Rare gases used as pressure transmitting medium in a diamond anvil cell (DAC) provide a purely hydrostatic environment (until they freeze) and are also stable over a wide range of pressure. In addition, rare gases are thermal insulators and transparent to IR radiation, making them particularly attractive in high temperature high pressure DAC experiments.
There are two ways to load gases in a DAC: the first is to use a gas compressor to densify the gases at room temperature before loading in the high pressure chamber of the cell. This is the so-called high pressure gas loading technique.
The second method is to use relatively simple and cost-effective cryogenic techniques wherein liquefied gas is loaded in to the DAC. This is the the cryogenic gas-loading technique and the Diacell® Cryoloader employs this method.
The Diacell® Cryoloader makes it easy and convenient to load liquid argon into a DAC since liquified argon (boiling temperature of about 87 K) can be cooled by liquid nitrogen (boiling temperature of 77 K). The Diacell® Cryoloader apparatus consists of a cylindrical chamber with a lid, gas inlet and outlets and a viewing port.
For operation, one can view the video in our YouTube channel demonstrating the various steps. The DAC is placed inside the Diacell® Cryoloader and its lid closed. Purging of the Cryoloader with pure argon gas will guarantee the presence of only argon in the chamber.
Then the Cryoloader may be placed inside a flask which will also hold the liquid nitrogen. Liquid nitrogen is then poured in to this flask, whilst pure argon gas is let into the vessel at an optimum rate. The level of liquid argon collected in the vessel is monitored through the top glass viewing port of the Cryoloader. Once the desired level is reached, the flow of argon can be stopped and the chamber opened. The DAC holder is then tightened so that liquid argon becomes trapped in the gasket hole between the diamond anvils.
The cell and holder can then be removed from the Cryoloader and slowly brought back to room temperature. A low temperature heat exchanger ensures a very efficient cooling and condensation of the argon gas. A loading can take as little as 15 minutes.
Compatible Almax easyLab’s DACs: OmniDACs, Bragg-(G)s, Bragg Mini, CryoDAC-ST, CryoDAC Mega, SymmDAC and PlateDAC. For other DACs, please consult us.