Characterization of new aluminides found in the ThT2Al20 alloys (where TÂ =Â Ti, V, Mn)

During the investigations on the Al-rich corner of the Th-T-Al system (where T = Ti, V, Mn), new intermetallic phases were revealed: ternary ThV2Al20, ThTi2Al20, ThMn2Al10 and pseudo-binary Th3Al11 (containing traces of vanadium). Their structure was investigated by means of Transmission Electron Microscopy and powder X-ray diffraction methods. Refinement of these structures was performed applying Rietveld analysis on X-ray diffraction data. It was established that ThV2Al20 and ThTi2Al20 phases can be ascribed to the CeCr2Al20 structure type, while ThMn2Al10 possesses the YbFe2Al10-type structure. The pseudo-binary (Th1−xVx)3Al11 phase was found to be orthorhombic (Immm; a = 4.4354(8) Å, b = 13.8394(9) Å and c = 10.3486(5) Å), isostructural to La3Al11. It was proposed that metastable Th3Al11 phase can be stabilized by small amount of vanadium, which was found in its content.