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Cu 1,45 Er 0,85 S 2 : Ein Kupfer(I)‐Erbium(III)‐Sulfid mit kationendefekter CaAl 2 Si 2 ‐Struktur
Author(s) -
Lauxmann Petra,
Schleid Thomas
Publication year - 2001
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/1521-3749(200101)627:1<9::aid-zaac9>3.0.co;2-m
Subject(s) - octahedron , crystallography , orthorhombic crystal system , sulfide , ternary operation , copper sulfide , tetrahedron , copper , materials science , reagent , crystal structure , chemistry , metallurgy , computer science , programming language
Cu 1.45 Er 0.85 S 2 : A Copper(I) Erbium(III) Sulfide with Cation‐Deficient CaAl 2 Si 2 ‐Type Structure Attempts to synthesize single‐phase CuYS 2 ‐type copper(I) erbium(III) disulfide (CuErS 2 ) from 1 : 1 : 2‐molar mixtures of the elements (Cu, Er and S) after seven days at 900 °C in sealed evacuated silica tubes failed with equimolar amounts of CsCl working as flux and reagent. In these cases, quaternary CsCu 3 Er 2 S 5 (orthorhombic, Cmcm; a = 394.82(4), b = 1410.9(1), c = 1667.2(2) pm, Z = 4) and ternary Cu 1.45 Er 0.85 S 2 (trigonal, P3m1; a = 389.51(4), c = 627.14(6) pm, Z = 1) become the unexpected by‐products. Both emerge even as yellow single crystals (lath‐shaped fibres and platelets, respectively, with triangular cross‐section) and both crystal structures contain condensed [CuS 4 ] and [ErS 6 ] units as dominating building blocks. The ternary sulfide Cu 1.45 Er 0.85 S 2 exhibits CdI 2 ‐analogous layers $^2_\infty$ {[(Er 3+ )(S 2– ) 6/3 ] – } of edge‐shared [ErS 6 ] octahedra (d(Er–S) = 272 pm, 6 × ) which are piled up parallel (001) and interconnected by interstitial Cu + cations in tetrahedral S 2– coordination (d(Cu–S) = 236 pm, 1 × ; 240 pm, 3 × ). The latter thereby form anionic layers $^2_\infty$ {([(Cu + )(S 2– ) 4/4 ] – ) 2 } as well, consisting of [CuS 4 ] tetrahedra which share three cis ‐oriented edges. When the S 2– anions arrange hexagonally closest‐packed and the corresponding layers are symbolized with capital Roman letters, the Er 3+ cations (small Roman) and the Cu + cations (small Greek letters) reside layerwise alternatingly within half of the octahedral (Er 3+ ) and tetrahedral (Cu + ) voids according to … AcB αβ AcB αβ A … . Since both kinds of cations occupy only a certain percentage (Cu + : 72.6%, Er 3+ : 85.1%) of their regular positions, the crystal structure of Cu 1.45 Er 0.85 S 2 can be addressed as a double cation‐deficient CaAl 2 Si 2 ‐type arrangement according to (Er 0.85 □ 0.15 )(Cu 1.45 □ 0.55 )S 2 . The partial occupation could be established by both released site occupation factors in the course of the crystal structure refinement and electron beam X‐ray microanalysis (EDX).