Hi,
I am looking to find out on tested methods for direct heating of samples held within diamond anvil cells (DAC's). Currently we rely upon the use of a heat gun to warm a sample - this is not the most controllable method and I now wish to investigate a more refined method. For our purpose laser heating methods are simply not practical.
I have considered the use of small surface mount resistors to provide resistive heating to the gasket material (that would be insulated from the surrounding cell). If anyone has used this method or similar then it would be great to hear from you. Similarly, if anyone has any idea on a neat solution to this problem it would be great to hear from you.
Failing this I think that an entire cell heating method (NiChrome wire based resistive heating) would be an alternative method for cell heating.
Dear Martin,
You can check the attached procedure from university of Chicago.
Dear Martin,
heating the gasket will not be very efficient as the diamonds heat conduct very well. In order to do that you should insulate the diamonds from the cell or better the seats. This in turn can lead to mechanical instabilities but you can try. If you find a material to place between the seats and the cell stiff enough and also very poor heat conductiong please let me know.
i heat the whole DAC externally with a clamp resistive heater.
my best regards
Federico
Dear Federico,
Thank you for the advice. I intend on playing around with materials and configurations over the next few weeks so if we find something that looks like it works I will update here.
Regarding the clamp resistive heater you mention in your work, is this a lab made item or something you can purchase?
Martin
Dear Ravit,
Thank you for uploading the useful PDF, I will look over this now.
Martin
Hi,
It would be useful if you could specify what temperature you need. To achieve stable temperatures up to about 250c I also use an external resistive heater (they can be purchased cheaply from Watlow Inc.)
How easy this is to do depends on the design of your DAC. For high T I use piston-cylinder DACs which are designed specifically for doing high T. They are about 10 cm long, and the heater just slides over the cylinder. The screw holding the heater in place can just be tightened as necessary to ensure good transfer of heat between the heater and DAC.
With other DACs there are 3 potential problems - 1) Getting good heat transfer between the heater and DAC, 2) Large pressure fluctuations and 3) The DAC jamming so you can't change pressure when you need to.
John
Hi John,
Thanks for your advice. I would not require extreme temperatures, but the ability to heat to ca. 200 deg C would be very useful.
My concern at the moment with the use of relatively bulky resistive heaters (heating tape and clamp on items) is their performance in the diffractometer i.e. restricting movement of the goniometer or accidental movement of the cell during data collection.
I am relatively new to this area and so still finding my feet, especially when it comes to experimental design so I do apologise if I am asking silly questions or missing anything obvious. If it is at all possible, might you be able to share with me the type of heater you use John from Watlow as I note on their website that they supply a wide range of products.
Many thanks,
Martin
We did lots of such work at Florida International University. You can see our paper:
https://www.researchgate.net/publication/245147513_Phase_stability_of_TiH_2_under_high_pressure_and_temperatures
Article Phase stability of TiH 2 under high pressure and temperatures
Hi,
You can email Watlow to request a catalogue. Their products come in many, many different shapes and sizes so you can choose the one that will fit your DAC the best. The one I use is a nozzle heater rated at 230v 300W but I run it with a 100v power supply - I can't remember exact V,I through it but I don't think we generally go up to 100v.
John
We use Diacell® μScopeDAC-HT(G) ( https://www.almax-easylab.com/ProductDetails.aspx?id=43&IID=10030 ) for high-temperature and simultaneously high-pressure measurements. This DAC work pretty well.
- Badges
- Science method
- Similar topics
- Methodology
- Crystallography