Prof. Jianqi Li (李建奇)

Education & Experience

1986-1990: Graduate student in Condensed Matter Physics at the Institute of Physics, Chinese Academy of Sciences (IOP, CAS). Received Ph.D. in 1990.

1991-1993: Postdoctoral fellow at the Department of Physics, Peking University.

1994-1995: Associate Professor at the National Laboratory for Superconductivity, IOP, CAS.

1995-1996: Postdoctoral fellow at the Electron Microscopy Laboratory, Max Planck Institute for Solid State Research, Germany.

1996-1998: Visiting Researcher at the National Institute for Materials Science, Japan.

1999-2001: Visiting Scholar at the Electron Microscopy Facility, Brookhaven National Laboratory, USA.

May 2002-Present: Professor and Group Leader at IOP, CAS.
(During this period, served as the Director of the Laboratory of Advanced Materials and Structural Analysis from 2002 to 2009).

Research Directions

1. Development of electron microscopy techniques, including: 4D Ultrafast Electron Microscopy (UTEM), in-situ electron microscopy, aberration-corrected microscopy, and electron holography.

2. Microstructural and structural dynamics analysis of functional materials.

3. Study of the structure and structural phase transitions in novel superconductors.

Main Work & Achievements

1. Microstructural Study of Functional Materials:

He has resolved several important structural issues in Fe-based superconductors, giant magnetoresistive Mn-oxides, and electronic ferroelectric systems, achieving numerous research breakthroughs. Key findings include the Fe-vacancy ordering and phase separation in the KxFe1.7As2 superconducting series; the issue of iron's variable valence states and the existence of pentavalent Fe; the electron orbital ordering in giant magnetoresistive Mn-oxide systems; stripe phases and electronic phase separation in high-Tc superconducting small polarons with perovskite structures; low-temperature structural phase transitions and charge ordering in the electronic ferroelectric LuFe2O4; antiphase stripe domain structures and strong magnetoelectric coupling at the magnetic phase transition point in Fe2OBO3; and the structure, vacancy ordering, and phase separation characteristics of novel Fe-based superconductors.

2. Development of 4D Ultrafast Transmission Electron Microscopy:

Electron microscopy plays a vital role in materials science and nano-device research. Recently, building on conventional high-resolution electron microscopy, we successfully developed China's first 4D Ultrafast Time-Resolved Transmission Electron Microscope, which was certified by a CAS expert panel in October 2015. In 2019, a new generation of time-resolved electron microscopes with a field-emission cathode was successfully developed. This ultrafast electron microscopy technique allows for capturing instantaneous microstructures and atomic images of materials (with a spatial resolution of 0.27 nm) at a femtosecond timescale (10⁻¹⁵ s), providing rich information on atomic structural evolution. Ultrafast electron microscopy has become a key development direction and a frontier in the field of electron microscopy. Additionally, our developed ultrafast microscope retains all the advanced functions of a conventional TEM for direct atomic structure observation and spectroscopic analysis. (International Patent No. 2014/CN2014/076846, Chinese Patent No. 201410007910.2).

He has published over 380 papers in major international academic journals, with over 6,800 citations and an H-index of 44. He has delivered over 80 invited talks at international conferences and has organized several international academic workshops on electron microscopy and functional materials in recent years.

Representative Publications & Patents

Multiple patents on integrated ultrafast electron microscopy technologies (1 international, 5 domestic)

• K. Sun, S.S. Sun, C.H. Zhu, H.F. Tian, H.X. Yang, J.Q. Li*, Hidden CDW states and insulator-to-metal transition after a pulsed femtosecond laser excitation in layered chalcogenide 1T-TaS2−xSex, Science advance 4 (2018) 9660.
• S. S. Sun, L. L. Wei, Z. W. Li, G. L. Cao, Y. Liu, W. J. Lu, Y. P. Sun, H. F. Tian, H. X. Yang, J. Q. Li*, Direct observation of an optically induced charge density wave transition in 1T-TaSe2. Physical Review B 92 (2015)5.
• Z. W. Li, S. S. Sun, Z. A. Li, M. Zhang, G. L. Cao, H. F. Tian, H. X. Yang, J. Q. Li*, Ultrafast structural dynamics of boron nitride nanotubes studied using transmitted electrons. Nanoscale 9(2017) 13313.
• L. L. Wei, S. S. Sun, C. Guo, Z. W. Li, K. Sun, Y. Liu, W. J. Lu, Y. P. Sun, H. F. Tian, H. X. Yang, J. Q. Li*, Dynamic diffraction effects and coherent breathing oscillations in ultrafast electron diffraction in layered 1T-TaSeTe. Structural dynamics 4 (2017)10.
• M. Zhang, G. L. Cao, H. F. Tian, S. S. Sun, Z. W. Li, X. Y. Li, C. Guo, Z. Li, H. X. Yang, J. Q. Li,* Picosecond view of a martensitic transition and nucleation in the shape memory alloy Mn50Ni40Sn10 by four-dimensional transmission electron microscopy. Physical Review B 96 (2017)7.
• ZW. Li, Z.-A. Li, S. Sun, D. Zheng, H. Wang, H. Tian, H. Yang, X. Bai, J.Q. Li*, Direct Observation of Inner-Layer Inward Contractions of Multiwalled Boron Nitride Nanotubes upon in Situ Heating. Nanomaterials (Basel, Switzerland) 8, (2018).
• G. L. Cao, S. S. Sun, Z. W. Li, H. F. Tian, H. X. Yang, J. Q. Li*, Clocking the anisotropic lattice dynamics of multi-walled carbon nanotubes by four-dimensional ultrafast transmission electron microscopy. Scientific reports 5 (2015) 7.
• C. Ma, Y. Lin, H. X. Yang, H. F. Tian, L. Shi , J. Zeng, and J. Q. Li*, Adv. Mater., 27(2015) 6328.
• Z. Wang, Y. Cai, Z. W. Wang, C. Ma, Z. Chen, H. X. Yang, H. F. Tian, and J. Q. Li*, Phys.Rev. B, 91(2015) 064513.
• S.S. Sun, L.L Wei, Z.W. Li, G.L. Cao, Y. Liu, W. J. Lu, Y. P. Sun, H.F. Tian, H.X. Yang, and J.Q. Li*, Phys. Rev. B, 92(2015)224303.
• C. Ma, L. J. Wu, W. G. Yin, H. X. Yang, H. L. Shi, Z. W. Wang, J. Q. Li, C. C. Homes, and Y. M. Zhu*, Phys. Rev. Lett, 112(2014) 077001.
• X. G. Guo, G. Z. Fang, G. Li, J. Q. Li, L. L. Sun, Z. C. Tang, X. L. Pan, X. H. Bao*, Science, 344( 2014) 616.
• J. Li, H. X. Yang, S.-W. Cheong, and J. Q. Li*. Phys. Rev. B, 87 (2013) 094106.
• S. Cao, J. Li, H.X.Yang & J.Q. Li*, Scientific Reports, 2 (2012)330.
• Z. Wang, Y.J. Song, J.Q. Li*, Phys. Rev. B 83(2011)140505(R) .
• H. X. Yang, H. Y. J. Song, and J. Q. Li*, Phys. Rev. Lett. 106(2011)016406.
• Y.J. Song, H.X. Yang, H.F. Tian, C. Ma, Y.B. Qin, and J.Q. Li*, Phys.Rev. B, 81 (2010) 020101 (R).
• C. Ma, H.X. Yang, H.F. Tian, H.L. Shi, J.B. Lu, and J.Q. Li*,. Phys. Rev. B 79 (2009) 060506(R).
• Y. Zhang, H.X. Yang, C. Ma, H.F. Tian, and J.Q. Li*, Phys. Rev. Lett. 98 (2007) 247602.

Current Research & Outlook

1. Investigating structural problems in strongly correlated physical systems; synthesizing and exploring novel superconducting and multiferroic materials.

2. Focusing on the development of low-temperature electron microscopy, EELS spectroscopy, and Lorentz microscopy.

3. Developing high-end ultrafast electron microscopes and conducting research on ultrafast structural dynamics.

Student Supervision

Has supervised 25 Ph.D. students to graduation. Currently supervising 8 Ph.D. students.

Plans to recruit 2 Master's students, 3 direct Ph.D. candidates, and 3 postdoctoral fellows. Candidates with backgrounds in physics, materials science, chemistry, and ultrafast lasers are welcome to apply.