High-Pressure Crystallography

Diamond Anvil Cells

Diamond Anvil cells (DACs) are a relatively simple way of generating high pressure on a single crystal.

In collaboration with Stephen Moggach at UWA, we developed a way to use micro-DACs on MX1. These DACs can be mounted on the goniometer like a normal sample, and can generate pressures up to 5 GPa.

If you use DACs on MX1, please reference this paper: High-pressure single-crystal diffraction at the Australian Synchrotron

Open Design of a mini-DAC	Open DAC scheme showing location of crystal

How to run high-pressure experiments:

During the current development phase, this work needs to be done in collaboration with the beamline staff and Stephen. If you have CAP beamtime scheduled on MX1, you can use this to run high pressure experiments. But you will need to do it during staff working hours and will need to allow most of the day to learn the protocol and collect data. You can also apply for rapid access time for high pressure experiments.

Further info: https://www.ansto.gov.au/facilities/australian-synchrotron/melbourne-access-proposals

Crystal requirements are:

• Well diffracting. They should be of sufficient quality to get good data on MX1.

• Up to 200 um. Any larger and they won’t fit in the DAC.

• Stable at room temperature and in air. The mounting of crystals in the DAC is quite tedious, so you won’t want to be doing it with crystals that are delicate.

• Well understood. You will need a good dataset of them at room temperature and ambient pressure. This will help you when solving and refining high pressure data.

Workflow:

Instruction pages:

https://asuserwiki.atlassian.net/wiki/spaces/UO/pages/1568538682

High pressure data analysis

https://asuserwiki.atlassian.net/wiki/spaces/UO/pages/1568571424

Generating and measuring pressure

The pressure on your sample is evenly applied by a hydrostatic media which surrounds your crystal within the sample chamber. This media can be many solvents or crystal mounting oil, but they need to be selected based on the pressure at which they will themselves crystallise, and if your crystal will dissolve. See below for some example solvents and solvent mixtures.

The pressure can be measured via a small piece of Ruby which is also included in the sample chamber. Ruby has a fluorescence doublet when excited with green light, and this doublet shifts according to the pressure the ruby is under.