On the ternary RE Mg1–Al2 (RE = Gd – Tm), RE3Ag5±Mg11±, REAg4+Mg2–, RE4Ag10.3Mg12 and RE4Ag10+Mg3– (RE = Ce – Nd, Sm) phases

Abstract

Twenty ternary magnesium based phases (fourteen of them for the first time) have been prepared by reacting the elements at high temperature. Their crystal structures were studied by means of powder X-ray diffraction. RE x Mg 1-x Al 2 (RE = Gd, Tb, Dy, Ho, Er, Yb and Tm) crystallize with the MgNi 2 structure type, RE 3 Ag 5±x Mg 11±x (RE = Ce, Pr, Nd and Sm) with the Gd 3 Ru 4 Al 12 structure type, REAg 4+x Mg 2-x (RE = Ce and Pr) with the YbMo 2 Al 4 structure type, RE 4 Ag 10.3 Mg 12 (RE = Ce, Pr and Nd) with the La 4 Ag 10.3 Mg 12 structure type and RE 4 Ag 10+x Mg 3-x (RE = Ce, Pr, Nd and Sm) with the Ca 4 Au 10 In 3 structure type. Description of the structures in terms of interatomic relations and coordination are briefly discussed.

From the Ternary Eu(Au/In)2 and EuAu4(Au/In)2 with Remarkable Au/In Distributions to a New Structure Type: The Gold-Rich Eu5Au16(Au/In)6 Structure

“…139) 24 63) and formally resembles a one-dimensional (or linear) intergrowth of "EuAu 4+x In 2−x "-related (the term "EuAu 4+x In 2−x " refers to segments showing the similar structural features as observed for EuAu 4+x In 2−x (x = 0.8 −1.0)) and EuAu 2 -related (two-dimensional) slabs. Strictly speaking, evaluation of a direct structural relationship between EuAu 4.75 In 1.25 (2) and Eu 5 Au 17.29 In 4.71 (3) is set hurdles by the dissimilar occupancies of the disordered positions in II and III; however, a topological analysis of all structures with an approximation of full indium occupancies for the mixed Au/ In 4d and 8f positions in II and III, respectively, guides to a structural relationship akin to a linear inhomogeneous intergrowth from EuAu 2 and II to III.…”

“…Such polymorphism could not be encountered for the structures of EuAu 4+ x In 2– x ( x = 0.8–1.0), as close inspection of the extinction conditions for the X-ray intensity data sets as well as E 2 -1 statistics for these structures clearly pointed to the space group I 4/ mmm . It is worth noting that mixed occupancies occur on the 4 d rather than the 8 h sites in the crystal structures of the YbAl 4 Mo 2 -type ternary phases with substitutional homogeneity ranges; ,,− however, conclusive hints accounting for this preference have not been provided. Electronic structure calculations on different “EuAu 5 In” models will provide insight into the origin for this site preference (see Coloring and Electronic Structure).…”

Crystal structure of the ternary compound Sc3Cu7.5Al7.5

“…The site 6g, which is also occupied by minority atoms in Gd 3 Ru 4 Al 12 , contains the major part of the remaining Ag atoms, but statistical Ag/Mg occupations were refined for three sites: 12k, 6h, 6g. Mixed occupation on all the sites occupied by the smaller atoms (Mg and Ag), except the site in 2a, was refined for Ce 3 Ag 4.7 Mg 11.3 [27], but the refinement clearly showed preferential occupation of site 6g by Ag atoms. Ordered structures were observed for the isotypic silicides R 3 Ni 12 Si 4 (R = Ho, Er, Tm) [28], where the positions of the p-and d-elements are interchanged with respect to the structure of Gd 3 Ru 4 Al 12 .…”

Eu1 − xSrxAu4Cd2: a ferromagnetic solid solution with adjustable Curie temperature

“…The prototype YbAl 4 Mo 2 [11] has more than 40 isotypic representatives [12]. The crystal chemistry and chemical bonding of YbAl 4 Mo 2 type phases has repeatedly been discussed in the original contributions [13][14][15][16][17][18][19][20]. Herein we therefore concentrate only on the structural peculiarities of the solid solution Eu 1 − x Sr x Au 4 Cd 2 .…”