G. Zanicchi

Some phases in ternary alloys of thorium and uranium with the Al4Ba-ThCu2SI2-type structure

Abstract The geometrical characteristics of Al4Ba-ThCu2Si2-type phases are discussed briefly in terms of reduced cell parameters ( a R A ) . Special reference is made to those ternary compounds of Th and U which have this type of structure; the data already known from the literature and those now obtained for 21 new compounds are considered.

The isothermal section at 400 °C of the Ce-Cu-Sn ternary system

Ternary Ce-Cu-Sn alloys have been studied by X-ray diffraction (XRD), optical and scanning electron microscopy and electron probe microanalysis (EPMA). Phase equilibria have been established in the isothermal section at 400 °C: 4 ternary compounds have been confirmed, 4 new compounds determined and 34 tie triangles identified.

Yb–Cu–Sn system: the isothermal section at 400°C

Abstract Phase equilibria in the ternary system Yb–Cu–Sn have been studied by X-ray powder diffraction analysis, optical and scanning electron microscopy and electron probe microanalysis. The isothermal section has been analysed at 400°C: 10 ternary compounds have been confirmed or determined and the corresponding tie-triangles defined. The ternary compounds are YbCu4.4Sn0.6, Yb3Cu13Cu4, Yb14Cu60Sn26, YbCu9Sn4, Yb30Cu39Sn31, YbCuSn, Yb5CuSn3, Yb23Cu42Sn35, Yb3Cu4Sn4, Yb36Cu18Sn46.

DETERMINATION OF HEATS OF FORMATION OF PRASEODYMIUM ANTIMONIDES

A systematic investigation of the heats of formation in the Pr-Sb system has been performed using a small-furnace, isoperibolic calorimeter. The compositions and the equilibrium states of the samples have been checked by metallographic and X-ray analyses. The following values have been found for the various compounds (kJ/g atom±2): Pr2Sb:-99; Pr5Sb3:-112; Pr4Sb3:-120; PrSb:-126; PrSb2:-97.The data available (both the results obtained in this work and those already known) are discussed briefly and related to the possible shape of the phase diagram.ZusammenfassungEs wurde eine systematische Untersuchung der Bildungswärmen im Pr/Sb-System unter Verwendung eines Kleinofen-Isoperibolkalorimeters ausgeführt. Die Zusammensetzung und der Gleichgewichtszustand der Proben wurden durch metallographische und röntgenographische Analyse ermittelt. Für die einzelnen Verbindungen wurden folgende Werte (kJ·mol−1 ±2.0) gefunden: Pr2Sb:-99; Pr5Sb3:-112; Pr4Sb3:-120;PrSb:-126; PrSb2:-97. Die als Ergebnis dieser Arbeit erhaltenen und aus der Literatur bereits bekannte Daten werden kurz diskutiert und mit einem möglichen Phasendiagramm in Verbindung gebracht.РезюмеПроведено системати ческое исследование теплот образования в системе Рг-Sb, используя изоперибо льный калориметр с ма лой печкой. Состав и равновесное состояние образцов проверены м еталлографическим и рентгеноструктурны м анализами. Для соеди нений различного состава б ыли определены следу ющие величины теплот обра зования (приведены в кдж(г-атом)−1 ±2.0): Pr2Sb-99; Pr5Sb3-112; PrSb3-120; PrSb-126; PrSb2-97. Полученные данные кр атко обсуждены наряд у с известными в литерат уре и связаны с возмож ной формой фазовой диагр аммы.

Contribution to the investigation of ternary Pr–Cu–Sn alloys

Abstract With regard to the work in progress on the ternary R–Cu–Sn alloys formed by the rare earths, the data obtained in a partial revision of the Pr–Cu–Sn system are reported. The isothermal section at 400°C has been studied in the composition range: PrCu 5 –Pr–Pr 5 Sn 3 –PrCuSn. The general characteristics of the systems formed by the light R are compared and discussed.

The isothermal section at 400°C of the Yb–Ag–Sn ternary system

Abstract The Yb–Ag–Sn isothermal section at 400°C has been investigated by means of X-ray diffraction, optical and scanning electron microscopy and electron probe microanalysis. The following ternary compounds have been identified or confirmed: τ1∼Yb25Ag50Sn25, τ2∼Yb50Ag25Sn25 to Yb46Ag24Sn30, τ3 ∼Yb19Ag50Sn31, τ4∼YbAgSn. Moreover a phase τx∼Yb50Ag35Sn15, not definitively confirmed, has been observed in a few samples. A subdivision of the composition triangle into tie-triangles has been obtained. The general characteristics of the section have been discussed in comparison with those of other R–Ag–Sn systems.

A contribution to the crystallochemistry of ternary 1:1:1 and 1:1:2 rare earth intermetallic phases with Pb and Pd

Abstract The ternary alloys of the rare earths with lead and palladium were studied for the stoichiometric ratios 1:1:1 and 1:1:2 with respect to the structure of these alloys and their existence field. RPbPd (R = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb) compounds have a hexagonal structure, hP9 Fe 2 P type, while RPbPd 2 (R = Pr, Sm, Gd, Tb, Dy, Ho, Er, Yb) alloys have the cubic AlCu 2 Mn-type structure (cF16, BiF 3 superstructure).

Correlations between Structural and Electronic Properties in the Filled Skutterudite Smy(FexNi1–x)4Sb12

A structural study of the filled skutterudite Smy(FexNi1-x)4Sb12 was performed by means of X-ray powder diffraction and μ-Raman spectroscopy with the aim to unveil the correlations between structural and electronic properties of this material and to favor the improvement of its thermoelectric performance. Samples were prepared by direct reaction of the elements at 1223 K, followed by quenching and subsequent sintering at 873 K; microstructure and composition of the obtained products were determined by SEM-EDS. The position of the boundary separating regions that obey hole- and electron-based conduction mechanisms was found by X-ray diffraction at x ≈ 0.63 and y ≈ 0.30, confirmed by measurements of room-temperature Seebeck coefficient, and discussed on the basis of crystallographic data. The presence of a discontinuity is observed in several structural and spectroscopic parameters at the p/n crossover; it is interpreted as associated with the change in the conduction mechanism. The role of the rare earth filling fraction in driving the structural response of the material is investigated too. The advantage of using X-ray diffraction and μ-Raman spectroscopy as aids in the study of electronic properties of this material is highlighted, as well as the complementarity of the two techniques.

The isothermal section at 400 °C of the phase diagram CeCuSn in the region between CeCu2Ce3Sn7Ce

Abstract The isothermal section at 400 °C of the phase diagram CeCuSn in the region between CeCu 2 Ce 3 Sn 7 -Ce was investigated by X-ray diffraction, optical microscopy and electron probe microanalysis. In this region of the isothermal section, five ternary compounds have been confirmed or determined and 14 tie triangles identified.

NdCuSn system: identification of ternary phases and partial determination of the isothermal section at 400°C

Abstract The partial isothermal section at 400°C of the phase diagram NdCuSn was investigated by X-ray diffraction, optical and scanning electron microscopy and electron probe microanalysis. In the studied region of the isothermal section, nine ternary compounds have been confirmed or determined and 14 tie-triangles identified.