Solid Solutions RE₁₆Rh_11–xZ_x (RE = La, Ce, Pr, Nd, Sm; Z = Ga, Zn, Cd, In, Sn, Sb, Pb, Bi) – Centrosymmetric n = 2 Variants of Parthé’s Homologous Series A_5n+6B_3n+5

Abstract

Several samples of solid solutions RE 16 Rh 11−x Z x (RE = La, Ce, Pr, Nd, Sm; Z = Ga, Zn, Cd, In, Sn, Sb, Pb, Bi) were synthesized by high-frequency melting of the elements in sealed tantalum ampoules. The samples were characterized by powder X-ray diffraction, and the structures of eight compounds were refined on the basis of single-crystal X-ray diffractometer data. The compounds crystallize with a centrosymmetric variant (space group P4/mbm) of the Ca 16 Sb 11 type (P42 1 m). The relation between both structure types is discussed on the basis of a group-subgroup scheme. Only for La 16 Rh 8 Sn 3 we observed full rhodium-tin ordering. The striking structural motif is a chain of face-sharing square prisms (filled with tin) and anti-prisms (filled with rhodium

Completing the Ba–As Compositional Space: Synthesis and Characterization of Three New Binary Zintl Arsenides, Ba3As4, Ba5As4, and Ba16As11

“…The A 16 Pn 11 (A = Ca, Sr, Ba, Eu, Yb; Pn = P, As, Sb, Bi) family of compounds comprises more than a dozen reported compositions [15,33,56], although the title Ba 16 As 11 phase is reported in this paper for the first time. Unlike the Ba 16 Sb 11 phase, which crystallizes in a disordered tetragonal structure of the Ca 16 Sb 11 -type and an ordered monoclinic coloring variant of the La 16 Rh 8 Sn 3 -type [57], we identified only the disordered tetragonal version of the Ba 16 As 11 phase, which could be partially due to the thermodynamic stability of the compositionally similar Ba 4 As 3 phase (Figure 1). We do not exclude the possibility that the ordered monoclinic phase exists and could be discovered in the future.…”