Crystal structure of new ternary compounds Al2R11Ge8 (R = Y, Gd, Tb, Dy, Ho, Er) and thermal properties of Al2Er11Ge8

The crystal structure of new ternary compounds Al2R11Ge8 (R = Y, Gd, Tb, Dy, Ho, Er) was studied using X-ray powder diffraction data by Rietveld method. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) was used for sample composition examination. The compounds crystallized in the Ge10Ho11 structure type (space group I4/mmm). The phase was not found in the systems with R = La, Ce, Pr and Nd. The lattice thermal expansion study of the Al2Er11Ge8 compound was carried out using high-temperature powder X-ray diffraction technique from 293 K to 743 K, and the calculated lattice and volume thermal expansion coefficients were αa = 0.88 × 10−5 K−1, αc = 1.22 × 10−5 K−1, and αV = 3.01 × 10−5 K−1, respectively.

► The new compounds Al2R11Ge8 (R = Y, Gd, Tb, Dy, Ho, Er) were found. ► The crystal structure of Al2R11Ge8 (R = Y, Gd, Tb, Dy, Ho, Er) was determined. ► The thermal expansion coefficients for Al2Er11Ge8 were experimentally determined.