Boehler-Almax Plate DAC
X-ray Spectroscopy, Laser heating, Pmax = 100 GPa, T = 300 K, WD = 10.5 mm, A = 85°
- The Boehler-Almax PlateDAC is based on the innovative design of R. Boehler and employs conical Boehler-Almax anvils supported by tungsten carbide seats as standard
- This cell is particularly well suited for X-ray experiments as it enables diffraction measurements with high transmission factor and very low background
- Two kinematically–mounted steel plates are elastically deflected with the use of a driving gearbox. This symmetrical deflection generates the required pressures
- A gas membrane adaptor kit is available for the Boehler-Almax PlateDAC. In addition, a Huber goniometer head is also available for this gas membrane adaptor
- Maximum pressure of up to above 100 GPa are enabled by the Boehler-Almax PlateDAC
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Description
The Almax Plate DAC is an innovative diamond anvil cell based on the novel design of Prof. Reinhard Boehler at the Max Planck Institute in Mainz, Germany. With the advent of conical diamond anvils described in the paper by R. Boehler et al., High Press. Res. 24, 391 (2004), comes the possibility of having diamond anvil cells with very large conical apertures without the drawback of obstructing materials for the incoming of outgoing beams.
In the Almax Plate DAC two kinematically-mounted steel plates are elastically deflected with the use of a driving gearbox. Based on the lever principle, the symmetrical deflection of the plates, although very small, is enough to bring into near-contact the diamond anvils and hence generate the required pressures in the sample space.
The conical anvils are supported by tungsten carbide seats, which provides several benefits. Firstly, it circumvents the need for beryllium plates as support for the diamond anvils. The net result is the avoidance of the usual halo coming the diffraction pattern of Be. Secondly, the mechanical resistance of tungsten carbide, being higher than that of beryllium, provides backing seats with longer lifetime. Thirdly, by having tungsten carbide backing plates it is possible to use the cell at high temperatures. Of particular interest then is the use of the Boehler-Almax Plate DAC in combination with a laser heating set-up by also taking advantage of its large conical access.
The Almax Plate DAC is very easy to handle and align. It makes use of distinctive tilt-adjustment screws and a special gear box. Diamond anvils cannot be accidentally broken because they are only brought into contact by applying the high force necessary to bend the plates.
The gearbox required to deflect the plates is made of three high-strength, high-precision spur gears which uniformly rotate the three matching clamping screws. These, in turn, act as levers. The conical aperture along the axis of the diamond anvil cell is 85°, whereas the Almax PlateDAC flat design offers a horizontal aperture (in the plane of the gasket) of more than 80° on 3 sectors, offering a near-panoramic view. The vertical opening is above 20°.
The Almax Plate DAC can be supplied with the usual selection of diamonds, type Ia Raman-selected for low- or ultra-low fluorescence or type IIas, with conical apertures of 85° degrees on both sides of the cell. The total height of the cell is around 21 mm for an external diameter of 49 mm.
The gasket is held in place by a convenient gasket holder, in a similar fashion to other Diacell® diamond anvil cells. Gasket materials such as steel, Inconel, beryllium copper alloy, rhenium, as well as pure beryllium (contact us for details) can be supplied with this cell.
This video shows how easy it is to align this cell.
A gas membrane adaptor kit is available for the Plate DAC. A video animation of this gas membrane upgrading kit can be seen here. A Huber goniometer head is also available for this gas membrane adaptor as well.
Applications
The Almax Plate DAC is particularly well suited for X-Ray experiments as it enables diffraction measurements with high transmission factor and very low background. Indeed, the absence of Be plates, which are replaced by large aperture tungsten carbide seats, combined with the fact that the conical anvils are nearly 15% thinner than the standard designs, considerably enhances the X-ray transmission. The large apertures on both side also makes the cell singularly suited for use with laser heating (particularly double-sided heating) set-ups.
Specifications
Cell Material | Maraging steel |
Anvil Support Plate | Tungsten Carbide |
Pressure Mechanism | Screw Drive |
Maximum Pressure | Â 100 GPa |
Temperature Range | 300 K |
Top Angle | X-Ray: conical 85º |
Bottom Angle | X-Ray: conical 85º |
Lateral Access | 3 sectors of 80° each in the gasket plane; > 23° vertically |
Heating | Laser heating (not included) |
Cooling | N/A |
DAC Diameter | 49 mm |
DAC Height | 21 mm |
Working Distance to Sample | 10.5 mm |
Numerical Aperture | 0.68 |
Interfacing Solution | Via lateral mounting holes or customized holding ring |
DAC Weight | 150 g |
Maximum pressure is dependent upon the culet size of the anvils. Almax easyLab is committed to its policy of continuous improvement. Specifications may change without notice. easyLab and Diacell are registered trademarks of Almax easyLab.
Documents
We have compiled a series of technical documents (brochures, articles, technical drawings, …) which you might find useful to help you understand this product better.
Technical documentation
Technical Drawing
Please contact us for further details on the engineering drawings.
Articles
2012 – Ribeiro, M – High Viscosity of Imidazolium Ionic Liquids with the Hydrogen Sulfate Anion: A Raman Spectroscopy Study.
2013 – Penna et al. – Pressure and temperature effects on intermolecular vibrational dynamics of ionic liquids.
2014 – Stinton et al. – Equation of state and high-pressure/high-temperature phase diagram of magnesium.
2018 – Yamaoka et al. – Reentrant valence transition in YbCu4.5 under pressure.
2021 – Finnegan et al. – High-Pressure Structural Systematics in Neodymium to 302 GPa.
2024 – McHardy et al. – Thermal equation of state of rhodium to 191 GPa and 2700 K using double-sided flash laser heating in a diamond anvil cell.
FAQs
What is the maximum pressure I can achieve with the PlateDAC and a given culet size?
Culet size (µm) | 200 | 300 | 400 | 500 | 600 | 800 | 1000 |
Pmax (GPa) (*) | 100 | 87 | 56 | 36 | 25 | 14 | 9 |
(*) The Pmax values are only indicative. The maximum pressure achievable with a DAC is influenced by many others experimental parameters, like the gasket characteristics (material, thickness and hole size) or the pressure transmitting medium.
What is the total weight of the set-up when using the PlateDAC in conjunction with the GM adapting Kit option?
The weight of the PlateDAC is around 145 g, the GM kit is around 370 g so the total weight is around 500 g.
Can the PlateDAC be used at low temperatures?
Yes, the PlateDAC can be used at low temperatures. Please inform us at the time of your order, so we can use a special lubricant for the screws (as the standard grease may stiffen at low temperatures), as well as a special epoxy to glue the anvils on the seats.
What makes a PlateDAC different from a piston – cylinder DAC type?
The PlateDAC operates on the principle of two kinematic plates spaced apart by three screwable pins. Using three clamping screws as levers, the plates are deflected equally to bring the central diamonds closer together. In contrast, the piston cylinder design involves a piston sliding inside a guiding cylinder, moved by clamping screws. The PlateDAC, though relatively simple in structure, achieves high pressure with Boehler-Almax anvils. It requires an additional gearbox for symmetrical tightening of the clamping screws, and aligning the anvils demands more practice compared to piston cylinder cells. The piston – cylinder DAC type offers a sturdy and stable guide for the piston inside the cylinder bore, facilitating easy anvil alignment and maintaining stability even at very high pressures. Both the PlateDAC and piston – cylinder DAC provide a large aperture of around 90 degrees, ideal for X-ray measurements.
Can we load hydrogen gas in the PlateDAC?
We do not recommend this, as the maraging steel that is used to machine the PlateDAC becomes brittle after gas loading with hydrogen.
What is the gearbox ratio of the PlateDAC?Â
The PlateDAC features a 13/60 pitch for the screw threads, translating to 0.35. This means that a full turn of the handle brings the diamond culets 75 µm closer together.
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