Redetermination of the perovskite-type compound YRh3B revealing a Rh deficiency

Makita, R.; Tanizawa, K.; Tanaka, K.; Takei, H.

doi:10.1107/S1600536808030754

inorganic compounds

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Volume 64| Part 10| October 2008| Page i72

doi:10.1107/S1600536808030754

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Redetermination of the perovskite-type compound YRh₃B revealing a Rh deficiency

Ryoko Makita,^a ^* Koutarou Tanizawa,^a Kiyoaki Tanaka ^a and Humihiko Takei ^b

^aGraduate School of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Japan, and ^bInstitute for Solid State Physics, University of Tokyo, Kashiwanoha, Kashiwa, Japan
^*Correspondence e-mail: 14515020@stn.nitech.ac.jp

(Received 5 September 2008; accepted 24 September 2008; online 27 September 2008)

In contrast with previous structural studies of ytterbium trirhodium boride, YbRh₃B, that suggest a boron deficiency, the current redetermination of the crystal structure of YbRh₃B revealed instead a rhodium deficiency with a refined composition of YbRh_2.67 (2)B. In the ABX₃ perovskite-type structure, Yb, B and Rh are located on the A, B and X positions, respectively, with site symmetries of m $[\overline{3}]$ m for the A and B sites, and 4/mm.m for the X site.

Related literature

For a previous powder diffraction study of YbRh₃B, see: Takei & Shishido (1984 ). For general background, see: Becker & Coppens (1975 ); Libermann et al. (1971 ); Mann (1968 ).

Experimental

Crystal data

YbRh_2.67B
M_r = 458.61
Cubic, $[P m \overline 3m ]$
a = 4.12992 (7) Å
V = 70.44 (1) Å³
Z = 1
Mo Kα radiation
μ = 47.90 mm⁻¹
T = 109 (1) K
Radius: 0.041 mm

Data collection

MacScience M06XHF22 four-circle diffractometer
Absorption correction: for a sphere [transmission coefficients for spheres tabulated in International Tables for X-ray Crystallography (Vol. II, 1972, Table 5.3.6B) were interpolated with Lagrange's method (four point interpolation; Yamauchi et al., 1965 )] T_min = 0.069, T_max = 0.169
953 measured reflections
193 independent reflections
193 reflections with F > 3σ(F)
R_int = 0.018

Refinement

R[F² > 2σ(F²)] = 0.014
wR(F²) = 0.029
S = 1.15
193 reflections
11 parameters
3 restraints
Δρ_max = 1.86 e Å⁻³
Δρ_min = −1.98 e Å⁻³

Table 1
Selected bond lengths (Å)

Rhⁱ—Rhⁱⁱ	2.92029 (7)
Bⁱ—Rhⁱ	2.06496 (7)
Bⁱ—Yb	3.57662 (7)
Rhⁱ—Yb	2.92029 (7)
Symmetry codes: (i) x+1, y, z; (ii) z, x, y.

Data collection: MXCSYS (MacScience, 1995 ) and IUANGLE (Tanaka et al., 1994 ); cell refinement: RSLC-3 UNICS system (Sakurai & Kobayashi, 1979 ); data reduction: RDEDIT (Tanaka, 2008 ); program(s) used to solve structure: QNTAO (Tanaka & Ōnuki, 2002 ; Tanaka et al., 2008 ); program(s) used to refine structure: QNTAO; molecular graphics: ATOMS for Windows (Dowty, 2000 ); software used to prepare material for publication: RDEDIT.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808030754/wm2195sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808030754/wm2195Isup2.hkl

checkCIF report

Comment top

Takei & Shishido (1984) reported various rare earth trirhodium borides with the perovskite structure (Fig. 1) and suggest a deficiency for the boron site. For a closer inspection of this assumption and since anisotropic displacement factors were not reported in the original study, we decided to re-determine the structure of YbRh₃B and present the results of the structure analysis in this communication.

In the ABX₃ perovskite-type structure, Yb, B and the partly occupied Rh atoms are located on the A, B and X positions, respectively, with site symmetries of m3m for the A and B sites and 4/mm.m for the X site.

Related literature top

For a previous powder diffraction study of YbRh₃B, see: Takei & Shishido (1984). For general background, see: Becker & Coppens (1975); Libermann et al. (1971); Mann (1968).

Experimental top

Single crystals were grown using a flux method with copper as the solvent. Stoichiometric quantities of Yb, Rh and B were mixed with copper in a ratio of about 1:8 by weight. The mixture was heated in a high purity alumina crucible by electric furnace under a purified He gas flow at a rate of about 400 Kh^-1. The sample was kept at a temperature between 1523 and 1623 K for 10 h and cooled at a rate of 1 Kh^-1 to 353 K. Then the furnace was cooled rapidly to room temperature. The boride crystals were separated from the copper by treatment with hot nitric acid. The sample was cut into small pieces and was finally ground into a sphere with 41 µm radius by a wind pressure granulation machine with diamond paste.

Computing details top

Data collection: MXCSYS (MacScience, 1995) and IUANGLE (Tanaka et al., 1994).; cell refinement: RSLC-3 UNICS system (Sakurai & Kobayashi, 1979); data reduction: RDEDIT (Tanaka, 2008); program(s) used to solve structure: QNTAO (Tanaka & Ōnuki, 2002; Tanaka et al., 2008); program(s) used to refine structure: QNTAO (Tanaka & Ōnuki, 2002; Tanaka et al., 2008); molecular graphics: ATOMS for Windows (Dowty, 2000); software used to prepare material for publication: RDEDIT (Tanaka, 2008).

Figures top

	Fig. 1. The structure of YbRh₃B with displacement ellipsoids drawn at the 90% probability level.
	Fig. 2. The difference density map around (a) Yb at (1/2, 1/2, 1/2) on the (002) plane with a range of 0 < x < 1 and 0 < y < 1, (b) around Rh at (1/2, 1/2, 1/2) on the (002) plane with a range of -0.5 < x < 0.5 and -0.5 < y < 0.5 and (c) around B at (1/2, 1/2, 0) on the (001) plane with a range of -0.5 < x < 0.5 and -0.5 < y < 0.5. For all atoms full occupancy is considered. Contour lines are at intervals of 0.5 e Å^-3. Zero contours are drawn as thick lines, positive contours are drawn as thin lines, negative contours are drawn as broken lines.
	Fig. 3. The difference density map around (a) Yb, (b) Rh and (c) B after the refinement of the site occupation factors for the Rh site. Contour lines are as in Fig. 2.

Ytterbium trirhodium boride top

Crystal data top

YbRh_2.67B	D_x = 10.81 Mg m⁻³
M_r = 458.61	Mo Kα radiation, λ = 0.71073 Å
Cubic, Pm3m	Cell parameters from 30 reflections
Hall symbol: -P 4 2 3	θ = 36.5–38.3°
a = 4.12992 (7) Å	µ = 47.90 mm⁻¹
V = 70.44 (1) Å³	T = 109 K
Z = 1	Sphere, black
F(000) = 195.14	0.08 × 0.08 × 0.08 × 0.04 (radius) mm

Data collection top

MacScience M06XHF22 four-circle diffractometer	193 independent reflections
Radiation source: fine-focus rotating anode	193 reflections with F > 3σ(F)
Graphite monochromator	R_int = 0.019
Detector resolution: 1.25 x 1.25° pixels mm^-1	θ_max = 74.9°, θ_min = 4.9°
ω/2θ scans	h = −7→9
Absorption correction: for a sphere [transmission coefficients for spheres tabulated in International Tables for X-ray Crystallography (Vol. II, 1972, Table 5.3.6B) were interpolated with Lagrange's method (four point interpolation; Yamauchi et al., 1965)]	k = −11→11
T_min = 0.069, T_max = 0.169	l = −11→11
953 measured reflections

Refinement top

Refinement on F	3 restraints
Least-squares matrix: full	Weighting scheme based on measured s.u.'s
R[F² > 2σ(F²)] = 0.014	(Δ/σ)_max = 0.00010
wR(F²) = 0.029	Δρ_max = 1.86 e Å⁻³
S = 1.15	Δρ_min = −1.98 e Å⁻³
193 reflections	Extinction correction: B-C type 1 Gaussian anisotropic (Becker & Coppens, 1975)
11 parameters	Extinction coefficient: 0.052 (2) times 10⁴

Crystal data top

YbRh_2.67B	Z = 1
M_r = 458.61	Mo Kα radiation
Cubic, Pm3m	µ = 47.90 mm⁻¹
a = 4.12992 (7) Å	T = 109 K
V = 70.44 (1) Å³	0.08 × 0.08 × 0.08 × 0.04 (radius) mm

Data collection top

MacScience M06XHF22 four-circle diffractometer	193 independent reflections
Absorption correction: for a sphere [transmission coefficients for spheres tabulated in International Tables for X-ray Crystallography (Vol. II, 1972, Table 5.3.6B) were interpolated with Lagrange's method (four point interpolation; Yamauchi et al., 1965)]	193 reflections with F > 3σ(F)
T_min = 0.069, T_max = 0.169	R_int = 0.019
953 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.014	11 parameters
wR(F²) = 0.029	3 restraints
S = 1.15	Δρ_max = 1.86 e Å⁻³
193 reflections	Δρ_min = −1.98 e Å⁻³

Special details top

Experimental. Multiple diffraction was avoided by using ψ-scans. Intensities was measured at the equi-temperature region of combinaion of angles ω and χ of a four-circle diffractometer.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Yb	0.5000	0.5000	0.5000	0.212 (1)
Rh	0.0000	0.0000	0.5000	0.143 (2)	0.891 (6)
B	0.0000	0.0000	0.0000	0.291 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Yb	0.00269 (4)	0.00269 (4)	0.00269 (4)	0	0	0
Rh	0.00202 (6)	0.00202 (6)	0.00139 (6)	0	0	0
B	0.0037 (2)	0.0037 (2)	0.0037 (2)	0	0	0

Geometric parameters (Å, º) top

Rhⁱ—Rhⁱⁱ	2.9203 (1)	Bⁱ—Yb	3.5766 (1)
Bⁱ—Rhⁱ	2.0650 (1)	Rhⁱ—Yb	2.9203 (1)

Rhⁱ—Bⁱ—Rhⁱⁱ	90.000	Rhⁱ—Yb—Bⁱ	35.264
Rhⁱ—Yb—Rhⁱⁱ	60.000	Yb—Bⁱ—Rhⁱⁱ	54.736

Symmetry codes: (i) x+1, y, z; (ii) z, x, y.

Experimental details

Crystal data
Chemical formula	YbRh_2.67B
M_r	458.61
Crystal system, space group	Cubic, Pm3m
Temperature (K)	109
a (Å)	4.12992 (7)
V (Å³)	70.44 (1)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	47.90
Crystal size (mm)	0.08 × 0.08 × 0.08 × 0.04 (radius)

Data collection
Diffractometer	MacScience M06XHF22 four-circle diffractometer
Absorption correction	For a sphere [transmission coefficients for spheres tabulated in International Tables for X-ray Crystallography (Vol. II, 1972, Table 5.3.6B) were interpolated with Lagrange's method (four point interpolation; Yamauchi et al., 1965)]
T_min, T_max	0.069, 0.169
No. of measured, independent and observed [F > 3σ(F)] reflections	953, 193, 193
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	1.358

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.014, 0.029, 1.15
No. of reflections	193
No. of parameters	11
No. of restraints	3
Δρ_max, Δρ_min (e Å⁻³)	1.86, −1.98

Computer programs: MXCSYS (MacScience, 1995) and IUANGLE (Tanaka et al., 1994)., RSLC-3 UNICS system (Sakurai & Kobayashi, 1979), RDEDIT (Tanaka, 2008), QNTAO (Tanaka & Ōnuki, 2002; Tanaka et al., 2008), ATOMS for Windows (Dowty, 2000).

Selected bond lengths (Å) top

Rhⁱ—Rhⁱⁱ	2.9203 (1)	Bⁱ—Yb	3.5766 (1)
Bⁱ—Rhⁱ	2.0650 (1)	Rhⁱ—Yb	2.9203 (1)

Symmetry codes: (i) x+1, y, z; (ii) z, x, y.

References

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CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 64| Part 10| October 2008| Page i72

doi:10.1107/S1600536808030754

Open

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