New ternary phases from the R–Au–Ga systems (R = Gd-Tm)

Abstract

Twenty rare-earth gold gallides, RAu 3 Ga 7 (ScRh 3 Si 7-type, space group R-3c, Z = 6, hR66), RAu 3±x Ga 3±x (YCd 6-type, space group Im-3, Z = 24, cI68), RAu 1+x Ga 2-x (MgCuAl 2-type, space group Cmcm, Z = 4, oS16) (R = Gd-Tm) and R 14 Au 34+x Ga 17-x (Gd 14 Ag 51-type, space group P6/m, Z = 1, hP65) (R = Er, Tm), were synthesized by arc-melting, followed by annealing at 400-600ºC. Six phases RAu 1+x Ga 3-x (BaAl 4-type, space group I4/mmm, Z = 2, tI10) (R = Gd) and R 3 Au 3+x Ga 8-x (La 3 Al 11-type, space group Immm, Z = 2, oI26) (R = Tb-Tm) were prepared by the flux method. Their crystal structures were studied by X-ray powder or single crystal diffraction. Structural peculiarities, coordination and interaction of the atoms in the investigated compounds are briefly discussed. Rare-earth intermetallics / Ternary gallides / Crystal growth / Single crystal / X-ray diffraction / Crystal structure Experimental details Starting materials for the synthesis of the R-Au-Ga alloys were rare-earth ingots (R > 99.9 wt.%), gold plate (99.99 wt.%) and gallium pieces (99.999 wt.%). Samples with a total weight of 300 mg were prepared by arc-melting buttons in a water-cooled copper crucible with a tungsten electrode under a purified argon atmosphere, using Ti/Zr as a getter. The products were turned over and re-melted at least three times in order to ensure homogeneity. Fragments of

From 3D to 2D: Structural, Spectroscopic and Theoretical Investigations of the Dimensionality Reduction in the [PtAl2]δ− Polyanions of the Isotypic MPtAl2 Series (M=Ca–Ba, Eu)

“…Due to the differences in the respective bonding situations, however, these compounds have to be considered isopointal rather than isotypic. For these 1‐1‐2 representatives the gallides ( MT Ga 2 ; M =Ca, Sc, Y, Gd–Lu; T =Ni, Pd, Pt, Au), the indides ( MT In 2 ; M =Na, Ca–Ba, Y, La–Nd, Eu–Dy, Yb; T =Ru, Rh, Ir, Ni, Pd, Pt, Cu, Au and Eu 1− x Sr x PtIn 2 ), the thallides ( MT Tl 2 ; M =Sr, Eu; T =Pd, Pt), the silicide ScPt 2 Si, the stannides MT Sn 2 ( M =Ca, Eu, Yb; T =Rh, Ir, Pd) and the phosphide PdNi 2 P have been reported. For aluminum finally, the representatives MT Al 2 ( M =Sc, Y, La–Nd, Sm, Gd–Lu; T =Co, Ni, Cu, Pd, Pt) have been prepared.…”

CeIr3Ge7: A local moment antiferromagnetic metal with extremely low ordering temperature

“…CeIr 3 Ge 7 crystallizes in the R 3c rhombohedral ScRh 3 Si 7 structure type 25,26 . The very few 1-3-7 compounds known so far are RAu 3 Ga 7 (R = Gd-Yb) 27,28 , non-magnetic RAu 3 Al 7 (R = Ce-Sm, Gd-Lu) 29 , and magnetic Eu(Rh,Ir) 3 Ge 7 30 . Recently we discovered the first magnetic Ce and Yb 1-3-7 compounds.…”

R14(Au, M)51 (R = Y, La–Nd, Sm–Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In, Sn, Sb, Bi): Stability Ranges and Site Preference in the Gd14Ag51 Structure Type

“…Representatives of R 14 (Au, M) 51 compounds comprise R = Y, La−Nd, Sm−Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In, Sn, Sb, Bi, including Yb 14 (Au, Sn) 51 , and Lu 14 (Au, Ga) 51 which are ternary representatives with no reported binary phase, as well as a replication of the recently reported Er 14 (Au, Ga) 51 ternary representative for comparison. 48 The details of the crystallographic investigation along with the positional data for three example compounds (Gd 14 (Au, Sb) 51 , Lu 14 (Au, Ga) 51 , and La 14 (Au, Bi) 51 ) are summarized in Tables 1 and 2. (See Appendix for CCDC numbers of all samples.)…”

“…The literature appears inconsistent with its allowance of mixing at this disordered atomic site. In the work previously mentioned by Verbovytskyy, mixing was determined by powder X-ray diffraction to exist at all seven sites, including the disordered Au7, 48 while in recent works by Belgacem et al and Lin and Corbett mixing at this site is discounted. 50 A disordered Er site in the Er 14 Cu 51-x Ga x (5.5 ≤ x ≤ 11.0) compound reported by Belgacem et al that is near the Au7 site would have likely shown preferential occupancy if the Au7 site showed mixing.…”

“…46,47 R-Au-M (R = rare earth, M = groups 13−15) representatives have only recently been reported solely for Ga and Sn. 48,49 Though studied more recently in detail, a consensus on how site mixing and coloring occur within these ternary compounds does not appear to exist, 48,50,51 and the numerous R-Au-M compounds studied within this work shed more light on this phenomenon.…”