eu^ix	142.4 (3)
O1ⁱⁱⁱ—Eu—Agⁱⁱ	114.28 (11)	P2—O6—Ag^viii	115.3 (2)
O6^iv—Eu—Agⁱⁱ	40.55 (12)	Eu^ix—O6—Ag^viii	100.06 (18)
O2ⁱⁱ—Eu—Agⁱⁱ	43.64 (11)	P2^vi—O7—P3	131.3 (3)
O8ⁱ—Eu—Agⁱⁱ	120.64 (11)	P3—O8—Ag^x	108.8 (3)
Ag—Eu—Agⁱⁱ	152.34 (2)	P3—O8—Eu^x	145.5 (3)
O8ⁱ—Ag—O12	80.67 (15)	Ag^x—O8—Eu^x	94.16 (15)
O8ⁱ—Ag—O6ⁱⁱⁱ	109.46 (15)	P3—O9—Eu^v	140.7 (3)
O12—Ag—O6ⁱⁱⁱ	93.64 (16)	P3—O10—P4	130.2 (3)
O8ⁱ—Ag—O1	110.19 (16)	P4—O11—Eu^x	150.8 (3)
O12—Ag—O1	132.06 (14)	P4—O12—Eu	137.3 (3)
O6ⁱⁱⁱ—Ag—O1	122.79 (16)	P4—O12—Ag	118.8 (2)
O8ⁱ—Ag—Eu	43.33 (11)	Eu—O12—Ag	96.31 (16)

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

Experimental details

Crystal data
Chemical formula	AgEu(PO₃)₄
M_r	575.72
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	298
a, b, c (Å)	9.9654 (3), 13.1445 (7), 7.2321 (3)
β (°)	90.42 (1)
V (Å³)	947.31 (7)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	9.37
Crystal size (mm)	0.19 × 0.18 × 0.17

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.167, 0.201
No. of measured, independent and observed [I > 2σ(I)] reflections	3371, 2019, 1704
R_int	0.042
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.109, 1.03
No. of reflections	2019
No. of parameters	164
Δρ_max, Δρ_min (e Å⁻³)	2.43, −2.06

Computer programs: COLLECT (Nonius, 2001), DENZO/SCALEPACK (Otwinowski & Minor, 1997), SHELXS08 (Sheldrick, 2008), SHELXL08 (Sheldrick, 2008), DIAMOND (Brandenburg, 1998).

Acknowledgements

This work is 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
Brandenburg, K. (1998). DIAMOND. University of Bonn, Germany. Google Scholar
Durif, A. (1995). In Crystal Chemistry of Condensed Phosphates. New York: Plenium Press. Google Scholar
Férid, M. (2006). In Etude des propriétés cristallochimiques et physiques des 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
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
Nonius (2001). COLLECT. Nonius BV, Delf, 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. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Trunov, V. K., Anisimova, N. Yu., Karmanovskaya, N. B. & Chudinova, N. N. (1990). Izv. Akad. Nauk SSSR Neorg. Mater. 26, 1288–1290. CAS Google Scholar
Yamada, T., Otsuka, K. & Nakano, J. (1974). Appl. Phys. 45, 5096–5097. CrossRef CAS Google Scholar