L Journal of Alloys and Compounds 307 (2000) 124–126 www.elsevier.com / locate / jallcom Crystal structure of the Cu CdSn S compound 2 3 8 a, b b b * S.I. Chykhrij , L.V. Sysa , O.V. Parasyuk , L.V. Piskach a Department of Analytical Chemistry, The Ivan Franko State University of L’ viv, Kyryla and Mefodiya Str. 6, 290005 L’ viv, Ukraine b Department of Inorganic and Physical Chemistry, Volyn State University, Voli Av. 13, 263009 Lutsk, Ukraine Received 16 December 1999; accepted 29 February 2000 Abstract The crystal structure of a new quaternary compound Cu CdSn S has been determined by X-ray powder diffraction. The Cu CdSn S 2 3 8 2 3 8 compound is a synthetic analoque of the natural mineral rhodostannite Cu FeSn S and crystallizes in the tetragonal space group I4 / a 2 3 8 1 with the lattice parameters a50.73827(4) and c51.04152(9) nm. The atomic parameters are refined in the anisotropic approximation to R50.053. The mode of filling the tetrahedral and octahedral cavities of the anionic close packing has been analyzed taking their sizes into account.  2000 Elsevier Science S.A. All rights reserved. Keywords: Rhodostannite; Lattice parameters; X-ray powder method; Quaternary compound 1. Introduction containers under residual argon pressure of 0.1 Pa. Syn- thesis was carried out in two steps. The first stage of A new quaternary phase Cu CdSn S was found during interaction took place in an oxygen–methane flame with 2 3 8 a systematic investigation of the quasi-ternary system visual control of the reaction, the aim of this stage being Cu S–CdS–SnS using DTA, X-ray diffraction and metal- partial reaction of pure sulfur. The second stage of the 2 2 lography [1]. The compound is formed by a peritectic synthesis process was carried out in the furnace by reaction L1CdS⇔Cu CdSn S at 1091 K and it under- gradually increasing the temperature (40–50 K / h) up to 2 3 8 goes a polymorphous transformation at 950 K. Chemical 1220 K. The samples then were heat treated at this analysis has indicated its stoichiometric composition to be temperature during 6 h and cooled to 670 K at a rate of 10 identical to that of the mineral rhodostannite Cu FeSn S . K / min. At the peritectic temperature (1091 K), the sam- 2 3 8 The rhodostannite crystallizes in a tetragonal unit cell ples were additionally treated during 10 h and then (space group I4 / a) with the lattice parameters a50.729 annealed at 670 K during 250 h, followed by quenching in 1 and c51.031 nm [2]. These results were confirmed in Ref. cold water without breaking the ampoules. [3], and the obtained lattice constants were a50.7305 and We have prepared five samples with compositions close c51.0330 nm. The purpose of the present study is a to the stoichiometric ratio Cu:Cd:Sn:S52:1:3:8 and studied detailed crystal structure investigation of the Cu CdSn S their phase composition by X-ray powder diffraction 2 3 8 compound. (diffractometer DRON-3M, Cu Ka radiation, continuous mode of registration of the diffraction intensities). The sample used for the crystal structure determination did not 2. Experimental procedure contain any additional reflections in the X-ray pattern. Analysis of the composition of the chosen sample by The samples for the investigation were prepared from energy-dispersive X-ray spectroscopy indicates good corre- elemental components of high purity (Cu, 99.994, Cd, lation with the Cu CdSn S stoichiometry (Table 1). 2 3 8 99.9999, Sn, 99.999 and S, 99.97wt.% of the main For the crystal structure determination of the compound, component). These were brought into evacuated quartz diffraction data were collected using a u –2 u scan tech- nique with a step of 0.058 of 2 u and an exposure time of 20 s at each point. All calculations were performed using *Corresponding author. E-mail address: oleg@lab.univer.lutsk.ua (S.I. Chykhrij) CSD software [4]. 0925-8388 / 00 / $ – see front matter  2000 Elsevier Science S.A. All rights reserved. PII: S0925-8388(00)00803-3