Abstract
TlIn5Se8 has been synthesized by means of solid-state reaction and densified by Spark Plasma Sintering. The compound is a semiconductor with a band gap of 1.62eV estimated from reflectance measurements. Its thermal conductivity is about 0.45Wm−1. K−1 in the temperature range 300−673K, an extremely low value attributed to its complex pseudo-1D structure reminiscent of the pseudo-hollandite. While attempting to dope TlIn5Se8 with Te, a new complex chalcogenide was discovered and characterized by the combination of TEM and XRD diffraction. It belongs to the A2In12X19 family, crystallizing in the R3̅:H space group. Single crystal X-ray diffraction study led to a refined composition of Tl0.98In13.12Se16.7Te2.3 with cell parameters: a=13.839(5)Å and c=35.18(3)Å. A static disorder is found on one indium site situated in an octahedral environment. The single crystal XRD study is in agreement with TEM analyses in STEM-HAADF image mode that do not show any extended defects or disorder at atomic scale.
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