Prof Defang Duan

Structure and Superconductivity of hydrogen-rich compounds at high pressures

Hydrogen-rich materials are potential high temperature superconductors at high pressure, which are expected to be a new member of superconductor family: hydrogen-based superconductor. I discovered a few high-temperature superconductors in hydrogen-rich materials at high pressure by means of theoretical exploration. In binary hydrogen-rich materials, some high-Tc superconductors have been triggered at high pressure. I first theoretically predicted H3S with Im-3m symmetry with Tc reaching as high as 200 K at high pressure, which have been confirmed by in situ high pressure experiments. Furthermore, we also explored high temperature superconductivity in ternary hydrides at high pressures. For ternary hydrides MgXH6, (X=Mg, Ge) it can stabilize above 200 GPa high Tc of 60 K.

Relevant publications

1. Defang Duan, Yunxian Liu, Fubo Tian, Da Li, Xiaoli Huang, Zhonglong Zhao, Hongyu Yu, Bingbing Liu, Wenjing Tian, and Tian Cui, Pressure-induced metallization of dense (H2S)2H2 with high-Tc superconductivity, Sci. Rep. 4, 6968 (2014) [Journal]

2. Defang Duan, Xiaoli Huang, Fubo Tian, Da Li, Hongyu Yu, Yunxian Liu, Yanbin Ma, Bingbing Liu, and Tian Cui, Pressure-induced decomposition of solid hydrogen sulfide, Physical Review B 91 (18), 180502(R) (2015) [Journal]

3. Defang Duan, Yunxian Liu, Yanbin Ma, Ziji Shao, Bingbing Liu, and Tian Cui, Structure and superconductivity of hydrides at high pressures, National Science Review 4 (1), 121 (2017) [Journal]

4. Yanbin Ma, Defang Duan, Ziji Shao, Hongyu Yu, Hanyu Liu, Fubo Tian, Xiaoli Huang, Da Li, Bingbing Liu and Tian Cui, Divergent synthesis routes and superconductivity of ternary hydride MgSiH6 at high pressure, Physical Review B 96, 144518 (2017) [Journal]

Theoretical design of high energy density materials

Polymeric nitrogen has attracted a great deal of attention as potential high energy density materials. I predicted hydrogen-passivated polymeric networks and five-member ring structures from NH4N3 by ab initio molecular dynamics simulations. At 60 and 90 GPa, the critical temperatures for polymerization are about 2200 and 1600 K, respectively. More importantly, it is predicted that they are stable at ambient conditions.

Relevant publications

1. Hongyu Yu, Defang Duan, Fubo Tian, Hanyu Liu, Da Li, Xiaoli Huang, Yunxian Liu, Bingbing Liu, and Tian Cui, Polymerization of Nitrogen in Ammonium Azide at High Pressures, The Journal of Physical Chemistry C 119 (45), 25268 (2015) [Journal]

Publications