USE OF A NEW DIAMOND COMPOSITE FOR MULTIANVIL HIGH-PRESSURE APPARATUS

A newly developed diamond composite (Advanced Diamond Composite, ADC) was tested as the anvil material for a double-stage multianvil (MA6-8) apparatus. Pressures over 30 GPa at room temperature were produced at relatively small press loads without any significant damages on the ADC anvils. The ADC anvil was found to be more transparent to X-ray beams of a wide range of energy as compared with a competitive sintered polycrystalline diamond (SYNDIE), and is accordingly suitable for an X-ray window under pressure. Electrical resistivity of ADC, however, is higher by about one order of magnitude than that of SYNDIE, which would restrict its use as a lead for electric power supply to the furnace. A hybrid anvil system with four ADC anvils plus four tungsten carbide anvils, the latter being used as the electric leads, was introduced for high temperature runs. This system has enabled to generate temperatures to 1500-degrees-C at pressures of 25-33 GPa and to synthesize high-pressure phases relevant to the lower mantle mineralogy.