Micro-/nanostructural investigation of laser-cut surfaces of single- and polycrystalline diamonds |
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Authors: | Hiroaki Ohfuji Takuo Okuchi Shoko Odake Hiroyuki Kagi Hitoshi Sumiya Tetsuo Irifune |
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Affiliation: | 1. Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 Ehime, Japan;2. Institute for study of the Earth''s interior, Okayama University, 827 Yamada, Misasa, 682-0193 Tottori, Japan;3. Geochemical Laboratory, Graduate School of Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan;4. Electronics & Materials R&D Laboratories, Sumitomo Electric Industries, LTD., 1-1-1 Koya-kita, Itami, 664-0016 Hyogo, Japan |
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Abstract: | Micrometer- to nanometer-scale structures of the cut surfaces of single- and polycrystalline diamonds by a pulsed ultraviolet laser have been thoroughly investigated by scanning and transmission electron microscopy. Within the laser-cut grooves, the processed diamond surfaces are extensively covered with laser-modified debris which consists of complex layered units of graphite with various crystallinities. The units consist of 1) highly oriented graphite, 2) corrugated graphite, and 3) nanocrystalline graphite, which are sequentially located from the surface of the underlying diamond substrate to the center of the grooves. Detailed textural examinations revealed that the highly oriented graphite unit is a product of the initial graphitization of diamond by a solid-state diffusion process, whereas the latter two units are deposition products from the liquid and/or vapor phases of carbon in the later stage. The present study demonstrates that the laser-cutting of diamonds proceeds in a two-step process: 1) extensive graphitization of laser-scanning path and 2) subsequent sublimation of the pre-formed graphite. These processes are basically identical among the three different types of diamonds (single crystal type Ib, single crystal type IIa and nano-polycrystalline aggregate) tested in this study. |
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