An internally heated composite gasket for diamond-anvil cells using the pressure-chamber wall as the heating element

Abstract

The implementation of a heating element to a composite gasket for high-temperature applications in the diamond-anvil cell was developed based on a double-gasket assemblage. The heating element is a thin platinum wall that covers the central borehole of the metal–ceramic–metal composite gasket and interconnects the two metal component parts of the gasket. Applying electric powers up to 35 W to the two gasket metal components result in ring-like heating around the sample inside the pressure chamber with temperatures exceeding ∼2000 K in individual cases. The ring-like distribution of the maximum temperature located at the pressure-chamber wall facilitates a homogeneous temperature distribution at the sample position. As a consequence of the concentration of the heating power to the pressure chamber region, gradients of surface temperatures, both at the gasket and the diamond anvil, appear to be more pronounced compared with those known for classical external electrical heating. Apart from the tests of the mechanical stability on high-pressure operation in the diamond anvil cell at room temperature, the influence of the anvils in contact with the gasket on the characteristic power–temperature curves, temperature gradients and thermal equilibration resulting from changes in electrical power settings have been evaluated within the scope of a series of experimental investigations.

Keywords:

• composite gasket
• internal electric heating
• pressure-chamber wall
• high-temperature application
• diamond anvil cell

Acknowledgements

We would like to thank all members of the Materialphysik group at the GSI, Darmstadt, for using the Raman spectrometer and in particular C. Weikusat, B. Schuster and R. Klein for their assistance in various pressure determinations. We would also like to thank I. Fin and O. Wienand, Institute of Geosciences, Heidelberg, for making the polished cross sections through the gaskets. We would like to express our gratitude to an anonymous reviewer for the positive comments and suggestions.