日時 ： ２００９年１１月１３日（金）※16：30～
場所 ： 愛媛大学総合研究棟Ⅰ 4F 共通会議室（理学部構内）
要 旨
Nano-polycrystalline diamond (NPD) converted directly from graphite under high pressure and high temperature consists of nano-diamond particles of tens nanometer and has extremely high hardness, equivalent to or even higher than that of the hardest plane of a single crystal diamond. Because of these features, NPD has immeasurable potential for applications to high pressure anvils, as well as for industrial use.
For applying this material to these applications, synthesis of NPD with larger dimensions is strongly desired. However, the dimension of NPD has been limited as small as 4mm because it has been needed for synthesis to generate pressure over 15 GPa. In order to enlarge the dimension of NPD, it is important to investigate the lower pressure limit for NPD formation because reduction of the pressure value leads to synthesis larger NPD by using a larger cell assembly. As the lower limit of pressure and temperature conditions have not been well known to date, I have investigated these lower limits for NPD synthesis. Although the synthesis of NPD has been made at pressure over 15 GPa in earlier study, experimental results of present study demonstrated that NPD can be formed at significantly lower pressure of ~12 GPa, which should be important progress to synthesize larger NPD sample under lower press load. Based on these results, synthesis of NPD with dimensions of ~8mm is now on challenging using a newly introduced 6000-ton Kawai-type multi-anvil apparatus “BOTCHAN-6000”. Adopting the apparatus with tungsten carbide anvils larger than those in earlier study, it is expected to enlarge the NPD dimensions because it is possible to generate the pressure required for synthesis with a larger cell assembly due to increment of the maximum press load. Details of recent experimental results in the apparatus will be also described in the seminar.
問い合わせ先：土屋 卓久 TEL （089）927-8198
E-mail takut@sci.ehime-u.ac.jp
