5 research outputs found
Interplanar stiffness in defect-free monocrystalline graphite
The interplanar bond strength in graphite has been identified to be very low
owing to the contribution of the van der Waals interaction. However, in this
study, we use microscopic picosecond ultrasound to demonstrate that the elastic
constant, , along the axis of defect-free monocrystalline graphite
exceeds 45 GPa, which is higher than reported values by 20\%. Existing theories
fail to reproduce this strongly correlated interplanar system, and our results,
thus, indicate the necessity for improvement. Since the LDA+U+RPA method,
including both random phase approximation correlation and short-range
correlation in Wannier orbitals, shows better agreement with the
observation than LDA or even than ACFDT-RPA, the experimental results indicate
non-negligible electron correlation effects with respect to both the
short-range and long-range interactions.Comment: (Main text) 5 pages, 3 figures, (Supplementary material A) 2 pages, 2
figures, (Supplementary material B) 12 pages, 1 figur
Fundamental Study for a Graphite-Based Microelectromechanical System
We aimed to develop a process for constructing a carbon-based microelectromechanical system (MEMS). First, we prepared a highly oriented pyrolytic graphite (HOPG) crystal microsheet by exfoliation. We fabricated cantilevers and a double-clamped beam by controlling the thickness of the HOPG microsheet using a MEMS process. Second, we used a graphite sheet with contour line adhesion by metal sputter deposition. Third, we used a highly accurate graphite sheet with face adhesion and laser cutting. The first resonance frequencies were evaluated. We confirmed improvement in Q values to 1/10 level of a quarts vibrator, high performance, and a simple structure
Development of a high-density highly oriented graphite stripper
High-density highly oriented graphite sheets provided by Kaneka Corporation have been applied as stripper disks for heavy-ion acceleration at RIKEN RI Beam Factory since 2014. The graphite sheets withstand increasing amounts of beam intensity. We observed the graphite sheets after beam irradiation with an electron microscope and their lifetime was discussed