We have measured the soft X-ray absorption and emission spectra of near B-K and C-K absorption edges of highly oriented pyrolytic graphite (HOPG) doped with a small amount (0.32 at.%) of boron (B), including incident/takeoff angle dependence.The main peak intensities at the B-K edge around 182 eV were almost independent on the change of takeoff angle. On the other hand, the satellite peak around 185 eV becomes larger as the takeoff angle becomes smaller. Based on this result, unlike the previous assignment of the main peak predicted from the quantum chemical calculation (π orbitals), it is reasonable to attribute the main peak to the σ orbitals. The takeoff angle dependence of the B-K emission is similar to the angle dependency of the C-K emission of undoped HOPG. Based on this and the theoretical consideration, it is presumable that the doped B atom does not intercalate between the layers of HOPG; it replaces the C atom of the hexagonal network structure and has a wave function similar to that of C atoms (sp 2 type hybridized orbital).
Abstract. This article introduces a MEMS batch fabrication process of micro magnet array with bipolar magnetic pole for an electromagnetic vibration energy harvester. In order to obtain the large electromotive force from large magnetic flux density change, we established the fine patterned alternating magnetized bipolar magnetic structure. The batch fabrication process of bipolar magnet array is composed of two wafers processing with S-pole and N-pole magnetization and bonding process. By the prototype fabrication of bipolar magnet with the 200 m SN-interval, we showed the usability of the batch fabrication process of the bipolar magnet array. In addition, we estimated the generated power of energy harvester with a bipolar magnet array. Compared to a harvester with monopolar magnet array, we showed the good result for bipolar one.
This paper shows the fabrication of the prototype of electromagnetic MEMS energy harvester and the power generation experiment al results. The electromagnetic energy harvester consists of the sputtered NdFeB magnet film on high aspect ratio corrugated Si trench and the Au serpentine coil. The each structure of the device is fabricated with the optimum geometry designed by the FEM simulation. In the result, we obtained 2.65 mV of the induced electromotive force and 7.60 nW of the output power. The experimental results agreed well with simulation results, and we confirmed the usefulness of the analytical method for the estimation of the power generation.
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