On the Structure and Stability of BaAl4‐Type Ordered Derivatives in the Sr–Au–Sn System for the 600 °C Section12. Issue 2 (22nd December 2014)

• Record Type: Journal Article
• Authors: Lin, Qisheng; Zhang, Yuemei; Taufour, Valentin; Lamichhane, Tej Nath; Bud'ko, Sergey L.; Canfield, Paul C.; Dennis, Kevin; Miller, Gordon
• Is Part Of: Zeitschrift für anorganische und allgemeine Chemie. Volume 641:Issue 2(2015)
• Page Start: 375
• Page End: 382
• Publication Date: 2014-12-22
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/zaac.201400549
• Languages: English
• ISSNs: 0044-2313

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p> The well‐known BaAl<sub>4</sub>‐type structure consists of three ordered ternary derivatives, i.e., BaNiSn<sub>3</sub>‐ (<italic>I</italic>4<italic>mm</italic>), ThCr<sub>2</sub>Si<sub>2</sub>‐ (<italic>I</italic>4/<italic>mmm</italic>), and CaBe<sub>2</sub>Ge<sub>2</sub>‐type (<italic>P</italic>4/<italic>nmm</italic>). Few systems, such as Ba‐Au‐Sn, have been confirmed to manifest all three types as a function of valence electron count. In this work, the SrAu<italic><sub>x</sub></italic>Sn<sub>4–<italic>x</italic></sub> solid solution at the 600 °C section was studied thoroughly using both single crystal and powder X‐ray diffraction. The crystal structures and phase width for the CaBe<sub>2</sub>Ge<sub>2</sub>‐type SrAu<italic><sub>x</sub></italic>Sn<sub>4–<italic>x</italic></sub> solid solution were established to be <italic>a</italic> = 4.6528(2)–4.6233(3) Å and <italic>c</italic> = 11.3753(4)–11.2945(10) Å for <italic>x</italic> ≈ 1.65(1)–2.19(1). In the structure of SrAu<sub>2</sub>Sn<sub>2</sub>, no Au/Sn mixing was found, but for <italic>x</italic> < 2 compositions, Au/Sn mixings were only located at the Wyckoff 2<italic>a</italic> (¾ ¼ 0) site and for <italic>x</italic> > 2 compositions, at the 2<italic>b</italic> (¾ ¼ ½) site. Differential scanning calorimetry (DSC) analyses indicated that no phase transition occurred for the CaBe<sub>2</sub>Ge<sub>2</sub>‐type SrAu<italic><sub>x</sub></italic>Sn<sub>4–<italic>x</italic></sub> phase up to 950 °C. Attempts to synthesize the ThCr<sub>2</sub>Si<sub>2</sub>‐ and BaNiSn<sub>3</sub>‐type SrAu<italic><sub>x</sub></italic>Sn<sub>4–<italic>x</italic></sub> phases under the same reaction conditions were unsuccessful, and the BaNiSn<sub>3</sub>‐type phase could not be attained even at a pressure of 3 GPa. The instability of a BaNiSn<sub>3</sub>‐type "SrAuSn<sub>3</sub>" was investigated by both DSC measurements and first principles electronic structure calculations.</p> </abstract>