NEW: PLATE DAC
Introduction:
New design:
The new diamond cell design* for a diamond cell offers a number of improvements and advantages compared to previous designs :
- kinematic principle provides very high precision and reproducibility in diamond anvil alignment necessary for megabar pressure application;
- the cell is easy to handle and to align;
- diamond anvils cannot be accidentally broken because they can only be brought into contact by applying the high force necessary to bend the plates.
- its simplicity significantly lowers manufacturing costs;
- example: culet of 0,30 mm => approximately 100 GPa
- the specifications may be changed without prior notice.
* R. Boehler, Rev. Sci. Instr. 77. 115103, (2006)
Please click on the pdf file (157 kb)
Guidelines for DAC newcomers.
A. Which culet size to choose for a desired pressure rang?
| Culet size (mm) | Pressure (GPa) | |
| 0.80 | 20 | see paper * |
| 0.70 | 30 | see paper * |
| 0.50 | 40 | approximate ** |
| 0.40 | 60 | approximate ** |
| 0.30 | 80 | approximate ** |
| 0.20 | 100 | approximate ** |
| 0.15 | 150 | approximate ** |
* R. Boehler, Rev. Sci. Instr. 77. 115103, (2006)
** Depends on sample size and pressure medium.
We recommend customers to have a small bevel around the culet of the anvils:
- Easier cleaning of culet.
- Reduce damage danger during alignment.
Best bevel sizes:
- C < 0.25 mm => Cb = 0.30 mm at 8°
- C > 0.25 mm => Cb = C + 0.05 mm at 8°
Recommended gasket thickness:
- Preferably between 0.13 and 0.25 mm.
- The thinner the gasket thickness, the less force is needed on the plate DAC.
B. Which optical or X-ray aperture is needed?
Data:
- Optical aperture: 2xα1
- X-ray 4theta aperture: 2xα2
- Seat aperture: A
- Refractive index of diamond: 2.42
- Height: H
- Outside diameter: D
- Table diameter: T
Formula:
- sin(α1)/sin(α2)=2.42
- tan(α2)=(T/2)/H
C. What size of diamond should you choose?
General rule:- T (table) will depend upon your choice made in the former paragraph (B.).
- T (table) minimum = + 1.30 mm.
- D (outer girdle diameter) = T (table) + 1.00 mm
- Make your choice from the Boehler-Almax anvils presented at the Boehler-Almax products page on this website.
D. How to align the plate DAC?
Plate DAC:
(a) The three outer screws are used to align the parallellity of the two diamond anvils and to determine the starting distance between the two culets (depends on the gasket thickness).
(b) The three inner screws are used to center the two diamond anvils (and push the lower seat against the bottom plate. The upper seat is pressed into the upper plate).
(c) The three middle screws are used to pull the two plates together and hence generate pressure (these screws get the same torque force with a torque wrench and can afterwards be turned simultaneously with a mechanical pressure applying mechanism (d)).