I.A Sviridov

Crystallographic data of new ternary Sm5Ge4-type R2Ti3Ge4 compounds (R=Gd-Er)

Abstract Investigations made by powder X-ray diffraction on five new ternary R2Ti3Ge4 compounds (R=Gd-Er) are reported. The (Gd0.97)2Ti3Ge4 (a=0.7042(1) nm, b=1.3494(2) nm, c=0.7186(1) nm), (Tb0.99)2Ti3Ge4 (a=0.7019(1) nm, b=1.3457(2) nm, c=0.7156(1) nm), (Dy0.97)2Ti3Ge4 (a=0.6987(1) nm, b=1.3409(2) nm, c=0.7122(1) nm), (Ho0.96)2Ti3Ge4 (a=0.6981(1) nm, b=1.3399(2) nm, c=0.7117(1) nm) and (Er0.91)2Ti3Ge4 (a=0.6962(1) nm, b=1.3367(2) nm, c=0.7099(1) nm) crystallize in the orthorhombic Sm5Ge4-type structure (space group Pnma).

CeScSi- and CeFeSi-type structures in compounds derived from GdTiGe

Abstract Physico-chemical analysis techniques, including X-ray phase analysis and metallographic analysis were employed in investigations of the solid solutions based on GdTiGe compounds. These solid solutions have existence regions of the CeScSi-type phase, the CeFeSi-type phase and of their mixture. Gd 0.9 TiGe, Sm x Gd 1− x TiGe ( x =0–0.1, 0.9–1), GdSc x Ti 1− x Ge ( x =0–0.1), Y x Gd 1− x TiGe ( x =0–1), Gd{Zr, Hf, V, Nb, Cr, Cu} 0.15 Ti 0.85 Ge, Gd{V, Mn} 0.3 Ti 0.7 Ge, GdTiGe 0.9 Si 0.1 form coherent mixtures of the CeScSi-type and CeFeSi-type phases, while GdTi 0.9 Ge and the solid solutions Sm x Gd 1− x TiGe ( x =0.2–0.9), GdSc x Ti 1− x Ge ( x =0.15–1), GdMo 0.15 Ti 0.85 Ge, Gd{Zr, Hf, Nb} 0.3 Ti 0.7 Ge, GdTiGe 0.9 {C, Sn, Pb} 0.1 form the CeScSi-type phase only. GdTiGe 0.9 forms in the CeFeSi-type structure. The replacement of Gd, Ti, Ge in GdTiGe by R-, T-, X-atoms, that facilitate the X–X interaction, leads to the formation of the CeScSi-type structure (R=rare earths, T=transition metals, X=p-elements). The magnetic ordering temperature of Sm x Gd 1− x TiGe compounds decreases with increasing Sm content: Sm 0.05 Gd 0.95 TiGe ( T m =365 K), Sm 0.3 Gd 0.7 TiGe ( T m =333 K), Sm 0.8 Gd 0.2 TiGe ( T m =297 K). GdSc 0.3 Ti 0.7 Ge ( T C =344 K), GdHf 0.3 Ti 0.7 Ge ( T C =398 K), GdV 0.3 Ti 0.7 Ge ( T C =370 K) and GdMn 0.3 Ti 0.7 Ge ( T C =376 K) give rise to a ferromagnetic type of ordering, while the GdNb 0.3 Ti 0.7 Ge ( T N >412 K) exhibits an antiferromagnetic type of ordering. The magnetic ordering temperature of these compounds increase with increasing c cell parameters.

New Ternary Compounds R117Fe52Ge112 (R = Gd, Dy, Ho, Er, Tm) and Sm117Cr52Ge112 of the Tb117Fe52Ge112-Type Structure

Abstract The new compounds Gd117Fe52Ge112 [a = 2.8711(4) nm], Dy117Fe52Ge112 [a = 2.8398(5) nm], Ho117Fe52Ge112 [a = 2.8293)(5) nm], Er117Fe52Ge112 [a = 2.8108(7) nm], Tm117Fe52Ge112 [a = 2.802(2) nm], and Sm117Cr52Ge112 [a = 2.9098(6) nm] belonging to the Tb117Fe52Ge112-type structure (space group Fm3m) were prepared and characterized using powder X-ray diffraction.

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

Abstract 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 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 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(Ti 0.8 Zr 0.2 )Ge compound has the CeScSi-type structure (space group I 4/ mmm , a = 0.4060(1), c = 1.5400(3) nm).

Phase equilibria in the Tb-Ti-Ge system at 1070 K

Abstract Physico-chemical analysis techniques, including X-ray phase analysis, electron probe X-ray analysis, differential thermal analysis and metallographic analysis were employed in constructing the isothermal section of the Tb–Ti–Ge system at 1070 K. The formation of the following ternary intermetallic compounds were detected in the Tb–Ti–Ge system at 1070 K: TbTiGe (high-temperature modification of CeFeSi structure type, space group P 4/ nmm , a =0.4050(2) nm, c =0.7652(3) nm: low-temperature modification of La 2 Sb structure type, space group I 4/ mmm , a =0.4053(2) nm, c =1.5293(3) nm) and Tb 22...15 Ti 34...41 Ge 44 (Sm 5 Ge 4 structure type, space group Pnma , a =0.7019(1)...0.6889(5) nm, b =1.3457(2)...1.332(1) nm, c =0.7156(1)...0.755(1) nm). The TbGe 3.5 compound belongs to the ThGe 2 structure type (space group Cmmm , a =2.0738(4) nm, b =0.4043(1) nm, c =0.3914(1) nm). The high-temperature modification of the Th 2 Ge 3 compounds belongs to the ThSi 2 structure type (space group I 4 1 / amd , a =0.4061(2) nm, c =1.372(1) nm).

Crystallographic data of new ternary CeFeSi-type RTiGe (R=Y, Gd–Tm) compounds

Abstract Investigations made by powder X-ray diffraction on new ternary RTiGe compounds (R=Y, Gd–Tm) are reported. They crystallize in the well-known tetragonal CeFeSi-type structure (space group P4 / nmm ).

Analysis of the melting temperatures of RTX2 (CeNiSi2 structure) and RT2X2 (CeGa2Al2 structure) compounds [R=La,Ce,Sm,Er,Tm; T=Fe,Co,Ni; X=Si,Ge]

Abstract Physico-chemical analysis techniques, including X-ray phase analysis and differential thermal analysis were employed for the characterisation of compounds including their melting temperature. The melting temperature of 23 RT 2 X 2 compounds belonging to the CeGa 2 Al 2 structure has been measured. The melting temperature of 19 RTX 2 compounds belonging to the CeNiSi 2 structure has been measured (LaCoSi 2 , LaNiSi 2 , CeFeSi 2 , CeCoSi 2 , CeNiSi 2 , SmCoSi 2 , SmNiSi 2 , ErCoSi 2 , ErNiSi 2 , TmCoSi 2 , TmNiSi 2 , LaCoGe 2 , LaNiGe 2 , CeFeGe 2 , CeCoGe 2 , CeNiGe 2 , SmFeGe 2 , SmCoGe 2 , SmNiGe 2 ). It is established, that the new ternary compound SmCoSi 2 belongs to the CeNiSi 2 structure type (group Cmcm, a =0.4088(1) nm, b =1.6320(3) nm, c =0.4008(1) nm).

New ternary CeFeSi-type RTiGe (R=La, Ce, Sm) compounds

Investigations made using powder X-ray diffraction on new ternary RTiGe compounds (R=La, Ce, Sm) are reported. LaTiGe (a=0.4157(1) nm, c=0.8013(1) nm), CeTiGe (a=0.4128(1) nm, c=0.7908(1) nm) and SmTiGe (a=0.4077(3) nm, c=0.7751(1) nm) crystallize into the well-known tetragonal CeFeSi-type structure (space group P4/nmm).

Crystallographic data of the ternary compounds RRhGe (R=Gd-Tm) of the TiNiSi-type structure

Investigations made by powder X-ray diffraction on the new ternary TmRhGe compound and already known RRhGe compounds (R=Gd-Er) are reported. They crystallize in the well-known orthorombic TiNiSi-type structure (space group Pnma).

Phase equilibria in the Dy–Zr–Sb system at 1070 K

Abstract Phase equilibria in the system Dy–Zr–Sb were investigated by X-ray powder diffraction and the isothermal cross-section at 1070 K was obtained. The existence of the Dy 33–28 Zr 33–38 Sb 33 ternary compound (CeScSi-type structure, space group I4/mmm , a =0.4248(1)–0.4190(1) nm, c =1.6316(3)–1.6190(3) nm) has been confirmed.