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The title compounds and the solid solution (Ba0.85Sr0.15)2Ga5As5 are synthesized from molten metal fluxes and characterized by single crystal and powder XRD, resistance and Seebeck coefficient measurements, and TB-LMTO electronic structure calculations.

The title compounds are prepared from the elements using an excess of Ga as flux (Ba:Ga:As,P = 1:10:2, 960 °C, alumina crucible in a sealed silica tube, 20 h).

Reported are the syntheses, crystal structure determinations from single-crystal X-ray diffraction, and magnetic properties of two new ternary compounds, Eu{sub 11}Cd{sub 6}Sb{sub 12} and Eu{sub 11}Zn{sub 6}Sb{sub 12}. Both crystallize with the complex Sr{sub 11}Cd{sub 6}Sb{sub 12} structure type-monoclinic, space group C2/m (no. 12), Z=2, with unit cell parameters a=31.979(4) A, b=4.5981(5) A, c=12.3499(14) A, {beta}=109.675(1){sup o} for Eu{sub 11}Zn{sub 6}Sb{sub 12}, and a=32.507(2) A, b=4.7294(3) A, c=12.4158(8) A, {beta}=109.972(1){sup o} for Eu{sub 11}Cd{sub 6}Sb{sub 12}. Their crystal structures are best described as made up of polyanionic {sub {infinity}}{sup 1}[Zn{sub 6}Sb{sub 12}]{sup 22-} and {sub {infinity}}{sup 1}[Cd{sub 6}Sb{sub 12}]{sup 22-} ribbons of corner-shared ZnSb{sub 4} and CdSb{sub 4} tetrahedra and Eu{sup 2+} cations. A notable characteristic of these structures is the presence of Sb-Sb interactions, which exist between two tetrahedra from adjacent layers, giving rise to unique channels. Detailed structure analyses shows that similar bonding arrangements are seen in much simpler structure types, such as Ca{sub 3}AlAs{sub 3} and Ca{sub 5}Ga{sub 2}As{sub 6} and the structure can be rationalized as their intergrowth. Temperature-dependent magnetization measurements indicate that Eu{sub 11}Cd{sub 6}Sb{sub 12} orders anti-ferromagnetically below 7.5 K, while Eu{sub 11}Zn{sub 6}Sb{sub 12} does not order down to 5 K. Resistivity measurementsmore » confirm that Eu{sub 11}Cd{sub 6}Sb{sub 12} is poorly metallic, as expected for a Zintl phase. - Graphical abstract: The synthesis, structure determination from single-crystal X-ray diffraction and magnetic properties of Eu{sub 11}Zn{sub 6}Sb{sub 12} and Eu{sub 11}Cd{sub 6}Sb{sub 12} are reported. Both compounds crystallize with the monoclinic space group C2/m, and their structure can be viewed as built of ZnSb{sub 4} or CdSb{sub 4} tetrahedra, which are connected through common corners and exo-bonds.« less

Two new rare-earth metal containing Zintl phases, Eu 11 InSb 9 and Yb 11 InSb 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 Iba 2 (No. 45), Z =4 with unit cell parameters a =12.224(2) A, b =12.874(2) A, c =17.315(3) A for Eu 11 InSb 9 , and a =11.7886(11) A, b =12.4151(12) A, c =16.6743(15) A for Yb 11 InSb 9 , respectively (Ca 11 InSb 9 -type, Pearson's code o I 84). 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 11 InSb 9 and Yb 11 InSb 9 . The close relationships between these structures and those of the monoclinic α -Ca 21 Mn 4 Sb 18 and Ca 21 Mn 4 Bi 18 are also discussed.