DIAMOND ANVILS

Diamond anvils

If the customer wants to measure the pressure with the Ruby scale with his existing Raman spectrometer (which happens to have at least the right resolution). Does this require normal, UV low fluorescence, Raman low fluorescence or Raman ultra low fluorescence diamond anvils in his DAC?

If a customer wants to measure the ruby fluorescence with his existing Raman system, then we always quote anvils which are at least Raman low fluorescence, to be safe.

(KDH, 19/02/2013)

For C = 0.20 and above the culet is defined +/-10microns

C. Thessieu (16/04/2019)

Type Ia natural (100)-oriented: 0.015 mm.

Type IIa synthetic (100)-oriented: 0.015 mm.

(KDH, 15/01/14)

Please describe the goods as “diamond tools” – harmonised code 8207.9010.00.  In addition, if possible, please declare a low value for the goods (preferably less than 125 USD).  These steps help prevent additional customs charges.   Nonetheless, please mention on your air waybill that taxes and duties are to be paid by the sender.  Temporary import is very expensive and by using the steps above we are able proceed with a full import, making it a much cheaper alternative for your repair.

(KDH, 16/09/2013)

See our mounting instructions on the productspages of the Boehler-Almax diamond anvils: www.almax-easylab.com/pdf/Mountinginstructions03.pdf, for completeness, you can also have a look at our video on You Tube: www.youtube.com/watch?v=JeAtLpDaBmI .

THREE MOST IMPORTANT THINGS:

–         The cone most be totally clean, no small grid or dust particles may be present in the cone of the seat or on the cone of the diamond.

–         Do not apply any glue between the cone of the seat and the anvil! The glue should be at the rim between the diamond diameter and the topside of the seat.

–         You need some kind of gluing jig, as you need to put some 10 kg of pressure on the anvil during the curing of the glue.

(KDH, 15/01/2014)

–         Mix some 9 to 12 µm boron carbide powder with some very fine cutting oil.

–         Apply some big drops of the above lapping compound on the black part of the lapping tool.

–         Make sure the seat is positioned flat and perpendicular to the lapping tool movement.

–         The 60° lapping tool / lapping stick should be perfectly centered and move up and down in the conical hole you want to lap. This vertical up and down movement should allow the lapping tool to constantly bring fresh lapping compound between the lapping tool and the cone.

–         We usually lap between 30 and 60 minutes.

(KDH, 22/08/2020)

Optical grade single crystal CVD diamond: Typically 100% single sector {100}, [N] < 1 ppm, [B] < 0.05 ppm.

Electronic grade single crystal CVD diamond: Typically 100% single sector {100}, [N]0 S < 5 ppb, [B] < 1 ppb.

(KDH, 14/03/2014)

–         broad band AR coating:

o   Multiple layer coating => more expensive.

o   Theoretical average reflection of 1% between 440 and 660nm

o   Theoretical peak reflection of 1.15%.

–         ‘V’ coat AR coating:

o   Single layer coating => less expensive.

o   Theoretical average reflection of 1.7% between 440 and 660nm,

o   Theoretical peak reflection of 5%.

TAKADA, Manabu  (KDH, 14/03/2014)

We remove the Boehler-Almax diamond anvils  mechanically by pressing them out from the backside. In order to re-use the seat, make sure you remove all the glue. We do this be sandblasting the carbide seat internal cone with glass beads.
JARON, Tomasz  (KDH, 21/05/2014)

0.020mm with double bevels OK.

Indeed with such small sizes it becomes more difficult to achieve some perfectly round culets.

It is possible to have 0.010mm with a single bevel at 0.25mm, 8 or 12 degrees (KDH – 08/10/2019)

See Google photo for example of 0.035mm bevelled anvil.

(FIB – January 2018)

Diamond anvil, type IA, standard design, 16-sided, diameter 3.50 mm, culet of 0.04 mm, bevels up to
0.30 mm at 8°, Raman low fluorescence

I used this type of diamind to do high pressure transport measurements on B nanowires and applyed pressure up to 240 GPa. I think this type diamond is what we need now. Do you have this?

(SUN, Liling, December 2014)

One can estimate as Cb = C +0.1 except for very small culet sizes (i.e. 0.05mm). For very small culet C<0.10 then the preferred Cb value is 0.30, although Cb = 0.25 can also be done if really required

(CCNT, 17/01/2015 – updated by CCNT after a chat with KDHw)

The refractive index of diamond is around 2.41 ( at 760 nm, as it varies with the wavelength)

(KDH 16/04/2015)

Publications can be found on EASYLAB DOCS\ET-MISC\VARIOUS ARTICLES (search for: “Boehler-Almax anvil use above 100 GPa”

(KDH, 16/04/2015)

The important factor for the scientist is the Raman fluorescence level. This is well defined by the Raman spectrum of the diamond and that is what we check. Naturally when we are looking for some low or ultra low Raman fluorescence, we are looking at diamonds in the color range from colorless to near colorless. The reality is that sometime some near colorless have a higher Raman background that some slightly yellow anvils with a low background.

What we are looking is the Raman spectrum not the colour of the anvil.

It is also important to underline that this selection is true for all our customers in the world. In other words, we are not operating on a different scale for our customers in China compared to other countries.

Hope this clarifies.

(easyMaterials – July 2016)

We can ONLY ship 25.000 euro maximum in an insured way.

“Some” we can make with 5° off the (111) orientation.

Some remarks though:

–        If not for a Mao connection, we would decline this request.

–        Price will depend upon size and required thickness. Mind that we have never polished any (111) ultra thin windows. Having said this, we have to admit we do not yet know whether this is feasible at all.

–        In fact, we would need to start up a small project (do we want to do this for free?) whether this is feasible or not…

–        Could they let us know the following:

o   Dimensions of the plates?

o   Are they OK with 5° off the (111) orientation?

o   How many plates would they be interested in?

–        We can understand it is difficult for them to give us some idea about the quantities, but they should bear in mind a price of at least 2 to 3 times the price of (100) oriented plates.

+/- 1micron

Natural diamond anvils all have some birefringence (stress). These diamonds have been selected for high pressure work out of thousands of rough diamonds. But still diamond anvils will have some stress. One can improve a little on this by opting for the “low birefringence” selection (but this comes with a price), but even then some birefringence will still be present in the diamonds.

The scratches on the bottom to which they refer are difficult to judge without picture.  Such scratches can often be the result of a more difficult facet to polish. If they look with even higher magnification, I’m sure they will find even more scratches or polishing lines.

The thermal coefficients for optical grade polycrystalline diamond will be around 1800 W/mK, whereas at will be up to 2200 W/mK  for single crystal diamonds.

The thinnest we can do is around 150microns in thickness. This is also dependant on the value of W. The larger this value is the more difficult it is to get very thin value of D. In your case and with a culet size of 1mm, the value of W would be around 300-350um and for maximum pressure of 1-3GPa, this would already be an anvil prone to break with such thin section in the middle of the anvil.

I hope this helps.

Can you give some examples of pressures achieved with (partially) perforated diamond anvils?

US customer: partially perforated up to 40 GPa, 3.75 mm standard design, culet of 0.30 mm, partially perforated from the table side, diameter of the end of perforation 0.30 mm, remaining diamond thickness 0.30 mm, aperture of 16°.

French customer: 8 GPa at ambient temperature in a membrane-type diamond anvil cell (with ruby as pressure sensor and water as a pressure transmitting medium).

French customer gave us the following feedback : Our last order was Boehler-Almax 3.10 mm – 70°, C=0.35, Cb=0.40 at 8°, W=0.06 ; D=0.15, A=30°, we’ve done 38 GPa by the way when our gasket unfortunately imploded…

Other French customer: we have succeeded to Helium gas load our set-up, completely perforated 600 micron diamond and 80 micron disk. Pressure in sample environment 16.5 GPa, measured by ruby luminescence.

Italian customer : small special double side diamond anvils with cylindrical perforation being test for high pressure. 5.5 GPa reached and not the limit.

UK customer (Paper 2020 – Louvel). Partially perforated anvil – BA design, C = 0.60mm, Pmax = 5GPa (1300K) [Added by CG]

(11/02/2020 addendum 19/08/2022)

What is the maximum A value you can do on partially perforated anvils?

We have made partially perforated anvils of up to 60 degrees (as long as there is enough diamond on the table side of course). In terms of impact on the effect maximum pressure, it is not quantified on our side but it does not make the anvil stronger.

(from private communication with KDH)

Mind that we can offer good quality PCD material. However in China there are numerous manufacturers of such PCD material (be it of poor quality)…

To give you some price idea, without asking price to our supplier, we can give you the guidance below:

Price per cube for 8 cubes of 25x25x25 mm, with a small truncated corner (in this case it was 2.50 mm): 1.995 euro/each

(13/06/2017)

We can only measure parallellity if a culet is at least 150 micrometer.

We also need to polish at least up to 150 micrometer in order have the right surface quality for high pressure work.

If he does not care about parallity and surface quality, we can polish a 100 micrometer culet “to best effort”. Although we should not recommend this from the quality reputation standpoint of our company.

532 nm, 7 watt laser.

(Junyue – HPSTAR – August 2017)

Yes, 10 off.

Visible and near-infrared absoroption spectra (Publication:  Synthetic Moissanite a New Diamond Substitute):

Infrared spectrum of Moissanite anvils (Publication:  Synthetic Moissanite a New Diamond Substitute):

Raman spectrum of Moissanite anvils  (Publication:  Synthetic Moissanite a New Diamond Substitute):

Moissanite anvils and laser heating?

A moissanite anvil was heated to 1100 ◦C in air for 36 h without damage, and temperatures close to 4000 ◦C have been reached in laser heating experiments.

What is the main difference between Moissanite and Diamond Anvils?

(Extract from Scientific report of the NWO-stipendium project (S77-184) carried out by Jan Bisschop from

November 2002 to October 2003 in the rock deformation laboratory at the geological institute of the

ETH-Zurich, Switzerland.)

Moissanite anvils are about 10 times cheaper than diamond ones and therefore we preferred to work with moissanite anvils in the many test-experiments carried out in this project. The optical properties of moissanite are less perfect than those of diamond. Moissanite is optically anisotropic and it has a higher dispersion than diamond. The anisotropy of moissanitecauses a strong birefringence in certain viewing orientations through the crystal. We tried moissanite anvils with the crystallographic c-axis perpendicular or parallel to the anvil culet face, thus with the c-axis either parallel or perpendicular to the viewing direction. Theoretically, no birefringence effect is to be expected when viewing parallel to the c-axis. However, we observed a

laminar structure in the moissanite anvils when viewing parallel to the c-axis in polarized light (see Fig. 4), which are probably a result of the growth of the synthetic crystals.

What pressures can be achieved with Moissanite anvils?

A Spanish customer went with Boehler-Almax Moissanite anvils up to 13 GPa with a 400µm culet.

Sept 2020: Moissanite anvil, standard design, diameter 4.25 mm, culet of 0.45 mm => 12 GPa.

(11/02/20 KDH)

How do you clean the culet surface if you have some marks or left over from sample/gasket?

The first thing to do is to wipe the culet with cotton bud and alcohol.

Then In order to clean the culets after an experiment, an easy way is to use fine sand paper (with small grain size) around tweezers and gently scratch the culet surface.

It should be enough to remove anything stuck to the culet.

After this, use a cotton bud with alcohol to wipe and clean the culet surface.

(23/07/2020)

What is the difference in surface quality for your diamond polishing services?

This is the measured information we have received as feedback from our customers on our different diamond polishing finishes:

–       Fine polishing: 20 µm image: guaranteed Ra < 5 nm => typically : Ra: 0.50 nm – Rz: 2 nm

–       Ultra-fine polishing: 20 µm image: guaranteed Ra < 2 nm => typically : Ra: 0.10 nm – Rz: 0.64 nm

–       Quantum polishing: 20 µm image: guaranteed Ra < 1 nm => typically : Ra: 0.038 nm – Rz: 0.31 nm

–       Mind that the final surface quality also depends upon the crystal orientation and the intrinsic diamond quality!

(13/11/2023)

Mini-diamonds

–       Diamond anvil, type Ia, Boehler-Almax design, 16-sided, diameter 1.00 mm, Ht=0.25+0.10+24.5°=0.575 mm, table of 0.7113 mm (according to Design_aug2016_1), culet of 0.10 mm, bevels up to 0.30 mm at 8° (100)-oriented [P01942]

–       Diamond anvil, type Ia, Boehler-Almax design, diameter 1.25 mm, total height of 0.39 mm, culet 0.70 mm, bottom angle 18°, Htc=0.30+0+0.09, T=0.90 mm, (100)-oriented, mounted in a carbide seat for Boehler-Almax design anvil, according to partnumber [P01287], diameter 16.00 mm, height 3.85 mm, aperture 110° [S1] => typically combined with: Diamond anvil, type Ia, Boehler-Almax design, diameter 2.50 mm, total height of 1.30 mm, culet 0.70 mm, bottom angle 18°, Htc=0.70+0.30+0.30, T=1.69 mm, (100)-oriented, mounted in a carbide seat for Boehler-Almax design anvil, according to partnumber [P01287], diameter 16.00 mm, height 3.85 mm, aperture 110° [S1]

–       Diamond anvil, type Ia, Boehler-Almax design, diameter 1.50 mm, total height 0.38 mm, culet 1.34 mm, bottom angle 20.56°, Htc=0.35+0+20.56°, T=1.10 mm, (100)-oriented, mounted in a carbide seat for Boehler-Almax design anvil, according to drawing [P01287] diameter 16.00 mm, height 3.96 mm, aperture 110° [P01408]

–       Diamond anvil, type Ia, Boehler-Almax design, diameter 1.50 mm, total height of 0.46 mm, culet 0.90 mm, bottom angle 20°, Htc=0.0.35+0+0.11, T=1.07 mm, (100)-oriented, mounted in a carbide seat for Boehler-Almax design anvil, according to partnumber [P01287], diameter 16.00 mm, height 3.96 mm, aperture 110° [P01408]

–       Diamond anvil, type Ia, Boehler-Almax design, diameter 1.65 mm, total height of 0.65 mm, culet 0.80 mm, bottom angle 19.44°, Htc=0.50+0.00+0.15, T=1.07 mm, (100)-oriented, mounted in a carbide seat for Boehler-Almax design anvil, according to partnumber [P01287], diameter 24.00 mm, height 4.17 mm, aperture 136.25°, with 0.50×45° chamfer on the top side [S1] => typically combined with: Diamond anvil, type Ia, Standard design, 16-sided, diameter 2.50 mm, culet of 0.80 mm, HTC=1.20 mm, ultra-low birefringence, (100)-oriented [P01003]

Patterned anvils

For feasibility, it is not a problem if they choose other culet sizes.

Culets between 0.40 and 0.79 mm would get an interdistance of electrodes of 0.10 mm.

Culets between 0.80 and up would get an interdistance of electrodes of 0.20 mm.

If the customer does decide not to take bevels on the culets. Fine with us, the (extra risk of cutting the coating at the edges) is his.

Minimum batch order for production is 10 pieces as you know.

(03/05/2016 CCNT)

–       Patterned diamond anvils: gold contacts coated on top of the anvils:

o   Price: +980 euro on top of the normal anvil price.

o   4 triangles are coated with the following dimensions:

§  C=0.80, Cb=0.85 at 8°: interdistance of the electrodes: +/- 200 µm.

§  C=0.40, Cb=0.45 at 8°: interdistance of the electrodes: +/-100 µm.

o   Mind that you still need to insulate your gasket in this case.

o   These gold contacts are unprotected and can be reused only a few times (depending upon the pressure used up to 3 or 4 times).

–       Intelligent diamond anvils: Tungsten contact, overgrown with CVD diamond layer (so called “intelligent anvils” from the UAB, Dr. Vohra):

o   Price: +1.750 euro on top of the normal anvil price.

o   8 fine leads are coated and overgrown with CVD diamond.

§  C=0.25 approx*, Cb=0.35 approx* at 12°: interdistance of the electrodes: 60 µm approx*.

§  *: due to the specific and intricate process of fabricating intelligent diamond anvils, the culet size, bevel size and interdistance can only be given by approximation upfront. For this reason, any accompanying diamond anvils that will be used to preindent the gasket to be used with this intelligent diamond anvil should mimic this intelligent anvil.

§  Microfabrication of the iDiamond anvils is very challenging. As transport measurements require only 4 probes, Almax easyLab guarantees that at least 4 of the 8 probes will work.

o   Mind that you do not need to insulate your gasket in this case.

o   These tungsten contacts are protected by a CVD diamond layer and can be reused all the time.

(0711/18 KDH)

–       What is the geometry of the contacts for the intelligent diamonds? 

The geometry for the contacts can be adapted to many types of experiments. We have made 8, 6, and 4 probe resistance patterns with large contact pads on the sides of the anvil. The probes in the center typically have a spacing of about 50-100um.

–       Is the surface of the intelligent diamond flat?

The top surface (culet) is flat.

–       And what is the contact thickness and can it be customized?

The contact thickness is a few hundred nanometers, I have not measured this personally. It could be varied by increasing the thickness of the contacts.

–       Would this setup work for 2D materials (thickness < 100 nm)?

I am not sure about 2D materials, but I suppose it could. Do you mean 2D materials as a sample in the DAC?

–       Can the intelligent diamond contacts withstand sonication?
Yes, they can withstand sonication.

(20/09/2023 KDH)

Depending on the nature of the sample (semiconductor, metallic, superconducting) typical currents we use, are in the range of tens of microamps to tens of milliamps. We don ‘t think we ever used more than 100 milliamps. Using very high current (in the amperes) might cause damage to the diamond itself as resistive heating effects might come into play. So I would advise to stay below 100 milliamps.

(25/05/21 KDH)

We indeed have some patterned anvils for electrical resistivity measurements.

We have two types (see below for a more detailed description.

Gold plated 4 tracks diamond anvils:

·        +ve: provides larger culet size and sample space

·        -ve: no insulation from the gasket & coating yields only for 5 pressure runs

Tungsten deposited & CVD covered 8 tracks diamond anvils:

·        +ve: Insulated from the gaskets, yield rate higher, maximum pressure higher

·        -ve: only small culet sizes available at the moment (typ 0.25mm) only suitable for very small samples

A more detail description is shown below:

What is the procedure when patterned diamond anvils have damaged electrodes?

When patterned diamond anvils have damaged electrodes, they can be returned to Almax easyLab and we can clean and repattern the diamond anvil. Mind that the diamond surfaces (culet and pavilion) where we remove the coated electrodes might be very slightly etched, but this should not be an issue to repattern and reuse these diamond anvils. Having said this, we assume the diamond anvils themselves were not damaged and do not require any repolishing (which would add to the repatterning price otherwise).

The minimum order quantity for repatterning is 2 diamond anvils.

(19/08/22 KDH)

Patterning (Coated diamonds) [P01862]

Patterned diamond anvils: gold contacts coated on top of the anvils:

o   Price: +980 euro on top of the normal anvil price.

o   4 triangles are coated with the following dimensions (Choose between one of the two options):

§  C=0.80, Cb=0.85 at 8°: interdistance of the electrodes: +/- 200 µm.

§  C=0.40, Cb=0.45 at 8°: interdistance of the electrodes: +/-100 µm.

Mind that you still need to insulate your gasket in this case.

These gold contacts are unprotected and can be reused only a few times (depending upon the pressure used up to 3 or 4 times).

Patterning (Intelligent diamonds – i-diamonds) [P02193]:

Tungsten contact, overgrown with CVD diamond layer (so called “intelligent anvils” from  the University of Alabama (UAB-USA) ref. Dr. Vohra:

o   Price: +1,750 euro on top of the normal anvil price.

o   8 fine leads are coated and overgrown with CVD diamond.

§  C=0.25 approx*, Cb=0.35 approx* at 12°: interdistance of the electrodes: 60 µm approx*.

§  *: due to the specific and intricate process of fabricating intelligent diamond anvils, the culet size, bevel size and interdistance can only be given by approximation upfront. For this reason, any accompanying diamond anvils that will be used to preindent the gasket to be used with this intelligent diamond anvil should mimic this intelligent anvil.

o   Mind that you do not need to insulate your gasket in this case.

o   These tungsten contacts are protected by a CVD diamond layer and can be reused all the time.

(CCNT – Singapore – 04/04/2019)

Can you do i-diamonds on any type of design?

Ideally we prefer to do them on Diacell design 2.50mm anvils. It is possible to make them on standard design anvils, and possibly on Boehler Almax anvils for which the pavilion angle is more than 25 degrees (incl 25 degrees)

(March 2020)

How do you connect the sample with the i-diamonds?

It is natural to doubt if the conducting tips might not be flush with the culet surface in some cases. But the geometry of the seed crystal has been specifically selected to avoid this issue. In an ideal case, this is how the finished surface of a designer anvil looks.(Figure 1)

Of course, sometimes the tips end up carburizing and we don’t see shiny tips on all of them (Figure 2). Some of them will look crude as shown below but they will still function. As you can see in the image only the shiny (and not so shiny) probe tips are exposed on the culet. As long as users take the time to compact the sample, it will make contact with the conducting leads.

A typical arrangement is as shown below. Place the sample on the leads and pack the rest of the gasket hole with an insulator like steatite to prevent shorting with the gasket. We have been following this routine for many many years and can vouch for its effectiveness. (Figure 3).

Gopi -August 2020

The method used often is the 4 probe one.

The electrical connections on the anvil are often made using conductive paint/epoxy/paste made from silver for example.

The same conductive paint could be used to carry on the electrical connections from the diamond to the PCB. Normal soldering using solder and a very sharp soldering tip could work as well but one must be careful not damage the PCB and not to put too much solder on the electrical pads.  

Our company does not supply wires for the electrical connections.

(internal)

One of our customers used the following steps.

1.       Position the sample onto the electrodes

2.       Sandwich it between the two anvils and squeeze gently to ensure a good contact is made between sample and electrodes (at that stage you can check that the contacts are OK and that you can measure a good signal

3.       Place the gasket and the hole around the sample

4.       Add the PTM (if solid, important to make sure that no powder goes underneath the sample (Step 2 should prevent this to happen)

5.       Close the cell and check again your signal.

(Jesus 2021)

How do you connect the sample to the patterned anvils?

We can suggest 2 ways to do that: Mechanical contact or Electrical contact.

Mechanical contact:

One of our customers used the following steps.

1.       Position the sample onto the electrodes

2.       Sandwich it between the two anvils and squeeze gently to ensure a good contact is made between sample and electrodes (at that stage you can check that the contacts are OK and that you can measure a good signal

3.       Place the gasket and the hole around the sample

4.       Add the PTM (if solid, important to make sure that no powder goes underneath the sample (Step 2 should prevent this to happen)

5.       Close the cell and check again your signal.

Electrical contact:

It is possible to connect tiny electrical wires (Au 25 microns for example) using either silver epoxy, silver paint or 2 components epoxy. This method will depend on the type of sample, expertise and available tools in the lab. It will  be more difficult that the mechanical contact.

One can see an example of such mechanical contact on the leaflet of the patterned anvil.

(CCNT – 28/04/2022)

Is it easy to mount the patterned anvils in your cells?

Replacement of current anvil with patterned anvil

It is possible to swap the two anvil/anvil ring (without pattern and with pattern) by yourself.

It is something that you would have to do routinely as you cannot preindent gaskets with the patterned anvil as this would damage prematurely the coating of the patterned anvils.

Thus the sequence is as follow

–         Indent with two normal anvils

–         Replace one anvil with the patterned anvil.

–         Check visually, side way and from above the concentricity of anvils, the lateral alignment of anvils (one is not able to carry out the alignment with the usual method of fringe alignment)

–         Prepare your sample, gasket and close the cell.

(April 2022)

How many times can you use the i-diamonds?

We do not have exact cycling values but experience show that diamond anvils which have been used up to 20GPa have been used several times without degradation of the electrodes and coating.

(February 2021)

Can I preindent gaskets with the i-diamonds?

For the pre-indentation we recommend to use 2 bare anvils. That is why normally we quote for 3 anvils (2 bare + 1 i-diamonds). In principle you can pre-indent with i-diamonds but there is always a risk as this is during the pre-indentation stage that the anvils are under the greatest stress.

Can you measure zero-resistivity in the superconducting state?

Here is an example of resistance measurements on an iron-nickel based superconductor done with designer anvils. The publication can be found at https://doi.org/10.1557/s43578-021-00110-y.

Gopi – August 2021

Gluing

How chemically resistant is the Loctite Hysol 9514 you are using?

Loctite Hysol 9514 is a toughened, single component heat curing epoxy adhesive. The table below summarises the strength of the cured epoxy when exposed to different chemical/solvents. We do not information about other solvents.