Development Of The Four-Dimensional Nano-Manipulator For In-Situ Transmission Electron Microscope

Three-dimensional(3D)reconstruction technologies for transmission electron microscope(TEM)have been demonstrated to be a powerful tool in addressing challenging problems,such as understanding 3D interactions among various microstructures.Advancing TEM 3D reconstruction technologies to broader applications requires novel instrumental design to break the bottlenecks both in theory and in practice.In this work,we independently developed a fourdegrees-of-freedom in-situ nano-manipulating system(i.e.,X-Nano system)for transmission electron microscope,which realizes stable and accurate positioning on three translational axes and one rotatory axis using miniature piezoelectric nano-manipulator,improving efficiency and quality of 3D reconstruction in various ways.Meanwhile,different in-situ stimulation modules can be seamless integrated into the X-Nano TEM holder in demand to perform different in-situ TEM experiments.With the X-Nano system,we combined nano-manipulation,dynamic observation and 3D reconstruction to uncover dynamic information of the microstructure evolution under stimuli and to establish its dynamic 3D model with quasi-four-dimensional(three dimensions on space and one dimension on time)TEM micro-nano mechanics characterizing experiment,proposing new method for the development of micro-nano mechanics characterizing system as well as the research of deformation mechanisms of covalent solids.For demonstration,we performed quasi-four-dimensional TEM experiment on single crystal Si nano-pillar,giving the evolution of 3D dislocation networks in Si specimen for the first time.The X-Nano system has promoted the development of the interdiscipline of mechanics and material science.Using the instrument,we collaborate with Yanshan University research group to bend diamond nanoneedles in TEM in situ,showing that its maximum reversible elastic deformation depends both on the diameter and orientation of nanoneedle.During experiment,a <100>-oriented nanoneedle with a diameter of 60 nm exhibit highest elastic tensile strain(13.4%)and tensile strength(125 GPa).These values are comparable with the theoretical elasticity and Griffith strength limits of diamond,respectively.We also performed in-situ compressional testing under TEM for submicron-sized diamond pillars,and demonstrated its dislocation plasticity on room-temperature.The result answered the long-standing controversy about whether diamond has room-temperature plasticity.Through 3D reconstruction and atomic resolution imaging of the dislocation network generated in the diamond pillars,it is found that dislocations slip in {100} planes under <111>-and <110>-oriental compression in general,but slip in {111} planes under <100>-oriental compression.The dislocation movement in diamond highly depends on loading direction.Due to the strong covalentity and anisotropy of its atomic bonds,the dislocation behavior of diamond is completely different from other face-centered cubic crystals,e.g.,Cu,Au,Ag,and Si,which changed the traditional perception of the dislocation slip of face-centered cubic crystals.The X-Nano system has been applied in research groups such as Suresh of the National University of Singapore,Jian Lu of the City University of Hong Kong.The instrument and research contribute to the development of 3D reconstruction method of TEM,and innovatively developed experimental method of quasi-dynamic evolution characterizing of 3D microstructures.The above progress has been highlighted by the website of the Nature Science Foundation of China.