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 measurement s are reported. Coherent phases GdTiGe with CeScSi-type structure and GdTiG e with CeFeSi-type structure were found to coexist in the GdTiGe alloy when the sample mass was 5 g (melting in electric are furnace in argon atmosphe re). Annealing at 1070 K for 200 h in argon atmosphere led to an increase i n GdTiGe (CeScSi-type structure) phase in the GdTiGe alloy. The GdTiGe with CeScSi-rype structure (a = 0.4065(1), c = 1.5450(1) nm) was characterized by Curie point T-c = 376 K, while GdTiGe with CeFeSi-type structure (a = 0. 4065(1), c = 0.7716(1) nm) demonstrated Neel point T-N = 412 K. The mechani cal hydrogenization of the GdTiGe alloy led to formation of the GdTiGeHsimi lar to 4, hydride with CeScSi-type structure and to a sharp decrease in mag netization; GdTiGe with CeFeSi-type structure remained passive. The X-ray s ingle crystal diffraction study confirmed that the Gd(Ti0.8Zr0.2)Ge compoun d has the CeScSi-tvpe structure (space group I4/mmm, a = 0.4060(1), c = 1.5 400(3) nm). (C) 2000 Elsevier Science Ltd.