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Die Kristallstruktur von Tl 3 Bi 2 I 9 : Eine komplexe Ausdünnungs‐ und Verzerrungsvariante des Perowskit‐Typs
Author(s) -
Wosylus Aron,
Schwarz Ulrich,
Ruck Michael
Publication year - 2005
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/zaac.200400484
Subject(s) - crystallography , monoclinic crystal system , octahedron , crystal structure , perovskite (structure) , chemistry , materials science
The Crystal Structure of Tl 3 Bi 2 I 9 : A Complex Defect and Deformation Variant of the Perovskite Structure Type Black crystals of trithallium(I) enneaiododibismuthate(III) Tl 3 Bi 2 I 9 were obtained by slow cooling of a melt with composition Tl : Bi : I = 3 : 2 : 9 from 800 K to ambient temperature. The compound is diamagnetic and decomposes peritectically at 619(2) K. X‐ray diffraction of single‐crystals revealed that Tl 3 Bi 2 I 9 crystallizes in the monoclinic space group P 2 1 / n with lattice parameters a = 1438.9(1), b = 771.54(7), c = 2091.0(1) pm and β = 93.309(6)°, ( Z = 4). The crystal structure can be described as a defect variant of the perovskite type ( ABX 3 ), where according to the formula Tl(Bi 2/3 □ 1/3 )I 3 the Bi atoms occupy only two thirds of the octahedral sites B . The vacancies are located in every third plane resulting in double layers of corner sharing [BiI 6 ] polyhedra. By distortion and rotation of the [BiI 6 ] polyhedra the coordination of the Tl atoms (cuboctahedral sites in the perovskite type, c.n. = 12) is reduced to bicapped trigonal prisms (c.n. = 8). The group‐subgroup relation between the Tl 3 Bi 2 I 9 structure and the perovskite type results in a subgroup index of 144.