Sample Environments

High pressure

Available DACs from the ESRF sample environment are membrane-driven LeToullec type DACs. The membrane pressure of these DACs is controlled remotely using a PACE pressure controller from GENERAL ELECTRIC. 

The beamline offers a high flexibility to mount other types of DACs (BX90, Chervin, etc..)

Low temperature – Room pressure

In order to have access to temperatures below 300 K, two different types of cryostats are available. One is dedicated to room pressure experiments while the second is adapted to cool down a DAC and to control the pressure and temperature independently. The first cryostat is a Helium flow device developed by the ESRF Sample environment. It has been designed to cool down the sample to 3 K, to work with the standard 4 degrees of freedom available on the beamline goniometer, and it has the possibility to adapt the entrance and exit windows for the particular scattering geometry required for the experiment. The thermal shielding and vacuum chamber caps (see Figure 12(B), numbers 2 and
3, respectively) can be machined to have the desired scattering opening. The sample holder is custom-made for each experiment (see Figure 14(B), number 1). In particular for single-crystal and powder XRD, we use a large diamond, thermally anchored to the sample holder, where the samples are deposited and fixed with vacuum grease to assure excellent thermal contact. A photo of three single crystals of polyoxovanadoborates is shown in the inset of Figure 12(B). The extremely small mass of the cryostat allows obtaining high-temperature variations in function of time, up to ∼50 K/min.

 (A) Helium flow cryostat installed on the goniometer. (B) Top: three crystals installed on the
cold finger, Bottom: scheme of the cryostat, 1 is the sample holder, 2 is the inner thermal shielding, 3
are the vacuum chamber caps and 4 is the external part drawing of the cryostat.

Low temperature – High pressure

To couple high pressure and low temperature, a dedicated cryostat has been designed, also with the Sample Environment group, in order to be able to locate a DAC. It has been optimized for XRD experiments using DAC, and it is also compatible with inelastic X-ray scattering on ID28, X-ray absorption spectroscopy on ID24/BM23 and Moessbauer spectroscopy on ID14. This cryostat permits to cool down the sample down to 3 K with cooling temperature rates as fast as 20 K/min but also slow rates of 1 K/min with excellent temperature control. The membrane-driven DAC specially constructed to be used with this cryostat allows controlling and following any desired P-T path. Two Mylar windows on the vacuum vessel give optical access to the sample chamber inside the DAC allowing complementary measurements, like sample visualization, Raman spectroscopy, ruby fluorescence measurements and XRD wide angular opening of 32°. A detailed description of the system will be summarized in another contribution. 

Photograph of the HP cryostat mounted on the goniometer. (B) and (C) Technical drawing of the HP cryostat vacuum vessel and interior, respectively.

High pressure and high temperature (resistive heating)

For high-temperature studies, membrane-driven DACs with large opening angles made on Inconel/PYRAD can be heated with an external heater ring to temperatures of 600 K (without vaccum box).

For higher temperatures applications two different types of resistively heated DAC under vacuum allow covering a temperature domain up to 1500 K.

1) For the temperature range up to 900 K the entire DAC is heated using an external heater ring that is clamped around the cell and placed in a vacuum box vessel. One K-type thermocouple is installed on the heater ring to control the temperature and a second one on the backside of one diamond. The temperature can be controlled remotely and stabilized within 1 degree.

2) Finally, for temperatures up to 1500 K, internally resistively heated DACs are available. These DACS
consists of two resistive heaters mounted around and in direct contact with each diamond. The temperature on both heaters can be controlled independently and remotely through two K-type thermocouples mounted below each heater and thermally anchored to the diamond. The diamonds are glued on zirconium seats to reduce heat losses. Copper wires and molybdenum electrodes provide the power to the heaters. Temperature variation rates up to 40 K/min are possible to be reached with
fine regulation down to 0.1 degree. A compact thin vacuum chamber allows protecting the DAC and the heaters from oxidation, and it is equipped with Mylar windows permitting to develop X-ray measurements, Raman measurements and sample visualization.

(A) Photograph of one part of the mounted internal resistive heating DAC. (B) View inside the vacuum box.

High pressure and high temperature (laser heating)

A single-sided laser-heating system (YAG infrared) is available at the beamline and in the laboratory of ID15b. It is equipped with a remotely controlled shutter. The laser power can be also controlled remotely. Different objectives can be mounted to change laser beam size.

Online-laser heating system ID15b.

Offline-laser heating system ID15b.

Reference publication:

G Garbarino, ME Hanfland, S Gallego-Parra, AD Rosa, M Mezouar, D. Duran, K. Martel, E. Papillon, T. Roth, P. Got, J. Jacobs (2024)  Extreme conditions x-ray diffraction and imaging beamline id15b on the esrf extremely brilliant source High Pressure Research 44 (3), 199-216