The new series of RZnGe compounds (R = rare earth element) with the YPtAs structure type

The synthesis and crystal structure of the new family of rare earth ternary equiatomic RZnGe phases are reported. The compounds are found to form for R = La to Nd, Sm, Gd to Tm, Y, all crystallizing with the hexagonal hP12-P63/mmc YPtAs structure type, a four-layers superstructure derivative of the AlB2 type. No formation of the equiatomic phase has been observed for R = Lu and Sc. The unit cell parameters, as obtained by the Guinier method on polycrystalline samples, vary regularly from the La [a = 4.333(1), c = 17.017(2) إ] to the Tm homologous [a = 4.192(1), c = 15.314(2) إ]. The crystal structure has been refined for the Ce, Gd and Y compounds by single crystal data.