L Journal of Alloys and Compounds 314 (2001) 177–180 www.elsevier.com / locate / jallcom Dy Co Sn , a new structure type of ternary intermetallic stannides 117 57 112 with a giant unit cell a,c, b c a b * P. Salamakha , O. Sologub , G. Bocelli , S. Otani , T. Takabatake a NIRIM 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan b 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 ˚ The crystal structure of a new ternary stannide Dy Co Sn , space group Fm-3m (N225), a529.831(4) A, Z54, V526546.26(1) 117 57 112 3 21 ˚ A, m 540.34 mm was refined from single-crystal X-ray diffraction data to R50.0689, Rw250.1119 from 1000 reflections hkl with I .4s( I ) and 89 variable parameters. The structure is related to the Tb Fe Ge structure type and contains 1144 atoms per unit cell. 117 52 112  2001 Elsevier Science B.V. All rights reserved. Keywords: Rare earth compounds; Transition metal compounds; Crystal structure; X-ray diffraction 1. Introduction was remelted in the induction furnace and slowly cooled down. Recently, the existence of ternary compounds with a For the X-ray single-crystal data collection, a single Tb Fe Ge structure was reported [1,2]. The atomic crystal was glued on the top of a glass fiber and mounted 117 52 112 parameters were refined only for an initial compound [3] on the goniometer head. A four-circle diffractometer whereas the crystal structures of the other isotypic com- Philips PW 1100 with graphite monochromatized Mo Ka ˚ pounds were studied with respect to establish their forma- radiation ( l50.71073 A) was used. The least-square tion and to derive the lattice parameters. We also reported refinement of the 2 u values of 25 strong and well centered on the existence of a compound with a giant unit cell in the reflections from the various regions of reciprocal space Nd–Ru–Sn system [4,5]. In this work we present the were used to obtain the unit-cell parameters. The data set results of a crystal structure investigation of a compound was recorded at room temperature in a v 22 u scan mode. with a gigantic unit cell observed in the Dy–Co–Sn The intensities were corrected for absorption, polarization system. 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 A single-crystal suitable for the X-ray measurements purity argon atmosphere on a water-cooled copper hearth. was isolated from the surface of the alloy with composition In order to ensure homogeneity, the arc melted button was |Dy CoSn . The structure was solved in space group 2 2 turned over and remelted several times. The weight losses Fm-3 m using SHELXS-86 [6] by means of direct methods during arc melting were less than 1%. The as-cast sample 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 *Corresponding author. E-mail address: salam@nirim.go.jp (P. Salamakha). 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