Campus Units

Chemistry

Document Type

Article

Publication Version

Published Version

Publication Date

1999

Journal or Book Title

Inorganic Chemistry

Volume

38

Issue

22

First Page

5139

Last Page

5150

DOI

10.1021/ic990652s

Abstract

The Rh−Te and Ir−Te binary systems for 50−78 atom % Te show remarkable differences in their phase and structural features at temperatures below 1100 °C. Extended Hückel calculations are employed to investigate the influence of various orbital interactions on these differences. In general, a strong interrelationship among valence electron count, orbital characteristics at and near the Fermi levels, and relative strengths of M−Te, Te−Te, and M−M orbital interactions control the occurrence and structures of various MxTe2 compounds (0.75 ≤ x ≤ 2). Stronger Ir−Te than Rh−Te orbital interactions lead to the different low-temperature structures of IrTe2 (CdI2-type) and RhTe2 (pyrite-type), but then short and intermediate-range Te−Te interactions lead to the pyrite-type structure for the defect phases M1-uTe2. At temperatures above 600 °C, RhTe2 (pyrite-type) is unstable relative to disproportionation to the “stuffed” CdI2-type Rh1+xTe2 and the defect pyrite-type Rh1-uTe2. The Rh-rich phases, Rh1+xTe2, show ordered vacancies in alternating layers of octahedral holes and can be formulated as (Rh3)x(Rh)1-2xTe2 (x1/2) and (Rh3)1-x(Rh)4x-2Te2 (x1/2) to emphasize the occurrence of linear Rh3 units in their structures. The pattern of vacancies in these structures follows the preference of Rh4n+3 oligomers over Rh4n+1 chains. Charge-iterative calculations of Rh atomic orbital energies in Rh1+xTe2 (x = 0.0, 0.5, 1.0) were carried out to analyze the electronic properties of Rh throughout the series. As x increases, Rh−Te orbital interactions become less attractive and the concentration of Rh−Rh repulsive interactions grows. Both effects control the maximum value of x (observed to be 0.84) for this series and influence the pattern of occupied octahedral holes in the close-packed tellurium matrix.

Comments

Reprinted (adapted) with permission from Inorg. Chem., 1999, 38 (22), pp 5139–5150. Copyright 1999 American Chemical Society.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

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