Microstructural Evolution in a CeO2-Gd2O3 System
Abstract Microstructural evolution in a CeO2-Gd2O3 system at atomic and nanoscale levels with increasing Gd concentration has been comprehensively investigated by transmission electron microscopy. When the Gd concentration was increased from 10 to 80 at.%, the phase transformation from ceria with fluorite structure to solid solution with C-type structure was not a sudden change but an evolution in the sequence of clusters, domains, and precipitates with C-type structure in the fluorite-structured matrix. Moreover, the ordering of aggregated Gd cations and oxygen vacancies in these microstructural inhomogeneities developed continuously with increasing Gd concentration. This microstructural evolution can be further described based on the development of defect clusters containing Gd cations and oxygen vacancies.
Crystal-structure effects in the Ce L3-edge x-ray-absorption spectrum of CeO2: Multiple-scattering resonances and many-body final states.
Here we report the interpretation of all spectral features of Ce ${\mathit{L}}_{3}$ x-ray-absorption near-edge structure (XANES) of ${\mathrm{CeO}}_{2}$ over a 40 eV range. The local partial unoccupied density of states in the initial state and in the fully relaxed final state have been calculated by the full multiple-scattering approach. The wave function of the excited electron in the final states of the Ce ${\mathit{L}}_{3}$-edge XANES spectrum is found to be determined by the multiple-scattering processes in a large size cluster formed by at least 45 atoms. We predict, in good agreement with the experimental data, the crystal-field splitting of 5d states in the final state ${\mathrm{\ensuremath{\Delta}}}_{\mathit{f}}$=4.0\ifmmode\pm\else\textpm\fi{}0.2 eV and its variation from the initial to the final state. The many-body final states for the 2p\ensuremath{\rightarrow}5,\ensuremath{\varepsilon}d transition, arising from the configuration interaction due to mixing of Ce 4f and O 2p valence orbitals, have been calculated taking into account the crystal-field splitting of the 5,\ensuremath{\varepsilon}d states and they give a full explanation for the low-energy shoulder on the Ce ${\mathit{L}}_{3}$ x-ray-absorption spectrum white line that was the object of a long-standing discussion. The origin of the pre-edge peak at about 10 eV below the white line maximum is explained as due to transitions at the bottom of the conduction band.
CNC Desktop Vertical Machining Bench Design and Cooling Fluid Application
Today's manufacturing technologies, the human work force is used and at least a minimum level of margin of error is used in CNC machines. Desktop CNC machine tools and CNC machine tools are developed in parallel with the development of personal computers. This study provides CNC training institutions for education, small and medium-sized enterprises for commercial purposes use the low-cost desktop machine has been designing and manufacturing of CNC vertical machining was carried out. Desktop CNC machine tools and production capacity to handle the kind of material was applied to increase the cooling fluid. Through A199 and Fe37 the cooling fluid application desktop CNC machine tools, such as processing of materials that are difficult to successfully processed. Keywords—CNC, Desktop CNC Machine, CNC Design