(IUCr) Crystallography Journals Online

Abstract top

Single crystals of europium(III) scandate(III), with ideal formula EuScO₃, were grown from the melt using the micro-pulling-down method. The title compound crystallizes in an orthorhombic distorted perovskite-type structure, where Eu occupies the eightfold coordinated A sites (site symmetry m) and Sc resides on the centres of corner-sharing [ScO₆] octahedra (B sites with site symmetry $\overline{1}$ ). The structure of EuScO₃ has been reported previously based on powder diffraction data [Liferovich & Mitchell (2004). J. Solid State Chem. 177, 2188-2197]. The results of the current redetermination based on single-crystal diffraction data shows an improvement in the precision of the structral and geometric parameters and reveals a defect-type structure. Site-occupancy refinements indicate an Eu deficiency on the A site coupled with O defects on one of the two O-atom positions. The crystallochemical formula of the investigated sample may thus be written as ^A( [white square] _0.032Eu_0.968)^BScO_2.952.

Comment top

Liferovich & Mitchell (2004) studied the crystal structure of lanthanoid scandates, including EuScO₃, by Rietveld analysis from powder diffraction data. Crystallographic data of DyScO₃, GdScO₃, SmScO₃ and NdScO₃ obtained from single crystals were recently reported by Veličkov et al. (2007), and for TbScO₃ by Veličkov et al. (2008). Based on these results it was possible to resolve disagreements concerning some structural characteristics and their dependence on the Ln-substitution. Whereas Liferovich & Mitchell (2004) observed no obvious continuous evolution, Veličkov et al. (2007) were able to show that the geometry and the distortion of the sites are linearly coupled with the size of the lanthanoid in the series from DyScO₃ to NdScO₃. With the structural refinement based on diffraction data collected from single crystalline EuScO₃, the present results provide further data for this series.

The orthorhombic distorted perovskite structure for EuScO₃ (Fig. 1) is confirmed from our refinements. Whereas the lattice parameters for EuScO₃ compare well with the data of Liferovich & Mitchell (2004), the fractional atomic coordinates show deviations of up to 0.006, resulting in slightly different geometrical parameters. The A-site is occupied by Eu in an eightfold coordination and has an average bond length of ^[8]<A—O> = 2.521 Å with a polyhedral bond length distortion of ^AΔ₈ = 7.98×10^-3 (Δn = 1/n Σ{(r_i-r)/r²). The B-site shows bond lengths typical for octahedrally coordinated scandium (<B—O> = 2.104 Å) and is rather distorted with ^BΔ₆ = 0.015×10^-3 and a bond angle variance of δ = 2.61°. The tilting of the corner sharing octahedra calculated after Zhao et al. (1993) are θ = 19.70° in [110] and Ø = 12.66° in [001] directions. From our data we can establish linear trends for the crystallochemical parameters from DyScO₃ to NdScO₃ depending on the Ln-substitution.

europium(III) scandate(III) top

Crystal data top

Eu_0.968ScO_2.952	F(000) = 422.4
M_r = 239.24	D_x = 6.307 Mg m⁻³
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 2218 reflections
a = 5.7554 (7) Å	θ = 2.6–29.2°
b = 7.9487 (10) Å	µ = 26.28 mm⁻¹
c = 5.5087 (6) Å	T = 293 K
V = 252.01 (5) Å³	Platy fragment, colourless
Z = 4	0.14 × 0.12 × 0.02 mm

Data collection top

Stoe IPDS-2 diffractometer	362 independent reflections
Radiation source: fine-focus sealed tube	345 reflections with I > 2σ(I)
graphite	R_int = 0.055
Detector resolution: 6.67 pixels mm^-1	θ_max = 29.1°, θ_min = 4.5°
ω scans	h = −7→7
Absorption correction: analytical (Alcock, 1970)	k = −10→9
T_min = 0.139, T_max = 0.397	l = −7→7
2168 measured reflections

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)] = 0.021	w = 1/[σ²(F_o²) + (0.0211P)² + 0.9412P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.051	(Δ/σ)_max = 0.011
S = 1.27	Δρ_max = 1.40 e Å⁻³
362 reflections	Δρ_min = −0.84 e Å⁻³
31 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.113 (5)

Crystal data top

Eu_0.968ScO_2.952	V = 252.01 (5) Å³
M_r = 239.24	Z = 4
Orthorhombic, Pnma	Mo Kα radiation
a = 5.7554 (7) Å	µ = 26.28 mm⁻¹
b = 7.9487 (10) Å	T = 293 K
c = 5.5087 (6) Å	0.14 × 0.12 × 0.02 mm

Data collection top

Stoe IPDS-2 diffractometer	362 independent reflections
Absorption correction: analytical (Alcock, 1970)	345 reflections with I > 2σ(I)
T_min = 0.139, T_max = 0.397	R_int = 0.055
2168 measured reflections	θ_max = 29.1°

Refinement top

R[F² > 2σ(F²)] = 0.021	Δρ_max = 1.40 e Å⁻³
wR(F²) = 0.051	Δρ_min = −0.84 e Å⁻³
S = 1.27	Absolute structure: ?
362 reflections	Flack parameter: ?
31 parameters	Rogers parameter: ?
1 restraint

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.

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	Occ. (<1)
Eu1	0.05854 (5)	0.25	0.01589 (6)	0.0090 (2)	0.9677 (13)
Sc2	0	0	0.5	0.0078 (3)
O1	0.4506 (8)	0.25	0.8815 (9)	0.0111 (9)
O2	0.1954 (6)	0.9378 (4)	0.8078 (6)	0.0112 (7)	0.9758 (10)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Eu1	0.0070 (3)	0.0102 (3)	0.0098 (3)	0	0.00051 (11)	0
Sc2	0.0064 (6)	0.0079 (6)	0.0090 (6)	0.0006 (6)	0.0000 (3)	0.0000 (3)
O1	0.011 (2)	0.008 (2)	0.014 (2)	0	−0.0025 (17)	0
O2	0.0096 (16)	0.0121 (17)	0.0119 (14)	−0.0019 (12)	−0.0018 (11)	0.0005 (12)

Geometric parameters (Å, °) top

Eu1—O1ⁱ	2.276 (5)	Sc2—O2ⁱⁱ	2.094 (3)
Eu1—O2ⁱⁱ	2.304 (3)	Sc2—O2^xii	2.094 (3)
Eu1—O2ⁱⁱⁱ	2.304 (3)	Sc2—O2^vi	2.107 (3)
Eu1—O1^iv	2.375 (5)	Sc2—O2^xiii	2.107 (3)
Eu1—O2^v	2.611 (3)	Sc2—O1^xiv	2.1108 (16)
Eu1—O2^vi	2.611 (3)	Sc2—O1^x	2.1108 (16)
Eu1—O2^vii	2.845 (3)	Sc2—Eu1^xv	3.2268 (4)
Eu1—O2^viii	2.845 (3)	Sc2—Eu1ⁱ	3.2268 (4)
Eu1—Sc2^ix	3.2268 (4)	Sc2—Eu1^xvi	3.3428 (4)
Eu1—Sc2^x	3.2268 (4)	Sc2—Eu1^xvii	3.4841 (4)
Eu1—Sc2^xi	3.3428 (4)	Sc2—Eu1^xviii	3.4841 (4)
Eu1—Sc2	3.3428 (4)

O1ⁱ—Eu1—O2ⁱⁱ	103.43 (12)	O2^xii—Sc2—O2^vi	90.88 (6)
O1ⁱ—Eu1—O2ⁱⁱⁱ	103.43 (12)	O2ⁱⁱ—Sc2—O2^xiii	90.88 (6)
O2ⁱⁱ—Eu1—O2ⁱⁱⁱ	80.77 (17)	O2^xii—Sc2—O2^xiii	89.12 (6)
O1ⁱ—Eu1—O1^iv	87.69 (11)	O2^vi—Sc2—O2^xiii	180
O2ⁱⁱ—Eu1—O1^iv	137.24 (9)	O2ⁱⁱ—Sc2—O1^xiv	87.46 (16)
O2ⁱⁱⁱ—Eu1—O1^iv	137.24 (9)	O2^xii—Sc2—O1^xiv	92.54 (16)
O1ⁱ—Eu1—O2^v	137.77 (9)	O2^vi—Sc2—O1^xiv	92.67 (15)
O2ⁱⁱ—Eu1—O2^v	117.06 (6)	O2^xiii—Sc2—O1^xiv	87.33 (15)
O2ⁱⁱⁱ—Eu1—O2^v	73.38 (8)	O2ⁱⁱ—Sc2—O1^x	92.54 (16)
O1^iv—Eu1—O2^v	71.14 (12)	O2^xii—Sc2—O1^x	87.46 (16)
O1ⁱ—Eu1—O2^vi	137.77 (9)	O2^vi—Sc2—O1^x	87.33 (15)
O2ⁱⁱ—Eu1—O2^vi	73.38 (8)	O2^xiii—Sc2—O1^x	92.67 (15)
O2ⁱⁱⁱ—Eu1—O2^vi	117.06 (6)	O1^xiv—Sc2—O1^x	180
O1^iv—Eu1—O2^vi	71.14 (12)	Sc2^xix—O1—Sc2^xv	140.6 (2)
O2^v—Eu1—O2^vi	69.74 (15)	Sc2^xix—O1—Eu1^xx	105.10 (13)
O1ⁱ—Eu1—O2^vii	71.82 (8)	Sc2^xv—O1—Eu1^xx	105.10 (13)
O2ⁱⁱ—Eu1—O2^vii	77.31 (12)	Sc2^xix—O1—Eu1^xviii	91.82 (14)
O2ⁱⁱⁱ—Eu1—O2^vii	155.61 (9)	Sc2^xv—O1—Eu1^xviii	91.82 (14)
O1^iv—Eu1—O2^vii	67.12 (8)	Eu1^xx—O1—Eu1^xviii	124.0 (2)
O2^v—Eu1—O2^vii	126.63 (6)	Sc2^xxi—O2—Sc2^xxii	143.00 (18)
O2^vi—Eu1—O2^vii	66.38 (5)	Sc2^xxi—O2—Eu1ⁱⁱ	98.83 (13)
O1ⁱ—Eu1—O2^viii	71.82 (8)	Sc2^xxii—O2—Eu1ⁱⁱ	117.90 (14)
O2ⁱⁱ—Eu1—O2^viii	155.61 (9)	Sc2^xxi—O2—Eu1^xxii	85.85 (11)
O2ⁱⁱⁱ—Eu1—O2^viii	77.31 (12)	Sc2^xxii—O2—Eu1^xxii	89.57 (12)
O1^iv—Eu1—O2^viii	67.12 (8)	Eu1ⁱⁱ—O2—Eu1^xxii	103.48 (13)
O2^v—Eu1—O2^viii	66.38 (5)	Sc2^xxi—O2—Eu1^xxiii	88.37 (12)
O2^vi—Eu1—O2^viii	126.63 (6)	Sc2^xxii—O2—Eu1^xxiii	79.82 (10)
O2^vii—Eu1—O2^viii	121.45 (13)	Eu1ⁱⁱ—O2—Eu1^xxiii	102.69 (12)
O2ⁱⁱ—Sc2—O2^xii	180	Eu1^xxii—O2—Eu1^xxiii	153.77 (14)
O2ⁱⁱ—Sc2—O2^vi	89.12 (6)

Symmetry codes: (i) x−1/2, y, −z+1/2; (ii) −x, −y+1, −z+1; (iii) −x, y−1/2, −z+1; (iv) x, y, z−1; (v) −x+1/2, y−1/2, z−1/2; (vi) −x+1/2, −y+1, z−1/2; (vii) x, y−1, z−1; (viii) x, −y+3/2, z−1; (ix) x+1/2, −y+1/2, −z+1/2; (x) −x+1/2, −y, z−1/2; (xi) −x, y+1/2, −z+1; (xii) x, y−1, z; (xiii) x−1/2, y−1, −z+3/2; (xiv) x−1/2, y, −z+3/2; (xv) −x+1/2, −y, z+1/2; (xvi) −x, −y, −z+1; (xvii) −x, −y, −z; (xviii) x, y, z+1; (xix) x+1/2, −y+1/2, −z+3/2; (xx) x+1/2, y, −z+1/2; (xxi) x, y+1, z; (xxii) −x+1/2, −y+1, z+1/2; (xxiii) x, y+1, z+1.

Table 1
Selected geometric parameters (Å) top

Eu1—O1ⁱ	2.276 (5)	Eu1—O2^v	2.845 (3)
Eu1—O2ⁱⁱ	2.304 (3)	Sc2—O2ⁱⁱ	2.094 (3)
Eu1—O1ⁱⁱⁱ	2.375 (5)	Sc2—O2^vi	2.107 (3)
Eu1—O2^iv	2.611 (3)	Sc2—O1^vii	2.1108 (16)

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

supplementary materials

Redetermination of EuScO₃

V. Kahlenberg, D. Maier and B. Velickov

	Fig. 1. The orthorhombic perovskite structure of EuScO₃ is characterized by a tilted corner sharing ScO₆ framework incorporating the 8-fold coordinated Eu sites. The ScO₆ octahedra are yellow, the Eu atoms are given in grey and the O atoms are presented in red.
	Fig. 2. Projection of the EuScO₃ structure along [010], showing the Eu atoms and the Sc coordination with displacement ellipsoids at the 80% probability level.

supplementary materials

Redetermination of EuScO3

V. Kahlenberg, D. Maier and B. Velickov

Redetermination of EuScO₃