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The New Crystalline Mixed Valent Solids TlIn 4 Se 5 X (X: Cl, Br) and TlIn 4 S 5 Cl: Structure and Nanoscopic Defects Investigated by Combined Application of X‐ray and HRTEM Studies
Author(s) -
Nickel V.,
Reiner C.,
Schlosser M.,
Deiseroth H.J.,
Kienle L.,
Xhaxhiu K.
Publication year - 2008
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.200800187
Subject(s) - crystallography , orthorhombic crystal system , monoclinic crystal system , crystal twinning , crystal structure , lamellar structure , octahedron , ternary operation , group (periodic table) , chemistry , high resolution transmission electron microscopy , type (biology) , materials science , nanotechnology , transmission electron microscopy , microstructure , organic chemistry , computer science , programming language , ecology , biology
The title compounds TlIn 4 Se 5 X (X = Cl: P 2 1 / m , a = 9.275(2) Å, b = 4.102(1) Å, c = 15.376(3) Å, β = 92.77(2)°; X = Br: P 2 1 / m , a = 9.294(2) Å, b = 4.117(1) Å, c = 15.376(3) Å, β = 92.48(2)°) and TlIn 4 S 5 Cl ( P 2 1 / m , a = 8.951(1) Å, b = 3.924(6) Å, c = 15.058(8) Å, β = 93.75(2)°) belong to a group of indium based mixed valent solids with In + replaced by Tl + according to a formulation Tl + (In 2 ) 4+ 2In 3+ 5Ch 2− X − . The ternary members of this group of solids crystallize either in the monoclinic In 5 Ch 5 Cl or in the orthorhombic In 5 Ch 5 Br type („Cl‐type, Br‐type”). All quaternary title compounds, surprisingly including the bromide TlIn 4 Se 5 Br, crystallize in the Cl‐type. In both structure types the M + coordination is topologically identical with the coordination of the (In 2 ) 4+ groups. This special structural aspect is the most important basis for an understanding of the differences between the two closely related structure types and their defect structures. A variety of nanoscaled defects (lamellar twinning, polymorphic and phasoid intergrowth) together with a pronounced needle shaped morphology („nanowires”) is observed for all crystals of this group of compounds. As a consequence X‐ray single crystal structure refinements are of limited precision (R‐ values) but are completed by HRTEM investigations in order to compensate this drawback. The combination of both methods offers deep insight into details of the differences between ideal structures and real structures.