The solid solutions <italic>RE</italic>Ti2Al20−<italic>x</italic>Ga <italic>x</italic> (0 ≤ <italic>x</italic> ≤ 10) with <italic>RE</italic> = Eu, Gd, Tb, Dy and Yb − first gallides with CeCr2Al20-type structure.

The CeCr2Al20-type aluminides <italic>RE</italic>Ti2Al20 (<italic>RE</italic> = Eu, Gd, Tb, Dy and Yb), space group F d 3 ‾ m $Fd\overline{3}m$ , show the formation of solid solutions <italic>RE</italic>Ti2Al20−<italic>x</italic>Ga <italic>x</italic> with gallium in the ranges 0 ≤ <italic>x</italic> ≤ 10. Polycrystalline samples were prepared from the elements in alumina crucibles or directly via arc-melting followed by annealing in order to increase crystallinity. The structures of six single crystals were refined from single crystal X-ray diffractometer data for determining the precise occupancy parameters of the aluminum and gallium atoms. The solubility limit of gallium was found at around <italic>x</italic> ≈ 10. The <italic>RE</italic>Ti2Al20−<italic>x</italic>Ga <italic>x</italic> structures show a MgCu2-related substructure of the rare earth and titanium atoms. The Al/Ga atoms then form Frank-Kasper type polyhedra around the <italic>RE</italic> and Ti atoms, i. e., <italic>RE</italic>@(Al/Ga)16 and Ti@(Al/Ga12). These are the basic building units of the <italic>RE</italic>Ti2Al20−<italic>x</italic>Ga <italic>x</italic> structures. Temperature-dependent magnetic susceptibility studies show Pauli paramagnetic behavior for the YbTi2Al10Ga10 sample, i. e., a stable divalent ytterbium ground state. [ABSTRACT FROM AUTHOR]