Elastic Strain Engineering :

When the dimension shrinks into micronano scale, solids can sustain up to 100 times higher elastic strain than their bulk counterparts, which provides us with new opportunities to engineer the performance of materials. We are aiming to design and synthesize high-quality nanocrystals, apply lattice strain in proper way, characterize and optimize its certain properties, from luminescence color/intensity to electrical conductance, from catalytic ability to phase transition point, and finally establish the general fundamental theory based on the experimental phenomena.

Development and application of synchrotron X-ray diffraction :

Synchrotron is a sort of rapidly developed light source in the last few decades. If we take the conventional laboratory X-ray or electron beam as a candle, synchrotron is like the sun. With this brilliant beam of light, people have a better chance to ‘see the unseen’ and ‘know the unknown’. Our interests is in the development and application of diffraction techniques based on synchrotron radiation. With these methods, we can reproduce the firing condition (temperature and oxygen content) of the Terracotta Warriors made in Qin Dynasty or a teaware made in Song Dynasty, predict the lifetime of your computer chips, measure the residual stress in a piece of corroded and cracked steel, and even explain how the rocks and minerals are deformed in a disastrous earthquake.

Aug. 2011 - present, Associate professor, School of Materials Science and Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, China
Director assistant, The Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano)
Associate director, Hysitron Applied Research Center (China)

Sep. 2010 - Jul. 2011 , Postdoc, National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Advised by Prof. A. M. Minor

Sep. 2009 - Jul. 2010 , Postdoc, Department of Earth and Planetary Science, University of California Berkeley, Advised by Prof. H.-R. Wenk

Mar. 2007 - Aug. 2009 , Visiting scholar, Advanced Light Source, Lawrence Berkeley National Laboratory, Hosted by Dr. Nobumichi Tamura

2005 - 2009 UNIVERSITY OF CALIFORNIA LOS ANGELES, Los Angeles, CA, USA, Ph.D in Electronic Materials, Department of Materials Science and Engineering

2001 - 2005 PEKING UNIVERSITY, Beijing, P. R. China, B.S. in Physical Chemistry, School of Chemistry and Molecular Engineering 

1. Jae-Woong Nah, Kai Chen, K. N. Tu, Bor-Rung Su, and Chih Chen, Mechanism of electromigration induced failure in flip-chip solder joints with a 10um-thick Cu under-bump metallization, Journal of Materials Research, 22(3) 763-769, DOI: 10.1557/JMR.2007.0084, 2007

2. Fan-Yi Ouyang, Kai Chen, K. N. Tu, and Yi-Shao Lai, Effect of current crowding on whisker growth at the anode in flip chip solder joints, Applied Physics Letters, 91, 231919, DOI: 10.1063/1.2822446, 2007

3. Di Xu, Wei Lek Kwan, Kai Chen, Xi Zhang, Vidvuds Ozolins, and K. N. Tu, Nanotwin formation in copper thin films by stress/strain relaxation in pulse electrodeposition, Applied Physics Letters, 91, 254105, DOI: 10.1063/1.2825412, 2007

4. Kai Chen*, N. Tamura, B. C. Valek and K. N. Tu, Plastic deformation in Al (Cu) interconnects stressed by electromigration and studied by synchrotron polychromatic X-ray microdiffraction, Journal of Applied Physics, 104, 013513, DOI: 10.1063/1.2952073, 2008

5. Kai Chen*, N. Tamura and K. N. Tu, In-situ early stage electromigration study in Al line using synchrotron polychromatic X-ray microdiffraction, Materials Research Society Symposium Proceedings, 1079E, N05-02, DOI: 10.1557/PROC-1079-N05-02, 2008

6. Martin Kunz, Nobumichi Tamura, Kai Chen, Alastair A. MacDowell, Richard S. Celestre, Matthew M. Church, Sirine Fakra, Edward E. Domning, James M. Glossinger, Dave W. Plate, Brian V. Smith, Tony Warwick, Howard A. Padmore and Ersan Ustundag, A dedicated superbend x-ray microdiffraction beamline for material-, geo- and environmental sciences at the Advanced Light Source, Review of Scientific Instruments, 80, 035108, DOI: 10.1063/1.3096295, 2009

7. Kai Chen*, Nobumichi Tamura, and K. N. Tu, In-situ study of electromigration-induced grain rotation in Pb-free solder joint by synchrotron microdiffraction, Materials Research Society Symposium Proceedings, 1116E, I05-06, DOI: 10.1557/PROC-1116-I05-06, 2009

8. Martin Kunz, Kai Chen, Nobumichi Tamura, and Hans-Rudolf Wenk, Evidence for residual elastic strain in deformed natural quartz, American Mineralogist, 94, 1059, DOI: 10.2138/am.2009.3216, 2009

9. N. Tamura, M. Kunz, K. Chen, R. S. Celestre, A. A. MacDowell, and T. Warwick, A superbend X-ray microdiffraction beamline at the Advanced Light Source, Materials Science and Engineering A, 524, 28, DOI: 10.1016/j.msea.2009.03.062, 2009

10. Kai Chen*, N. Tamura, M. Kunz, K. N. Tu, and Yi-Shao Lai, In situ measurement of electromigration-induced transient stress in Pb-free Sn-Cu solder joints by synchrotron radiation based X-ray polychromatic microdiffraction, Journal of Applied Physics, 106, 023502, DOI: 10.1063/1.3157196, 2009

11. Hans-Rudolf Wenk, Paulo J. M. Monteiro, Martin Kunz, Kai Chen, Nobumichi Tamura, Luca Lutterotti, and John Delacroz, Preferred orientation of ettringite in concrete fractures, Journal of Applied Crystallography, 42, 429, DOI: 10.1107/S0021889809015349, 2009

12. J. Cao, Y. Gu, W. Fan, L. Q. Chen, D. F. Ogletree, K. Chen, N. Tamura, M. Kunz, C. Barrett, J. Seidel, and J. Wu, Extended Mapping and Exploration of the Vanadium Dioxide Stress-Temperature Phase Diagram, Nano Letters, 10, 2667, DOI: 10.1021/nl101457k, 2010

13. J. Cao, W. Fan, K. Chen, N. Tamura, M. Kunz, V. Eyert, and J. Wu, Constant threshold resistivity in the metal-insulator transition of VO2, Physical Review B, 82, 241101, DOI: 10.1103/PhysRevB.82.241101, 2010

14. Kai Chen, N. Tamura, Wei Tang, M. Kunz, Yi-Chia Chou, K. N. Tu, and Yi-Shao Lai, High precision thermal stress study on flip chips by synchrotron polychromatic X-ray microdiffraction, Journal of Applied Physics, 107, 063502, DOI: 10.1063/1.3309750, 2010

15. Gyuhyon Lee, Ju-Young Kim, Arief Suriadi Budiman, Nobumichi Tamura, Martin Kunz, Kai Chen, Michael J. Burek, Julia R. Greer, and Ting Y, Tsui Fabrication, Structure, and Mechanical Properties of Indium Nanopillars, Acta Materialia, 58, 1361, DOI: 10.1016/j.actamat.2009.10.042, 2010

16. Alexandra Friedrich, Björn Winkler, Lkhamsuren Bayarjargal, Wolfgang H. Morgenroth, Erick A. Juarez-Arellano, Victor Milman, Keith Refson, Martin Kunz, and Kai Chen, Novel nitrides of rhenium, Physical Review Letters, 105, 085504, DOI: 10.1103/PhysRevLett.105.085504, 2010

17. Jun Liu, Martin Kunz, Kai Chen, Nobumichi Tamura, and Thomas J. Richardson, Visualization of charge distribution in a Lithium battery electrode, The Journal of Physical Chemistry Letters, 1(14), 2120, DOI: 10.1021/jz100634n, 2010

18. Kai Chen, Martin Kunz, Nobumichi Tamura, and Hans-Rudolf Wenk, Evidence for high stress in quartz from the impact site of Vredefort, South Africa European Journal of Mineralogy, 23(2), 169-178, DOI: 10.1127/0935-1221/2011/0023-2082, 2011

19. Bongjin Simon Mun, Kai Chen, Youngchul Leem, Catherine Dejoie, Nobumichi Tamura, Martin Kunz, Zhi Liu, Michael Grass, Changwoo Park, and Honglyoul Ju, Unusual structural transitions in macro-sized VO2 single crystals, Physics Stats Solidi (RRL), 5(3), 107-109, 2011

20. Kai Chen, Martin Kunz, Nobumichi Tamura, and Hans-Rudolf Wenk, Deformation twinning and residual stress in calcite studied using synchrotron polychromatic x-ray microdiffraction, Physics and Chemistry of Minerals, 38(6), 491-500, DOI: 10.1007/s00269-011-0422-7, 2011

21. Catherine Dejoie, Martin Kunz, Nobumichi Tamura, Colin Bousige, Kai Chen, Simon Teat, Christine Beavers, and Christian Baerlocher, Determining the effective white beam flux curve of a synchrotron beamline using Laue patterns, Journal of Applied Crystallography, 44, 177-183, DOI: 10.1107/S0021889810052015, 2011

22. E. Rybacki, C. Janssen , R. Wirth, K. Chen, H. R. Wenk, D. Stromeyer, and G. Dresen, Low-temperature deformation in calcite veins of SAFOD core samples (San Andreas Fault) - microstructural analysis and implications for fault rheology, Tectonophysics, 509, 107-119, DOI: 10.1016/j.tecto.2011.05.014, 2011

23. Hua Guo#, Kai Chen#, J. Oh, S. A. Syed Asif, O. L. Warren, Z. Shan, Kevin Wang, J. Wu, and A. M. Minor (# joint first author), Mechanics and Dynamics of the Strain-Induced M1-M2 Structural Phase Transition in Individual VO2 Nanowires, Nano Letters, 11, 3207-3213, DOI: 10.1021/nl201460v, 2011

24. Hans-Rudolf Wenk, Kai Chen, and Rebecca Smith, Morphology and microstructure of magnetite and ilmenite inclusions in plagioclase from Adirondack anorthositic gneiss, American Mineralogist, 96, 1316-1324, DOI: 10.2138/am.2011.3760, 2011

25. B.S. Budiman, N. Li, Q. Wei, J. K. Baldwin, J. Xiong, H. Luo, D. Trugman, Q. X. Jia, N. Tamura, M. Kunz,K. Chen, and A. Misra, Growth and structural characterization of epitaxial Cu/Nb multilayers, Thin Solid Films, 519(13), 4137-4143, DOI: 10.1016/j.tsf.2010.12.077, 2011

26. Tian Tian, Kai Chen, A. A. MacDowell, Dula Parkinson, Yi-Shao Lai, and K. N. Tu, Quantitative x-ray micro-tomography study of 3D void growth induced by electromigration in eutectic SnPb flip chip solder joints, Scripta Materialia, 65, 646-649, DOI: 10.1016/j.scriptamat.2011.07.002, 2011

28. Taiji Zhang, Yurong Ma, Kai Chen, Martin Kunz, Nobumichi Tamura, Jun Xu, and Limin Qi, Ultra-thin flexible armor in Nature: interlocked Helical aragonite Nanofibers in Cavolinia Uncinata Shell and Its Relationship with Mechanical Properties, Angewandte Chemie International Edition, 50, 10361-10365, DOI: 10.1002/anie.201103407, 2011

29. Bongjin Simon Mun, Kai Chen, Joonseok Yoon, Catherine Dejoie, Nobumichi Tamura, Martin Kunz, Zhi Liu, Michael E. Grass, Sung-Kwan Mo, Changwoo Park, Y. Yvette Lee, and Honglyoul Ju, Nonpercolative metal-insulator transition in VO2 single crystals, Physical Review B, 84, 113109, DOI: 10.1103/PhysRevB.84.113109, 2011

30. Qian Yu, Liang Qi, Kai Chen, Raja K. Mishra, Ju Li, and Andrew M. Minor, The Nanostructured Origin of Deformation Twinning, Nano Letters, 12, 887-892, DOI: 10.1021/nl203937t, 2012

31. B. S. Mun, J. Yoon, S. K. Mo, K. Chen, N. Tamura, C. Dejoie, M. Kunz, Z. Liu, Y. Y. Lee, K. Moon, C. Park, and H. Ju, Metal insulator transition characteristics of macro-size single domain VO2 crystals,Phase Transitions: A Multinational Journal, DOI: 10.1080/01411594.2012.717291, 2012.

32. K. Chen*, C. Dejoie, and H. R. Wenk, Unambiguous indexing of trigonal crystals from white-beam Laue diffraction patterns: application to Dauphiné twinning and lattice stress mapping in deformed quartz, Journal of Applied Crystallography, 45, 982-989, DOI: 10.1107/S0021889812031287, 2012

33. B.S. Mun, J. Yoon, S.K. Mo, K. Chen, N. Tamura, C. Dejoie, M. Kunz, Z. Liu, C. Park, K. Moon, and H. Ju,Role of joule heating effect and bulk-surface phases in voltage-driven metal-insulator transition in VO2 crystal, Applied Physics Letters, 103, 061902, DOI: 10.1063/1.4817727, 2013

34. Xiaofei Sun, Youlong Xu, Mingrui Jia, Peng Ding, Yanghao Liu, and Kai Chen, High performance LiV0.96Mn0.04PO4F/C cathodes for lithium-ion batteries, Journal of Materials Chemistry A, 1(7), 2501-2507, DOI: 10.1039/c2ta01338j, 2013

35. Catherine Dejoie, Philippe Sciau, Weidong Li, Laure Noe´, Apurva Mehta, Kai Chen, Hongjie Luo, Martin Kunz, Nobumichi Tamura, and Zhi Liu, Learning from the past: Rare e-Fe2O3 in the ancient black-glazed Jian (Tenmoku) wares, Scientific Reports, DOI: 10.1038/srep04941, 2014

36. Lupinacci, K. Chen*, Y. Li, M. Kunz, Z. Jiao, G.S. Was, M.D. Abad, A.M. Minor, and P. Hosemann* (* joint corresponding authors), Characterization of ion beam irradiated 304 stainless steel utilizing nanoindentation and Laue microdiffraction, Journal of Nuclear Materials, 458, 70-76, DOI: 10.1016/j.jnucmat.2014.11.050, 2015

37. Kai Chen, Martin Kunz, Nobumichi Tamura, and Hans-Rudolf Wenk, Residual stress preserved in quartz from the San Andreas Fault Observatory at Depth, Geology, 43(3), 219-222, DOI: 10.1130/G36443.1, 2015

38. Yao Li, Liang Wan, and Kai Chen*, A look-up table based approach to characterize crystal twinning for synchrotron X-ray Laue microdiffraction scans, Journal of Applied Crystallography, 48, 747-757, DOI: 10.1107/S1600576715004896, 2015

39. Yi-Chia Chou, Wei Tang, Chien-Jyun Chiou, Kai Chen, Andrew Minor, and King-Ning Tu, Effect of elastic strain fluctuation on atomic layer growth of epitaxial silicide in Si nanowires by point contact reactions, Nano Letters, 15 (6), 4121-4128, DOI: 10.1021/acs.nanolett.5b01234, 2015

40. Hongwei Cheng, Bin Leng, Kai Chen, Yanyan Jia, Jiasheng Dong, Zhijun Li, and Xingtai Zhou, EPMA and TEM characterization of intergranular tellurium corrosion of Ni–16Mo–7Cr–4Fe superalloy, Corrosion Science, 97, DOI: 10.1016/j.corsci.2015.04.017, 2015

41. Liang Wan, Weizhong Han, and Kai Chen, Bi-crystallographic lattice structure directs grain boundary motion under shear stress, Scientific Reports, 5, 13441, DOI:10.1038/srep13441, 2015

42. Jiawei Xue, Anfeng Zhang, Yao Li, Dan Qian, Jingchun Wan, Baolu Qi, Nobumichi Tamura, Zhongxiao Song, and Kai Chen*, A synchrotron study of microstructure gradient in laser additively formed epitaxial Ni-based superalloy, Scientific Reports, 5, 14903, DOI:10.1038/srep14903, 2015

43. Eric Yue Ma, Yong-Tao Cui, Kentaro Ueda, Shujie Tang, Kai Chen, Nobumichi Tamura, Phillip M. Wu, Jun Fujioka, Yoshinori Tokura, and Zhi-Xun Shen, Mobile metallic domain walls in an all-in-all-out magnetic insulator, Science, 350, 6260, 538-541, DOI: 10.1126/science.aac8289, 2015

44. Yao Li, Dan Qian, Jiawei Xue, Jingchun Wan, Anfeng Zhang, Nobumichi Tamura, Zhongxiao Song, andKai Chen*, A synchrotron study of defect and strain inhomogeneity in laser-assisted three-dimensionally-printed Ni-based superalloy, Applied Physics Letters, 107, 181902, DOI: 10.1063/1.4934839, 2015

45. Xiaoguang Wang, Kai Chen, Yongqiang Zhang, Jingchun Wan, Oden L. Warren, Jason Oh, Ju Li, Evan Ma, and Zhiwei Shan, Growth Conditions Control the Elastic and Electrical Properties of ZnO Nanowires, Nano Letters, 15, 7886-7892, DOI: 10.1021/acs.nanolett.5b02852, 2015

46. Hao Shen, Wenxin Zhu, Yao Li, Nobumichi Tamura, and Kai Chen*, In situ synchrotron study of electromigration induced grain rotations in Sn solder joints, Scientific Reports, 6, 24418, DOI: 10.1038/srep24418, 2016

47. Klaus-Dieter Liss* and Kai Chen*, Frontiers of synchrotron research in materials science, MRS Bulletin, 41, 6, 435-441, DOI:10.1557/mrs.2016.112, 2016

48. Guangni Zhou^#, Wenxin Zhu^#, (# contributed equally) Hao Shen, Yao Li, Anfeng Zhang, Nobumichi Tamura, and Kai Chen*, Real-time microstructure imaging by Laue microdiffraction: A sample application in laser 3D printed Ni-based superalloys, Scientific Reports, 6, 28144, DOI:10.1038/srep28144, 2016

49. Kai Chen, Martin Kunz, Yao Li, Eloisa Zepeda-Alarcon, Manuel Sintubin, and Hans-Rudolf Wenk,Compressional residual stress in Bastogne boudins revealed by synchrotron X-ray microdiffraction, Geophysical Research Letters, 43, doi:10.1002/2016GL069236, 2016

50. Dan Qian, Anfeng Zhang, Jianxue Zhu, Yao Li, Wenxin Zhu, Baolu Qi, Nobumichi Tamura, Dichen Li, Zhongxiao Song, and Kai Chen*, Hardness and microstructural inhomogeneity at the epitaxial interface of laser 3D-printed Ni-based superalloy, Applied Physics Letters, 109, 101907, DOI: 10.1063/1.4962485, 2016 (APL Editor's Pick).