O. Sologub

On the crystal structure and magnetic properties of the ternary rare earth compounds RETSb2 with RE≡rare earth and T≡Ni, Pd, Cu and Au

Abstract Novel compounds RETSb 2 have been prepared and characterized for T  Cu (RE  rare earth from La to Lu), Ni (RE  La to Ho), Pd (RE  La to Tb) and Au (RE  La to Sm). From X-ray powder diffraction analyses all compounds were found to crystallize as the ZrCuSi 2 type. Magnetic susceptibilities were generally measured in the temperature range from 4 to 100 K. YCuSb 2 and LaTSb z are temperature-independent paramagnets. RETSb 2 compounds are found to order antiferromagnetically below T  20 K. PrPdSb 2 and TbPdSb 2 undergo metamagnetic transitions, whereas PrCuSb 2 and ErCuSb 2 are simple ferromagnets. The Sm-containing compounds are typical Van Vleck paramagnets owing to the closely spaced multiplets.

Formation, crystal chemistry and magnetism of compounds RE2TGe6, RE rare earth, T Pd, Pt, Cu, Ag and Au

Abstract Novel ternary compounds RE 2 TGe 6 (RE  Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb; T  Pd, Pt, Ag, Au) were synthesized by argon arc melting followed by a heat treatment at 600 or 800 °C for 150 h. From X-ray powder analysis all compounds were found to be isotypic with structure type Ce 2 CuGe 6 . Magnetic susceptibilities were measured for RE 2 CuGe 6 (RE  Ce, Pr, Nd, Sm) and Ce 2 PdGe 6 . All compounds exhibit antiferromagnetic ordering below 20 K. The paramagnetic effective moments agree with the values for tripositive RE ion moments. The Sm containing sample reveals typical Van Vleck type paramagnetism above the Neel point.

CeNiGe and NdNiGe phase diagrams: systematics of rare earth-nickel-germanium compounds

Abstract The ternary systems Ce(Nd)NiGe have been investigated and phase relations have been determined at 870 K, where respectively 20 and nine compounds were observed. A critical assessment on the interaction of rare earth elements with nickel and germanium has been made.

Ternary compounds REMSb2, RE≡La, Ce, Pr, Nd, Sm, Gd; M≡Mn, Zn, Cd; compound formation, crystal structure and magnetism

Abstract Ternary compounds REMnSb 2 (RE  La, Ce, Pr, Nd, Sm), REZnSb 2 (RE  La, Ce, Pr, Nd, Sm, Gd) and RECdSb 2 (RE  La, Ce, Pr, Nd, Sm) were synthesized. From room temperature X-ray powder diffractometry all compounds were found to crystallize with the ZrCuSi 2 -type structure. The magnetic behavior of REMnSb 2 compounds is characterized by the onset of ferromagnetism of the Mn sublattice in the temperature range between 100 and 520 K. Ordering of the rare-earth sublattice below 50 K is indicated for samples containing Ce, Pr and Nd. CeZnSb 2 remains paramagnetic in the temperature range investigated (4.2–550 K).

Isothermal section at 750°C of the U–Fe–Sn ternary system

A systematic investigation of the isothermal section at 850 8C of the U–Fe–Al ternary system was done by means of scanning electron microprobe analysis and X-ray powder diffraction. At this temperature the phase diagram is characterized by the formation of seven ternary phases and two extended ranges of solubility. Three compounds form with non-existing, or negligible, homogeneity domains: UFe2Al10 (YbFe2Al10-type, aZ8.9146(3) A u , bZ10.1986(3) A u , cZ9.0114(3) A u ); U2Fe3.6Al13.4 (Th2Ni17-type, aZ8.8589(2) A u , cZ8.9824(2) A u ); and U2Fe12Al5 (Th2Ni17-type, aZ8.5631(7) A u , cZ8.438(1) A u ). Four other phases exhibit more or less extended homogeneity ranges: UFe1CxAl1Kx (MgZn2-type); U3Fe4CxAl12Kx (Gd3Ru4Al12-type); U2Fe17KxAlx (Th2Zn17-type); and UFexAl12Kx (ThMn12-type). The two extended solid solutions, UAl2KxFex and UFe2KxAlx, are formed from the UAl2 and UFe2 binary compounds, respectively, both crystallizing in the cubic MgCu2-type structure. q 2004 Elsevier Ltd. All rights reserved.

On the cerium valence in ternary compounds CeMSb2 and CeM'Bi2 ; M=Mn,Fe,Co,Ni,Cu,Zn,Pd,Ag,Au and M'= Ni,Cu,Zn,Ag

Abstract Ternary compounds CeMSb2 and CeM′Bi2 have been synthesized by arc melting followed by a heat treatment at 400, 600 or 800°C for 300 h. Bismuth-containing compounds have been observed for the first time. From X-ray powder diffractometry all compounds were found to be isotypic with ZrCuSi2-type. In CeMn0.9Sb2, the manganese sublattice orders ferromagnetically at T∼130 K, and the cerium sublattice shows additional ordering at ∼20 K. CeMSb2 (M=Fe, Ni, Pd, Cu, Ag, Au, Zn) are antiferromagnets below T=12 K. In the paramagnetic regime, the cerium atom adopts the Ce- 2 F 5 2 tripositive groundstate. CeCu0.9Bi2 is also an antiferromagnet, whereas for Ce(Ag,Zn)Bi2 no magnetic order was encountered. X-Ray absorption spectroscopy shows that Ce in all compounds CeMSb2 and CeMBi2 is in the trivalent, or nearly trivalent, state.

CeFeGe, NdFeGe and HoFeGe phase diagrams: systematics of rare earth-iron-germanium compounds

Abstract The ternary systems Ce(Nd,Ho)FeGe have been investigated and phase relations have been determined at 870 K, where respectively seven, eight and six compounds were observed. A critical assessment on the interaction of rare earth elements with iron and germanium has been made.

Interaction behaviour of neodymium and silver with elements of Group IVa at 600°C

Abstract Phase equilibria have been established in the ternary NdAgGe(Sn) systems over the whole concentration region and in the ternary NdAgPb system within 0–33 at.% Nd for an isothermal section at 600°C. Seven ternary intermetallic compounds of silver and neodymium have been observed: NdAg 2 Ge 2 , Nd 2 AgGe 6 , NdAg 1.1 Ge 0.9 , Nd 6 Ag 8 (Ge)Sn 8 and NdAgSn(Pb).

Crystal structure of novel Ni-Zn borides: first observation of a boron-metal nested cage unit: B20Ni6.

The crystal structures of three ternary Ni-Zn borides have been elucidated by means of X-ray single-crystal diffraction (XSC) and X-ray powder diffraction techniques (XPD) in combination with electron microprobe analyses (EMPA) defining the Ni/Zn ratio. Ni(21)Zn(2)B(24) crystallizes in a unique structure type (space group I4/mmm; a = 0.72103(1) nm and c = 1.42842(5) nm; R(F)(2) = 0.017), which contains characteristic isolated cages of B(20) units composed of two corrugated octogonal boron rings, which are linked at four positions via boron atoms. The B(20) units appear to have eight-membered rings on all six faces like the faces of a cube. Each face is centered by a nickel atom. The six nickel atoms are arranged in the form of an octahedron nested within the B(20) unit. Such a boron aggregation is unique and has never been encountered before in metal-boron chemistry. The crystal structure of Ni(12)ZnB(8-x) (x = 0.43; space group Cmca, a = 1.05270(2) nm, b = 1.45236(3) nm, c = 1.45537(3) nm; R(F)(2) = 0.028) adopts the structure type of Ni(12)AlB(8) with finite zigzag chains of five boron atoms. The compound Ni(3)ZnB(2) crystallizes in a unique structure type (space group C2/m, a = 0.95101(4) nm, b = 0.28921(4) nm, c = 0.84366(3) nm, β = 101.097(3)°, and R(F)(2) = 0.020) characterized by B(4) zigzag chain fragments with B-B bond lengths of 0.183-0.185 nm. The Ni(3)ZnB(2) structure is related to the Dy(3)Ni(2) type.

Magnetic behavior of holmium-platinum group metal-germanium ternary alloys

Abstract A series of selected ternary holmium germanides with platinum group metals was synthesized and characterized by room temperature X-ray powder diffraction: Ho3(Ru,Os)4Ge13 (Y3Co4Ge13-type). Ho2(Ru,Os)Ge2 (Sc2CoSi2-type), Ho(Ru,Pd1)2Ge2 (CeGa2Al2-type), Ho(Ru,Ir,Pt)Ge (TiNiSi-type), HoAuGe (LiGaGe-type), Ho2Ru3Ge5 (U2Co3Si5-type), Ho3Ru2Ge3 (Hf3Ni2Si3-type), Ho5Os4Ge10 (Sc5Co4Si10-type). Ho3Pd4Ge4 (Gd3Cu4Ge4-type) and HoPdGe (CeCu2-type). Magnetic measurements of the HoMGe compounds revealed that Ho3(Ru,Os)4Ge13, Ho5Os4Ge10, HoPtGe and HoPt2Ge2 are paramagnets above T = 4.5 K. Ho2Ru3Ge5, HoRuGe, Ho3Pd4Ge4 and HoAuGe are ferromagnets. HoRu2Ge2 and HoPd2Ge2 are metamagnets. Ho2(Ru,Os)Ge2, Ho3Ru2Ge3, HoIrGe as well as HoPdGe undergo an antiferromagnetic ordering at higher temperatures, whereas a spin reorientation to a ferromagnetic spin alignment occurs at lower temperatures. No superconductivity was observed down to around 2 K.