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Type IIas Boehler-Almax design
All type IIas anvils are Raman ultra-low fluorescence and ultra-low birefringence, (100)-oriented. Conical crown design offering superior mechanical stability.
Smaller anvil reducing beam absorption.
Tungsten carbide seat with large aperture for diffracted patterns and signal.
Used in the following DACs: Plate DAC, Braggs (Plus), Bragg Mini and HeliosDAC Plus.

Conical low birefringence diamond anvils for optical and X-ray experiments

Boehler-Almax diamond anvils are based on a novel design for anvils introduced in 2004*. This design provides an optimised mechanical support for the anvil’s crown section achieved by a perfect match between the anvil and the tungsten carbide (WC) seat. The differences between conventional WC and Beryllium (Be) seats are shown in the schematic below:
Conventional WC seat/anvil(Optical) Conventional Be seat/anvil(X-ray) Boehler-Almax seat/anvil(Optical + X-ray)

*R. Boehler, K. De Hantsetters, High Pressure Research, September 2004, Vol. 24, no. 3, PP 391-396.


The Boehler-Almax diamond anvils can be used both for optical spectroscopy measurements and for X-ray diffraction where large apertures (up to 85°) are required. These anvils can be used in conjunction with:

Almax easyLab diamond anvil cells:

Optical: Diacell® μScopeDAC Plus and HeliosDACPlus.
X-ray: Plate DAC, Diacell® BraggPlus and Bragg Mini.

Newly designed or existing DACs (retrofit):

In most cases, the WC seat can be adapted to the dimension requirements of your DAC. Consult us.


It is essential to have a perfect match between the anvil and the supporting seat when mounting Boehler-Almax diamond anvils, This is achieved by lapping the two components together.
We recommend you to purchase these two parts as matched pairs.
The Boehler-Almax anvils are glued onto their carbide seats either by our technicians or alternatively in the laboratory by using our gluing jig (A74200).


Most likely the main parameter you will have to decide upon is the conical aperture 2θ required. We have a choice ranging from 30° up to 85° (X-ray). The schematic below shows the difference between optical (a) and X-ray apertures (aX).

Generally speaking X-ray diffraction will require larger aperture whereas for optical spectroscopy apertures up to 50° will usually be sufficient.

Type IIas – Boehler-Almax design – (100)-oriented
Applications Drawing
(Product code)
Product code
50° 2.50 1.69 Optical P01927
70° 3.10 2.29 IR
70° 3.30 2.38 IR
80° 4.00 3.19 IR
P01931 - check for availability
85° 3.30 2.50 IR

Note: our Boehler-Almax design anvils are made from rough diamonds. They are polished according to the (100)-crystal orientation for the highest strength.

FT-IR Spectrum

Culet size and modification

Choose culet size as a function of:

maximum pressure

culet size

< 5 GPa

> 1.00 mm

5 – 100 GPa

1.00 mm – 0.20 mm

> 100 GPa

<0.20 mm, bevels up to 0.30 mm at 8°

Note: Typical sample space is given by the gasket thickness (typically 0.10 mm or less) and the central hole diameter (typically 30-50% culetsize).
Note: single and double bevels are recommended for very high pressure and electrical measurements.
Note: single bevels around the culet ease the cleaning of the culet and reduce the risk of damage during alignment.

WC seat

Almax easyLab offers four types of WC seats which are represented below. At the time of ordering, you will be able to specify the key dimensions (D, H, T, S, A).
Cylindrical Cylindrical with top taper
(P01287) (P01289)
Tapered Tapered with top taper
(P01290) (P01288)

Boehler-Almax anvils are glued into their carbide seats. The gluing procedure can be received upon simple request or downloaded from our website. Open the Mountinginstructions03 document, or open the following You Tube 3 minute video clip. We can supply you with the appropriated gluiing jig.

easyGlue (A74600): spring-loaded gluing and curing jig suitable for all Boehler-Almax seats/anvils.
Horizon (A23000): compact laser alignment tool to be used in conjunction with the Diacell easyGlue. It enables one to achieve an accurate optical alignment of a Boehler-Almax anvil and a WC seat prior to the actual epoxying.

Glue low temperature (P00534):

two components, thermally conductive epoxy(low coefficient of thermal expansion).

Glue room temperature (P00979):

single component heat cured. Adhesive with high shear and peel strength.

Glue high temperature (P00946): two components, high purity alumina based adhesive.
Examples of typical requests for quote:

Diamond anvil, type IIas, Boehler-Almax design, 16-sided, 2.50 mm – 30°, culet of 0.10 mm, bevels up to 0.30 at 8°, (100)-oriented:

Article nr.: P01927
Quantity: 6 anvils.

Diamond anvil, type IIas, Boehler-Almax design, 16-sided, 3.10 mm – 70°, culet of 0.30 mm, (100)-oriented:

Article nr.: P01928
Quantity: 4 anvils.

NEW ANVIL DESIGNS IN DIAMOND-CELLS (PUBLISHED:High Pressure Research, September 2004, Vol. 24, no. 3, PP 391-396)
R. Boehler, K. De Hantsetters

New diamond anvils with conical support are introduced. Compared to conventional anvils the new design offers superior alignment stability, larger aperture, and reduced cost owing to significantly smaller anvil diameters. Except for table and culet, all surfaces are precision ground on a lathe, which lowers cost compared to faceted anvils. The conical design allows for steel supports, which are significantly easier and cheaper to manufacture than tungsten carbide supports. Conical support also prevents seat damage upon diamond failure.

Please click on the pdf (0.3 MB) to read this publication.

Pressure-dependent structures of amorphous red phosphorus and the origin of the first sharp diffraction peaks. (Published online: 12 October 2008; doi:10.1038/nmat2290) JOSEPH M. ZAUG, ALAN K. SOPER AND SIMON M. CLARK

A custom-designed diamond anvil cell (DAC) built to enable X-ray diffraction out to very high angles was used in our study. This DAC consists of a four-post symmetrical design with WC Boehler-Almax type backing plates and a 1.7-mm-tall, 6.5-mm-girdle-diameter, type-IB diamond on the downstream side and a conventional backing plate and diamond on the upstream side. This combination enables diffraction data to be collected at angles of up to 110°2θ. Scattering intensity varies smoothly as X-rays traverse only through air, the sample and diamond windows. The minimum sample-to-detector distance available on BL 12.2.2 is 135 mm, which combined with the highest useful energy of 35 keV limited the maximum Q-range to ~10 °A−1.

Please click on the pdf (5.2 MB) to read this publication.

Incorporation of a new design of backing seat and anvil in a Merrill-Bassett diamond anvil cell. (Published: (2008). J.Appl.Cryst. 41, 249-251 [doi:10.1107/S0021889808000514].)   Stephen A. Moggach, David R. Allan, Reinhard Boehler, Simon Parsons, Koen de Hantsetters and John E. Warren.

A modification to the Merrill-Bassett miniature diamond anvil cell is reported here with the inclusion of W-carbide backing seats with Boehler-Almax cut diamonds to replace the previously used beryllium seats and (typically) modified brilliant cut anvils. This has led to the removal of troublesome beryllium powder lines from our diffraction images, while maintaining the pressure range and opening angle of the original design.

Please click on the pdf (1.1 MB) to read this publication

Miniature diamond anvils for X-ray Raman scattering spectroscopy experiments at high pressure (Published: (2017). J.Synchrotron Rad. 24, 276-282 [].) S. Petitgirard, G. Spiekermann, C. Weis, C. Sahle, C. Sternemann and M. Wilke.

X-ray Raman scattering (XRS) spectroscopy is an inelastic scattering method that uses hard X-rays of the order of 10 keV to measure energy-loss spectra at absorption edges of light elements (Si, Mg, O etc.), with an energy resolution below 1 eV. The high-energy X-rays employed with this technique can penetrate thick or dense sample containers such as the diamond anvils employed in high-pressure cells. Here, we describe the use of custom-made conical miniature diamond anvils of less than 500 µm thickness which allow pressure generation of up to 70 GPa. This set-up overcomes the limitations of the XRS technique in very high-pressure measurements (>10 GPa) by drastically improving the signal-to-noise ratio. The conical shape of the base of the diamonds gives a 70° opening angle, enabling measurements in both low- and high-angle scattering geometry. This reduction of the diamond thickness to one-third of the classical diamond anvils considerably lowers the attenuation of the incoming and the scattered beams and thus enhances the signal-to-noise ratio significantly. A further improvement of the signal-to-background ratio is obtained by a recess of ~20 µm that is milled in the culet of the miniature anvils. This recess increases the sample scattering volume by a factor of three at a pressure of 60 GPa. Examples of X-ray Raman spectra collected at the O K-edge and Si L-edge in SiO2 glass at high pressures up to 47 GPa demonstrate the significant improvement and potential for spectroscopic studies of low-Z elements at high pressure.

Please click on the pdf (1.2 MB) to read this publication