Flux Growth and Electronic Properties of Ba2In5Pn5 (Pn = P, As): Zintl Phases Exhibiting Metallic Behavior

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• 作者：Josiah Mathieu ; Randall Achey ; Ju-Hyun Park ; Kenneth M. Purcell ; Stanley W. Tozer ; Susan E. Latturner
• 刊名：Chemistry of Materials
• 出版年：2008
• 出版时间：September 9, 2008
• 年：2008
• 卷：20
• 期：17
• 页码：5675-5681
• 全文大小：265K
• 年卷期：v.20,no.17(September 9, 2008)
• ISSN：1520-5002

文摘

Ba<sub>2sub>In<sub>5sub>P<sub>5sub> and Ba<sub>2sub>In<sub>5sub>As<sub>5sub> were grown from the reaction of barium and the pnictogen elements in indium flux. These Zintl phases feature a new structure type in orthorhombic space group Pnma (for the phosphorus analogue, a = 17.2572(2) Å, b = 4.1599(1) Å, c = 17.4895(2) Å, R<sub>1sub> = 0.0376). The layered structure features anionic slabs of interconnected main group atoms, with hexagonal channels defined by In−In bonds and capped on the outer edges by the pnictides; Ba<sup>2+sup> cations reside in between these layers. Despite the apparently charge-balanced nature of the structure and the band gaps indicated in density of states calculations, the rising resistivities with increasing temperature indicate these materials behave as metals (ρ<sub>RTsub> for Ba<sub>2sub>In<sub>5sub>P<sub>5sub> = 1.0 × 10<sup>−3sup> Ω cm, and ρ<sub>RTsub> Ba<sub>2sub>In<sub>5sub>As<sub>5sub> = 6.1 × 10<sup>−3sup> Ω cm). NMR studies of the <sup>115sup>In Knight shifts and the Korringa relationship observed for the temperature dependence of the <sup>31sup>P resonance of Ba<sub>2sub>In<sub>5sub>P<sub>5sub> characterize these compounds as semiconductors doped into the metallic regime. The flux growth method is the likely source of doping.