Dear Colleagues,
I have synthesised YBCO superconducting material and formed the pallet.
The levitation is very good.
But, after sintering the pallet the levitation is lost .
Does this mean the superconducting property is lost after sintering.
Thanks and Regards
N Das
Hi Nityananda Das
You don't describe the sintering conditions. Most likely you used higher temperature and/or lower oxygen content in the gas phase than you had used for the synthesis. As a result the material lost some oxygen, and therefore the superconductivity critical temperature, Tc, decreased to below the boiling point of nitrogen and you can't observe levitation anymore. (I assume you use liquid nitrogen for this experiment - it would be overkill to use liquid helium.)
Dear Emanuel Cooper,
Thanks for your kind response.
I used atmospheric pressure and atmospheric oxygen for sintering at high temperature.
Should I increase the oxygen content and then I will get the levitation after sintering?
Please suggest.
Thanks and Regards
N Das
Hi Nityananda Das
Sorry for my inaccurate answer (haven't touched the subject in 30 years).
It is important to anneal and cool down in oxygen (not air). See for example
Article YBCO films on nickel substrates prepared by spraying a suspension
(Yoshimura & al.). It may not be essential to sinter in oxygen.
If you look at their Fig. 2 (visible and expandable from the Elsevier / ScienceDirect abstract) you'll see that they make the YBCO under Ar ( that is, low oxygen), but then cool down in oxygen, anneal in oxygen for 2 hours at 600degC, and continue to cool down to ambient in oxygen. Other authors anneal at different T
Dear Emanuel Cooper,
Thanks for your helpful discussion.
Regards
N Das
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