Synthesis, Structure, and Bonding of the Zintl Phase Ba₃Cd₂Sb₄

Abstract

Reported are the synthesis of the new ternary compound Ba3Cd2Sb4 and its structure determination by single-crystal X-ray diffraction. Ba3Cd2Sb4 crystallizes with the monoclinic space group C2/m (No. 12); unit cell parameters a = 17.835(2) A, b = 4.8675(5) A, c = 7.6837(7) A, and beta = 112.214(1) degrees; Z = 4. Its structure can be viewed as made of Ba2+ cations and [Cd2Sb4] double chains that are interconnected through Sb-Sb bonds to form 2D infinity2[Cd2Sb4]6- layers. The bonding arrangement in Ba3Cd2Sb4 can also be derived from other known structure types that feature similar fragments, such as TiNiSi, Ca3AlAs3, and Ca5Al2Sb6. Tight-binding linear muffin-tin-orbital band structure calculations are presented as well and show that the constituent elements have closed-shell configurations, indicative of Ba3Cd2Sb4 being a Zintl phase with poor metallic behavior. Crystal orbital Hamilton population analyses on selected atomic interactions in this structure are discussed within the context of the site preference, manifested in the mixed-cation compounds and Ba3-xAxCd2Sb4, where A = Ca, Sr, Eu, and Yb.

Gallium Pnictides of the Alkaline Earth Metals, Synthesized by Means of the Flux Method: Crystal Structures and Properties of CaGa2Pn2, SrGa2As2, Ba2Ga5As5, and Ba4Ga5Pn8 (Pn = P or As)

“…[10] Motivated by the discoveries of high ZT among such compounds, [6][7][8][9][10] our research group has been very active in this field. Past efforts have been focused on the search for new thermoelectric materials in the ternary systems A-MPn (A = Ca, Sr, Ba, Eu, Yb; M = Zn, Cd; Pn = P, As, Sb, Bi), and we have already reported a number of new compounds, such as Ca 2 CdSb 2 and Yb 2 CdSb 2 , [11] Na 2 ACdSb 2 and K 2 ACdSb 2 , [12] Eu 11 Zn 6 Pn 12 and Eu 11 Cd 6 Sb 12 , [13] Ba 11 Cd 8 Bi 14 , [14] A 9 Zn 4+x Pn 9 and A 9 Cd 4+x Pn 9 , [15] Ba 3 Cd 2 Sb 4 , [16] and Ba 2 Cd 2 Pn 3 . [17] The synthesis of most of these materials has been facilitated by the metal-flux method, [18] which, unlike the traditional solidstate route, allows the reactants to dissolve in a "solvent" and thereby achieve higher diffusion rates at lower temperatures.…”

Ba5Cd2Sb4O2—A New Antimonide Oxide with a Complex Structure

“…Over the past seven years, our research group has systematically explored the alkaline-earth metal and rare-earth metal antimonide systems. The resulting new compounds have often been Zintl phases [4][5][6] with complex crystal and electronic structures, and unusual properties [7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Although oxide research is not our focus, it is sometimes the case that adventurous oxygen molecules find their way into our experiments and OPEN ACCESS surprise us with an atypical compound, such as the previously reported Ba 5 Cd 2 Sb 5 O x (0.5 < x < 0.7) [17].…”

Dibarium tricadmium bismuthide(-I,-III) oxide, Ba2Cd3−δBi3O

“…Condensed trigonal CdBi 5 bi-pyramids and distorted CdBi 6 octahedra are known for Ba 2 Cd 3 Bi 4 (Cordier et al, 1982;Xia & Bobev, 2006b). The serendipitous discovery of the title compound was the result of a systematic study of the Ba-Cd-Bi system, inspired from the identification of Ba 3 Cd 2 Sb 4 (Saparov et al, 2008). The compound BaCdSbF (Saparov & Bobev, 2010) is an example of a structure that epitomizes the BaCdBiO slabs.…”

“…The reaction was aimed at growing crystals of Ba 3 Cd 2 Bi 4 , a hitherto unknown phase with the Ba 3 Cd 2 Sb 4 structure (Saparov et al, 2008), using excess of bismuth as a metal flux. The crucible was subsequently enclosed and flame-sealed in an evacuated fused silica ampoule, and then was heated at 200Kh -1 to 973 K, homogenized at 973 K for 20 h, cooled at a rate of -5Kh -1 to 723 K, where the excess Bi was removed by decanting it, leaving behind some irregularly shaped silver pieces and a few dark-to-black plates.…”