Study of the structural transition and hydrogenation of CeTiGe

There remains some disagreement in the literature on CeTiGe over the presence of a structural transition from the low temperature CeFeSi-type form to the high temperature CeScSi-type structure. We present a detailed study of the effect of temperature on this structural transition. Furthermore, the same hydride is obtained after hydrogenation of both forms. Using neutron powder diffraction we find that the structure of CeTiGeH1.5 corresponds to a stuffed variant of the CeScSi-type structure with space group I4/mmm, a = 4.0785(1) Å and c = 17.1060(8) Å. The H atoms occupy both the Ce4 tetrahedral sites and the Ti4Ce square based pyramidal sites for a total hydrogen occupancy of 1.5 H f.u.−1. Preliminary examinations of the magnetic properties after hydrogenation reveal the onset of low temperature magnetic order around 3.5 K, suggesting for the first time a hydrogen induced magnetic order for an intermetallic with CeScSi-type structure