GdTiGe (CeScSi-type structure) and GdTiGe (CeFeSi-type structure) as the coherent phases with different magnetic and hydrogenization properties

The results of investigations of new ternary coherent GdTiGe compounds and corresponding hydrides by X-ray powder diffraction and magnetic measurements are reported. Coherent phases GdTiGe with CeScSi-type structure and GdTiGe with CeFeSi-type structure were found to coexist in the GdTiGe alloy when the sample mass was 5 g (melting in electric arc furnace in argon atmosphere). Annealing at 1070 K for 200 h in argon atmosphere led to an increase in GdTiGe (CeScSi-type structure) phase in the GdTiGe alloy. The GdTiGe with CeScSi-type structure (a = 0.4065(1), c = 1.5450(1) nm) was characterized by Curie point Tc = 376 K, while GdTiGe with CeFeSi-type structure (a = 0.4065(1), c = 0.7716(1) nm) demonstrated Neel point TN = 412 K. The mechanical hydrogenization of the GdTiGe alloy led to formation of the GdTiGeH∼4 hydride with CeScSi-type structure and to a sharp decrease in magnetization; GdTiGe with CeFeSi-type structure remained passive. The X-ray single crystal diffraction study confirmed that the Gd(Ti0.8Zr0.2)Ge compound has the CeScSi-type structure (space group I4/mmm, a = 0.4060(1), c = 1.5400(3) nm).