Eleven new compounds in the RE–Cd–Ge systems (RE=Pr, Nd, Sm, Gd–Yb; Y): Crystal chemistry of the RE2CdGe2 series

A large new family of rare-earth metal–cadmium–germanides RE2CdGe2 (RE=Y, Pr, Nd, Sm, Gd–Yb) has been synthesized and structurally characterized. All eleven structures have been established from single-crystal X-ray diffraction data and have been found to belong to the tetragonal Mo2FeB2 structure type (ordered ternary variant of the U3Si2 structure type—space group P4/mbm (No. 127), Z=2; Pearson symbol tP10). The structural variations among the three series of isostructural RE2MgGe2, RE2InGe2, and RE2CdGe2 compounds are discussed, as well as the crystal chemistry changes as a function of the decreasing size of the rare-earth metals (lattice constants a=7.176(2)–7.4589(12) Å and c=4.1273(14)–4.4356(13) Å). The experimental results have been complemented by tight-binding linear muffin-tin orbital (TB–LMTO) electronic structure calculations.