Empathy List Archives

VR

vallidivya rajendran

Fri, Oct 9, 2026 9:14 AM

Dear mineralogists,
I am a PhD student of earth sciences and I am trying to do a high pressure
experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my
first experiment using DAC. We are using methanol-ethanol mixture as the
pressure transmitting medium and ruby as a pressure calibrant for raman
studies. We are observing the ruby lines not shifting with pressure. What
can be the possible reasons for it and solutions?
We suspect two things may be the reason:

Sample and ruby not in central position. I am unable to align it exactly
at the centre. Either it flies away or it moves to the edges of the
gasket as mixture is applied.
The mixture is evaporating or leaking.
Is there any trick to overcome these challenges?

Any comments or suggestions are useful for me.

Regards,
R Valli Divya

Dear mineralogists, I am a PhD student of earth sciences and I am trying to do a high pressure experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my first experiment using DAC. We are using methanol-ethanol mixture as the pressure transmitting medium and ruby as a pressure calibrant for raman studies. We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions? We suspect two things may be the reason: 1. Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied. 2. The mixture is evaporating or leaking. Is there any trick to overcome these challenges? Any comments or suggestions are useful for me. Regards, R Valli Divya

ZJ

Zhang, Jin

Fri, Oct 9, 2026 9:11 PM

Dear R. Valli Divya,

Where your ruby fluorescence line is located? At ambient pressure (1 atm), the R1 line should be around 694.1–694.3 nm depending on the spectrometer and rubies you use. If your measured value is within this range, one possibility is that some of the methanol–ethanol mixture leaked out during loading, leaving the sample and ruby at close to ambient pressure. In that case, tightening the screws may not necessarily increase the pressure.

One other side note, the methanol–ethanol mixture may not be the best pressure medium for measurements up to 20 GPa, as it solidifies at around 10–11 GPa. Above that pressure, it becomes quite rigid and may no longer provide good hydrostatic conditions. If gas loading is available, it could be a better option for your high-pressure measurements.

Best,

--
Dr. Jin Zhang (张瑾)
She/her/hers
Associate Professor
Rosie M. and Murray D. Page Geology & Geophysics Endowed Professorship
Department of Geology and Geophysics
Texas A&M University
Halbouty 157
3115 TAMU
College Station, TX 77843
Phone: 979-845-4959
Email: jinzhang@tamu.edu mailto:jinzhang@tamu.edu

From: vallidivya rajendran via MSA-talk msa-talk@minlists.org
Reply-To: vallidivya rajendran vallidivya.rajendran@gmail.com
Date: Friday, October 9, 2026 at 3:45 PM
To: "MSA-talk@minlists.org" msa-talk@minlists.org
Subject: [MSA-talk] Query in High Pressure experiment

Dear mineralogists, I am a PhD student of earth sciences and I am trying to do a high pressure experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my first experiment using DAC. We are using methanol-ethanol mixture as the
ZjQcmQRYFpfptBannerStart
This Message Is From an External Sender
This message came from outside your organization.
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Dear mineralogists,
I am a PhD student of earth sciences and I am trying to do a high pressure experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my first experiment using DAC. We are using methanol-ethanol mixture as the pressure transmitting medium and ruby as a pressure calibrant for raman studies. We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions?
We suspect two things may be the reason:

Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied.
The mixture is evaporating or leaking.
Is there any trick to overcome these challenges?

Any comments or suggestions are useful for me.

Regards,
R Valli Divya

Dear R. Valli Divya, Where your ruby fluorescence line is located? At ambient pressure (1 atm), the R1 line should be around 694.1–694.3 nm depending on the spectrometer and rubies you use. If your measured value is within this range, one possibility is that some of the methanol–ethanol mixture leaked out during loading, leaving the sample and ruby at close to ambient pressure. In that case, tightening the screws may not necessarily increase the pressure. One other side note, the methanol–ethanol mixture may not be the best pressure medium for measurements up to 20 GPa, as it solidifies at around 10–11 GPa. Above that pressure, it becomes quite rigid and may no longer provide good hydrostatic conditions. If gas loading is available, it could be a better option for your high-pressure measurements. Best, -- Dr. Jin Zhang (张瑾) She/her/hers Associate Professor Rosie M. and Murray D. Page Geology & Geophysics Endowed Professorship Department of Geology and Geophysics Texas A&M University Halbouty 157 3115 TAMU College Station, TX 77843 Phone: 979-845-4959 Email: jinzhang@tamu.edu<mailto:jinzhang@tamu.edu> From: vallidivya rajendran via MSA-talk <msa-talk@minlists.org> Reply-To: vallidivya rajendran <vallidivya.rajendran@gmail.com> Date: Friday, October 9, 2026 at 3:45 PM To: "MSA-talk@minlists.org" <msa-talk@minlists.org> Subject: [MSA-talk] Query in High Pressure experiment Dear mineralogists, I am a PhD student of earth sciences and I am trying to do a high pressure experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my first experiment using DAC. We are using methanol-ethanol mixture as the ZjQcmQRYFpfptBannerStart This Message Is From an External Sender This message came from outside your organization. ZjQcmQRYFpfptBannerEnd Dear mineralogists, I am a PhD student of earth sciences and I am trying to do a high pressure experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my first experiment using DAC. We are using methanol-ethanol mixture as the pressure transmitting medium and ruby as a pressure calibrant for raman studies. We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions? We suspect two things may be the reason: 1. Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied. 2. The mixture is evaporating or leaking. Is there any trick to overcome these challenges? Any comments or suggestions are useful for me. Regards, R Valli Divya

DZ

Dongzhou Zhang

Fri, Oct 9, 2026 9:48 PM

Hi Valli Divya,

"We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions?"
From my limited experience, I've seen two possibilities

The ruby is not from a good batch. Try to load a diamond cell with only salt or water and a few ruby spheres. Compress the DAC and see if the ruby pressure goes up. Good ruby should give very clear fluorescence around 695 nm, which shifts up with increasing pressure.
2.
If the ruby has no problem, then did you observe clear gasket hole shrinkage during compression? If so, you probably didn't fill the sample chamber with enough pressure medium, or it evaporated before you close the DAC.

"Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied."
I would try to load the sample and ruby on the opposite side diamond, where there is no gasket attached. You would indent the gasket and drill a hole at the very center, then load the sample and ruby on the diamond culet center that's not attached to the gasket, then fill the sample chamber with your pressure medium and quickly close the DAC before the medium evaporates.

Dongzhou

From: vallidivya rajendran via MSA-talk msa-talk@minlists.org
Sent: Friday, October 9, 2026 4:14 AM
To: MSA-talk@minlists.org MSA-talk@minlists.org
Subject: [MSA-talk] Query in High Pressure experiment

Dear mineralogists,
I am a PhD student of earth sciences and I am trying to do a high pressure experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my first experiment using DAC. We are using methanol-ethanol mixture as the pressure transmitting medium and ruby as a pressure calibrant for raman studies. We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions?
We suspect two things may be the reason:

Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied.
The mixture is evaporating or leaking.
Is there any trick to overcome these challenges?

Any comments or suggestions are useful for me.

Regards,
R Valli Divya

Hi Valli Divya, "We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions?" From my limited experience, I've seen two possibilities 1. The ruby is not from a good batch. Try to load a diamond cell with only salt or water and a few ruby spheres. Compress the DAC and see if the ruby pressure goes up. Good ruby should give very clear fluorescence around 695 nm, which shifts up with increasing pressure. 2. If the ruby has no problem, then did you observe clear gasket hole shrinkage during compression? If so, you probably didn't fill the sample chamber with enough pressure medium, or it evaporated before you close the DAC. "Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied." I would try to load the sample and ruby on the opposite side diamond, where there is no gasket attached. You would indent the gasket and drill a hole at the very center, then load the sample and ruby on the diamond culet center that's not attached to the gasket, then fill the sample chamber with your pressure medium and quickly close the DAC before the medium evaporates. Dongzhou ________________________________ From: vallidivya rajendran via MSA-talk <msa-talk@minlists.org> Sent: Friday, October 9, 2026 4:14 AM To: MSA-talk@minlists.org <MSA-talk@minlists.org> Subject: [MSA-talk] Query in High Pressure experiment Dear mineralogists, I am a PhD student of earth sciences and I am trying to do a high pressure experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my first experiment using DAC. We are using methanol-ethanol mixture as the pressure transmitting medium and ruby as a pressure calibrant for raman studies. We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions? We suspect two things may be the reason: 1. Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied. 2. The mixture is evaporating or leaking. Is there any trick to overcome these challenges? Any comments or suggestions are useful for me. Regards, R Valli Divya

VR

vallidivya rajendran

Sat, Oct 10, 2026 1:49 AM

Dear mineralogists,
Thank you everyone for the response. The culet diameter is 350 micrometer.
The gasket hole is 126.1 micrometer on one side and 112.6 micrometer on the
other side. There was no visible change in the shape of the gasket hole
with initial compression. As there was no ruby lines R1 shift I didn't
increase it too much. From the rotation of the screws it should be 2-3GPa.

R1 is at 694.5 nm. Yes methanol-ethanol has hydrostaticity upto 10.5 GPa
but we don't have gas loading facility for now. Hence the cheapest and
easiest option for now is methanol-ethanol mixture alone.

I will check the rubies and try the sample loading technique you have
mentioned.

We tried to do it a couple of times but only once it showed pressure
increase with rubies only. Then after some attempts even with only rubies
the R1 line shift was not there.

I really appreciate the help. Thank you.

Regards,
Valli Divya

On Sat, 10 Oct 2026, 03:19 Dongzhou Zhang, dzzhang@cars.uchicago.edu
wrote:

Hi Valli Divya,

"We are observing the ruby lines not shifting with pressure. What can be
the possible reasons for it and solutions?"
From my limited experience, I've seen two possibilities

1. The ruby is not from a good batch. Try to load a diamond cell with
only salt or water and a few ruby spheres. Compress the DAC and see if the
ruby pressure goes up. Good ruby should give very clear fluorescence around
695 nm, which shifts up with increasing pressure.
2. If the ruby has no problem, then did you observe clear gasket hole
shrinkage during compression? If so, you probably didn't fill the sample
chamber with enough pressure medium, or it evaporated before you close the
DAC.

"Sample and ruby not in central position. I am unable to align it exactly
at the centre. Either it flies away or it moves to the edges of the
gasket as mixture is applied."
I would try to load the sample and ruby on the opposite side diamond,
where there is no gasket attached. You would indent the gasket and drill a
hole at the very center, then load the sample and ruby on the diamond culet
center that's not attached to the gasket, then fill the sample chamber with
your pressure medium and quickly close the DAC before the medium evaporates.

Dongzhou

From: vallidivya rajendran via MSA-talk msa-talk@minlists.org
Sent: Friday, October 9, 2026 4:14 AM
To: MSA-talk@minlists.org MSA-talk@minlists.org
Subject: [MSA-talk] Query in High Pressure experiment

Dear mineralogists,
I am a PhD student of earth sciences and I am trying to do a high pressure
experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my
first experiment using DAC. We are using methanol-ethanol mixture as the
pressure transmitting medium and ruby as a pressure calibrant for raman
studies. We are observing the ruby lines not shifting with pressure. What
can be the possible reasons for it and solutions?
We suspect two things may be the reason:

Sample and ruby not in central position. I am unable to align it
exactly at the centre. Either it flies away or it moves to the edges of the
gasket as mixture is applied.
The mixture is evaporating or leaking.
Is there any trick to overcome these challenges?

Any comments or suggestions are useful for me.

Regards,
R Valli Divya

Dear mineralogists, Thank you everyone for the response. The culet diameter is 350 micrometer. The gasket hole is 126.1 micrometer on one side and 112.6 micrometer on the other side. There was no visible change in the shape of the gasket hole with initial compression. As there was no ruby lines R1 shift I didn't increase it too much. From the rotation of the screws it should be 2-3GPa. R1 is at 694.5 nm. Yes methanol-ethanol has hydrostaticity upto 10.5 GPa but we don't have gas loading facility for now. Hence the cheapest and easiest option for now is methanol-ethanol mixture alone. I will check the rubies and try the sample loading technique you have mentioned. We tried to do it a couple of times but only once it showed pressure increase with rubies only. Then after some attempts even with only rubies the R1 line shift was not there. I really appreciate the help. Thank you. Regards, Valli Divya On Sat, 10 Oct 2026, 03:19 Dongzhou Zhang, <dzzhang@cars.uchicago.edu> wrote: > Hi Valli Divya, > > "We are observing the ruby lines not shifting with pressure. What can be > the possible reasons for it and solutions?" > From my limited experience, I've seen two possibilities > > 1. The ruby is not from a good batch. Try to load a diamond cell with > only salt or water and a few ruby spheres. Compress the DAC and see if the > ruby pressure goes up. Good ruby should give very clear fluorescence around > 695 nm, which shifts up with increasing pressure. > 2. If the ruby has no problem, then did you observe clear gasket hole > shrinkage during compression? If so, you probably didn't fill the sample > chamber with enough pressure medium, or it evaporated before you close the > DAC. > > > "Sample and ruby not in central position. I am unable to align it exactly > at the centre. Either it flies away or it moves to the edges of the > gasket as mixture is applied." > I would try to load the sample and ruby on the opposite side diamond, > where there is no gasket attached. You would indent the gasket and drill a > hole at the very center, then load the sample and ruby on the diamond culet > center that's not attached to the gasket, then fill the sample chamber with > your pressure medium and quickly close the DAC before the medium evaporates. > > Dongzhou > > ------------------------------ > *From:* vallidivya rajendran via MSA-talk <msa-talk@minlists.org> > *Sent:* Friday, October 9, 2026 4:14 AM > *To:* MSA-talk@minlists.org <MSA-talk@minlists.org> > *Subject:* [MSA-talk] Query in High Pressure experiment > > Dear mineralogists, > I am a PhD student of earth sciences and I am trying to do a high pressure > experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my > first experiment using DAC. We are using methanol-ethanol mixture as the > pressure transmitting medium and ruby as a pressure calibrant for raman > studies. We are observing the ruby lines not shifting with pressure. What > can be the possible reasons for it and solutions? > We suspect two things may be the reason: > 1. Sample and ruby not in central position. I am unable to align it > exactly at the centre. Either it flies away or it moves to the edges of the > gasket as mixture is applied. > 2. The mixture is evaporating or leaking. > Is there any trick to overcome these challenges? > > Any comments or suggestions are useful for me. > > Regards, > R Valli Divya >

RJ

Ross John Angel

Sat, Oct 10, 2026 11:16 AM

Dear R. Valli Divya,

If I may add a comment on your pressure medium; Dr Zhang is absolutely
correct, the standard methanol: ethanol mixture supports shear waves and
therefore non hydrostatic stress above 9.8 GPa. This will deform your
sample and in addition will result in the shifts of the ruby lines
deviating from their hydrostatic behaviour. Therefore the apparent
pressure that you would obtain from the position of the ruby lines above
9.8 GPa will not be the mean stress in your DAC, and any data collected
in meth:eth above 9.8 GPa will not be meaningful (unless you are
intending to study the effects of non-hydrostatic stress).

There is more detail in the following publications:

Chai M, Brown JM (1996) Geophysical Research Letters 23:3539-3542.
Angel RJ, Bujak M, Zhao J, Gatta GD, Jacobsen SD (2007) Journal of
Applied Crystallography 40:26-32.

Ross Angel

On 09/10/2026 23:11, Zhang, Jin via MSA-talk wrote:

Dear R. Valli Divya,

Where your ruby fluorescence line is located? At ambient pressure (1
atm), the R1 line should be around 694.1–694.3 nm depending on the
spectrometer and rubies you use. If your measured value is within this
range, one possibility is that some of the methanol–ethanol mixture
leaked out during loading, leaving the sample and ruby at close to
ambient pressure. In that case, tightening the screws may not
necessarily increase the pressure.

One other side note, the methanol–ethanol mixture may not be the best
pressure medium for measurements up to 20 GPa, as it solidifies at
around 10–11 GPa. Above that pressure, it becomes quite rigid and may
no longer provide good hydrostatic conditions. If gas loading is
available, it could be a better option for your high-pressure
measurements.

Best,

--

Dr. Jin Zhang (张瑾)

/She/her/hers/

Associate Professor

Rosie M. and Murray D. Page Geology & Geophysics Endowed Professorship

Department of Geology and Geophysics

Texas A&M University

Halbouty 157

3115 TAMU

College Station, TX 77843

Phone: 979-845-4959

Email: jinzhang@tamu.edu mailto:jinzhang@tamu.edu

*From: *vallidivya rajendran via MSA-talk msa-talk@minlists.org
*Reply-To: *vallidivya rajendran vallidivya.rajendran@gmail.com
*Date: *Friday, October 9, 2026 at 3:45 PM
*To: *"MSA-talk@minlists.org" msa-talk@minlists.org
*Subject: *[MSA-talk] Query in High Pressure experiment

Dear mineralogists, I am a PhD student of earth sciences and I am
trying to do a high pressure experiment up to 20GPa using Diamond
Anvil Cell for a mineral. This is my first experiment using DAC. We
are using methanol-ethanol mixture as the

ZjQcmQRYFpfptBannerStart

*This Message Is From an External Sender *

This message came from outside your organization.

ZjQcmQRYFpfptBannerEnd

Dear mineralogists,

I am a PhD student of earth sciences and I am trying to do a high
pressure experiment up to 20GPa using Diamond Anvil Cell for a
mineral. This is my first experiment using DAC. We are using
methanol-ethanol mixture as the pressure transmitting medium and ruby
as a pressure calibrant for raman studies. We are observing the ruby
lines not shifting with pressure. What can be the possible reasons for
it and solutions?

We suspect two things may be the reason:

Sample and ruby not in central position. I am unable to align it
exactly at the centre. Either it flies away or it moves to the edges
of the gasket as mixture is applied.
The mixture is evaporating or leaking.

Is there any trick to overcome these challenges?

Any comments or suggestions are useful for me.

Regards,

R Valli Divya

MSA-talk mailing list --msa-talk@minlists.org
To unsubscribe send an email tomsa-talk-leave@minlists.org

--
Dr. Ross John Angel
Istituto di Geoscienze, CNR
Corso Stati Uniti 4, 35127 Padova, Italy

rossjohnangel@gmail.com
Websites:www.rossangel.net |www.mineralogylab.com

Jeder Gipfel ist in Wirklichkeit nur ein Umweg zur nächsten Kneipe

Dear R. Valli Divya, If I may add a comment on your pressure medium; Dr Zhang is absolutely correct, the standard methanol: ethanol mixture supports shear waves and therefore non hydrostatic stress above 9.8 GPa. This will deform your sample and in addition will result in the shifts of the ruby lines deviating from their hydrostatic behaviour. Therefore the apparent pressure that you would obtain from the position of the ruby lines above 9.8 GPa will not be the mean stress in your DAC, and any data collected in meth:eth above 9.8 GPa will not be meaningful (unless you are intending to study the effects of non-hydrostatic stress). There is more detail in the following publications: Chai M, Brown JM (1996) Geophysical Research Letters 23:3539-3542. Angel RJ, Bujak M, Zhao J, Gatta GD, Jacobsen SD (2007) Journal of Applied Crystallography 40:26-32. Ross Angel On 09/10/2026 23:11, Zhang, Jin via MSA-talk wrote: > > Dear R. Valli Divya, > > Where your ruby fluorescence line is located? At ambient pressure (1 > atm), the R1 line should be around 694.1–694.3 nm depending on the > spectrometer and rubies you use. If your measured value is within this > range, one possibility is that some of the methanol–ethanol mixture > leaked out during loading, leaving the sample and ruby at close to > ambient pressure. In that case, tightening the screws may not > necessarily increase the pressure. > > One other side note, the methanol–ethanol mixture may not be the best > pressure medium for measurements up to 20 GPa, as it solidifies at > around 10–11 GPa. Above that pressure, it becomes quite rigid and may > no longer provide good hydrostatic conditions. If gas loading is > available, it could be a better option for your high-pressure > measurements. > > Best, > > -- > > *Dr. Jin Zhang (**张瑾**)* > > /She/her/hers/ > > Associate Professor > > Rosie M. and Murray D. Page Geology & Geophysics Endowed Professorship > > Department of Geology and Geophysics > > Texas A&M University > > Halbouty 157 > > 3115 TAMU > > College Station, TX 77843 > > Phone: 979-845-4959 > > Email: _jinzhang@tamu.edu <mailto:jinzhang@tamu.edu>_ > > *From: *vallidivya rajendran via MSA-talk <msa-talk@minlists.org> > *Reply-To: *vallidivya rajendran <vallidivya.rajendran@gmail.com> > *Date: *Friday, October 9, 2026 at 3:45 PM > *To: *"MSA-talk@minlists.org" <msa-talk@minlists.org> > *Subject: *[MSA-talk] Query in High Pressure experiment > > Dear mineralogists, I am a PhD student of earth sciences and I am > trying to do a high pressure experiment up to 20GPa using Diamond > Anvil Cell for a mineral. This is my first experiment using DAC. We > are using methanol-ethanol mixture as the > > ZjQcmQRYFpfptBannerStart > > *This Message Is From an External Sender * > > This message came from outside your organization. > > ZjQcmQRYFpfptBannerEnd > > Dear mineralogists, > > I am a PhD student of earth sciences and I am trying to do a high > pressure experiment up to 20GPa using Diamond Anvil Cell for a > mineral. This is my first experiment using DAC. We are using > methanol-ethanol mixture as the pressure transmitting medium and ruby > as a pressure calibrant for raman studies. We are observing the ruby > lines not shifting with pressure. What can be the possible reasons for > it and solutions? > > We suspect two things may be the reason: > > 1. Sample and ruby not in central position. I am unable to align it > exactly at the centre. Either it flies away or it moves to the edges > of the gasket as mixture is applied. > > 2. The mixture is evaporating or leaking. > > Is there any trick to overcome these challenges? > > Any comments or suggestions are useful for me. > > Regards, > > R Valli Divya > > > _______________________________________________ > MSA-talk mailing list --msa-talk@minlists.org > To unsubscribe send an email tomsa-talk-leave@minlists.org -- Dr. Ross John Angel Istituto di Geoscienze, CNR Corso Stati Uniti 4, 35127 Padova, Italy rossjohnangel@gmail.com Websites:www.rossangel.net |www.mineralogylab.com Jeder Gipfel ist in Wirklichkeit nur ein Umweg zur nächsten Kneipe

DS

Dorfman, Susannah

Sat, Oct 10, 2026 9:15 PM

I think the key is that "From the rotation of the screws" is not at all a reliable measure of what pressure should be. If you change your screws and washers for example, the turns of the screw will be different. If the gasket hole hasn't shrunk and the ruby shows no pressure, you probably just need to keep turning!

Susannah Dorfman
Associate Professor, Department of Earth and Environmental Sciences
Adjunct Associate Professor, Department of Physics and Astronomy
288 Farm Lane
East Lansing, MI 48824
Http://sukidorfman.rocks
She/her/hers

From: vallidivya rajendran via MSA-talk msa-talk@minlists.org
Sent: Friday, 09 October 2026 21:49:02
To: Dongzhou Zhang dzzhang@cars.uchicago.edu
Cc: MSA-talk@minlists.org msa-talk@minlists.org
Subject: [MSA-talk] Re: Query in High Pressure experiment

Dear mineralogists,
Thank you everyone for the response. The culet diameter is 350 micrometer. The gasket hole is 126.1 micrometer on one side and 112.6 micrometer on the other side. There was no visible change in the shape of the gasket hole with initial compression. As there was no ruby lines R1 shift I didn't increase it too much. From the rotation of the screws it should be 2-3GPa.

R1 is at 694.5 nm. Yes methanol-ethanol has hydrostaticity upto 10.5 GPa but we don't have gas loading facility for now. Hence the cheapest and easiest option for now is methanol-ethanol mixture alone.

I will check the rubies and try the sample loading technique you have mentioned.

We tried to do it a couple of times but only once it showed pressure increase with rubies only. Then after some attempts even with only rubies the R1 line shift was not there.

I really appreciate the help. Thank you.

Regards,
Valli Divya

On Sat, 10 Oct 2026, 03:19 Dongzhou Zhang, <dzzhang@cars.uchicago.edu mailto:dzzhang@cars.uchicago.edu> wrote:
Hi Valli Divya,

"We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions?"
From my limited experience, I've seen two possibilities

The ruby is not from a good batch. Try to load a diamond cell with only salt or water and a few ruby spheres. Compress the DAC and see if the ruby pressure goes up. Good ruby should give very clear fluorescence around 695 nm, which shifts up with increasing pressure.
2.
If the ruby has no problem, then did you observe clear gasket hole shrinkage during compression? If so, you probably didn't fill the sample chamber with enough pressure medium, or it evaporated before you close the DAC.

"Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied."
I would try to load the sample and ruby on the opposite side diamond, where there is no gasket attached. You would indent the gasket and drill a hole at the very center, then load the sample and ruby on the diamond culet center that's not attached to the gasket, then fill the sample chamber with your pressure medium and quickly close the DAC before the medium evaporates.

Dongzhou

From: vallidivya rajendran via MSA-talk <msa-talk@minlists.org mailto:msa-talk@minlists.org>
Sent: Friday, October 9, 2026 4:14 AM
To: MSA-talk@minlists.org mailto:MSA-talk@minlists.org <MSA-talk@minlists.org mailto:MSA-talk@minlists.org>
Subject: [MSA-talk] Query in High Pressure experiment

Dear mineralogists,
I am a PhD student of earth sciences and I am trying to do a high pressure experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my first experiment using DAC. We are using methanol-ethanol mixture as the pressure transmitting medium and ruby as a pressure calibrant for raman studies. We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions?
We suspect two things may be the reason:

Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied.
The mixture is evaporating or leaking.
Is there any trick to overcome these challenges?

Any comments or suggestions are useful for me.

Regards,
R Valli Divya

I think the key is that "From the rotation of the screws" is not at all a reliable measure of what pressure should be. If you change your screws and washers for example, the turns of the screw will be different. If the gasket hole hasn't shrunk and the ruby shows no pressure, you probably just need to keep turning! Susannah Dorfman Associate Professor, Department of Earth and Environmental Sciences Adjunct Associate Professor, Department of Physics and Astronomy 288 Farm Lane East Lansing, MI 48824 Http://sukidorfman.rocks She/her/hers ________________________________ From: vallidivya rajendran via MSA-talk <msa-talk@minlists.org> Sent: Friday, 09 October 2026 21:49:02 To: Dongzhou Zhang <dzzhang@cars.uchicago.edu> Cc: MSA-talk@minlists.org <msa-talk@minlists.org> Subject: [MSA-talk] Re: Query in High Pressure experiment Dear mineralogists, Thank you everyone for the response. The culet diameter is 350 micrometer. The gasket hole is 126.1 micrometer on one side and 112.6 micrometer on the other side. There was no visible change in the shape of the gasket hole with initial compression. As there was no ruby lines R1 shift I didn't increase it too much. From the rotation of the screws it should be 2-3GPa. R1 is at 694.5 nm. Yes methanol-ethanol has hydrostaticity upto 10.5 GPa but we don't have gas loading facility for now. Hence the cheapest and easiest option for now is methanol-ethanol mixture alone. I will check the rubies and try the sample loading technique you have mentioned. We tried to do it a couple of times but only once it showed pressure increase with rubies only. Then after some attempts even with only rubies the R1 line shift was not there. I really appreciate the help. Thank you. Regards, Valli Divya On Sat, 10 Oct 2026, 03:19 Dongzhou Zhang, <dzzhang@cars.uchicago.edu<mailto:dzzhang@cars.uchicago.edu>> wrote: Hi Valli Divya, "We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions?" From my limited experience, I've seen two possibilities 1. The ruby is not from a good batch. Try to load a diamond cell with only salt or water and a few ruby spheres. Compress the DAC and see if the ruby pressure goes up. Good ruby should give very clear fluorescence around 695 nm, which shifts up with increasing pressure. 2. If the ruby has no problem, then did you observe clear gasket hole shrinkage during compression? If so, you probably didn't fill the sample chamber with enough pressure medium, or it evaporated before you close the DAC. "Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied." I would try to load the sample and ruby on the opposite side diamond, where there is no gasket attached. You would indent the gasket and drill a hole at the very center, then load the sample and ruby on the diamond culet center that's not attached to the gasket, then fill the sample chamber with your pressure medium and quickly close the DAC before the medium evaporates. Dongzhou ________________________________ From: vallidivya rajendran via MSA-talk <msa-talk@minlists.org<mailto:msa-talk@minlists.org>> Sent: Friday, October 9, 2026 4:14 AM To: MSA-talk@minlists.org<mailto:MSA-talk@minlists.org> <MSA-talk@minlists.org<mailto:MSA-talk@minlists.org>> Subject: [MSA-talk] Query in High Pressure experiment Dear mineralogists, I am a PhD student of earth sciences and I am trying to do a high pressure experiment up to 20GPa using Diamond Anvil Cell for a mineral. This is my first experiment using DAC. We are using methanol-ethanol mixture as the pressure transmitting medium and ruby as a pressure calibrant for raman studies. We are observing the ruby lines not shifting with pressure. What can be the possible reasons for it and solutions? We suspect two things may be the reason: 1. Sample and ruby not in central position. I am unable to align it exactly at the centre. Either it flies away or it moves to the edges of the gasket as mixture is applied. 2. The mixture is evaporating or leaking. Is there any trick to overcome these challenges? Any comments or suggestions are useful for me. Regards, R Valli Divya