A. Palenzona

Zinc-rich phases of the rare-earth-zinc alloys

Abstract The crystal structures of the intermetallic compounds in the composition range 89–100% at.% zinc have been investigated for the rare earth (RE)-Zn systems. Five crystal structure types have been found, corresponding to the formulae: REZn13, REZn12, REZn11 and RE2Zn17. The existence of the different structures appears to be closely related to the dimensions of the RE atoms. Eu and Yb behave as divalent elements.

The ytterbium-cadmium system

Abstract A phase diagram is presented for the ytterbium-cadmium system on the basis of differential thermal, microscopic and X-ray analyses. Six intermetallic compounds were found, all of which are in the cadmium-rich part of the system. Four of these, YbCd, YbCd2, YbCd3.6 and YbCd5.7, melt congruently at 796 °, 703 °, 655 ° and 636 ° C, respectively; the other two, Yb3Cd8 and YbCd6, form peritectically at 654 ° and 614 ° C, respectively. Eutectic points occur at 22.3 at. % Cd and 467 ° C; 61.2 at. % Cd and 680 ° C; 75.0 at.% Cd and 648 °C; 82.5 at.% Cd and 627 °C and at about 99.0 at.% Cd and 317 °C. YbCd2 shows a high-temperature modification with a transformation temperature of 695 °C. Magnetic susceptibility measurements indicate the divalency of ytterbium over all alloy compositions.

Magnetic susceptibility and expansion coefficient of the intermetallic compounds YbAl2 and YbAl3

Abstract Magnetic susceptibilities and lattice constants of the intermetallic compounds YbAl2 and YbAl3 have been measured in the temperature range −180 °C to 550 °C. YbAl3 shows a behavior closely resembling that of an isomorphous trivalent REAl3 compound but YbAl2 appears to contain a percentage of YbIII which increases with temperature.

The crystal structure and lattice constants of R.E.2In and some R.E.5In3 compounds

Abstract A new series of isomorphous compounds of composition R.E. 2 In has been prepared by alloying rare earths with indium. The structure of these compounds corresponds to that of the Ni 2 In type and is observed for all trivalent rare earths from La to Lu with the exception of Eu and Yb which do not form this phase. For Ho, Er, Tm and Lu the phase R.E. 5 In 3 was additionally found; this phase has the Mn 5 Si 3 type of structure which is closely related to that of Ni 2 In.

The crystal structure and lattice constants of RE3Pd4, Y3Pd4 and Th3Pd4 compounds

Abstract Alloys of the rare earths (R.E.), yttrium, thorium, hafnium and uranium with palladium of the M3Pd4 composition have been studied. For this composition, with the exception of Eu, U and Hf, single phases are formed, crystallizing with the Pu3Pd4-type of structure. The stability of these compounds appears to be restricted to the radius ratio ( R M R Pd ) range between 1.20 and 1.37.

The ytterbium-aluminum system

Abstract The ytterbium-aluminum system has been investigated by differential thermal, microscopic and X-ray analysis. Aluminum lowers the transformation temperature of pure ytterbium from 740 °C to 712 °C by an inverse peritectic reaction. A eutectic reaction occurs at 22.5 at.% Al and 675 °C between ytterbium and the compound YbAl2 which melts congruently at 1360 °C. Another eutectic occurs at 96.0 at.% Al between aluminum and YbAl3 which forms peritectically at 980 °C. The structures and the lattice constant values of these two phases, already known, have been confirmed. No other intermetallic compound has been found in this system.

The ytterbium-nickel system

Abstract The binary system ytterbium-nickel has been investigated by X-ray diffraction, differential thermoanalysis and metallography and the corresponding constitutional diagram has been derived. At least five intermetallic compounds are present in this system: YbNi, YbNi2, YbNi3, YbNi5 and Yb2Ni17. Crystallographic data already known from preceding work have been confirmed. From lattice constant values of these compounds and from preliminary measurements of their magnetic properties it appears that ytterbium can form intermetallic compounds with nickel in the trivalent state but in the divalent state gives rise to an extended immiscibility gap in the solid as well as in the liquid phase.

Crystal structure of the ternary R.E.Mo2Al4 phases (R.E. = Gd, Er, Yb)

Abstract The crystal structure of the ternary phase YbMo 2 Al 4 , space group I 4 mmm ,a = 6.717 and c= 5.312 A , Z = 2 , has been determined. GdMo 2 Al 4 and ErMo 2 Al 4 have been found to be isomorphous. The close structural relationship between these phases and the ternary MT 4 Al 8 ( M = Ce , Y ; T = Cr , Mn , Fe , Cu ), crystallizing in a superstructure of the ThMn 12 type, is pointed out.

Crystal structure of the so-called R.E.5Pd2 compounds

The crystal structure of Dy5Pd2 has been determined using single-crystal photographic data. The compound is cubic, a = 13.529 A, space group Fd3m, and the elementary cell contains 68 Dy and 28 Pd atoms with three crystallographic sets partially filled. The R.E.5Pd2 compounds, where R.E. = Tb, Ho, Er, Tm, LuandY, are isotypic with Dy5Pd2, and their lattice constant values are reported.