Whole-cell heater for the diamond anvil cell

An external heating assemblage allowing diamond anvil cell (DAC) experiments at megabar pressures and temperatures above 1200 K was constructed. The complete high-pressure high-temperature system consists of an anvil assembly made from a special high-temperature alloy, a mechanical loading mechanism, and external resistive heaters placed around the cell. The new system allows fine adjustment of the pressure (within 1 GPa) over the whole temperature range. It maintains constant pressure (within 1 GPa at megabar pressures) and constant temperature (within 5 K at 1000 K) for several hours. Temperature is measured with an external thermocouple. The pressure chamber does not have a measurable temperature gradient. The new heating assemblage is easily coupled with a experimental setup at synchrotron radiation facilities and Raman spectrometers. We tested the performance of the new system by measuring the thermal expansion of Fe0.90Ni0.05 at different pressures and by studying phase transformations in TiO2 and the melting curve of H2O. (C) 2003 American Institute of Physics.