Cu 2 MnM IV S 4 (M IV ¼ Si, Ge, Sn) analysis of crystal structures and tetrahedra volumes of normal tetrahedral compounds

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1 968 Z. Kristallogr. 0 (005) # by Oldenbourg Wissenschaftsverlag, München Cu MnM IV S 4 (M IV ¼ Si, Ge, Sn) analysis of crystal structures and tetrahedra volumes of normal tetrahedral compounds Thomas Bernert and Arno Pfitzner* Institut für Anorganische Chemie, Universität Regensburg, Universitätsstraße 3, Regensburg, Germany Received April, 004; accepted May 0, 005 Dedicated to Professor Dr. Hans Hartl on the occasion of his 65 th birthday Tetrahedral structures / Quaternary copper chalcogenides / Wurtzite structure type / Sphalerite structure type / Single crystal structure analysis / X-ray diffraction Abstract. The crystal structures of the normal tetrahedral compounds Cu MnSiS 4,Cu MnGeS 4, and Cu MnSnS 4 are presented. The structures were refined from single crystal X-ray data. Cu MnSiS 4 and Cu MnGeS 4 crystallize in the space group Pmn in a wurtzite type superstructure. The refinement of Cu MnSiS 4 converged to R ¼ 0.04 and wr ¼ The redetermination of Cu MnGeS 4 converged to R ¼ 0.08, wr ¼ The tetrahedra volumes of the coordination polyhedra of the cations in these compounds are calculated and compared with those of Cu MnSnS 4 (redetermination, spacegroup I4m, sphalerite type superstructure, R ¼ 0.046, wr ¼ 0.045). In the wurtzite type structures the tetrahedra volumes differ significantly for different cations while they differ only in a small range in the sphalerite type structure. Introduction * Correspondence author ( arno.pfitzner@chemie.uni-regensburg.de) Many publications deal with tetrahedral structures because there exists a manifold of compounds with interesting properties for many applications (e.g. semiconducting, magnetical or optical properties). The prediction of the structure type or even the estimation of the precision of older structure determinations by simple checking routines is still an open problem although many investigations have been performed in the past. Some approaches have been made, see e.g. [, ], but a useful concept is not available. Recently we published a new model to predict the structure type of multinary normal tetrahedral compounds [3]. This model bases on the volumes of the different tetrahedra in a compound. In wurtzite type compounds the tetrahedra volumes differ significantly while in sphalerite type compounds the volumes are similar. We have been able to support this idea by experimental work on chalcogenides in the systems Cu 3 AsS 4 Cu 3 SbS 4 [3] and Cu 3 PS 4 Cu 3 SbS 4 [4]. The model was manifested by using structural data from the literature. Herein, we present the quaternary compounds Cu MnSiS 4,Cu MnGeS 4, and Cu MnSnS 4 and calculations analogous to those described in [3]. Some publications describe quaternary compounds of the type Cu M II M IV Q 4 (Q ¼ S, Se) [5, 6] but only a few compounds with Te as the Q atom are known [7]. Mostly lattice constants determined by powder diffraction are given. For a detailed view at the tetrahedra volumes an inspection of the crystal structures is necessary. The interest in the crystal structures of these compounds raised in the last years [8, 9]. A structure determination for M II ¼ Mn and M IV ¼ Ge, Sn can be found in the literature [0, ]. The given data in [0] were obtained by film methods and therefore a new structure determination by modern methods seems desirable. The data on Cu MnSnS 4 in [] were obtained by single crystal neutron diffraction. We redetermined the structural data by single crystal X-ray diffraction just in order to have the same basis for all compounds for our calculations of the tetrahedral volumes. These Mn þ containing materials are especially interesting due to their magnetic properties [ 3]. Experimental The title compounds were prepared by heating stoichiometric mixtures of the elements (metals: AlfaAesar %, sulphur: Riedel de Haën %) in evacuated sealed quartz ampoules to 800 C. The reaction mixtures were ground intensively between three heating periods of about one week. For the last heating period the mixtures were pressed to pellets in order to obtain single crystals. This method was very effective in the case of Cu MnSiS 4. The purity of the products was confirmed by powder diffraction on a STOE Stadi P. Single crystals of Cu MnGeS 4 and Cu MnSnS 4 were measured on a STOE IPDS. Single crystal X-ray data of Cu MnSiS 4 were collected on a Siemens P4. For the solution and refinement of the crystal structures we used the SHELX97 program

2 Cu Mn(Si, Ge, Sn)S 4 crystal structures and tetrahedra volumes 969 Table. Crystallographic data for the X-ray structure determinations of Cu MnSiS 4, Cu MnGeS 4, and Cu MnSnS 4. package [4]. The structure solutions were performed using direct methods. No evidence for inversion twins was found as the Flack parameters for the non-centrosymmetric structures were 0.000(7), 0.0(), and 0.005(8) for Cu MnSiS 4,Cu MnGeS 4, and Cu MnSnS 4 respectively. A numerical absorption correction was performed with the STOE X-SHAPE and X-RED routines [5]. Table shows crystallographic data of the title compounds. Results and discussion Crystal structures Atomic and anisotropic displacement parameters for the investigated compounds are collected in Tables and 3. Table 4 shows selected distances d(m S). Compound Cu MnSiS 4 Cu MnGeS 4 Cu MnSnS 4 Formula weight in g mol Crystal size in mm Colour black black black Crystal system orthorhombic orthorhombic tetragonal Spacegroup Pmn (No. 3) Pmn (No. 3) I4m (No. ) Lattice constants in A from single crystal data a ¼ 7.543() b ¼ 6.446() c ¼ 6.93() a ¼ 7.635() b ¼ 6.567(7) c ¼ 6.438(7) a ¼ 5.548() c ¼ 0.844() Cell volume in A 3, Z 30.(), 3.3(6), (), r X-ray in g cm Diffractometer Siemens P4 STOE IPDS MoK a, k ¼ A, oriented graphite monochromator Image plate distance in mm j-range, Dj in 0 j 359.8,.4 05 j 45,.0 Absorption correction numerical, shape optimized with X-SHAPE [5] No. of faces for crystal description Irradiation time/image 7 4 in min. Temperature in C q-range in 6.3 < q <60 6.<q < < q < 58. hkl-range 0 h 0 9 k l 8 0 h 0 8 k 8 8 l 7 7 h 7 7 k 7 4 l 4 No. of reflections, R int. 79, , , 0.07 No. of independent reflections No. of parameters Program SHELXL97 [4] R (I > s I ), 0.094, , , R (all reflections) # wr (I > s I ), , , , wr (all reflections) a GooF Largest difference peaks Dr max ; Dr min in e A , , , a: Definition of R and wr: P sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi P P jjfo j jf c jj R ¼ P, wr ¼ o Fc Þ Š P jfo j o Þ, GooF ¼ o Fc Þ Š Š n p Cu MnSiS 4 and Cu MnGeS 4 crystallize in a wurtzite type superstructure in the spacegroup Pmn while Cu MnSnS 4 crystallizes in a sphalerite type superstructure, spacegroup I4m. In both structure types the metal atoms are coordinated tetrahedrally by four sulphur atoms and vice versa. The superstructures are caused by an ordering of the cations on the cation sites. This class of compounds is called normal adamantane structures [6]. Further details of the crystal structure investigations are available from the Fachinformationszentrum Karlsruhe, D Eggenstein-Leopoldshafen (Germany), Fax: , crysdata@fiz-karlsruhe.de, on quoting the depository number CSD (Cu MnSiS 4 ), CSD (Cu MnGeS 4 ), and CSD (Cu MnSnS 4 ), the name of the authors, and the reference of the publication.

3 970 T. Bernert and A. Pfitzner Table. Atomic parameters (e.s.d.s) and U eq a (in A ) for the title compounds. Atom Wyckoff position x y z U eq Cu MnSiS 4 Cu 4b () () (4) (4) Mn a (4) (4) 0.06(6) Si a (6) (8) (9) S 4b 0.790(3) (4) (5) 0.05(6) S a (6) (7) 0.033(8) S3 a (6) (7) 0.04(8) Cu MnGeS 4 Cu 4b 0.488() 0.340() () 0.09() Mn a () () 0.084() Ge a () () 0.04() S 4b 0.646() () 0.63() 0.040() S a () 0.64() 0.05() S3 a () 0.07() 0.040() Cu MnSnS 4 Cu 4d 0 = 3 = (5) Mn b = = (5) Sn a () S 8i (3) x 0.343() (9) a: U eq is defined as one third of the trace of the orthogonalized U ij tensor. Analysis of the tetrahedral volumes We calculated a measure for the distortion of the tetrahedra as described in [3]. The tetrahedra volumes were calculated according to Ref. [7]. Figure shows the labelling scheme of the edges of the tetrahedra. Atom U U U 33 U U 3 U 3 Cu MnSiS 4 Cu 0.00(6) 0.046(6) (7) (6) (6) (8) Mn (9) 0.077() 0.05() () Si 0.0() 0.00() () () S (9) 0.03() 0.003() 0.006(9) () () S 0.053() 0.005() 0.0() () S3 0.04() 0.048() () () Cu MnGeS 4 Cu 0.034() 0.05() 0.008() () () 0.000() Mn 0.079() 0.083() 0.09(3) (3) Ge 0.04() 0.009() 0.038() () S 0.044() 0.035(3) 0.04(3) () () () S 0.058(3) 0.068(4) 0.07(4) (3) S3 0.07(3) 0.0(3) 0.038(4) (3) Atom U ¼ U U 33 U U 3 ¼ U 3 Cu MnSnS 4 Cu (5) 0.058() 0 0 Mn (6) 0.09() 0 0 Sn 0.03() (4) 0 0 S 0.049() 0.05() (7) (5) Fig.. Labelling of the tetrahedra edges. 0 0 r q a r 0 p b V ¼ 88 q p 0 c B C a b c 0 A 0 The tetrahedra volumes of the compounds under discussion are collected in Table 5. The tetrahedra [CuS 4 ] have about the same size in all compounds (as they have in many other ternary copper chalcogenides, too; see [3]). The volumes of the tetrahedra [MnS 4 ] also remain unchanged in the title compounds. As Sn has a bigger radius than Ge and Si the tetrahedra [SnS 4 ] are bigger than [GeS 4 ] and [SiS 4 ], respectively, see Table 5. The combination of these tetrahedra [M IV S 4 ] with two tetrahedra [CuS 4 ] and one tetrahedron [MnS 4 ] of almost constant and similar size leads to wurtzite type compounds Cu MnSiS 4 and Cu MnGeS 4, and to Cu MnSnS 4 of the zincblende type, respectively. Figure gives an impression of this fact. Obviously the relation of the sizes of different tetrahedra plays the most important role with respect to the resulting structure type. In [3] we calculated DV i values for the different compounds in order to receive a measure for the distinction of the structure types. DV i is the average Table 3. Anisotropic displacement parameters U ij (in A ) for Cu MnSiS 4, Cu MnGeS 4, and Cu MnSnS 4.

4 Cu Mn(Si, Ge, Sn)S 4 crystal structures and tetrahedra volumes 97 Table 4. Selected interatomic distances d in A for Cu MnM IV S 4 (M IV ¼ Si, Ge, Sn). Table 5. Tetrahedra volumes V and DV i values (for definition see text below) for Cu MnM IV S 4. Tetrahedra V(Cu MnSiS 4 ) V(Cu MnGeS 4 ) V(Cu MnSnS 4 ) A 3 A 3 A 3 [CuS 4 ] [MnS 4 ] [M IV S 4 ] DV i deviation of the different tetrahedra of their mean volume. Therefore we calculate the average V of all tetrahedra volumes P n V i V ¼ : n The differences of the different volumes V i from this average volume are computed for each tetrahedron DV i ¼ V i V : V Finally we determine the average value of all these differences as a measure for the distortions of the tetrahedra P DV i i DV i ¼ : i The data for the compounds given herein are DV i ¼ : for Cu MnSiS 4, DV i ¼ 7:7 for Cu MnGeS 4, and DV i ¼ 6: for Cu MnSnS 4. Wurtzite type variants are expected to have quite big DV i values while sphalerite type Fig.. Comparison of the tetrahedra [MS 4 ]incu MnM IV S 4. Notice that the tilting of the tetrahedra decreases from M IV ¼ Si to M IV ¼ Sn. Table 5 quantifies this finding. Cu MnSiS 4 Cu MnGeS 4 Cu MnSnS 4 Cu S.306(6) Cu S.309(7) Cu S (3) S.454(7) S.35(6) Mn S (4) S3.4603(5) S3.337(6) Sn S 4.470(4) S.3507(5) S.349(7) Mn S.4603(5) Mn S.4583(6) S.454(7) S.47() S3.470(6) S3.45() Si S.37(5) Ge S.95(6) S.33(6) S.9() S3.363(8) S3.9(9) variants have smaller ones. As reported earlier there exists no sharp border line in these values but an overlap range 5 DV i 8. The value for Cu MnSiS 4 is greater than 0. This clearly indicates the wurtzite type variant. The closer the differences between the volumes of the tetrahedra, the smaller are the DV i values. The values for Cu MnGeS 4 and Cu MnSnS 4 fall in the range of the overlap region but the value for the wurtzite type superstructure is significantly bigger than the value of the sphalerite type superstructure. For this region one might expect the existence of the alternative structure types, both for Ge and Sn. Cu MnGeS 4 and Cu MnSnS 4 form mixed crystals [8]. The miscibility gap is in the range of Cu MnGe 0.3 Sn 0.7 S 4 and Cu MnGe 0.5 Sn 0.5 S 4 at 800 C. Between 0 and 0% Ge content the mixed crystals belong to the stannite type. From 60 to 00% Ge content the wurtzstannite type is formed. Further investigations on the mixed crystals will be presented in the near future. Acknowledgments. Financial support of the University of Regensburg and the State of Bavaria is gratefully acknowledged. References [] O Keeffe, M.; Hyde, B. G.: Non-bonded interactions and the crystal chemistry of tetrahedral structures related to the wurtzite typ (B4). Acta Crystallogr. B34 (978) [] Fleet, M. E.: Axial ratios of MX compounds with the wurtzite structure. Mater. Res. Bull. (976) [3] Pfitzner A.; Bernert T.: The system Cu 3 AsS 4 Cu 3 SbS 4 and investigations on normal tetrahedral structures. Z. Kristallogr. 9 (004) 0 6. [4] Pfitzner A.; Reiser S.: Refinement of the crystal structures of Cu 3 PS 4 and Cu 3 SbS 4 and a comment on normal tetrahedral structures. Z. Kristallogr. 7 (00) [5] Schäfer, W.; Nitsche, R.: Tetrahedral quaternary chalcogenides of the type Cu II IV S 4 (Se 4 ). Mater. Res. Bull. 9 (974) [6] Himmrich, M. M.: Präparative und Schwingungsspektroskopische Untersuchungen an Verbindungen mit Stannit-, Wurtzstannit- und Zinkindiumsulfid-(IIIa)-Struktur. Ph.D. Thesis, Universität Siegen, 990. [7] Haeuseler, H.; Ohrendorf, F. W.; Himmrich, M.: Zur Kenntnis quaternärer Telluride Cu MM 0 Te 4 mit Tetraederstrukturen. Z. Naturforsch. 46B (99) [8] Olekseyuk, I. D.; Gulay, L. D.; Dydchak, I. V.; Piskach, L. V.; Parasyuk, O. V.; Marchuk, O. V.: Single crystal preparation and crystal structure of the Cu Zn/Cd,Hg/SnSe 4 compounds. J. Alloys Compd. 340 (00) [9] Gulay, L. D.; Nazarchuk, O. P.; Olekseyuk, I. D.: Crystal structures of the compounds Cu CoSi(Ge,Sn)S 4 and Cu CoGe(Sn)Se 4. J. Alloys Compd. 377 (004)

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