GRAPHITE-DIAMOND TRANSITION IN GEM ANVIL CELLS

By replacing the anvils in a diamond cell with transparent gem materia ls, a gem anvil cell (GAC) has been constructed for high-pressure gene ration. We reached pressures of 8.9 and 7.8 GPa with cubic zirconia an d sapphire anvil cell, respectively. For high-temperature studies the cell can be heated to temperatures as high as 2000-degrees-C with resi stive heating of the gasket. Simultaneously high temperature and press ure approaching 1700-degrees-C and 6 Gpa were obtained as indicated by the direct conversion of graphite to diamond in the high-temperature GAC.