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Dy117Co57Sn112, a new structure type of ternary intermetallic stannides with a giant unit cell
Journal of Alloys and Compounds 314 (2001) 177–180
L
www.elsevier.com / locate / jallcom
Dy 117 Co 57 Sn 112 , a new structure type of ternary intermetallic stannides with a giant unit cell P. Salamakha b
a,c ,
*, O. Sologub b , G. Bocelli c , S. Otani a , T. Takabatake b
a NIRIM 1 -1 Namiki, Tsukuba, Ibaraki 305 -0044, Japan Department of Quantum Matter, ADSM, Hiroshima University, 1 -3 -1 Kagamiyama, Higashi-Hiroshima 739 -8526, Japan c Centro per la Strutturistica Diffrattometrica CNR, 43100 Parma, Italy
Received 15 August 2000; accepted 26 August 2000
Abstract ˚ Z54, V526546.26(1) The crystal structure of a new ternary stannide Dy 117 Co 57 Sn 112 , space group Fm-3 m (N225), a529.831(4) A, ˚ 3 , m 540.34 mm 21 was refined from single-crystal X-ray diffraction data to R50.0689, Rw250.1119 from 1000 reflections hkl with A I.4s (I) and 89 variable parameters. The structure is related to the Tb 117 Fe 52 Ge 112 structure type and contains 1144 atoms per unit cell. 2001 Elsevier Science B.V. All rights reserved. Keywords: Rare earth compounds; Transition metal compounds; Crystal structure; X-ray diffraction
1. Introduction Recently, the existence of ternary compounds with a Tb 117 Fe 52 Ge 112 structure was reported [1,2]. The atomic parameters were refined only for an initial compound [3] whereas the crystal structures of the other isotypic compounds were studied with respect to establish their formation and to derive the lattice parameters. We also reported on the existence of a compound with a giant unit cell in the Nd–Ru–Sn system [4,5]. In this work we present the results of a crystal structure investigation of a compound with a gigantic unit cell observed in the Dy–Co–Sn system.
was remelted in the induction furnace and slowly cooled down. For the X-ray single-crystal data collection, a single crystal was glued on the top of a glass fiber and mounted on the goniometer head. A four-circle diffractometer Philips PW 1100 with graphite monochromatized Mo Ka ˚ was used. The least-square radiation ( l50.71073 A) refinement of the 2u values of 25 strong and well centered reflections from the various regions of reciprocal space were used to obtain the unit-cell parameters. The data set was recorded at room temperature in a v 22u scan mode. The intensities were corrected for absorption, polarization and Lorentz effect. Further details are listed in Table 1.
2. Experimental details 3. Results and discussion A ternary sample with a total mass 2 g was synthesized by arc melting of the constituent elements under a high purity argon atmosphere on a water-cooled copper hearth. In order to ensure homogeneity, the arc melted button was turned over and remelted several times. The weight losses during arc melting were less than 1%. The as-cast sample
*Corresponding author. E-mail address: [email protected] (P. Salamakha).
A single-crystal suitable for the X-ray measurements was isolated from the surface of the alloy with composition |Dy 2 CoSn 2 . The structure was solved in space group Fm-3 m using SHELXS-86 [6] by means of direct methods that revealed the positions of the Dy and Sn atoms. The Co atoms were localized from the analyses of Fourier maps. The structure was refined by a full-matrix least-squares program using atomic scattering factors provided by the program package SHELXL-97 [7]. The absorption correc-
0925-8388 / 01 / $ – see front matter 2001 Elsevier Science B.V. All rights reserved. PII: S0925-8388( 00 )01212-3
P. Salamakha et al. / Journal of Alloys and Compounds 314 (2001) 177 – 180
178
Table 1 Parameters for the single-crystal X-ray data collection Compound Space group [10] ˚ Lattice parameters (A) a ˚ 3) Cell volume (A Formula units per cell, Z Calculated density (g cm 23 ) Linear absorption coefficient (mm 21 ) 2umax Range in h,k,l Number of measured reflections Number of unique reflections Number of reflections with Io .4s (Io ) Number of refined parameters R, Rw2 Goodness of fit ˚ –3) Highest / lowest residual electron density (e A
Dy 117 Co 57 Sn 112 Fm-3 m 29.831(4) 26546.26(1) 4 7.919 40.34 53.99 0#h#18, 0#k#26, 3#l#38 5722 1349 1000 89 0.0689, 0.1119 1.042 3.44 / 22.38
tion was performed with the assistance of program DIFABS [8]. The weighting schemes included a term, which accounted for the counting statistics, and the parameter correcting for isotropic secondary extinction was optimized. The final residuals are presented in Table 1. The atomic coordinates, which correspond to their standardized form according to STIDY [9] and isotropic thermal parameters are shown in Table 2. The interatomic distances ˚ and coordination numbers of atoms are up to 4.05 A presented in Table 3. The projection of the
Dy 117 Co 57 Sn 112 structure on the XY plane is presented in Fig. 1. Unit cell parameters indicated prima facie a close correspondence between the observed compound and the Tb 117 Fe 52 Ge 112 structure, whereas the analysis of the atomic coordinates revealed distinctions between two structures. The Dy, Sn1–Sn8, Co1 and Co3 atoms occupy the atomic positions of Tb, Ge and Fe, Sn9 and Co4 being placed in the atomic sites of Fe and Ge, respectively. In the Tb 117 Fe 52 Ge 112 structure the 48h (x x 0, x50.0723)
Table 2 Atomic parameters of the Dy 117 Co 57 Sn 112 compound Atom
Wyckoff position
x
y
z
Occ.
˚ 2) Ueq (A
Dy1 Dy2 Dy3 Dy4 Dy5 Dy6 Dy7 Dy8 Co1 Co2 Co3 Co4 Co5 Co6 Sn1 Sn2 Sn3 Sn4 Sn5 Sn6 Sn7 Sn8 Sn9
96k 96k 96k 96j 48i 24e 8c 4a 96k 96k 32f 32f 4b 32f 96k 96k 48i 48h 48g 32f 24e 24e 32f
0.0677(1) 0.1800(1) 0.2008(1) 0.2531(1) 0.1214(1) 0.3391(4) 0.25 0 0.1688(3) 0.0801(5) 0. 3907(5) 0.3060(4) 0.5 0.0574(9) 0.0732(1) 0.1074(1) 0.2078(2) 0.1457(2) 0.25 0.1461(2) 0.1086(4) 0.2160(4) 0.4441(3)
0.0677(1) 0.1800(1) 0.2008(1) 0.1051(1) 0.1214(1) 0 0.25 0 0.1688(3) 0.0801(5) 0. 3907(5) 0.3060(4) 0.5 0.0574(9) 0.0732(1) 0.1074(1) 0.2078(2) 0.1457(2) 0.25 0.1461(2) 0 0 0.4441(3)
0.1541(1) 0.4031(1) 0.0669(1) 0 0.5 0 0.25 0 0.2318(4) 20.0155(6) 0.3907(5) 0.3060(4) 0.5 0.0574(9) 0.3236(2) 0.2398(2) 0.5 0 0.1416(2) 0.1461(2) 0 0 0.4441(3)
1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.50(2) 1.0 1.0 1.0 0.50(2) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
0.0194(9) 0.0185(8) 0.0183(8) 0.0174(8) 0.0324(15) 0.0356(24) 0.0187(29) 0.0149(39) 0.0226(25) 0.0246(18) 0.0358(52) 0.0291(49) 0.0430(79) 0.0246(18) 0.0217(12) 0.0170(12) 0.0214(18) 0.0163(16) 0.0141(16) 0.0186(20) 0.0180(24) 0.0472(27) 0.0530(36)
P. Salamakha et al. / Journal of Alloys and Compounds 314 (2001) 177 – 180
179
Table 3 ˚ and coordination numbers of atoms (CN) for the compound Dy 117 Co 57 Sn 112 Selected interatomic distances d (A) Atoms
˚ d (A)
CN
Atoms
˚ d (A)
CN
Atoms
˚ d (A)
CN
Dy1–2 Co2 Co6 Sn2 2 Sn4 Sn7 Sn6 2 Co2 Sn8 2 Dy1 2 Dy4 2 Dy1 Dy2–Co4 Co3 Sn3 2 Sn2 Sn5 2 Sn1 2 Co1 2 Dy2 2 Dy3 Dy5 Dy3–Sn5 Sn4 2 Sn2 Sn6 2 Co1 2 Sn3 2 Dy2 Dy4 Dy3 Dy4–2 Sn1 2 Sn2 Sn3 Sn8 Sn4 2 Dy1 Dy5 2 Dy3 Dy6 Dy5–4 Sn1 2 Sn9 2 Co3 Sn3 2 Dy4 Dy2 Dy 6
2.713 (15) 2.923 (27) 3.058 (6) 3.093 (3) 3.158 (6) 3.324 (7) 3.345 (17) 3.395 (7) 3.648 (6) 3.748 (5) 4.041 (5) 2.955 (16) 3.005 (19) 3.118 (5) 3.237 (4) 3.241 (4) 3.261 (5) 3.418 (9) 3.506 (6) 3.717 (3) 3.798 (6) 3.046 (6) 3.061 (6) 3.251 (3) 3.297 (4) 3.313 (6) 3.387 (5) 3.717 (3) 3.817 (3) 3.998 (5) 3.180 (5) 3.230 (4) 3.273 (5) 3.331 (5) 3.423 (4) 3.748 (4) 3.767 (5) 3.817 (3) 4.050 (3) 3.085 (3) 3.242 (9) 3.301 (11) 3.636 (11) 3.767 (5) 3.798 (6) 3.813 (4)
17
Dy6–4 Sn1 Sn8 4 Dy5 4 Sn9 Dy4 Dy7–4 Co4 6 Sn5 6 Co1 Dy8–8 Co6 4 Sn7 Co2 Co1–Co4 Sn2 2 Sn5 2 Co1 Sn6 2 Dy3 2 Dy2 Dy7 Co2–Co6 2 Sn7 2 Dy1 2 Co2 Sn4 2 Dy1 Dy8 Co3–3 Sn1 Sn9 3 Dy2 3 Dy5 Co4–3 Co1 3 Sn5 Dy7 3 Dy2 Co5–8 Sn9 Co6–3 Co2 3 Sn7 3 Dy1 Dy8 Sn1–Co3 Sn2 2 Dy5 Dy6 2 Dy4 2 Dy2 Sn9
3.126 (5) 3.677 (8) 3.813 (4) 3.919(6) 4.050 (3) 2.894 (22) 3.229 (7) 3.466 (10) 2.962 (39) 3.254 (12) 3.433 (22) 2.461 (11) 2.603 (11) 2.611 (5) 2.643 (19) 2.714 (13) 3.314 (6) 3.418 (9) 3.466 (10) 2.394 (21) 2.593 (10) 2.713 (15) 2.730 (35) 2.792 (22) 3.345 (17) 3.433 (22) 2.509 (5) 2.779 (30) 3.005 (19) 3.301 (11) 2.461 (11) 2.830 (9) 2.894 (22) 2.955 (16) 2.868 (15) 2.394 (21) 2.870 (16) 2.923 (27) 2.962 (39) 2.509 (5) 2.883 (8) 3.085 (3) 3.126 (5) 3.180 (5) 3.261 (5) 3.679 (6)
14
Sn2–Co1 Sn1 Dy1 2 Dy4 2 Dy2 Sn6 2 Dy3 Sn3–2 Dy2 2 Dy4 4 Dy3 Dy5 Sn3 Sn4–2 Co2 2 Dy3 4 Dy1 2 Dy4 Sn5–4 Co1 2 Co4 2 Dy3 Dy7 2 Dy2 Sn6–3 Co1 3 Sn2 3 Dy3 3 Dy1 Sn7–4 Co2 2 Co6 2 Dy1 Sn8 Dy8 Sn8–Sn7 4 Dy4 4 Dy1 Dy6 Sn9–Co3 Co5 3 Dy5 3 Sn9 Sn1 Dy6
2.603 (11) 2.883 (8) 3.058 (6) 3.230 (4) 3.237 (4) 3.239 (5) 3.251 (3) 3.118 (5) 3.273 (5) 3.387 (5) 3.636 (11) 3.560 (9) 2.792 (22) 3.061 (6) 3.093 (3) 3.424 (4) 2.610 (5) 2.830 (9) 3.046 (6) 3.229 (7) 3.241 (4) 2.714 (13) 3.239 (5) 3.297 (4) 3.324 (7) 2.593 (10) 2.868 (16) 3.159 (6) 3.181 (17) 3.254 (12) 3.181 (17) 3.331 (5) 3.395 (7) 3.677 (8) 2.779 (30) 2.868 (15) 3.242 (9) 3.313 (7) 3.679(6) 3.910(6)
10
15
13
13
13
Wyckoff position is occupied by the Fe2 atom; in the Dy 117 Co 57 Sn 112 structure this position is split into two half-filled atomic sites with the very close coordinates, 32f (x x x, x50.0574) and 96k (x x z, x50.0801, z520.0155) occupied by Co6 and Co2, respectively (see Fig. 1, atoms printed in black colour). A resembling relation exists between the Yb 3 Rh 4 Sn 13 [11] and Y 3 Co 4 Ge 13 [12] structures: the 24k site occupied by tin atoms in the Yb 3 Rh 4 Sn 13 structure, is split in the Y 3 Co 4 Ge 13 structure into two partly filled atomic positions occupied by Ge atoms. The principal distinction between the two structures
16
13
12
11
10
10
8 10
10
10
10
11
12
10
10
10
consist in the fact that in the Dy 117 Co 57 Sn 112 structure the 4b Wyckoff position (0.5 0.5 0.5) is occupied by Co5, whereas in the Tb 117 Fe 52 Ge 112 structure the 4b site is unfilled. This can be taken as evidence to regard the Dy 117 Co 57 Sn 112 structure as a new structure type of intermetallic compounds.
Acknowledgements O.S. thanks JSPS for a 2-year fellowship in Japan.
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P. Salamakha et al. / Journal of Alloys and Compounds 314 (2001) 177 – 180
Fig. 1. Projection of the Dy 117 Co 57 Sn 112 on the XY plane. Large size circles indicate Dy atoms, Sn and Co atoms are marked by middle and small size circles, respectively.
References [1] P.S. Salamakha, O.L. Sologub, O.I. Bodak, in: K. Gschneidner, L. Eyring (Eds.), Handbook on Physics and Chemistry of Rare Earths, Vol. 27, 1999, Chapter 173. [2] P.S. Salamakha, in: K. Gschneidner, L. Eyring (Eds.), Handbook on Physics and Chemistry of Rare Earths, Vol. 27, 1999, Chapter 174. [3] E.I. Gladyshevsky, O.I. Bodak, V.K. Pecharsky, in: K. Gschneidner, L. Eyring (Eds.), Handbook on Physics and Chemistry of Rare Earths, Vol. 13, 1990, Chapter 88. [4] J. Stepien-Damm, P. Salamakha, O. Bodak, in: XVII Congress and General Assembly of the International Union of Crystallography, Seattle, Washington, USA, 1996. [5] P. Salamakha, P. Demchenko, J. Stepien-Damm, J. Alloys Comp. 260 (1997) L1–L3.
[6] G.M. Sheldrick, SHELXS-86, Program for Crystal Structure De¨ termination, University of Gottingen, Germany, 1986. [7] G.M. Sheldrick, SHELXS-97, Program for Crystal Structure Refine¨ ment, University of Gottingen, Germany, 1997. [8] N. Walker, O. Stewart, Acta Crystallogr. A39 (1983) 158. ´ L. Gelato, B. Chabot, M. Penzo, K. Cenzual, R. [9] E. Parthe, Gladyshevskii, TYPIX. Standardized data and crystal chemical characterization of inorganic structure types, in: 8th Edition, Gmelin Handbook of Inorganic and Organometallic Chemistry, Vol. 1, Springer-Verlag, Berlin, 1993. [10] International Tables for Crystallography, in: T. Hahn (Ed.), SpaceGroup Symmetry, Vol. A, D. Reidel, Dordrecht, 1983. [11] J.L. Hodeau, J. Chenavas, M. Marezio, J.P. Remeika, Solid State Communications 36 (1980) 839. [12] V.A. Bruskow, V.K. Pecharsky, O.I. Bodak, Izv. Akad. Nauk SSSR, Neorg. Mater. 22 (1986) 1471.
L
www.elsevier.com / locate / jallcom
Dy 117 Co 57 Sn 112 , a new structure type of ternary intermetallic stannides with a giant unit cell P. Salamakha b
a,c ,
*, O. Sologub b , G. Bocelli c , S. Otani a , T. Takabatake b
a NIRIM 1 -1 Namiki, Tsukuba, Ibaraki 305 -0044, Japan Department of Quantum Matter, ADSM, Hiroshima University, 1 -3 -1 Kagamiyama, Higashi-Hiroshima 739 -8526, Japan c Centro per la Strutturistica Diffrattometrica CNR, 43100 Parma, Italy
Received 15 August 2000; accepted 26 August 2000
Abstract ˚ Z54, V526546.26(1) The crystal structure of a new ternary stannide Dy 117 Co 57 Sn 112 , space group Fm-3 m (N225), a529.831(4) A, ˚ 3 , m 540.34 mm 21 was refined from single-crystal X-ray diffraction data to R50.0689, Rw250.1119 from 1000 reflections hkl with A I.4s (I) and 89 variable parameters. The structure is related to the Tb 117 Fe 52 Ge 112 structure type and contains 1144 atoms per unit cell. 2001 Elsevier Science B.V. All rights reserved. Keywords: Rare earth compounds; Transition metal compounds; Crystal structure; X-ray diffraction
1. Introduction Recently, the existence of ternary compounds with a Tb 117 Fe 52 Ge 112 structure was reported [1,2]. The atomic parameters were refined only for an initial compound [3] whereas the crystal structures of the other isotypic compounds were studied with respect to establish their formation and to derive the lattice parameters. We also reported on the existence of a compound with a giant unit cell in the Nd–Ru–Sn system [4,5]. In this work we present the results of a crystal structure investigation of a compound with a gigantic unit cell observed in the Dy–Co–Sn system.
was remelted in the induction furnace and slowly cooled down. For the X-ray single-crystal data collection, a single crystal was glued on the top of a glass fiber and mounted on the goniometer head. A four-circle diffractometer Philips PW 1100 with graphite monochromatized Mo Ka ˚ was used. The least-square radiation ( l50.71073 A) refinement of the 2u values of 25 strong and well centered reflections from the various regions of reciprocal space were used to obtain the unit-cell parameters. The data set was recorded at room temperature in a v 22u scan mode. The intensities were corrected for absorption, polarization and Lorentz effect. Further details are listed in Table 1.
2. Experimental details 3. Results and discussion A ternary sample with a total mass 2 g was synthesized by arc melting of the constituent elements under a high purity argon atmosphere on a water-cooled copper hearth. In order to ensure homogeneity, the arc melted button was turned over and remelted several times. The weight losses during arc melting were less than 1%. The as-cast sample
*Corresponding author. E-mail address: [email protected] (P. Salamakha).
A single-crystal suitable for the X-ray measurements was isolated from the surface of the alloy with composition |Dy 2 CoSn 2 . The structure was solved in space group Fm-3 m using SHELXS-86 [6] by means of direct methods that revealed the positions of the Dy and Sn atoms. The Co atoms were localized from the analyses of Fourier maps. The structure was refined by a full-matrix least-squares program using atomic scattering factors provided by the program package SHELXL-97 [7]. The absorption correc-
0925-8388 / 01 / $ – see front matter 2001 Elsevier Science B.V. All rights reserved. PII: S0925-8388( 00 )01212-3
P. Salamakha et al. / Journal of Alloys and Compounds 314 (2001) 177 – 180
178
Table 1 Parameters for the single-crystal X-ray data collection Compound Space group [10] ˚ Lattice parameters (A) a ˚ 3) Cell volume (A Formula units per cell, Z Calculated density (g cm 23 ) Linear absorption coefficient (mm 21 ) 2umax Range in h,k,l Number of measured reflections Number of unique reflections Number of reflections with Io .4s (Io ) Number of refined parameters R, Rw2 Goodness of fit ˚ –3) Highest / lowest residual electron density (e A
Dy 117 Co 57 Sn 112 Fm-3 m 29.831(4) 26546.26(1) 4 7.919 40.34 53.99 0#h#18, 0#k#26, 3#l#38 5722 1349 1000 89 0.0689, 0.1119 1.042 3.44 / 22.38
tion was performed with the assistance of program DIFABS [8]. The weighting schemes included a term, which accounted for the counting statistics, and the parameter correcting for isotropic secondary extinction was optimized. The final residuals are presented in Table 1. The atomic coordinates, which correspond to their standardized form according to STIDY [9] and isotropic thermal parameters are shown in Table 2. The interatomic distances ˚ and coordination numbers of atoms are up to 4.05 A presented in Table 3. The projection of the
Dy 117 Co 57 Sn 112 structure on the XY plane is presented in Fig. 1. Unit cell parameters indicated prima facie a close correspondence between the observed compound and the Tb 117 Fe 52 Ge 112 structure, whereas the analysis of the atomic coordinates revealed distinctions between two structures. The Dy, Sn1–Sn8, Co1 and Co3 atoms occupy the atomic positions of Tb, Ge and Fe, Sn9 and Co4 being placed in the atomic sites of Fe and Ge, respectively. In the Tb 117 Fe 52 Ge 112 structure the 48h (x x 0, x50.0723)
Table 2 Atomic parameters of the Dy 117 Co 57 Sn 112 compound Atom
Wyckoff position
x
y
z
Occ.
˚ 2) Ueq (A
Dy1 Dy2 Dy3 Dy4 Dy5 Dy6 Dy7 Dy8 Co1 Co2 Co3 Co4 Co5 Co6 Sn1 Sn2 Sn3 Sn4 Sn5 Sn6 Sn7 Sn8 Sn9
96k 96k 96k 96j 48i 24e 8c 4a 96k 96k 32f 32f 4b 32f 96k 96k 48i 48h 48g 32f 24e 24e 32f
0.0677(1) 0.1800(1) 0.2008(1) 0.2531(1) 0.1214(1) 0.3391(4) 0.25 0 0.1688(3) 0.0801(5) 0. 3907(5) 0.3060(4) 0.5 0.0574(9) 0.0732(1) 0.1074(1) 0.2078(2) 0.1457(2) 0.25 0.1461(2) 0.1086(4) 0.2160(4) 0.4441(3)
0.0677(1) 0.1800(1) 0.2008(1) 0.1051(1) 0.1214(1) 0 0.25 0 0.1688(3) 0.0801(5) 0. 3907(5) 0.3060(4) 0.5 0.0574(9) 0.0732(1) 0.1074(1) 0.2078(2) 0.1457(2) 0.25 0.1461(2) 0 0 0.4441(3)
0.1541(1) 0.4031(1) 0.0669(1) 0 0.5 0 0.25 0 0.2318(4) 20.0155(6) 0.3907(5) 0.3060(4) 0.5 0.0574(9) 0.3236(2) 0.2398(2) 0.5 0 0.1416(2) 0.1461(2) 0 0 0.4441(3)
1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 0.50(2) 1.0 1.0 1.0 0.50(2) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
0.0194(9) 0.0185(8) 0.0183(8) 0.0174(8) 0.0324(15) 0.0356(24) 0.0187(29) 0.0149(39) 0.0226(25) 0.0246(18) 0.0358(52) 0.0291(49) 0.0430(79) 0.0246(18) 0.0217(12) 0.0170(12) 0.0214(18) 0.0163(16) 0.0141(16) 0.0186(20) 0.0180(24) 0.0472(27) 0.0530(36)
P. Salamakha et al. / Journal of Alloys and Compounds 314 (2001) 177 – 180
179
Table 3 ˚ and coordination numbers of atoms (CN) for the compound Dy 117 Co 57 Sn 112 Selected interatomic distances d (A) Atoms
˚ d (A)
CN
Atoms
˚ d (A)
CN
Atoms
˚ d (A)
CN
Dy1–2 Co2 Co6 Sn2 2 Sn4 Sn7 Sn6 2 Co2 Sn8 2 Dy1 2 Dy4 2 Dy1 Dy2–Co4 Co3 Sn3 2 Sn2 Sn5 2 Sn1 2 Co1 2 Dy2 2 Dy3 Dy5 Dy3–Sn5 Sn4 2 Sn2 Sn6 2 Co1 2 Sn3 2 Dy2 Dy4 Dy3 Dy4–2 Sn1 2 Sn2 Sn3 Sn8 Sn4 2 Dy1 Dy5 2 Dy3 Dy6 Dy5–4 Sn1 2 Sn9 2 Co3 Sn3 2 Dy4 Dy2 Dy 6
2.713 (15) 2.923 (27) 3.058 (6) 3.093 (3) 3.158 (6) 3.324 (7) 3.345 (17) 3.395 (7) 3.648 (6) 3.748 (5) 4.041 (5) 2.955 (16) 3.005 (19) 3.118 (5) 3.237 (4) 3.241 (4) 3.261 (5) 3.418 (9) 3.506 (6) 3.717 (3) 3.798 (6) 3.046 (6) 3.061 (6) 3.251 (3) 3.297 (4) 3.313 (6) 3.387 (5) 3.717 (3) 3.817 (3) 3.998 (5) 3.180 (5) 3.230 (4) 3.273 (5) 3.331 (5) 3.423 (4) 3.748 (4) 3.767 (5) 3.817 (3) 4.050 (3) 3.085 (3) 3.242 (9) 3.301 (11) 3.636 (11) 3.767 (5) 3.798 (6) 3.813 (4)
17
Dy6–4 Sn1 Sn8 4 Dy5 4 Sn9 Dy4 Dy7–4 Co4 6 Sn5 6 Co1 Dy8–8 Co6 4 Sn7 Co2 Co1–Co4 Sn2 2 Sn5 2 Co1 Sn6 2 Dy3 2 Dy2 Dy7 Co2–Co6 2 Sn7 2 Dy1 2 Co2 Sn4 2 Dy1 Dy8 Co3–3 Sn1 Sn9 3 Dy2 3 Dy5 Co4–3 Co1 3 Sn5 Dy7 3 Dy2 Co5–8 Sn9 Co6–3 Co2 3 Sn7 3 Dy1 Dy8 Sn1–Co3 Sn2 2 Dy5 Dy6 2 Dy4 2 Dy2 Sn9
3.126 (5) 3.677 (8) 3.813 (4) 3.919(6) 4.050 (3) 2.894 (22) 3.229 (7) 3.466 (10) 2.962 (39) 3.254 (12) 3.433 (22) 2.461 (11) 2.603 (11) 2.611 (5) 2.643 (19) 2.714 (13) 3.314 (6) 3.418 (9) 3.466 (10) 2.394 (21) 2.593 (10) 2.713 (15) 2.730 (35) 2.792 (22) 3.345 (17) 3.433 (22) 2.509 (5) 2.779 (30) 3.005 (19) 3.301 (11) 2.461 (11) 2.830 (9) 2.894 (22) 2.955 (16) 2.868 (15) 2.394 (21) 2.870 (16) 2.923 (27) 2.962 (39) 2.509 (5) 2.883 (8) 3.085 (3) 3.126 (5) 3.180 (5) 3.261 (5) 3.679 (6)
14
Sn2–Co1 Sn1 Dy1 2 Dy4 2 Dy2 Sn6 2 Dy3 Sn3–2 Dy2 2 Dy4 4 Dy3 Dy5 Sn3 Sn4–2 Co2 2 Dy3 4 Dy1 2 Dy4 Sn5–4 Co1 2 Co4 2 Dy3 Dy7 2 Dy2 Sn6–3 Co1 3 Sn2 3 Dy3 3 Dy1 Sn7–4 Co2 2 Co6 2 Dy1 Sn8 Dy8 Sn8–Sn7 4 Dy4 4 Dy1 Dy6 Sn9–Co3 Co5 3 Dy5 3 Sn9 Sn1 Dy6
2.603 (11) 2.883 (8) 3.058 (6) 3.230 (4) 3.237 (4) 3.239 (5) 3.251 (3) 3.118 (5) 3.273 (5) 3.387 (5) 3.636 (11) 3.560 (9) 2.792 (22) 3.061 (6) 3.093 (3) 3.424 (4) 2.610 (5) 2.830 (9) 3.046 (6) 3.229 (7) 3.241 (4) 2.714 (13) 3.239 (5) 3.297 (4) 3.324 (7) 2.593 (10) 2.868 (16) 3.159 (6) 3.181 (17) 3.254 (12) 3.181 (17) 3.331 (5) 3.395 (7) 3.677 (8) 2.779 (30) 2.868 (15) 3.242 (9) 3.313 (7) 3.679(6) 3.910(6)
10
15
13
13
13
Wyckoff position is occupied by the Fe2 atom; in the Dy 117 Co 57 Sn 112 structure this position is split into two half-filled atomic sites with the very close coordinates, 32f (x x x, x50.0574) and 96k (x x z, x50.0801, z520.0155) occupied by Co6 and Co2, respectively (see Fig. 1, atoms printed in black colour). A resembling relation exists between the Yb 3 Rh 4 Sn 13 [11] and Y 3 Co 4 Ge 13 [12] structures: the 24k site occupied by tin atoms in the Yb 3 Rh 4 Sn 13 structure, is split in the Y 3 Co 4 Ge 13 structure into two partly filled atomic positions occupied by Ge atoms. The principal distinction between the two structures
16
13
12
11
10
10
8 10
10
10
10
11
12
10
10
10
consist in the fact that in the Dy 117 Co 57 Sn 112 structure the 4b Wyckoff position (0.5 0.5 0.5) is occupied by Co5, whereas in the Tb 117 Fe 52 Ge 112 structure the 4b site is unfilled. This can be taken as evidence to regard the Dy 117 Co 57 Sn 112 structure as a new structure type of intermetallic compounds.
Acknowledgements O.S. thanks JSPS for a 2-year fellowship in Japan.
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P. Salamakha et al. / Journal of Alloys and Compounds 314 (2001) 177 – 180
Fig. 1. Projection of the Dy 117 Co 57 Sn 112 on the XY plane. Large size circles indicate Dy atoms, Sn and Co atoms are marked by middle and small size circles, respectively.
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