Synthesis, crystal structures, magnetic and electric transport properties of Eu 11InSb 9 and Yb 11InSb 9

Abstract

Two new rare-earth metal containing Zintl phases, Eu 11InSb 9 and Yb 11InSb 9 have been synthesized by reactions of the corresponding elements in molten In metal to serve as a self-flux. Their crystal structures have been determined by single crystal X-ray diffraction—both compounds are isostructural and crystallize in the orthorhombic space group Iba2 (No. 45), Z=4 with unit cell parameters a=12.224(2) Å, b=12.874(2) Å, c=17.315(3) Å for Eu 11InSb 9, and a=11.7886(11) Å, b=12.4151(12) Å, c=16.6743(15) Å for Yb 11InSb 9, respectively (Ca 11InSb 9-type, Pearson's code o I84). Both structures can be rationalized using the classic Zintl rules, and are best described in terms of discrete In-centered tetrahedra of Sb, [InSb 4] 9−, isolated Sb dimers, [Sb 2] 4−, and isolated Sb anions, Sb 3−. These anionic species are separated by Eu 2+ and Yb 2+ cations, which occupy the empty space between them and counterbalance the formal charges. Temperature-dependent magnetic susceptibility and resistivity measurements corroborate such analysis and indicate divalent Eu and Yb, as well as poorly metallic behavior for both Eu 11InSb 9 and Yb 11InSb 9. The close relationships between these structures and those of the monoclinic α-Ca 21Mn 4Sb 18 and Ca 21Mn 4Bi 18 are also discussed.