Structural relationships,phase stability and bonding of compounds PdSnn (n=2, 3, 4) |
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| Institution: | 1. Department of Inorganic Chemistry, Stockholm University, 10691 Stockholm, Sweden;2. Institut für Physikalische Chemie, Universität Münster, Schlossplatz 4/7, 48149 Münster, Germany;3. Institut für Anorganische und Analytische Chemie, Universität Münster, Wilhelm-Klemm-Straße 8, 48149 Münster, Germany;1. Key Lab for Robot & Welding Automation of Jiangxi Province, School of Mechanical & Electrical Engineering, Nanchang University, Nanchang 330031, China;2. State Key Laboratorial of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China;1. Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan;2. Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan;1. Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1-3, GSP-1, 119991 Moscow, Russian Federation;2. N.S. Kurnakov Institute of General and Inorganic Chemistry, RAS, Leninsky pr. 31, GSP-1, 119991 Moscow, Russian Federation;3. Center for Emerging Energy Technologies, University of New Mexico, Albuquerque, NM 87131-1070, USA |
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| Abstract: | The Sn rich part of the binary system PdSn has been investigated for possible temperature dimorphism. Well-shaped single crystals of PdSn4, PdSn3 and PdSn2 were obtained under self-flux condition where the stannide is in equilibrium with the melt. The melt was subsequently removed by centrifugation at the synthesis temperature. The obtained products were characterised by X-ray diffraction, thermal analysis and 119Sn Mössbauer spectroscopy. The crystal structures of the obtained products corresponded to the already assigned structure types PtSn4, PdSn3 and PdSn2. The structures of PdSnn (n=2, 3, 4) represent stackings of similar building blocks and are closely related. Structural stability of compounds PdSnn (n=2, 3, 4) with respect to different stacking possibilities of building blocks was investigated by ab initio calculations in the framework of density functional theory. It was found that differently stacked alternatives to the experimentally determined structure types are very close in energy. Nevertheless, experimentally no indications of polytype formation or even stacking disorder were obtained for PdSnn (n=2, 3, 4). The peritectic decompositions of PdSnn were investigated by differential scanning calorimetry. The obtained decomposition temperatures are 330, 370, 617±3 °C for n=4, 3, 2, respectively. The 119Sn Mössbauer isomer shifts of compounds PdSnn are relatively high (δ≈2.4 mm s−1) and decrease with increasing Pd content. This behaviour coincides with the trend in the number of occupied Sn 5s states as obtained from theoretical calculations. |
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