纳米材料和纳米结构2透射电子显微镜及其能谱学习教案

1、会计学1纳米材料和纳米结构纳米材料和纳米结构(jigu)2透射电子显微透射电子显微镜及其能谱镜及其能谱第一页，共37页。第1页/共37页第二页，共37页。Instrument Structure of TEM第2页/共37页第三页，共37页。Schematic structure of a TEM第3页/共37页第四页，共37页。第4页/共37页第五页，共37页。第5页/共37页第六页，共37页。2. 3 Imaging Interpretation and theoretical simulation第6页/共37页第七页，共37页。Theoretically simulated image

2、s for a decahedral Au partical at various orientations and at different focuses (f = 42 nm and 70 nm)第7页/共37页第八页，共37页。3. 1 Polyhedral Shapes of Nanocrystales第8页/共37页第九页，共37页。第9页/共37页第十页，共37页。Geometrical shapes of cubo-octahedral nanocrystals as a function of the ratio, R, of the growth rate along to

3、 第10页/共37页第十一页，共37页。 The particles with 0.87 R1.73 have the 1 1 1 and 1 0 0 facets, the other group of particles has a fixed (111) base with exposed 1 1 1 and 1 0 0 facets. An increase in the area ratio of 111 to 100 results in the evolution of particle shapes from a triangle-based pyramid to a tetr

4、ahedron （四面体）（四面体）.第11页/共37页第十二页，共37页。Geometrical shapes of multiply twinned decahedral （十面体）（十面体）and icosahedral （二十面体）（二十面体）particles第12页/共37页第十三页，共37页。HRTEM images of cubic Pt nanocrystals oriented along (a) 001 and (b) 110, showing surface steps/ledges and thermodynamically nonequilibrium shapes

5、 第13页/共37页第十四页，共37页。HRTEM images of Pt nanocrystals (a) with a truncated（去顶的） octahedral shape and oriented along 110, and (b) with a octahedral shape and oriented along 110 and 001. The inset in (a) is a model of the particle shape 第14页/共37页第十五页，共37页。第15页/共37页第十六页，共37页。HRTEM images of truncated tet

6、rahedral Pt nanocrystals oriented along 110. The surface steps and ledges at the truncated corners are clearly resolved第16页/共37页第十七页，共37页。3. 2 Twinning Structure and Stacking Faults第17页/共37页第十八页，共37页。HRTEM images of (a) Pt and (b) Au nanocrystals having twin (T) and stacking fault (S) structures, re

7、spectively. The twin plane and stacking fault are parallel to the direction of the electron beam第18页/共37页第十九页，共37页。3. 3 Decahedral and Icosahedral Particles The two most typical examples of multiple twinned particles are the decahedral (十面体）十面体）a n d i c o s a h e d r a l（ 二 十 面 体 ）（ 二 十 面 体 ）, a n

8、d t h e corresponding particles are the most extensively studied twinned nanocrystals.第19页/共37页第二十页，共37页。Atomic models of (a) decahedral, and (b, c) icosahedral nanocrystals第20页/共37页第二十一页，共37页。TEM images of decahedral Au nanocrystals when the incident electron beam is parallel or nearly parallel to

9、the five-fold symmetry axis. The strain field introduced by the five-fold twins is apparent in (a). A fourier transform of the image clearly reveals the five-fold symmetry 第21页/共37页第二十二页，共37页。3. 4 Nucleation and Growth ofNanoparticlesHRTEM images recorded from the centers of carbon spheres, showing

10、the spiral growth near the centers第22页/共37页第二十三页，共37页。2. 4 Electron Holography（全息（全息(qunx)）Holography is based on the interference and diffraction properties of waves, thereby producing a true image of an object (including amplitude and phase) without any distortion of the lenses.第23页/共37页第二十四页，共37页

11、。(a) Formation of off-axis electron hologram in TEM using an electrostatic biprism, and (b) Reconstruction of electron hologram using laser diffraction第24页/共37页第二十五页，共37页。HRTEM image of a Co-Sm film第25页/共37页第二十六页，共37页。Comparison of TEM (upper images) and simulated nanodiffraction patterns (bottom im

12、ages) of 0001 zone axis (three layer stacking ABCABC), 20-21 zone axis (stacking ABACABAC), 10-10 zone axis (five layer stacking ABCABABCAB.)第26页/共37页第二十七页，共37页。Comparison of TEM (upper images) and simulated nanodiffraction patterns (bottom images) of 11-20 zone axis (three layer stacking ABCABC), 1

13、1-20 zone axis (four layer stacking ABACABAC), 11-20 zone axis (five layer stacking ABCABABCAB.)第27页/共37页第二十八页，共37页。Identifications of possible ordering by 0001 zone axis patterns: (a) Co3V type ordering in the close packed plane and (b) Co3Ni type ordering in the close packed plane.(c, d) are corresponding diffraction patterns.(e) Diffraction pattern of a disordered HCP structure(f) TEM pattern第28页/共37页第二十九页，共37页。Comparison of nanodiffraction patterns (a) from a crystallite and (b) from