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Deformation of the Diamond Anvil Cell from Finite Element Modeling

The Diamond Anvil Cell is used in ultra high pressures experiments.  It allows us to create conditions of pressures of several millions of atmospheres and to sutdy the physical properties of our sample under these conditions.

Recent x-ray experiments imaged deformations of the diamond tip under multimegabar pressures. Although often considered as a rigid body, diamond was found to undergo very large elastic deformations near the sample region. We performed  a theoretical study of this phenomenon using a finite-element modeling and first-principles calculation. The approach allowed us to understand the x-ray observations and to obtain predictions of the stress and strain relations that are not accessible experimentally.

It also provided the following images showing three-dimensional views of the deformation and pressure distribution in a diamond anvil cell (100 GPa = 1 million atmospheres pressure). The views show a cross-sectional cut through the diamond and the metal (or gasket) being compressed. The calculations show that diamond elastically bends like rubber  under these ultrahigh pressure conditions, in agreement with experimental observations. On some of the pictures the diamond and the gasket  were artificially separated in order to show the pressure  distribution inside the device and along the interfaces.

Diamond Anvil Cell at 350 GPa
Diamond Anvil Cell at 280 GPa
Diamond Anvil Cell at 280 GPa
Diamond Anvil Cell at 280 GPa
Diamond Anvil Cell at 280 GPa, with the FEM grid
Sebastien Merkel, 06/1999

© Sébastien Merkel, Université de Lille, France

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