Three-dimensional(3D)structural analysis is an important field in physical and biological sciences.There exist two groups of electron microscopy methods that are capable of providing 3D structural information of an ob...Three-dimensional(3D)structural analysis is an important field in physical and biological sciences.There exist two groups of electron microscopy methods that are capable of providing 3D structural information of an object,i.e.,electron tomography and depth sectioning.Electron tomography is capable of resolving atoms in all three dimensions,but the accuracy in atomic positions is low and the object size that can be reconstructed is limited.Depth sectioning methods give high positional accuracy in the imaging plane,but the spatial resolution in the third dimension is low.In this work,electron tomography and depth sectioning are combined to form a method called multiple-section local-orbital tomography,or nLOT in short.The nLOT method provides high spatial resolution and high positional accuracy in all three dimensions.The object size that can be reconstructed is extended to a million atoms.The present method establishes a foundation for the widespread application of atomic electron tomography.展开更多
Amorphous materials such as glass,polymer and amorphous alloy have broad applications ranging from daily life to extreme conditions due to their unique properties in elasticity,strength and electrical resistivity.A be...Amorphous materials such as glass,polymer and amorphous alloy have broad applications ranging from daily life to extreme conditions due to their unique properties in elasticity,strength and electrical resistivity.A better understanding of atomic structure of amorphous materials will provide invaluable information for their further engineering and applications.However,experimentally determining the three-dimensional(3D)atomic structure of amorphous materials has been a long-standing problem.Due to the disordered atomic arrangement,amorphous materials do not have any translational and rotational symmetry at long-range scale.Conventional characterization methods,such as the scattering and the microscopy imaging,can only provide the statistic structural information which is averaged over the macroscopic region.The knowledge of the 3D atomic structure of amorphous materials is limited.Recently atomic resolution electron tomography(AET)has proven an increasingly powerful tool for atomic scale structural characterization without any crystalline assumptions,which opens a door to determine the 3D structure of various amorphous materials.In this review,we summarize the state-of-art characterization methods for the exploration of atomic structures of amorphous materials in the past few decades,including X-ray/neutron diffraction,nano-beam and angstrom-beam electron diffraction,fluctuation electron microscopy,high-resolution scanning/transmission electron microscopy,and atom probe tomography.From experimental data and theoretical descriptions,3D structures of various amorphous materials have been built up.Particularly,we introduce the principles and recent progress of AET,and highlight the most recent groundbreaking feat accomplished by AET,i.e.,the first experimental determination of all 3D atomic positions in a multi-component glass-forming alloy and the 3D atomic packing in amorphous solids.We also discuss the new opportunities and challenges for characterizing the chemical and structural defects in amorphous materials.展开更多
基金supported by Basic Science Center Project of the National Natural Science Foundation of China(52388201)the National Natural Science Foundation of China(51525102)。
文摘Three-dimensional(3D)structural analysis is an important field in physical and biological sciences.There exist two groups of electron microscopy methods that are capable of providing 3D structural information of an object,i.e.,electron tomography and depth sectioning.Electron tomography is capable of resolving atoms in all three dimensions,but the accuracy in atomic positions is low and the object size that can be reconstructed is limited.Depth sectioning methods give high positional accuracy in the imaging plane,but the spatial resolution in the third dimension is low.In this work,electron tomography and depth sectioning are combined to form a method called multiple-section local-orbital tomography,or nLOT in short.The nLOT method provides high spatial resolution and high positional accuracy in all three dimensions.The object size that can be reconstructed is extended to a million atoms.The present method establishes a foundation for the widespread application of atomic electron tomography.
基金supported by the National Natural Science Foundation of China(22172003)High-performance Computing Platform of Peking University.
文摘Amorphous materials such as glass,polymer and amorphous alloy have broad applications ranging from daily life to extreme conditions due to their unique properties in elasticity,strength and electrical resistivity.A better understanding of atomic structure of amorphous materials will provide invaluable information for their further engineering and applications.However,experimentally determining the three-dimensional(3D)atomic structure of amorphous materials has been a long-standing problem.Due to the disordered atomic arrangement,amorphous materials do not have any translational and rotational symmetry at long-range scale.Conventional characterization methods,such as the scattering and the microscopy imaging,can only provide the statistic structural information which is averaged over the macroscopic region.The knowledge of the 3D atomic structure of amorphous materials is limited.Recently atomic resolution electron tomography(AET)has proven an increasingly powerful tool for atomic scale structural characterization without any crystalline assumptions,which opens a door to determine the 3D structure of various amorphous materials.In this review,we summarize the state-of-art characterization methods for the exploration of atomic structures of amorphous materials in the past few decades,including X-ray/neutron diffraction,nano-beam and angstrom-beam electron diffraction,fluctuation electron microscopy,high-resolution scanning/transmission electron microscopy,and atom probe tomography.From experimental data and theoretical descriptions,3D structures of various amorphous materials have been built up.Particularly,we introduce the principles and recent progress of AET,and highlight the most recent groundbreaking feat accomplished by AET,i.e.,the first experimental determination of all 3D atomic positions in a multi-component glass-forming alloy and the 3D atomic packing in amorphous solids.We also discuss the new opportunities and challenges for characterizing the chemical and structural defects in amorphous materials.
