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Crystal structure of three polymorphs of Y(PO3)3
Solid State Sciences 5 (2003) 393–402 www.elsevier.com/locate/ssscie
Crystal structure of three polymorphs of Y(PO3 )3 Mohsen Graia a,b , Ahmed Driss a , Tahar Jouini a,∗ a Laboratoire de matériaux et de cristallochimie, département de chimie, faculté des sciences de Tunis, campus universitaire, 1060, Tunis, Tunisia b Institut préparatoire aux études d’ingénieurs de Sfax, BP 805, 3000, Sfax, Tunisia
Received 2 June 2002; received in revised form 7 October 2002; accepted 23 October 2002
Abstract Three polymorphs of yttrium polyphosphate Y(PO3 )3 were prepared and their crystal structures were determined by single-crystal Xray diffraction. Each structure is composed of (PO3 )n infinite chains linked together by corner-sharing YO6 octahedra. Crystal data: Y(PO3 )3 T, Mr = 162.91, trigonal, space group R-3, a = b = 21.042(3) Å, c = 12.159(1) Å, V = 4662(1) Å3 , dc = 2.785, Z = 24, R = 0.033, wR = 0.073. Y(PO3 )3 M, Mr = 162.91, monoclinic, space group C2/c, a = 14.176(1) Å, b = 6.70750(9) Å, c = 10.0853(8) Å, β = 127.597(7)◦ , V = 759.81(8) Å3 , dc = 2.848, Z = 4, R = 0.055, wR = 0.107. Y(PO3 )3 M , Mr = 162.91, monoclinic, space group P 21 /m, a = 6.997(1) Å, b = 9.693(1) Å, c = 10.989(1) Å, β = 91.84(1)◦ , V = 744.9(2) Å3 , dc = 2.905, Z = 4, R = 0.035, wR = 0.080. 2003 Éditions scientifiques et médicales Elsevier SAS. All rights reserved. Keywords: Synthesis; Structure; Polymorphs; Polyphosphate; Yttrium
1. Introduction In recent years, the yttrium and rare earth phosphates have been the subject of interest in particular due to their Laser applications [1]. Trivalent cation long-chain polyphosphates belong to two groups. The first group comprises compounds of the general formula MIII (PO3 )3 with MIII = Al, Cr, Ga, V, Mn, Fe, Rh, Ti, Mo, Sc, In and Tl [2]. The second group contains compounds of yttrium, lanthanides and bismuth. In this second family of compounds two different formulas have been observed: MIII H(PO3 )4 and MIII (PO3 )3 [2]. Only five crystal structures of MIII (PO3 )3 compounds belonging to the second group have been established [3–7]. The main crystallographic features for these compounds are reported in Table 1. However, other investigations carried out on powder have shown that some of these compounds are polymorphs [1,3, 8,9], for example Yb(PO3 )3 which presents five allotropic forms [3]. A summary of the literature concerning the polymorphism of yttrium polyphosphate Y(PO3 )3 is presented below. Up to now, no crystal structure of yttrium polyphosphate Y(PO3 )3 has been determined probably due to the difficulty of producing single crystal of these compounds. Only * Corresponding author.
E-mail address: [email protected] (T. Jouini).
characterization from powder data are available. Three diffractograms of Y(PO3 )3 have been reported [10–12]. Only that published by Szuszkiewics et al. is indexed [12]. The refined unit cell parameters of Y(PO3 )3 are a = 14.152(2) Å, b = 20.149(4) Å, c = 10.061(1) Å and β = 127.9(1)◦. This study excludes the isotypy of this phase with C-Yb(PO3 )3 . The samples studied during these studies are obtained at temperatures ranging between 500 and 900 ◦ C. In this temperature interval Y(PO3 )3 has only one stable form. Indeed, the investigations of Y2 O3 –P2 O5 and Y(PO3 )3 –La(PO3)3 systems [5,10] at 1980 and 1986, respectively, did not point out any phase transition of yttrium polyphosphate Y(PO3 )3 up to the fusion temperature (1460 ◦ C). In 1986 Shklover et al. concluded that Y(PO3 )3 had a single stable structure between 180 ◦ C and 1000 ◦ C [13]. Federova et al. observed that Y(PO3 )3 remained stable until 1400 ◦ C before it undergoes a polymorphic transition [9]. The present work deals with preparation and crystal structures of three forms of Y(PO3 )3 proving the polymorphism of this salt for temperatures lower than 550 ◦ C.
2. Chemical preparation and elementary analysis Three crystalline forms of Y(PO3 )3 were isolated during our systematic investigations of the Y2 O3 –P2 O5 –SrO system. Single crystal of these Y(PO3 )3 polymorphs were ob-
1293-2558/03/$ – see front matter 2003 Éditions scientifiques et médicales Elsevier SAS. All rights reserved. doi:10.1016/S1293-2558(03)00012-8
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Table 1 Main crystallographic data for the MIII (PO3 )3 polyphosphates (M = Ln and Bi) Space group
a (Å) α (◦ )
b (Å) β (◦ )
C-Yb(PO3 )3
P 21 /c
11.219(2)
T -Yb(PO3 )3
R3
20.974(4)
19.983(3) 97.3(0) 20.974(4)
Nd(PO3 )3 Er(PO3 )3
C2221 P 11m
11.172(2) 10.943(3)
8.533(2) 6.971(2)
Bi(PO3 )3
P 21 /a
13.732(2)
6.933(1) 93.3(0)
Formula
V (Å3 )
Z
Ref.
9.999(3)
2223.5
12
[3]
12.134(3) 120.0 7.284(2) 9.670(2) 91.8(0) 7.152(1)
4622.7
24
[4]
694.4 737.3
4 4
[5] [6]
679.7
4
[7]
c (Å) γ (◦ )
Table 2 Crystallographic data, recording conditions, and refinement results for T-, M- and M -Y(PO3 )3 Crystal data Formula weight Volume (Å3 ) Temperature Shape Color Crystal dimensions (mm) Crystal system Space group Cell dimensions
T-Y(PO3 )3
M-Y(PO3 )3
M -Y(PO3 )3
325.82 4662 (1) 293(2) K rhombohedron colourless 0.05 × 0.09 × 0.11 rhombohedral R-3 (N◦ 148) a = 21.042(3) Å c = 12.159(1) Å γ = 120◦
325.82 759.81 (8) 293(2) K irregular colourless 0.20 × 0.18 × 0.17 monoclinic C2/c (N◦ 15) a = 14.176(1) Å b = 6.70750(9) Å c = 10.0853(8) Å β = 127.597(7)◦ 2.848 4 8.330 mm−1
325.82 744.9 (2) 293(2) K platelet colourless 0.22 × 0.18 × 0.05 monoclinic P 21 /m (N◦ 11) a = 6.997(1) Å b = 9.693(1) Å c = 10.989(1) Å β = 91.84(1)◦ 2.905 4 8.496 mm−1
2.79 to 27.02◦ 4912 2268 [R(int) = 0.036]
3.54 to 25.96◦ 906 749 [R(int) = 0.106]
2.80 to 26.97◦ 1808 1718 [R(int) = 0.028]
159 R1 = 0.0328 wR = 0.0734 0.00004(3) 1.085 0.863 and −1.912
67 R1 = 0.0546 wR = 0.1069 0.0008(4) 1.055 1.471 and −0.980
131 R1 = 0.0353 wR = 0.0803 0.0035(7) 1.106 0.877 and −0.815
Density calc. (g cm−3 ) 2.785 Z 24 Absorption coefficient 8.145 mm−1 Radiation, graphite monochromator: Mo Kα (λ = 0.71069 Å) Data collection Diffractometer: Enraf-Nonius CAD-4 Scan mode: ω − 2θ θ range for data collection Measured reflections Independent reflections Refinement Refinement on F 2 Parameters refined Final R indices [I > 4σ (I )] Extinction correction s(F 2 ) (∆ρ)max and (∆ρ)min (e·A−3 )
Weighting scheme: T-Y(PO3 )3 : w = 1/[σ 2 (Fo2 ) + (0.0195P)2 + 72.7821P], where P = (Fo2 + 2Fc2 )/3. M-Y(PO3 )3 : w = 1/[σ 2 (Fo2 ) + (0.0000P)2 + 26.7352P], where P = (Fo2 + 2Fc2 )/3. M -Y(PO3 )3 : w = 1/[σ 2 (Fo2 ) + (0.0419P)2 + 0.7655P], where P = (Fo2 + 2Fc2 )/3.
tained by adding 0.212 g of Sr(NO3 )2 and 0.452 g of Y2 O3 to a mixture of 15 ml of water, 10 ml of concentrated HNO3 and of 1 ml of H3 PO4 (85%) at room temperature. The mixture was preheated in a porcelain crucible at 140 ◦ C for 12 h, held at 550 ◦ C for 24 h, and cooled at 3 ◦ C min−1 to room temperature. After being washed with hot water to dissolve any excess of phosphoric acid, the sample was found to include crystals with three different forms. The role played
by Sr(NO3 )2 is not explained. However, pure Y(PO3 )3 was never obtained even with appropriate amounts of Y2 O3 and P2 O5 when the composition was known based on X-ray crystal structure analysis. Elementary analysis of single crystal of each form using a scanning electron microscope showed the presence of oxygen, phosphorus, and yttrium in each of the analysed samples. As will be shown later, these crystals correspond
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Table 3 Fractional atomic coordinates and equivalent thermal parameters (Å2 ) for T-Y(PO3 )3 a . Standard deviations are given in parentheses Atom
x
y
z
Ueq
Y(1) Y(2) Y(3) P(1) P(2) P(3) P(4) O(1) O(2) O(3) O(4) O(5) O(6) O(7) O(8) O(9) O(10) O(11) O(12)
0.1072(1) −1/3 0 −0.2067(1) −0.0879(1) −0.1213(1) −0.0809(1) −0.1072(3) −0.0110(2) −0.1294(2) −0.0129(2) −0.1208(2) 0.1185(2) −0.2471(2) −0.0736(2) 0.1115(2) 0.1234(2) −0.0658(3) 0.2261(2)
0.6982(1) 1/3 0 0.4882(1) 0.6073(1) 0.7086(1) 0.8346(1) 0.5815(3) 0.6427(2) 0.5391(2) 0.8467(3) 0.6588(2) 0.7475(2) 0.4197(2) 0.7891(2) 0.8010(2) 0.6070(2) 0.9064(2) 0.7574(2)
0.4296(1) 1/3 1/2 0.5061(1) 0.3740(1) 0.4970(1) 0.3534(1) 0.2598(3) 0.4075(4) 0.4528(4) 0.2853(3) 0.3990(3) 0.2606(3) 0.4427(3) 0.4515(3) 0.4902(3) 0.3728(3) 0.3969(4) 0.4691(3)
0.011(1) 0.011(1) 0.023(1) 0.012(1) 0.017(1) 0.013(1) 0.017(1) 0.048(1) 0.038(1) 0.043(1) 0.044(1) 0.022(1) 0.021(1) 0.026(1) 0.024(1) 0.021(1) 0.029(1) 0.039(1) 0.026(1)
a U = (1/3) U a ∗ a ∗ ·a ·a . eq ij i j ij i j i j
Table 4 Fractional atomic coordinates and equivalent thermal parameters (Å2 ) for M-Y(PO3 )3 a . Standard deviations are given in parentheses Atom
x
Y P(1) P(2) O(1) O(2) O(3) O(4) O(5)
0 −0.1543(2) −1/4 −0.0646(9) −0.1169(6) −0.2357(8) −0.3571(7) −0.2154(11) a U = (1/3) U a ∗ a ∗ ·a ·a . eq i j ij i j i j
y
z
Ueq
Occupation
0 −0.1475(4) 0.1677(4) −0.0790(16) −0.2230(11) 0.0235(14) 0.2746(16) −0.2950(30)
0 0.1602(3) 1/4 0.1438(14) −0.1988(9) 0.1418(10) 0.1258(12) 0.0180(19)
0.034(1) 0.035(1) 0.037(1) 0.104(4) 0.053(2) 0.077(3) 0.105(4) 0.082(6)
1/2
Table 5 Fractional atomic coordinates and equivalent thermal parameters (Å2 ) for M - Y(PO3 )3 a . Standard deviations are given in parentheses Atom
x
y
z
Ueq
Y(1) Y(2) P(1) P(2) P(3) P(4) O(1) O(2) O(3) O(4) O(5) O(6) O(7) O(8) O(9) O(10) O(11)
0.8110(1) 0.13270(1) 0.7666(2) 0.11731(2) 0.11848(2) 0.6782(2) 0.12203(5) 0.8276(5) 0.12715(5) 0.9490(5) 0.6496(5) 0.16487(7) 0.4886(7) 0.0107(7) 0.1265(7) 0.2031(5) 0.6511(5)
1/4 −1/4 0.0095(1) −0.0338(1) 1/4 −1/4 −0.0900(4) 0.0839(4) −0.0914(4) −0.0506(4) 0.0853(4) −1/4 1/4 −1/4 1/4 0.1283(3) −0.1255(4)
0.9820(1) 0.5365(1) 0.2326(1) 0.2841(1) 0.3737(2) 0.1035(2) 0.1630(3) 0.1222(3) 0.3944(3) 0.3051(3) 0.3202(3) 0.5389(4) 0.9834(4) 0.5766(5) 0.9450(5) 0.2775(3) 0.1965(3)
0.008(1) 0.008(1) 0.009(1) 0.009(1) 0.008(1) 0.009(1) 0.016(1) 0.017(1) 0.017(1) 0.014(1) 0.016(1) 0.014(1) 0.014(1) 0.016(1) 0.015(1) 0.012(1) 0.017(1)
a U = (1/3) U a ∗ a ∗ ·a ·a . eq i j ij i j i j
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Fig. 1. Projection of the structure of T-Y(PO3 )3 along [001].
Fig. 2. Projection of the structure of M-Y(PO3 )3 along [010].
to three allotropic varieties of Y(PO3 )3 which we designed by T, M and M .
3. Crystal data and structure determination Suitable single crystal of T-, M- and M -Y(PO3 )3 were selected and epoxies onto a thin glass fibers. Intensity measurements were made at 20 ◦ C using an Enraf Nonius CAD4 automated 4-circles diffractometer (Mo Kα radiation, λ = 0.71069 Å). Data were corrected for Lorentz and polarization effects. Absorption corrections were performed for the room temperature measurements on a four-circle diffractometer using semi-empirical psi-scan method. All structures were solved by Patterson method using SHELXS86 [14] and
subsequent difference Fourier syntheses and then refined by full-matrix least-squares method on F 2 using SHELXL97 [15]. The details of the data collections and structure refinements for T-, M- and M -Y(PO3 )3 are listed in Table 2. The final atomic coordinates and isotropic displacement parameters are listed in Tables 3, 4 and 5, respectively.
4. Structural description and discussion In each case, the structure is built up from isolated YO6 linked through infinite (PO3 )n chains of PO4 tetrahedra. The three dimensional cohesion of each framework results from Y–O–P bridges. Each octahedron shares its six apices with six different PO4 tetrahedra. The crystal structures of T-, M-
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Table 6 Selected bond distances (Å) and bond angles (◦ ) for T-Y(PO3 )3 . Standard deviations are given in parentheses and average Y–O distances in bracket P(1)O4 tetrahedra P(1)–O(7) P(1)–O(13)#10 P(1)–O(4)#1 P(1)–O(3)
1.473(4) 1.474(4) 1.564(4) 1.572(4)
O(7)–P(1)–O(13)#10 O(7)–P(1)–O(4)#1 O(13)#10–P(1)–O(4)#1 O(7)–P(1)–O(3) O(13)#10–P(1)–O(3) O(4)#1–P(1)–O(3)
119.1(2) 110.9(2) 106.5(2) 110.2(2) 109.8(2) 98.2(3)
P(2)O4 tetrahedra P(2)–O(2) P(2)–O(1) P(2)–O(3) P(2)–O(5)
1.462(4) 1.472(4) 1.576(4) 1.580(4)
O(2)–P(2)–O(1) O(2)–P(2)–O(3) O(1)–P(2)–O(3) O(2)–P(2)–O(5) O(1)–P(2)–O(5) O(3)–P(2)–O(5)
118.8(3) 105.2(3) 108.2(3) 110.5(2) 107.4(2) 106.0(2)
P(3)O4 tetrahedra P(3)–O(6)#1 P(3)–O(9)#10 P(3)–O(8) P(3)–O(5)
1.482(3) 1.485(4) 1.576(4) 1.590(3)
O(6)#1–P(3)–O(9)#10 O(6)#1–P(3)–O(8) O(9)#10–P(3)–O(8) O(6)#1–P(3)–O(5) O(9)#10–P(3)–O(5) O(8)–P(3)–O(5)
119.3(2) 105.5(2) 110.5(2) 111.3(2) 105.6(2) 103.5(2)
P(4)O4 tetrahedra P(4)–O(10)#5 P(4)–O(11) P(4)–O(4) P(4)–O(8)
1.472(4) 1.477(4) 1.561(4) 1.584(3)
O(10)#5–P(4)–O(11) O(10)#5–P(4)–O(4) O(11)–P(4)–O(4) O(10)#5–P(4)–O(8) O(11)–P(4)–O(8) O(4)–P(4)–O(8)
117.7(2) 112.3(2) 108.3(3) 110.5(2) 108.2(2) 98.0(2)
Y(1)O6 octahedra Y(1)–O(2) Y(1)–O(1)#1 Y(1)–O(13) Y(1)–O(10) Y(1)–O(9) Y(1)–O(6)
2.171(4) 2.219(4) 2.220(3) 2.221(4) 2.242(3) 2.259(3) 2.222(4)
O(2)–Y(1)–O(1)#1 O(2)–Y(1)–O(13) O(1)#1–Y(1)–O(13) O(2)–Y(1)–O(10) O(1)#1–Y(1)–O(10) O(13)–Y(1)–O(10) O(2)–Y(1)–O(9) O(1)#1–Y(1)–O(9) O(13)–Y(1)–O(9) O(10)–Y(1)–O(9) O(2)–Y(1)–O(6) O(1)#1–Y(1)–O(6) O(13)–Y(1)–O(6) O(10)–Y(1)–O(6) O(9)–Y(1)–O(6)
86.9(2) 174.3(2) 88.9(2) 97.2(2) 85.6(2) 86.32(14) 92.5(2) 95.3(2) 84.08(13) 170.33(14) 88.0(2) 174.8(2) 96.27(14) 95.02(14) 84.97(13)
Y(2)O6 octahedra Y(2)–O(7)# Y(2)–O(7)#3 Y(2)–O(7)#4 Y(2)–O(7) Y(2)–O(7)#5 Y(2)–O(7)#6
2 2.251(3) 2.251(3) 2.251(3) 2.251(3) 2.251(3) 2.251(3) 2.251(3)
O(7)#2–Y(2)–O(7)#3 O(7)#2–Y(2)–O(7)#4 O(7)#3–Y(2)–O(7)#4 O(7)#2–Y(2)–O(7) O(7)#3–Y(2)–O(7) O(7)#4–Y(2)–O(7) O(7)#2–Y(2)–O(7)#5 O(7)#3–Y(2)–O(7)#5 O(7)#4–Y(2)–O(7)#5 O(7)–Y(2)–O(7)#5 O(7)#2–Y(2)–O(7)#6 O(7)#3–Y(2)–O(7)#6 O(7)#4–Y(2)–O(7)#6 O(7)–Y(2)–O(7)#6 O(7)#5–Y(2)–O(7)#6
91.34(14) 91.34(14) 88.66(14) 88.66(14) 91.34(14) 179.998(1) 180.0 88.66(14) 88.66(14) 91.34(14) 88.66(14) 180.0 91.34(14) 88.66(14) 91.34(14)
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Table 6 (Continued) Y(3)O6 octahedra Y(3)–O(11)#7 Y(3)–O(11)#8 Y(3)–O(11)#9 Y(3)–O(11)#10 Y(3)–O(11) Y(3)–O(11)#11
2.154(4) 2.154(4) 2.154(4) 2.154(4) 2.154(4) 2.154(4) 2.154(4)
O(11)#7–Y(3)–O(11)#8 O(11)#7–Y(3)–O(11)#9 O(11)#8–Y(3)–O(11)#9 O(11)#7–Y(3)–O(11)#10 O(11)#8–Y(3)–O(11)#10 O(11)#9–Y(3)–O(11)#10 O(11)#7–Y(3)–O(11) O(11)#8–Y(3)–O(11) O(11)#9–Y(3)–O(11) O(11)#10–Y(3)–O(11) O(11)#7–Y(3)–O(11)#11 O(11)#8–Y(3)–O(11)#11 O(11)#9–Y(3)–O(11)#11 O(11)#10–Y(3)–O(11)#11 O(11)–Y(3)–O(11)#11
90.5(2) 89.5(2) 90.5(2) 89.5(2) 180.0 89.5(2) 90.5(2) 89.5(2) 180.0 90.5(2) 179.999(1) 89.5(2) 90.5(2) 90.5(2) 89.5(2)
P(2)–O(1)–Y(1)#12 P(2)–O(2)–Y(1) P(3)#12–O(6)–Y(1) P(1)–O(7)–Y(2)
150.1(3) 170.9(3) 151.3(2) 159.6(2)
P(1)–O(3)–P(2) P(4)–O(4)–P(1)#12 P(2)–O(5)–P(3) P(3)–O(8)–P(4)
141.6(3) 145.0(3) 138.1(2) 135.4(2)
P(3)#7–O(9)–Y(1) P(4)#3–O(10)–Y(1) P(4)–O(11)–Y(3) P(1)#7–O(13)–Y(1)
135.0(2) 149.3(3) 148.7(3) 177.1(2)
Symmetry codes: #1: y + 2/3, x − y + 4/3, z + 1/3; #2: −x + y − 1, −x, z; #3: y − 2/3, −x + y − 1/3, −z + 2/3; #4: −x − 2/3, −y + 2/3, −z + 2/3; #5: x − y + 1/3, x + 2/3, −z + 2/3; #6: −y, x − y + 1, z; #7: x − y + 1, x + 1, −z+; #8: −y + 1, x − y + 2, z; #9: −x, −y + 2, −z + 1, #10: y − 1, −x + y, −z + 1, #11: −x + y − 1, −x + 1, z, #12: −x + y − 2/3, −x + 2/3, z − 1/3.
and YO7 [17] polyhedra of YNH4 (PO3 )4 and Y2 P4 O13 , respectively. The three forms differ by the polyphosphate chains configuration. The chains that were observed in Y(PO3 )3 T form and in T-Yb(PO3 )3 isotypic compound [4] are identical. These (PO3 )n chains are helical with a period of 12 tetrahedra (Fig. 4a). The M and M -Y(PO3 )3 polyphosphate anions have a period of six tetrahedra (Fig. 4b and 4c). The three forms exhibit an internal symmetry within a period. The T form (Fig. 4a) has a 31 helical axis, an inversion center occurs for the M form (Fig. 4b) whereas the M form has a mirror perpendicular to the b axis and which intercept the lattice at P(3) or P(4) (Fig. 4c). The Fig. 4b shows an oxygen atom position split around the i special position with ½ occupation each. The three structures also differ by the relative arrangements of the polyhedra YO6 and of the (PO3 )n polyphosphate chains: Fig. 3. Projection of the structure of T -Y(PO3 )3 along [001].
and M -Y(PO3 )3 are shown in Figs. 1, 2 and 3 respectively. The corresponding bond lengths and angles are given in Tables 6, 7 and 8, respectively. These values agree with those usually found for polyphosphates [2]. It should be noted that the Y–O average distances in the YO6 octahedra of the three polymorphs compounds are significantly shorter than those observed in the YO8 [16]
• M-Y(PO3 )3 structure is composed of alternate planar layers of (PO3 )n infinite chains and layers of YO6 polyhedra (Fig. 2). • M -Y(PO3 )3 structure consists also of alternating layers but, the (PO3 )n infinite chains and layers of associated cations are corrugated in the same manner (Fig. 3). Y(1)O6 and Y(2)O6 octahedra takes place in the “hollows” of the (PO3 )n chains zigzag. • Finally, in the T form of Y(PO3 )3 one cannot highlight layers alternated in the structure. The YO6 octahedra
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Fig. 4. (PO3 )n chains: (a) in T-Y(PO3 )3 ; (b) in M-Y(PO3 )3 ; (c) in M -Y(PO3 )3 .
Fig. 5. Some details of YO6 and PO4 polyhedra connections showing differences between the three forms of Y(PO3 )3 (a): in M-Y(PO3 )3 ; (b): in M -Y(PO3 )3 ; (c): in T-Y(PO3 )3 .
and the PO4 tetrahedra are overlapped in a threedimensional arrangement (Fig. 1). Taking into consideration the connections of YO6 and PO4 polyhedra in the three forms, the following differences appear: • In the M variety of Y(PO3 )3 , each polyhedron YO6 sets up two Y–O–P links with two tetrahedron P(1)O4
separated by two links in the polyphosphate chain (Fig. 5a). • In the variety M of Y(PO3 )3 , each polyhedron YO6 (Y = Y(1) or Y(2)) sets up three links with three PO4 groups of a single (PO3 )n chain, separated by one link (Fig. 5b). • In the variety T of Y(PO3 )3 , an octahedron Y(1)O6 sets up three links with three tetrahedra P(3)O4 , P(2) O4
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Table 7 Selected bond distances (Å) and bond angles (◦ ) for M-Y(PO3 )3 . Standard deviations are given in parentheses and average Y–O distances in bracket P(1)O4 tetrahedra P(1)–O(1) P(1)–O(2)#4 P(1)–O(5) P(1)–O(3) P(1)–O(5)#5
1.453(7) 1.462(7) 1.51(2) 1.555(8) 1.655(13)
O(1)–P(1)–O(2)#4 O(1)–P(1)–O(5) O(2)#4–P(1)–O(5) O(1)–P(1)–O(3) O(2)#4–P(1)–O(3) O(5)–P(1)–O(3) O(1)–P(1)–O(5)#5 O(2)#4–P(1)–O(5)#5 O(5)–P(1)–O(5)#5 O(3)–P(1)–O(5)#5
118.4(5) 97.7(9) 101.1(9) 112.9(6) 110.9(4) 114.6(6) 115.1(9) 114.8(9) 36.9(9) 77.7(6)
P(2)O4 tetrahedra P(2)–O(4) P(2)–O(4)#6 P(2)–O(3) P(2)–O(3)#6
1.438(7) 1.438(7) 1.562(8) 1.562(8)
O(4)–P(2)–O(4)#6 O(4)–P(2)–O(3) O(4)#6–P(2)–O(3) O(4)–P(2)–O(3)#6 O(4)#6–P(2)–O(3)#6 O(3)–P(2)–O(3)#6
120.1(9) 102.6(5) 113.5(6) 113.5(6) 102.6(5) 103.5(6)
YO6 octahedra Y–O(1) Y–O(1)#1 Y–O(4)#2 Y–O(4)#3 Y–O(2) Y–O(2)#1
2.201(7) 2.201(7) 2.205(8) 2.205(8) 2.225(7) 2.225(7) 2.210(8)
O(1)–Y–O(1)#1 O(1)–Y–O(4)#2 O(1)#1–Y–O(4)#2 O(1)–Y–O(4)#3 O(1)#1–Y–O(4)#3 O(4)#2–Y–O(4)#3 O(1)–Y–O(2) O(1)#1–Y–O(2) O(4)#2–Y–O(2) O(4)#3–Y–O(2) O(1)–Y–O(2)#1 O(1)#1–Y–O(2)#1 O(4)#2–Y–O(2)#1 O(4)#3–Y–O(2)#1 O(2)–Y–O(2)#1
180.0 93.5(4) 86.5(4) 86.5(4) 93.5(4) 180.0 92.9(3) 87.1(3) 88.6(3) 91.4(3) 87.1(3) 92.9(3) 91.4(3) 88.6(3) 180.0
153.6(8) 154.8(4) 162.6(7)
P(1)–O(3)–P(2) P(1)–O(5)–P(1)#5 O(5)–O(5)#5
140.9(5) 143.1(9) 1.01(3)
P(1)–O(1)–Y P(1)#7–O(2)–Y P(2)–O(4)–Y#8
Symmetry codes: #1: −x, −y, −z; #2: x + 1/2, y − 1/2, z; #3: −x − 1/2, −y + 1/2, −z; #4: x, −y − 1/2, z + 1/2; #5: −x − 1/2, −y − 1/2, −z; #6: −x − 1/2, y, −z + 1/2; #7: x, −y − 1/2, z − 1/2; #8: x − 1/2, y + 1/2, z.
and P(2) O4 separated by 5 and 9 links, inducing an important curve of the polyphosphate chains (Fig. 5c). Within the three compounds under study, only the T variety of Y(PO3 )3 shows a known isotype T-Yb(PO3 )3 [4]. It is noted that the published diffractograms attributed to Y(PO3 )3 [10–12], can actually be indexed in the M-Y(PO3)3 cell. XRD study on Y(PO3 )3 phase evolution has revealed that as the firing temperature increases the T and M forms transform into M form. The later can then be considered as the high temperature form, which remained stable up to 1000 ◦ C. It is worth noting that the monoclinic M form of Y(PO3 )3 with P 21 /m space group is probably isotypic to Er(PO3 )3 that has been studied by Dorokhova and Karpov [6]. Despite the comparable lattice parameters of these two
phases, the erbium polyphosphate was resolved in the noncentrosymetrical space group Pm [6]. The outcome of this structural investigation has been contested [18].
5. Conclusion Three forms of Y(PO3 )3 have been shown to exist at temperatures lower than 550 ◦ C. X-ray single crystal diffraction investigation revealed one trigonal (T) and two monoclinic (M and M ) forms of Y(PO3 )3 yttrium polyphosphate. The T and M two forms have not been mentioned yet in the yttrium polyphosphate literature. The M form is found to be stable up to 1000 ◦ C. Therefore it must be considered as the high temperature form. The three structures are formed by (PO3 )n polyphosphate chains and YO6 octahedra. They differ by the mutual arrangement of these chains and polyhedra.
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Table 8 Selected bond distances (Å) and bond angles (◦ ) for M -Y(PO3 )3 . Standard deviations are given in parentheses and average Y–O distances in bracket P(1)O4 tetrahedra P(1)–O(5) P(1)–O(2) P(1)–O(11) P(1)–O(4)
1.479(3) 1.486(4) 1.582(3) 1.594(3)
O(5)–P(1)–O(2) O(5)–P(1)–O(11) O(2)–P(1)–O(11) O(5)–P(1)–O(4) O(2)–P(1)–O(4) O(11)–P(1)–O(4)
118.0(2) 106.6(2) 110.8(2) 107.9(2) 109.8(2) 102.6(2)
P(2)O4 tetrahedra P(2)–O(3) P(2)–O(1) P(2)–O(10) P(2)–O(4)
1.483(3) 1.485(3) 1.587(3) 1.600(3)
O(3)–P(2)–O(1) O(3)–P(2)–O(10) O(1)–P(2)–O(10) O(3)–P(2)–O(4) O(1)–P(2)–O(4) O(10)–P(2)–O(4)
118.9(2) 110.6(2) 106.8(2) 105.9(2) 109.8(2) 103.8(2)
P(3)O4 tetrahedra P(3)–O(6)#7 P(3)–O(8)#5 P(3)–O(10)#1 P(3)–O(10)
1.485(5) 1.489(5) 1.592(3) 1.592(3)
O(6)#7–P(3)–O(8)#5 O(6)#7–P(3)–O(10)#1 O(8)#5–P(3)–O(10)#1 O(6)#7–P(3)–O(10) O(8)#5–P(3)–O(10) O(10)#1–P(3)–O(10)
118.3(3) 110.6(2) 109.7(2) 110.6(2) 109.7(2) 95.6(2)
P(4)O4 tetrahedra P(4)–O(9)#2 P(4)–O(7)#8 P(4)–O(11)#4 P(4)–O(11)
1.482(5) 1.485(5) 1.597(3) 1.597(3)
O(9)#2–P(4)–O(7)#8 O(9)#2–P(4)–O(11)#4 O(7)#8–P(4)–O(11)#4 O(9)#2–P(4)–O(11) O(7)#8–P(4)–O(11) O(11)#4–P(4)–O(11)
119.0(3) 111.1(2) 107.7(2) 111.1(2) 107.7(2) 98.2(3)
Y(1)O6 octahedra Y(1)–O(2)#1 Y(1)–O(2) Y(1)–O(1)#2 Y(1)–O(1)#3 Y(1)–O(7) Y(1)–O(9)
2.228(3) 2.228(3) 2.230(3) 2.230(3) 2.256(5) 2.257(5) 2.238(5)
O(2)#1–Y(1)–O(2) O(2)#1–Y(1)–O(1)#2 O(2)–Y(1)–O(1)#2 O(2)#1–Y(1)–O(1)#3 O(2)–Y(1)–O(1)#3 O(1)#2–Y(1)–O(1)#3 O(2)#1–Y(1)–O(7) O(2)–Y(1)–O(7) O(1)#2–Y(1)–O(7) O(1)#3–Y(1)–O(7) O(2)#1–Y(1)–O(9) O(2)–Y(1)–O(9) O(1)#2–Y(1)–O(9) O(1)#3–Y(1)–O(9) O(7)–Y(1)–O(9)
92.5(2) 176.7(1) 89.6(1) 89.6(1) 176.7(1) 88.2(2) 91.4(1) 91.4(1) 86.0(1) 86.0(1) 95.5(1) 95.5(1) 86.9(1) 86.9(1) 170.0(2)
Y(2)O6 octahedra Y(2)–O(3) Y(2)–O(3)#4 Y(2)–O(5)#5 Y(2)–O(5)#6 Y(2)–O(6) Y(2)–O(8)
2.217(3) 2.217(3) 2.245(3) 2.245(3) 2.250(5) 2.271(5) 2.241(5)
O(3)–Y(2)–O(3)#4 O(3)–Y(2)–O(5)#5 O(3)#4–Y(2)–O(5)#5 O(3)–Y(2)–O(5)#6 O(3)#4–Y(2)–O(5)#6 O(5)#5–Y(2)–O(5)#6 O(3)–Y(2)–O(6) O(3)#4–Y(2)–O(6) O(5)#5–Y(2)–O(6) O(5)#6–Y(2)–O(6) O(3)–Y(2)–O(8) O(3)#4–Y(2)–O(8) O(5)#5–Y(2)–O(8) O(5)#6–Y(2)–O(8) O(6)–Y(2)–O(8)
87.8(2) 90.5(1) 174.0(1) 174.0(1) 90.5(1) 90.7(2) 99.3(1) 99.3(1) 86.6(1) 86.6(1) 89.2(1) 89.2(1) 85.0(1) 85.0(1) 168.1(2)
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Table 8 (Continued) P(1)–O(4)–P(2) P(2)–O(10)–P(3) P(1)–O(11)–P(4)
131.5(2) 133.6(2) 135.7(2)
P(2)–O(1)–Y(1)#2 P(1)–O(2)–Y(1) P(2)–O(3)–Y(2) P(1)–O(5)–Y(2)#5 P(3)#7–O(6)–Y(2) P(4)#8–O(7)–Y(1) P(3)#5–O(8)–Y(2) P(4)#2–O(9)–Y(1)
151.2(2) 154.8(2) 154.5(2) 141.3(2) 140.5(3) 139.6(3) 169.7(3) 169.4(3)
Symmetry codes: #1: x, −y + 1/2, z; #2: −x + 2, −y, −z + 2; #3: −x + 2, y + 1/2, −z + 2; #4: x, −y − 1/2, z; #5: −x + 2, −y, −z + 3; #6: −x + 2, y − 1/2, −z + 3; #7: −x + 3, −y, −z + 3; #7: x − y + 1, x + 1, −z+; #8: −x + 1, −y, −z + 2.
References [1] J. Matuszewski, J. Kropiwnicka, T. Znamierowska, J. Solid State Chem. 75 (1988) 285. [2] A. Durif, Crystal Chemistry of Condensed Phosphates, Hing Corporation, New York, 146–149. [3] H.Y.-P. Hong, Acta Crystallogr. B 30 (1974) 1857. [4] N.Tu. Anisimova, V.K. Trunov, N.B. Karmanovskaya, N.N. Chudinova, Izv. Akad. Nauk. SSSR Neorg. Mater 28 (1992) 441. [5] H.Y.-P. Hong, Acta Crystallogr. B 30 (1974) 468. [6] G.I. Dorokhova, O.G. Karpov, Kristallografiya 29 (1984) 677. [7] K. Palkina, K.-H. Jost, Acta Crystallogr. B 31 (1975) 2281. [8] D. Agrawel, F.A. Hummel, J. Electrochem. Soc. 127 (7) (1980) 1550. [9] N.N. Chudinova, L.P. Shklover, L.I. Shkol’nikova, A.E. Balanevskaya, G.M. Balagina, Izv. Akad. Nauk SSSR Neorg. Mater 14 (1978) 1324.
[10] E.N. Federova, L.K. Shmatok, I.I. Kozhina, T.R. Barabanova, Izv. Akad. Nauk SSSR Neorg. Mater 22 (1986) 480. [11] N.N. Chudinova, Koord. Khim. 4 (1978) 550. [12] W. Szuszkiewics, T. Znamierowska, Pol. J. Chem. 63 (1989) 381. [13] L.P. Shklover, A.E. Obodovskaya, A.E. Balanevskaya, L.M. Shkolnikova, H.H. Tchudinova, Izv. Akad. Nauk SSSR, Neorg. Mat. (1986) 1752. [14] G.M. Sheldrick, Acta Crystallogr. A 46 (1990) 467. [15] G.M. Sheldrick, SHELXL93, Program for the Refinement of Crystal Structures, Göttingen University, Germany, 1993. [16] M. Bagieu-Beucher, J.C. Guitel, Z. Anorg. Allg. Chem. 559 (1988) 123. [17] A. Hamady, Thèse de doctorat, Faculté des Sciences de Tunis (1996). [18] Inorganic Crystal Structure Database “ICSD version 1997”.
Crystal structure of three polymorphs of Y(PO3 )3 Mohsen Graia a,b , Ahmed Driss a , Tahar Jouini a,∗ a Laboratoire de matériaux et de cristallochimie, département de chimie, faculté des sciences de Tunis, campus universitaire, 1060, Tunis, Tunisia b Institut préparatoire aux études d’ingénieurs de Sfax, BP 805, 3000, Sfax, Tunisia
Received 2 June 2002; received in revised form 7 October 2002; accepted 23 October 2002
Abstract Three polymorphs of yttrium polyphosphate Y(PO3 )3 were prepared and their crystal structures were determined by single-crystal Xray diffraction. Each structure is composed of (PO3 )n infinite chains linked together by corner-sharing YO6 octahedra. Crystal data: Y(PO3 )3 T, Mr = 162.91, trigonal, space group R-3, a = b = 21.042(3) Å, c = 12.159(1) Å, V = 4662(1) Å3 , dc = 2.785, Z = 24, R = 0.033, wR = 0.073. Y(PO3 )3 M, Mr = 162.91, monoclinic, space group C2/c, a = 14.176(1) Å, b = 6.70750(9) Å, c = 10.0853(8) Å, β = 127.597(7)◦ , V = 759.81(8) Å3 , dc = 2.848, Z = 4, R = 0.055, wR = 0.107. Y(PO3 )3 M , Mr = 162.91, monoclinic, space group P 21 /m, a = 6.997(1) Å, b = 9.693(1) Å, c = 10.989(1) Å, β = 91.84(1)◦ , V = 744.9(2) Å3 , dc = 2.905, Z = 4, R = 0.035, wR = 0.080. 2003 Éditions scientifiques et médicales Elsevier SAS. All rights reserved. Keywords: Synthesis; Structure; Polymorphs; Polyphosphate; Yttrium
1. Introduction In recent years, the yttrium and rare earth phosphates have been the subject of interest in particular due to their Laser applications [1]. Trivalent cation long-chain polyphosphates belong to two groups. The first group comprises compounds of the general formula MIII (PO3 )3 with MIII = Al, Cr, Ga, V, Mn, Fe, Rh, Ti, Mo, Sc, In and Tl [2]. The second group contains compounds of yttrium, lanthanides and bismuth. In this second family of compounds two different formulas have been observed: MIII H(PO3 )4 and MIII (PO3 )3 [2]. Only five crystal structures of MIII (PO3 )3 compounds belonging to the second group have been established [3–7]. The main crystallographic features for these compounds are reported in Table 1. However, other investigations carried out on powder have shown that some of these compounds are polymorphs [1,3, 8,9], for example Yb(PO3 )3 which presents five allotropic forms [3]. A summary of the literature concerning the polymorphism of yttrium polyphosphate Y(PO3 )3 is presented below. Up to now, no crystal structure of yttrium polyphosphate Y(PO3 )3 has been determined probably due to the difficulty of producing single crystal of these compounds. Only * Corresponding author.
E-mail address: [email protected] (T. Jouini).
characterization from powder data are available. Three diffractograms of Y(PO3 )3 have been reported [10–12]. Only that published by Szuszkiewics et al. is indexed [12]. The refined unit cell parameters of Y(PO3 )3 are a = 14.152(2) Å, b = 20.149(4) Å, c = 10.061(1) Å and β = 127.9(1)◦. This study excludes the isotypy of this phase with C-Yb(PO3 )3 . The samples studied during these studies are obtained at temperatures ranging between 500 and 900 ◦ C. In this temperature interval Y(PO3 )3 has only one stable form. Indeed, the investigations of Y2 O3 –P2 O5 and Y(PO3 )3 –La(PO3)3 systems [5,10] at 1980 and 1986, respectively, did not point out any phase transition of yttrium polyphosphate Y(PO3 )3 up to the fusion temperature (1460 ◦ C). In 1986 Shklover et al. concluded that Y(PO3 )3 had a single stable structure between 180 ◦ C and 1000 ◦ C [13]. Federova et al. observed that Y(PO3 )3 remained stable until 1400 ◦ C before it undergoes a polymorphic transition [9]. The present work deals with preparation and crystal structures of three forms of Y(PO3 )3 proving the polymorphism of this salt for temperatures lower than 550 ◦ C.
2. Chemical preparation and elementary analysis Three crystalline forms of Y(PO3 )3 were isolated during our systematic investigations of the Y2 O3 –P2 O5 –SrO system. Single crystal of these Y(PO3 )3 polymorphs were ob-
1293-2558/03/$ – see front matter 2003 Éditions scientifiques et médicales Elsevier SAS. All rights reserved. doi:10.1016/S1293-2558(03)00012-8
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Table 1 Main crystallographic data for the MIII (PO3 )3 polyphosphates (M = Ln and Bi) Space group
a (Å) α (◦ )
b (Å) β (◦ )
C-Yb(PO3 )3
P 21 /c
11.219(2)
T -Yb(PO3 )3
R3
20.974(4)
19.983(3) 97.3(0) 20.974(4)
Nd(PO3 )3 Er(PO3 )3
C2221 P 11m
11.172(2) 10.943(3)
8.533(2) 6.971(2)
Bi(PO3 )3
P 21 /a
13.732(2)
6.933(1) 93.3(0)
Formula
V (Å3 )
Z
Ref.
9.999(3)
2223.5
12
[3]
12.134(3) 120.0 7.284(2) 9.670(2) 91.8(0) 7.152(1)
4622.7
24
[4]
694.4 737.3
4 4
[5] [6]
679.7
4
[7]
c (Å) γ (◦ )
Table 2 Crystallographic data, recording conditions, and refinement results for T-, M- and M -Y(PO3 )3 Crystal data Formula weight Volume (Å3 ) Temperature Shape Color Crystal dimensions (mm) Crystal system Space group Cell dimensions
T-Y(PO3 )3
M-Y(PO3 )3
M -Y(PO3 )3
325.82 4662 (1) 293(2) K rhombohedron colourless 0.05 × 0.09 × 0.11 rhombohedral R-3 (N◦ 148) a = 21.042(3) Å c = 12.159(1) Å γ = 120◦
325.82 759.81 (8) 293(2) K irregular colourless 0.20 × 0.18 × 0.17 monoclinic C2/c (N◦ 15) a = 14.176(1) Å b = 6.70750(9) Å c = 10.0853(8) Å β = 127.597(7)◦ 2.848 4 8.330 mm−1
325.82 744.9 (2) 293(2) K platelet colourless 0.22 × 0.18 × 0.05 monoclinic P 21 /m (N◦ 11) a = 6.997(1) Å b = 9.693(1) Å c = 10.989(1) Å β = 91.84(1)◦ 2.905 4 8.496 mm−1
2.79 to 27.02◦ 4912 2268 [R(int) = 0.036]
3.54 to 25.96◦ 906 749 [R(int) = 0.106]
2.80 to 26.97◦ 1808 1718 [R(int) = 0.028]
159 R1 = 0.0328 wR = 0.0734 0.00004(3) 1.085 0.863 and −1.912
67 R1 = 0.0546 wR = 0.1069 0.0008(4) 1.055 1.471 and −0.980
131 R1 = 0.0353 wR = 0.0803 0.0035(7) 1.106 0.877 and −0.815
Density calc. (g cm−3 ) 2.785 Z 24 Absorption coefficient 8.145 mm−1 Radiation, graphite monochromator: Mo Kα (λ = 0.71069 Å) Data collection Diffractometer: Enraf-Nonius CAD-4 Scan mode: ω − 2θ θ range for data collection Measured reflections Independent reflections Refinement Refinement on F 2 Parameters refined Final R indices [I > 4σ (I )] Extinction correction s(F 2 ) (∆ρ)max and (∆ρ)min (e·A−3 )
Weighting scheme: T-Y(PO3 )3 : w = 1/[σ 2 (Fo2 ) + (0.0195P)2 + 72.7821P], where P = (Fo2 + 2Fc2 )/3. M-Y(PO3 )3 : w = 1/[σ 2 (Fo2 ) + (0.0000P)2 + 26.7352P], where P = (Fo2 + 2Fc2 )/3. M -Y(PO3 )3 : w = 1/[σ 2 (Fo2 ) + (0.0419P)2 + 0.7655P], where P = (Fo2 + 2Fc2 )/3.
tained by adding 0.212 g of Sr(NO3 )2 and 0.452 g of Y2 O3 to a mixture of 15 ml of water, 10 ml of concentrated HNO3 and of 1 ml of H3 PO4 (85%) at room temperature. The mixture was preheated in a porcelain crucible at 140 ◦ C for 12 h, held at 550 ◦ C for 24 h, and cooled at 3 ◦ C min−1 to room temperature. After being washed with hot water to dissolve any excess of phosphoric acid, the sample was found to include crystals with three different forms. The role played
by Sr(NO3 )2 is not explained. However, pure Y(PO3 )3 was never obtained even with appropriate amounts of Y2 O3 and P2 O5 when the composition was known based on X-ray crystal structure analysis. Elementary analysis of single crystal of each form using a scanning electron microscope showed the presence of oxygen, phosphorus, and yttrium in each of the analysed samples. As will be shown later, these crystals correspond
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Table 3 Fractional atomic coordinates and equivalent thermal parameters (Å2 ) for T-Y(PO3 )3 a . Standard deviations are given in parentheses Atom
x
y
z
Ueq
Y(1) Y(2) Y(3) P(1) P(2) P(3) P(4) O(1) O(2) O(3) O(4) O(5) O(6) O(7) O(8) O(9) O(10) O(11) O(12)
0.1072(1) −1/3 0 −0.2067(1) −0.0879(1) −0.1213(1) −0.0809(1) −0.1072(3) −0.0110(2) −0.1294(2) −0.0129(2) −0.1208(2) 0.1185(2) −0.2471(2) −0.0736(2) 0.1115(2) 0.1234(2) −0.0658(3) 0.2261(2)
0.6982(1) 1/3 0 0.4882(1) 0.6073(1) 0.7086(1) 0.8346(1) 0.5815(3) 0.6427(2) 0.5391(2) 0.8467(3) 0.6588(2) 0.7475(2) 0.4197(2) 0.7891(2) 0.8010(2) 0.6070(2) 0.9064(2) 0.7574(2)
0.4296(1) 1/3 1/2 0.5061(1) 0.3740(1) 0.4970(1) 0.3534(1) 0.2598(3) 0.4075(4) 0.4528(4) 0.2853(3) 0.3990(3) 0.2606(3) 0.4427(3) 0.4515(3) 0.4902(3) 0.3728(3) 0.3969(4) 0.4691(3)
0.011(1) 0.011(1) 0.023(1) 0.012(1) 0.017(1) 0.013(1) 0.017(1) 0.048(1) 0.038(1) 0.043(1) 0.044(1) 0.022(1) 0.021(1) 0.026(1) 0.024(1) 0.021(1) 0.029(1) 0.039(1) 0.026(1)
a U = (1/3) U a ∗ a ∗ ·a ·a . eq ij i j ij i j i j
Table 4 Fractional atomic coordinates and equivalent thermal parameters (Å2 ) for M-Y(PO3 )3 a . Standard deviations are given in parentheses Atom
x
Y P(1) P(2) O(1) O(2) O(3) O(4) O(5)
0 −0.1543(2) −1/4 −0.0646(9) −0.1169(6) −0.2357(8) −0.3571(7) −0.2154(11) a U = (1/3) U a ∗ a ∗ ·a ·a . eq i j ij i j i j
y
z
Ueq
Occupation
0 −0.1475(4) 0.1677(4) −0.0790(16) −0.2230(11) 0.0235(14) 0.2746(16) −0.2950(30)
0 0.1602(3) 1/4 0.1438(14) −0.1988(9) 0.1418(10) 0.1258(12) 0.0180(19)
0.034(1) 0.035(1) 0.037(1) 0.104(4) 0.053(2) 0.077(3) 0.105(4) 0.082(6)
1/2
Table 5 Fractional atomic coordinates and equivalent thermal parameters (Å2 ) for M - Y(PO3 )3 a . Standard deviations are given in parentheses Atom
x
y
z
Ueq
Y(1) Y(2) P(1) P(2) P(3) P(4) O(1) O(2) O(3) O(4) O(5) O(6) O(7) O(8) O(9) O(10) O(11)
0.8110(1) 0.13270(1) 0.7666(2) 0.11731(2) 0.11848(2) 0.6782(2) 0.12203(5) 0.8276(5) 0.12715(5) 0.9490(5) 0.6496(5) 0.16487(7) 0.4886(7) 0.0107(7) 0.1265(7) 0.2031(5) 0.6511(5)
1/4 −1/4 0.0095(1) −0.0338(1) 1/4 −1/4 −0.0900(4) 0.0839(4) −0.0914(4) −0.0506(4) 0.0853(4) −1/4 1/4 −1/4 1/4 0.1283(3) −0.1255(4)
0.9820(1) 0.5365(1) 0.2326(1) 0.2841(1) 0.3737(2) 0.1035(2) 0.1630(3) 0.1222(3) 0.3944(3) 0.3051(3) 0.3202(3) 0.5389(4) 0.9834(4) 0.5766(5) 0.9450(5) 0.2775(3) 0.1965(3)
0.008(1) 0.008(1) 0.009(1) 0.009(1) 0.008(1) 0.009(1) 0.016(1) 0.017(1) 0.017(1) 0.014(1) 0.016(1) 0.014(1) 0.014(1) 0.016(1) 0.015(1) 0.012(1) 0.017(1)
a U = (1/3) U a ∗ a ∗ ·a ·a . eq i j ij i j i j
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Fig. 1. Projection of the structure of T-Y(PO3 )3 along [001].
Fig. 2. Projection of the structure of M-Y(PO3 )3 along [010].
to three allotropic varieties of Y(PO3 )3 which we designed by T, M and M .
3. Crystal data and structure determination Suitable single crystal of T-, M- and M -Y(PO3 )3 were selected and epoxies onto a thin glass fibers. Intensity measurements were made at 20 ◦ C using an Enraf Nonius CAD4 automated 4-circles diffractometer (Mo Kα radiation, λ = 0.71069 Å). Data were corrected for Lorentz and polarization effects. Absorption corrections were performed for the room temperature measurements on a four-circle diffractometer using semi-empirical psi-scan method. All structures were solved by Patterson method using SHELXS86 [14] and
subsequent difference Fourier syntheses and then refined by full-matrix least-squares method on F 2 using SHELXL97 [15]. The details of the data collections and structure refinements for T-, M- and M -Y(PO3 )3 are listed in Table 2. The final atomic coordinates and isotropic displacement parameters are listed in Tables 3, 4 and 5, respectively.
4. Structural description and discussion In each case, the structure is built up from isolated YO6 linked through infinite (PO3 )n chains of PO4 tetrahedra. The three dimensional cohesion of each framework results from Y–O–P bridges. Each octahedron shares its six apices with six different PO4 tetrahedra. The crystal structures of T-, M-
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Table 6 Selected bond distances (Å) and bond angles (◦ ) for T-Y(PO3 )3 . Standard deviations are given in parentheses and average Y–O distances in bracket P(1)O4 tetrahedra P(1)–O(7) P(1)–O(13)#10 P(1)–O(4)#1 P(1)–O(3)
1.473(4) 1.474(4) 1.564(4) 1.572(4)
O(7)–P(1)–O(13)#10 O(7)–P(1)–O(4)#1 O(13)#10–P(1)–O(4)#1 O(7)–P(1)–O(3) O(13)#10–P(1)–O(3) O(4)#1–P(1)–O(3)
119.1(2) 110.9(2) 106.5(2) 110.2(2) 109.8(2) 98.2(3)
P(2)O4 tetrahedra P(2)–O(2) P(2)–O(1) P(2)–O(3) P(2)–O(5)
1.462(4) 1.472(4) 1.576(4) 1.580(4)
O(2)–P(2)–O(1) O(2)–P(2)–O(3) O(1)–P(2)–O(3) O(2)–P(2)–O(5) O(1)–P(2)–O(5) O(3)–P(2)–O(5)
118.8(3) 105.2(3) 108.2(3) 110.5(2) 107.4(2) 106.0(2)
P(3)O4 tetrahedra P(3)–O(6)#1 P(3)–O(9)#10 P(3)–O(8) P(3)–O(5)
1.482(3) 1.485(4) 1.576(4) 1.590(3)
O(6)#1–P(3)–O(9)#10 O(6)#1–P(3)–O(8) O(9)#10–P(3)–O(8) O(6)#1–P(3)–O(5) O(9)#10–P(3)–O(5) O(8)–P(3)–O(5)
119.3(2) 105.5(2) 110.5(2) 111.3(2) 105.6(2) 103.5(2)
P(4)O4 tetrahedra P(4)–O(10)#5 P(4)–O(11) P(4)–O(4) P(4)–O(8)
1.472(4) 1.477(4) 1.561(4) 1.584(3)
O(10)#5–P(4)–O(11) O(10)#5–P(4)–O(4) O(11)–P(4)–O(4) O(10)#5–P(4)–O(8) O(11)–P(4)–O(8) O(4)–P(4)–O(8)
117.7(2) 112.3(2) 108.3(3) 110.5(2) 108.2(2) 98.0(2)
Y(1)O6 octahedra Y(1)–O(2) Y(1)–O(1)#1 Y(1)–O(13) Y(1)–O(10) Y(1)–O(9) Y(1)–O(6)
2.171(4) 2.219(4) 2.220(3) 2.221(4) 2.242(3) 2.259(3) 2.222(4)
O(2)–Y(1)–O(1)#1 O(2)–Y(1)–O(13) O(1)#1–Y(1)–O(13) O(2)–Y(1)–O(10) O(1)#1–Y(1)–O(10) O(13)–Y(1)–O(10) O(2)–Y(1)–O(9) O(1)#1–Y(1)–O(9) O(13)–Y(1)–O(9) O(10)–Y(1)–O(9) O(2)–Y(1)–O(6) O(1)#1–Y(1)–O(6) O(13)–Y(1)–O(6) O(10)–Y(1)–O(6) O(9)–Y(1)–O(6)
86.9(2) 174.3(2) 88.9(2) 97.2(2) 85.6(2) 86.32(14) 92.5(2) 95.3(2) 84.08(13) 170.33(14) 88.0(2) 174.8(2) 96.27(14) 95.02(14) 84.97(13)
Y(2)O6 octahedra Y(2)–O(7)# Y(2)–O(7)#3 Y(2)–O(7)#4 Y(2)–O(7) Y(2)–O(7)#5 Y(2)–O(7)#6
2 2.251(3) 2.251(3) 2.251(3) 2.251(3) 2.251(3) 2.251(3) 2.251(3)
O(7)#2–Y(2)–O(7)#3 O(7)#2–Y(2)–O(7)#4 O(7)#3–Y(2)–O(7)#4 O(7)#2–Y(2)–O(7) O(7)#3–Y(2)–O(7) O(7)#4–Y(2)–O(7) O(7)#2–Y(2)–O(7)#5 O(7)#3–Y(2)–O(7)#5 O(7)#4–Y(2)–O(7)#5 O(7)–Y(2)–O(7)#5 O(7)#2–Y(2)–O(7)#6 O(7)#3–Y(2)–O(7)#6 O(7)#4–Y(2)–O(7)#6 O(7)–Y(2)–O(7)#6 O(7)#5–Y(2)–O(7)#6
91.34(14) 91.34(14) 88.66(14) 88.66(14) 91.34(14) 179.998(1) 180.0 88.66(14) 88.66(14) 91.34(14) 88.66(14) 180.0 91.34(14) 88.66(14) 91.34(14)
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Table 6 (Continued) Y(3)O6 octahedra Y(3)–O(11)#7 Y(3)–O(11)#8 Y(3)–O(11)#9 Y(3)–O(11)#10 Y(3)–O(11) Y(3)–O(11)#11
2.154(4) 2.154(4) 2.154(4) 2.154(4) 2.154(4) 2.154(4) 2.154(4)
O(11)#7–Y(3)–O(11)#8 O(11)#7–Y(3)–O(11)#9 O(11)#8–Y(3)–O(11)#9 O(11)#7–Y(3)–O(11)#10 O(11)#8–Y(3)–O(11)#10 O(11)#9–Y(3)–O(11)#10 O(11)#7–Y(3)–O(11) O(11)#8–Y(3)–O(11) O(11)#9–Y(3)–O(11) O(11)#10–Y(3)–O(11) O(11)#7–Y(3)–O(11)#11 O(11)#8–Y(3)–O(11)#11 O(11)#9–Y(3)–O(11)#11 O(11)#10–Y(3)–O(11)#11 O(11)–Y(3)–O(11)#11
90.5(2) 89.5(2) 90.5(2) 89.5(2) 180.0 89.5(2) 90.5(2) 89.5(2) 180.0 90.5(2) 179.999(1) 89.5(2) 90.5(2) 90.5(2) 89.5(2)
P(2)–O(1)–Y(1)#12 P(2)–O(2)–Y(1) P(3)#12–O(6)–Y(1) P(1)–O(7)–Y(2)
150.1(3) 170.9(3) 151.3(2) 159.6(2)
P(1)–O(3)–P(2) P(4)–O(4)–P(1)#12 P(2)–O(5)–P(3) P(3)–O(8)–P(4)
141.6(3) 145.0(3) 138.1(2) 135.4(2)
P(3)#7–O(9)–Y(1) P(4)#3–O(10)–Y(1) P(4)–O(11)–Y(3) P(1)#7–O(13)–Y(1)
135.0(2) 149.3(3) 148.7(3) 177.1(2)
Symmetry codes: #1: y + 2/3, x − y + 4/3, z + 1/3; #2: −x + y − 1, −x, z; #3: y − 2/3, −x + y − 1/3, −z + 2/3; #4: −x − 2/3, −y + 2/3, −z + 2/3; #5: x − y + 1/3, x + 2/3, −z + 2/3; #6: −y, x − y + 1, z; #7: x − y + 1, x + 1, −z+; #8: −y + 1, x − y + 2, z; #9: −x, −y + 2, −z + 1, #10: y − 1, −x + y, −z + 1, #11: −x + y − 1, −x + 1, z, #12: −x + y − 2/3, −x + 2/3, z − 1/3.
and YO7 [17] polyhedra of YNH4 (PO3 )4 and Y2 P4 O13 , respectively. The three forms differ by the polyphosphate chains configuration. The chains that were observed in Y(PO3 )3 T form and in T-Yb(PO3 )3 isotypic compound [4] are identical. These (PO3 )n chains are helical with a period of 12 tetrahedra (Fig. 4a). The M and M -Y(PO3 )3 polyphosphate anions have a period of six tetrahedra (Fig. 4b and 4c). The three forms exhibit an internal symmetry within a period. The T form (Fig. 4a) has a 31 helical axis, an inversion center occurs for the M form (Fig. 4b) whereas the M form has a mirror perpendicular to the b axis and which intercept the lattice at P(3) or P(4) (Fig. 4c). The Fig. 4b shows an oxygen atom position split around the i special position with ½ occupation each. The three structures also differ by the relative arrangements of the polyhedra YO6 and of the (PO3 )n polyphosphate chains: Fig. 3. Projection of the structure of T -Y(PO3 )3 along [001].
and M -Y(PO3 )3 are shown in Figs. 1, 2 and 3 respectively. The corresponding bond lengths and angles are given in Tables 6, 7 and 8, respectively. These values agree with those usually found for polyphosphates [2]. It should be noted that the Y–O average distances in the YO6 octahedra of the three polymorphs compounds are significantly shorter than those observed in the YO8 [16]
• M-Y(PO3 )3 structure is composed of alternate planar layers of (PO3 )n infinite chains and layers of YO6 polyhedra (Fig. 2). • M -Y(PO3 )3 structure consists also of alternating layers but, the (PO3 )n infinite chains and layers of associated cations are corrugated in the same manner (Fig. 3). Y(1)O6 and Y(2)O6 octahedra takes place in the “hollows” of the (PO3 )n chains zigzag. • Finally, in the T form of Y(PO3 )3 one cannot highlight layers alternated in the structure. The YO6 octahedra
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Fig. 4. (PO3 )n chains: (a) in T-Y(PO3 )3 ; (b) in M-Y(PO3 )3 ; (c) in M -Y(PO3 )3 .
Fig. 5. Some details of YO6 and PO4 polyhedra connections showing differences between the three forms of Y(PO3 )3 (a): in M-Y(PO3 )3 ; (b): in M -Y(PO3 )3 ; (c): in T-Y(PO3 )3 .
and the PO4 tetrahedra are overlapped in a threedimensional arrangement (Fig. 1). Taking into consideration the connections of YO6 and PO4 polyhedra in the three forms, the following differences appear: • In the M variety of Y(PO3 )3 , each polyhedron YO6 sets up two Y–O–P links with two tetrahedron P(1)O4
separated by two links in the polyphosphate chain (Fig. 5a). • In the variety M of Y(PO3 )3 , each polyhedron YO6 (Y = Y(1) or Y(2)) sets up three links with three PO4 groups of a single (PO3 )n chain, separated by one link (Fig. 5b). • In the variety T of Y(PO3 )3 , an octahedron Y(1)O6 sets up three links with three tetrahedra P(3)O4 , P(2) O4
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Table 7 Selected bond distances (Å) and bond angles (◦ ) for M-Y(PO3 )3 . Standard deviations are given in parentheses and average Y–O distances in bracket P(1)O4 tetrahedra P(1)–O(1) P(1)–O(2)#4 P(1)–O(5) P(1)–O(3) P(1)–O(5)#5
1.453(7) 1.462(7) 1.51(2) 1.555(8) 1.655(13)
O(1)–P(1)–O(2)#4 O(1)–P(1)–O(5) O(2)#4–P(1)–O(5) O(1)–P(1)–O(3) O(2)#4–P(1)–O(3) O(5)–P(1)–O(3) O(1)–P(1)–O(5)#5 O(2)#4–P(1)–O(5)#5 O(5)–P(1)–O(5)#5 O(3)–P(1)–O(5)#5
118.4(5) 97.7(9) 101.1(9) 112.9(6) 110.9(4) 114.6(6) 115.1(9) 114.8(9) 36.9(9) 77.7(6)
P(2)O4 tetrahedra P(2)–O(4) P(2)–O(4)#6 P(2)–O(3) P(2)–O(3)#6
1.438(7) 1.438(7) 1.562(8) 1.562(8)
O(4)–P(2)–O(4)#6 O(4)–P(2)–O(3) O(4)#6–P(2)–O(3) O(4)–P(2)–O(3)#6 O(4)#6–P(2)–O(3)#6 O(3)–P(2)–O(3)#6
120.1(9) 102.6(5) 113.5(6) 113.5(6) 102.6(5) 103.5(6)
YO6 octahedra Y–O(1) Y–O(1)#1 Y–O(4)#2 Y–O(4)#3 Y–O(2) Y–O(2)#1
2.201(7) 2.201(7) 2.205(8) 2.205(8) 2.225(7) 2.225(7) 2.210(8)
O(1)–Y–O(1)#1 O(1)–Y–O(4)#2 O(1)#1–Y–O(4)#2 O(1)–Y–O(4)#3 O(1)#1–Y–O(4)#3 O(4)#2–Y–O(4)#3 O(1)–Y–O(2) O(1)#1–Y–O(2) O(4)#2–Y–O(2) O(4)#3–Y–O(2) O(1)–Y–O(2)#1 O(1)#1–Y–O(2)#1 O(4)#2–Y–O(2)#1 O(4)#3–Y–O(2)#1 O(2)–Y–O(2)#1
180.0 93.5(4) 86.5(4) 86.5(4) 93.5(4) 180.0 92.9(3) 87.1(3) 88.6(3) 91.4(3) 87.1(3) 92.9(3) 91.4(3) 88.6(3) 180.0
153.6(8) 154.8(4) 162.6(7)
P(1)–O(3)–P(2) P(1)–O(5)–P(1)#5 O(5)–O(5)#5
140.9(5) 143.1(9) 1.01(3)
P(1)–O(1)–Y P(1)#7–O(2)–Y P(2)–O(4)–Y#8
Symmetry codes: #1: −x, −y, −z; #2: x + 1/2, y − 1/2, z; #3: −x − 1/2, −y + 1/2, −z; #4: x, −y − 1/2, z + 1/2; #5: −x − 1/2, −y − 1/2, −z; #6: −x − 1/2, y, −z + 1/2; #7: x, −y − 1/2, z − 1/2; #8: x − 1/2, y + 1/2, z.
and P(2) O4 separated by 5 and 9 links, inducing an important curve of the polyphosphate chains (Fig. 5c). Within the three compounds under study, only the T variety of Y(PO3 )3 shows a known isotype T-Yb(PO3 )3 [4]. It is noted that the published diffractograms attributed to Y(PO3 )3 [10–12], can actually be indexed in the M-Y(PO3)3 cell. XRD study on Y(PO3 )3 phase evolution has revealed that as the firing temperature increases the T and M forms transform into M form. The later can then be considered as the high temperature form, which remained stable up to 1000 ◦ C. It is worth noting that the monoclinic M form of Y(PO3 )3 with P 21 /m space group is probably isotypic to Er(PO3 )3 that has been studied by Dorokhova and Karpov [6]. Despite the comparable lattice parameters of these two
phases, the erbium polyphosphate was resolved in the noncentrosymetrical space group Pm [6]. The outcome of this structural investigation has been contested [18].
5. Conclusion Three forms of Y(PO3 )3 have been shown to exist at temperatures lower than 550 ◦ C. X-ray single crystal diffraction investigation revealed one trigonal (T) and two monoclinic (M and M ) forms of Y(PO3 )3 yttrium polyphosphate. The T and M two forms have not been mentioned yet in the yttrium polyphosphate literature. The M form is found to be stable up to 1000 ◦ C. Therefore it must be considered as the high temperature form. The three structures are formed by (PO3 )n polyphosphate chains and YO6 octahedra. They differ by the mutual arrangement of these chains and polyhedra.
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Table 8 Selected bond distances (Å) and bond angles (◦ ) for M -Y(PO3 )3 . Standard deviations are given in parentheses and average Y–O distances in bracket P(1)O4 tetrahedra P(1)–O(5) P(1)–O(2) P(1)–O(11) P(1)–O(4)
1.479(3) 1.486(4) 1.582(3) 1.594(3)
O(5)–P(1)–O(2) O(5)–P(1)–O(11) O(2)–P(1)–O(11) O(5)–P(1)–O(4) O(2)–P(1)–O(4) O(11)–P(1)–O(4)
118.0(2) 106.6(2) 110.8(2) 107.9(2) 109.8(2) 102.6(2)
P(2)O4 tetrahedra P(2)–O(3) P(2)–O(1) P(2)–O(10) P(2)–O(4)
1.483(3) 1.485(3) 1.587(3) 1.600(3)
O(3)–P(2)–O(1) O(3)–P(2)–O(10) O(1)–P(2)–O(10) O(3)–P(2)–O(4) O(1)–P(2)–O(4) O(10)–P(2)–O(4)
118.9(2) 110.6(2) 106.8(2) 105.9(2) 109.8(2) 103.8(2)
P(3)O4 tetrahedra P(3)–O(6)#7 P(3)–O(8)#5 P(3)–O(10)#1 P(3)–O(10)
1.485(5) 1.489(5) 1.592(3) 1.592(3)
O(6)#7–P(3)–O(8)#5 O(6)#7–P(3)–O(10)#1 O(8)#5–P(3)–O(10)#1 O(6)#7–P(3)–O(10) O(8)#5–P(3)–O(10) O(10)#1–P(3)–O(10)
118.3(3) 110.6(2) 109.7(2) 110.6(2) 109.7(2) 95.6(2)
P(4)O4 tetrahedra P(4)–O(9)#2 P(4)–O(7)#8 P(4)–O(11)#4 P(4)–O(11)
1.482(5) 1.485(5) 1.597(3) 1.597(3)
O(9)#2–P(4)–O(7)#8 O(9)#2–P(4)–O(11)#4 O(7)#8–P(4)–O(11)#4 O(9)#2–P(4)–O(11) O(7)#8–P(4)–O(11) O(11)#4–P(4)–O(11)
119.0(3) 111.1(2) 107.7(2) 111.1(2) 107.7(2) 98.2(3)
Y(1)O6 octahedra Y(1)–O(2)#1 Y(1)–O(2) Y(1)–O(1)#2 Y(1)–O(1)#3 Y(1)–O(7) Y(1)–O(9)
2.228(3) 2.228(3) 2.230(3) 2.230(3) 2.256(5) 2.257(5) 2.238(5)
O(2)#1–Y(1)–O(2) O(2)#1–Y(1)–O(1)#2 O(2)–Y(1)–O(1)#2 O(2)#1–Y(1)–O(1)#3 O(2)–Y(1)–O(1)#3 O(1)#2–Y(1)–O(1)#3 O(2)#1–Y(1)–O(7) O(2)–Y(1)–O(7) O(1)#2–Y(1)–O(7) O(1)#3–Y(1)–O(7) O(2)#1–Y(1)–O(9) O(2)–Y(1)–O(9) O(1)#2–Y(1)–O(9) O(1)#3–Y(1)–O(9) O(7)–Y(1)–O(9)
92.5(2) 176.7(1) 89.6(1) 89.6(1) 176.7(1) 88.2(2) 91.4(1) 91.4(1) 86.0(1) 86.0(1) 95.5(1) 95.5(1) 86.9(1) 86.9(1) 170.0(2)
Y(2)O6 octahedra Y(2)–O(3) Y(2)–O(3)#4 Y(2)–O(5)#5 Y(2)–O(5)#6 Y(2)–O(6) Y(2)–O(8)
2.217(3) 2.217(3) 2.245(3) 2.245(3) 2.250(5) 2.271(5) 2.241(5)
O(3)–Y(2)–O(3)#4 O(3)–Y(2)–O(5)#5 O(3)#4–Y(2)–O(5)#5 O(3)–Y(2)–O(5)#6 O(3)#4–Y(2)–O(5)#6 O(5)#5–Y(2)–O(5)#6 O(3)–Y(2)–O(6) O(3)#4–Y(2)–O(6) O(5)#5–Y(2)–O(6) O(5)#6–Y(2)–O(6) O(3)–Y(2)–O(8) O(3)#4–Y(2)–O(8) O(5)#5–Y(2)–O(8) O(5)#6–Y(2)–O(8) O(6)–Y(2)–O(8)
87.8(2) 90.5(1) 174.0(1) 174.0(1) 90.5(1) 90.7(2) 99.3(1) 99.3(1) 86.6(1) 86.6(1) 89.2(1) 89.2(1) 85.0(1) 85.0(1) 168.1(2)
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Table 8 (Continued) P(1)–O(4)–P(2) P(2)–O(10)–P(3) P(1)–O(11)–P(4)
131.5(2) 133.6(2) 135.7(2)
P(2)–O(1)–Y(1)#2 P(1)–O(2)–Y(1) P(2)–O(3)–Y(2) P(1)–O(5)–Y(2)#5 P(3)#7–O(6)–Y(2) P(4)#8–O(7)–Y(1) P(3)#5–O(8)–Y(2) P(4)#2–O(9)–Y(1)
151.2(2) 154.8(2) 154.5(2) 141.3(2) 140.5(3) 139.6(3) 169.7(3) 169.4(3)
Symmetry codes: #1: x, −y + 1/2, z; #2: −x + 2, −y, −z + 2; #3: −x + 2, y + 1/2, −z + 2; #4: x, −y − 1/2, z; #5: −x + 2, −y, −z + 3; #6: −x + 2, y − 1/2, −z + 3; #7: −x + 3, −y, −z + 3; #7: x − y + 1, x + 1, −z+; #8: −x + 1, −y, −z + 2.
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