ausblenden:
Schlagwörter:
alkali metal; chalcogen; indium; crystal structures; HRTEM
Zusammenfassung:
Systematic X-ray and HRTEM investigations on the ternary
systems alkali metal (or thallium)-indium-chalcogen proved the
existence of mixed valent solids with the simultaneous
occurrence of indium species in different states of oxidation.
Additionally to the earlier described solids MIn5S7 (M: Na, K,
Tl: isotypic to InIn5S7 = In6S7 and TlIn5S7) and KIn5S6 (isotyp
to TlIn5S6) in the actual work we present with MIn7X9 (M: Rb,
Cs; X: S, Se) a new structure type which also contains indium
in the states of oxidation +3 and +2. The formal state of
oxidation In2+ corresponds to (In-2)(4+) ions. A reasonable
ionic formulation of these structures is given by: MIn5S7 = M+
3[In3+] [(In-2)(4+)] 7[S2-] (M = Na, K, Tl), MIn5S6 = M+ [In3+]
2[(In-2)(4+)] 6[S2-] (M = K, Tl), MIn7X9 = M+ 3[In3+] 2[(In-
2)(4+)] 9[S2-]. The three structure types show common two
dimensional structure elements which contain ethane analogous
In2X6 units and cis and trans edge sharing double octahedron
chains. The main interest of this work is a crystalchemical
discussion taking into account the new compounds MIn7X9 and the
results of special HRTEM investigations on MIn7X9. The HRTEM
investigations aim on the identification and subsequent
preparation of new phases which initially might be visible as
nano size crystals or inclusions in the HRTEM only.
