Yb5In2Sb6: A New Rare Earth Zintl Phase with a Narrow Band Gap

• Published in: Journal of solid state chemistry 2000-11, Vol.155 (1), p.55-61
• Main Authors: Kim, Sung-Jin, Ireland, John R., Kannewurf, Carl R., Kanatzidis, Mercouri G.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electron density of states and band structure of crystalline solids; Electron states; Exact sciences and technology; Inorganic compounds; Physics; Semiconductor compounds; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.2000.8891

The new Zintl phase Yb5In2Sb6 was obtained from a direct element combination reaction in a sealed graphite tube at 700°C and its structure was determined. It crystallizes in the orthorhombic space group Pbam (No. 55), in the Ba5Al2Bi6 structure type, with a unit cell of a=7.3992(5) Å, b=23.001(6) Å, c=4.5139(4) Å, and Z=2. Yb5In2Sb6 has a one-dimensional structure with infinite anionic double chains (In2Sb6)10− separated by Yb2+ ions. Each single chain is made of corner-sharing InSb4 tetrahedra. Two such chains are bridged by Sb2 groups to form double chains 1∞ [In2Sb10−6]. The compound satisfies the classical Zintl concept and is a narrow gap semiconductor. Band structure calculations suggest an direct band gap. Polycrystalline ingots of Yb5In2Sb6 showed electrical conductivity of 100 S/cm and a Seebeck coefficient of ∼+30 μV/K at room temperature. The thermal conductivity of Yb5In2Sb6 is about 1.7 W/mK in the temperature range of 150–300 K.