The pressure generated by the repeated loading in a girdle high pressure apparatus was calibrated for the purpose of measuring the geophysically important properties at high pressures and temperatures. The calibration was based on the transition in bismuth, thallium, cesium and barium at room temperature, and on the quartz-coesite and coesite-stishovite transitions at high temperatures. The press load necessary for each calibrated transition decreased with frequency of repetition approaching asymptotically a convergent value. The convergent value was attained by the five time repetition up to 50 kb of sample pressure and by the ten time repetition up to 80 kb. The efficiency of the generated pressure to applied load at 70 kb was 51% in the first loading, 58% in the second and finally attained to 66%. The calibration curves at room temperature were applicable at high temperatures.
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