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A study of the ternary Rh-Mn-Bi phase diagram revealed the existence of two new ternary bismuthides, viz. hexarhodium pentamanganese octadecabismuthide (Rh 6 Mn 5 Bi 18 ) and rhodium manganese tribismuthide (RhMnBi 3 ). Their crystal structures represent new structure types. Rh 6 Mn 5 Bi 18 , with a Wyckoff sequence a f2 g2 i5, crystallizes in the tetragonal system (space group P4 2 /mnm; Pearson symbol tP58), and RhMnBi 3 , with a Wyckoff sequence a c g i q, crystallizes in the orthorhombic system (Cmmm; oS20). In the Rh 6 Mn 5 Bi 18 structure, the transition metal atoms are linked into ribbon-like structural units aligned along the [001] direction, whereas planar sheets are formed in RhMnBi 3 . In both crystal structures, the units formed by the transition metal atoms are enveloped by Bi atoms, which themselves form a loosely bound network. The linkage results in a layer structure for RhMnBi 3 , while in the case of Rh 6 Mn 5 Bi 18 , a three-dimensional network is formed; the latter, however, contains several areas where Bi...Bi distances suggest van der Waals interactions. Both phases under discussion have analogous structural motifs., (open access.)

The binary bismuth-rhodium (Bi-Rh) phase diagram was reinvestigated from 23 to 60 at.% Rh with focus on the BiRh phase, applying powder-x-ray diffraction (XRD), high temperature powder-XRD, differential thermal analyses and scanning electron microscopy. The phase boundaries of the BiRh phase at 750 °C and the temperature of its peritectic decomposition were refined. In addition, the existence of the two phases Bi 4 Rh and Bi 2 Rh (in two modifications depending on temperature) could be confirmed. Most of the reaction temperatures reported in the literature could be verified within a range of about ± 10 °C. Nevertheless, a few temperatures had to be revised, such as those of the peritectic reactions L + Rh  ⇌  BiRh at 979 °C and L + BiRh  ⇌   β -Bi 2 Rh at 785 °C. No evidence could be found for the presence of a stable Bi 3 Rh phase in well annealed samples; from the present results it must be concluded that Bi 3 Rh is actually metastable. On the other hand, a new orthorhombic phase BiRh 0.81 was discovered which crystallizes in the MnP structure type (Pmna). It was found that the temperatures of the transition between the low-temperature modification α -Bi 2 Rh and its high-temperature form β -Bi 2 Rh depend considerably on the presence or absence of metastable Bi 3 Rh and stable BiRh 0.81 , respectively., (© The Author(s) 2017.)