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Classical Size Effect In Copper Thin Films: Impact Of Surface And Grain Boundary Scattering On Resistivity, Tik Sun
Electronic Theses and Dissertations
Surface and grain boundary electron scattering contribute significantly to resistivity as the dimensions of polycrystalline metallic conductors are reduced to, and below, the electron mean free path. A quantitative measurement of the relative contributions of surface and grain boundary scattering to resistivity is very challenging, requiring not only the preparation of suitably small conductors having independent variation of the two relevant length scales, namely, the sample critical dimension and the grain size, but also independent experimental quantification of these two length scales. In most work to date the sample grain size has been either assumed equal to conductor dimension or …
Quantitative Thickness Mapping In High-Angle Annular Dark-Field (Haadf) Scanning Transmission Electron Microscopy (Stem), Haritha Nukala
Quantitative Thickness Mapping In High-Angle Annular Dark-Field (Haadf) Scanning Transmission Electron Microscopy (Stem), Haritha Nukala
Electronic Theses and Dissertations
Only a few methods are currently available for the measurement of sample thicknesses in Transmission Electron Microscopy (TEM). These methods, Convergent-Beam Electron Diffraction (CBED) and thickness mapping in Energy-Filtered TEM (EFTEM), are either elaborate or complex. In this present work, I have investigated and come up with a simple straight-forward method to measure the local thickness of a TEM sample with the atomic number (Z-contrast) imaging using High-Angle Annular Dark Field (HAADF) Scanning Transmission Electron Microscopy (STEM). HAADF STEM shows atomic number contrast for high scattering angles of the electrons, owing to predominant electron scattering at the potential of the …
N Multilayer Thin Film Reactions To Form L10 Fept And Exchange Spring Magnets, Bo Yao
N Multilayer Thin Film Reactions To Form L10 Fept And Exchange Spring Magnets, Bo Yao
Electronic Theses and Dissertations
FePt films with the L10 phase have potential applications for magnetic recording and permanent magnets due to its high magnetocrystalline anisotropy energy density. Heat treatment of n multilayer films is one approach to form the L10 FePt phase through a solid state reaction. This thesis has studied the diffusion and reaction of n multilayer films to form the L10 FePt phase and has used this understanding to construct exchange spring magnets. The process-structure-property relations of n multilayer films were systematically examined. The transmission electron microscopy (TEM) study of the annealed multilayers indicates that the Pt layer grows at the expense …
Transmission Electron Microscopy Studies In Shape Memory Alloys, Madhavi Tiyyagura
Transmission Electron Microscopy Studies In Shape Memory Alloys, Madhavi Tiyyagura
Electronic Theses and Dissertations
In NiTi, a reversible thermoelastic martensitic transformation can be induced by temperature or stress between a cubic (B2) austenite phase and a monoclinic (B19') martensite phase. Ni-rich binary compositions are cubic at room temperature (requiring stress or cooling to transform to the monoclinic phase), while Ti-rich binary compositions are monoclinic at room temperature (requiring heating to transform to the cubic phase). The stress induced transformation results in the superelastic effect, while the thermally induced transformation is associated with strain recovery that results in the shape memory effect. Ternary elemental additions such as Fe can additionally introduce an intermediate rhombohedral (R) …
Evolution Of Lamellar Structures In Al-Ag Alloys, Sephalika Senapati
Evolution Of Lamellar Structures In Al-Ag Alloys, Sephalika Senapati
Electronic Theses and Dissertations
In the present study, the formation and the evolution of lamellar structures in different Al-Ag alloys were investigated by transmission electron microscopy (TEM). Plates of the hexagonal [gamma] phase form semi-coherently on the {111} planes of the face centered cubic lattice of the alloy after the formation of Guinier-Preston zones. Guinier-Preston zones are metastable coherent preprecipitates which are silver rich in the aluminum-rich Al-Ag alloys. The decomposition of aluminum rich Al-Ag alloys, particularly the sequence of the later stages of precipitate formation was studied. With scanning electron microscopy and high-resolution transmission electron microscopy the development of the [gamma] phase was …