Abstract: In the Ca/Si phase diagram, many compositions are known. In these calcium silicides, silicon atoms form many different organizations, for example, at low pressure silicons are isolated silicon atoms in Ca2Si, Si chains in CaSi and corrugated hexagonal Si layers and a three-dimensional network of sp2 bonds in CaSi2. The crystal structures for these silicides under pressure have not been studied completely, and we are very interested in the new chemical and physical behavior of Si in these silicides under pressure. Therefore, we take a theoretical study of Ca2Si, CaSi and CaSi2 under pressure.

We predicted many interesting Si networks in the calcium silicides under pressure. Si atoms form Si chains in Ca2Si, flat quadrangular and hexagonal Si layers in CaSi, and 6-coordinated Si tetrahedrons and 4, 8-coordinated Si octahedrons in CaSi2 at high pressure. All of these predicted structures are dynamically stable. Moreover, these calcium silicides are all metals. Some of them might be good candidates to be superconductors.

个人简介: 高国英博士：2011年于12月毕业于超硬材料国家重点实验室博士毕业，已在Phys. Rev. Lett.，PNAS, JACS, Phys. Rev. B等刊物上发表SCI论文17篇。曾经荣获“宝钢优秀学生奖学金”，“教育部博士研究生学术新人奖”，第15届全国高压讨论会优秀青年论文奖和第六届全国青年计算物理学术会议优秀论文奖，吉林大学第23、24届“精英杯”学术成果大奖赛特等奖，吉林省优秀硕士毕业论文等。现在在美国康奈尔大学师从诺贝尔化学奖获得者Roald Hoffmann和国际著名理论物理学家Neil Ashcroft读博士后。

Date&Time: January 9, 2014 (Thursday), 15:00-16:00
Location: 606 Conference Room, No.3 Heqing Road, Haidian District