|Budget Amount *help
¥5,800,000 (Direct Cost: ¥5,800,000)
Fiscal Year 1989: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1988: ¥4,600,000 (Direct Cost: ¥4,600,000)
(1) High-pressure generation by a multiple anvil system with sintered diamond. Sintered diamonds are employed for the anvil of second-stage MA8 high pressure system and the anvil of fist stage is used tungsten carbide anvil for MA6 system. The sintered diamond blocks (SYNDAX L555, De Beers Diamond Co. Ltd) are cemented with silicon carbide, therefore, the composites have excellent transparency for the x-ray beam. The sintered diamonds are polished to form cubes and their corner are truncated to form the anvil head of the MA8 apparatus. The truncated edge lengths are 0.5 and l.0mm. The edge length of the octahedron of the magnesia pressure medium is 3.4mm for the anvil with TEL=l.0mm. The pressure generated was determined by measuring the lattice constant of gold. Pressures generated up to 28GPa for TEL=l.0mm and 41GPa for TEL=0.5mm.
(2) High pressure generation In large volume In order to attain higher pressure in larger volume, we have to clear three factors, that is, 1) the large forc
e utilized, 2) high strength of material, and also 3) the large pressure derivative of strength. The no bander sintered diamond can be clear the three factors, but it is not possible to get it. The sintered diamond blocks (SYNDIE, 1285/D27, De Beers Diamond Co. Ltd) are polished to form cubes, and their corners are truncated to form the anvil head of the MA8 apparatus. A side of a sintered diamond cube after polishing has 8.45mm in length. The truncated edge length(TEL)of the anvil used for the present is 2mm. In this case, it is easy to generate pressure up to 28GPa(Fe85%V%15 alpha - epsilon transition), but press of the anvil head increase up to 6GPa, therefore, it is not possible to increase pressure.
(3) 64-type high pressure apparatus The high pressure system used present experimentare constituted with eight blocks. A block is consisted with one sintered diamond anvile (8.45mm) and 7 pieces of WC cubic(8mm) anvils. Metal gaskets are put in between the an vils. The system is pressed by DIA-30. Pressures in excess of 35GPa were obtained on the basis of minimum point of electrical resistance of the Fe80%V20%. Less