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A Cu 12 Sb 3.6 Bi 0.4 S 10 Se 3 glass was prepared by melt spinning and crystallized by heat treatments at selected temperatures, the total preparation procedure taking less than one day. The sample characterization by powder X-ray diffraction, scanning and transmission electron microscopy complemented with EDS indicate the formation of compact materials, with a tetrahedrite relative weight fraction higher than 90% when treated at temperatures close to the crystallization peaks (∼200° C). Selenium enters the tetrahedrite structure, while bismuth precipitates in submicron and nanosized spherical shape phases depleted in copper and enriched in antimony, sulfur and selenium (when compared with the matrix composition). The characterization of electrical transport properties (electrical resistivity and Seebeck coefficient) indicate a behavior similar to that obtained by other methods on Cu 12 Sb 4 S 13 , with a maximum power factor of ∼400 μW/K 2 m at room temperature.

We report here our results showing the occurrence of magnetic order in the intermetallic compounds NdCu2Sn2 and PrCu2Sn2. For comparison, non-magnetic analogue, LaCu2Sn2, was also prepared. X-ray diffraction (XRD) result confirms that all the three compounds form in the tetragonal CaBe2Ge2-type structure. A cusp is observed at not, vert, similar3 K in the magnetic susceptibility of NdCu2Sn2 and PrCu2Sn2, which arises due to the antiferromagnetic ordering of the magnetic moments in these two compounds. The bulk nature of magnetic order in both the compounds is confirmed from the observation of peaks in the heat capacity at the magnetic transition temperature. X-ray absorption measurements at the LIII edge show that Pr ions are in the trivalent state in PrCu2Sn2., © Elsevier

The compounds Yb(Cu,Ag,Au)Sb were synthesized via high frequency melting of the elements in a closed Ta-crucible. The crystal structure of the novel phases was determined from X-ray powder Rietveld refinements. Dependent on the ratio R Yb / R (Cu,Ag,Au) different structure types were encountered: YbCuSb (ordered Ni 2 In-type, R F =0.036), YbAgSb (TiNiSi-type, R F =0.054) and YbAuSb (LiGaGe-type, R F =0.038). The results of the magnetic measurements revealed that the compounds YbCuSb and YbAgSb are temperature independent Pauli-type paramagnets whilst a small magnetic moment (≈1β B ) was observed for YbAuSb. In good agreement, X-ray absorption spectroscopy (at 10 and 300 K) confirmed for all three compounds dipositive Yb temperature independent valencies of 2.06 (M = Ag), 2.08 (Cu) and 2.14 (Au); possibly owing to small amounts (less than upo to ≈ 4%) of Yb 3+ grain boundary effects.

Compounds YbTGa2 with TNi, Pd, Pt and alloys YbPd1−xAgxGa2 have been synthesized by argon high frequency melting from metal ingots in tantalum crucibles followed by homogenization annealing at 600 or 400°C respectively. From X-ray powder diffraction data. Yb{Ni.Pd,Pt}Ga2 was found to be isotypic with MgCuAl2-type, with a small solid solubility for Ag in YbPdGa2 (0 ⩽ x ⩽ 0 2). At 600°C the solid solubility of Pd in βYbAgGa2 (βYbAgGa2-type) was 0.7 ⩽ x ⩽ 1.0. The YbTGa2 (T = Ni, Pd, Pt) compounds are paramagnets, where the ytterbium adopts the 2 F 7 2 ground state. The magnetic results of the solid solution YbPd1−xAgxGa2 are characterized by an intermediate or mixed valence behavior of the ytterbium atom (Yb2+a Yb3+), whereas XAS measurements establish a mixed valence system.

We report here the changes in the europium valence in Eu 1−x Ln x Pd 2 Si 2 (LnLa, Y, Yb; 0 x - III absorption edge spectroscopy. On the basis of the simple unit-cell volume considerations and from the fact that the unit-cell volume of EuPd 2 Si 2 is intermediate between that of LaPd 2 Si 2 and Y(Yb)Pd 2 Si 2 , one expects the europium valence to vary in both cases as a function of x , with the variation taking place in the opposite directions in the two pseudoternaries Eu 1−x La x Pd 2 Si 2 and Eu 1−x Y(Yb) x Pd 2 Si 2 . However, we find that the valence does not change as a consequence of lanthanum substitution and increases with the addition of yttrium (ytterbium). These results are discussed in terms of the local environment of europium atoms in these systems.