Prediction of Stable Ruthenium Silicides from First-Principles Calculations: Stoichiometries, Crystal Structures, and Physical Properties

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• 作者：Chuanzhao Zhang ; Xiaoyu Kuang ; Yuanyuan Jin ; Cheng Lu ; Dawei Zhou ; Peifang Li ; Gang Bao ; Andreas Hermann
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：December 9, 2015
• 年：2015
• 卷：7
• 期：48
• 页码：26776-26782
• 全文大小：413K
• ISSN：1944-8252

文摘

We present results of an unbiased structure search for stable ruthenium silicide compounds with various stoichiometries, using a recently developed technique that combines particle swarm optimization algorithms with first-principles calculations. Two experimentally observed structures of ruthenium silicides, RuSi (space group P2₁3) and Ru₂Si₃ (space group Pbcn), are successfully reproduced under ambient pressure conditions. In addition, a stable RuSi₂ compound with 尾-FeSi₂ structure type (space group Cmca) was found. The calculations of the formation enthalpy, elastic constants, and phonon dispersions demonstrate the Cmca-RuSi₂ compound is energetically, mechanically, and dynamically stable. The analysis of electronic band structures and densities of state reveals that the Cmca-RuSi₂ phase is a semiconductor with a direct band gap of 0.480 eV and is stabilized by strong covalent bonding between Ru and neighboring Si atoms. On the basis of the Mulliken overlap population analysis, the Vickers hardness of the Cmca structure RuSi₂ is estimated to be 28.0 GPa, indicating its ultra-incompressible nature.