A slide-type multianvil ultrahigh pressure apparatus and calibrations of its pressure and temperature

Abstract

A slide-type ultrahigh pressure apparatus with 6/8 anvils is described. The three-supporting pillars of the main framework and the slide-type multi-anvils have conformable mechanical symmetry. Under the loading uniaxial pressure, the first-stage anvils can be self-corrected and run with excellent synchronicity and reproducibility. In the present experiments, the edge length of pyrophyllite octahedron is 125 mm and the truncation edge length of tungsten carbide anvil is 8 mm. The cell pressure was calibrated at room temperature by means of the known pressure-induced phase transitions of Bi and ZnTe at 255, 77, 96 and 120 GPa. The cell temperature under 10 GPa was measured up to 1560 ℃ by WRe3-WRe25 thermocouple. The temperature calibration was reconfirmed and extended to the higher range by observation of diamond formation on the interface between graphite heater and steel plug, and by comparison of the variational details of recorded data and the Fe—C phase diagram, and then the axial temperature gradient was estimated to be about 21 ℃/mm.