The first ternary lanthanide telluride-bromide La3Te4Br was obtained from a mixture of LaTe and LaBr3 (in the presence of iridium) in a sealed tantalum container at elevated temperatures. The crystal structure (orthorhombic, Pnma, a = 1634.3(2), b = 435.0(1), c = 1426.6(2) pm, Z = 4, R1 (I0 > 2s(I0)) = 0.0349) is built from dicapped trigonal prisms of tellurium and bromine atoms surrounding lanthanum in two different ways. The dicapped trigonal prisms are connected via common edges to a threedimensional structure, in the same fashion as is known for the binary U3Te5. La3Te4Br is a valence compound according to (La3+)3(Te2-)4(Br-) and one out of three lanthanide telluride-halides known to date.
- Crystal structure
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