YbF3 powder color becomes gray/black when I sinter at 400C or 500C or 600C even when I sinter with a cover on the powder. I am using Yb acetate as a Yb source.
When I use Yb nitrate as a source, then at 600C, YbF3 powder color is white but in XRD, there is a peak of YbOOH.
I want to synthesize pure YbF3 with white color and particle size less than 40 nm.
By the way, I am using sol-gel process and using Et-OH as a solvent to avoid YbOOH peak.
Did you check if coke is produced during the sintering process? The fact that a carbon containing salt is causing the grey colour, in contrast to non carbon containing salt, supports this theory.
Hi Zain,
After the sol gel synthesis, your YbF3 sample must have traces of carbon (inherent from the sol). My experience from calcination of carbonates is that white CaCO3 from many source would first turn black or at least dark (at about 300 to 550oC) before sparkling again at higher temperature range (probably, after the carbon/black substance is consumed).
I suggest you increase the sintering temperature and time and ensure slight ventilation/aeration if possible.
Thank you very much Vanessa and Onyeka.
According to your recommendation, I am now sintering YbF3 (synthesized by using Yb acetate source) at 900C for 3 hours. I will post the results here.
Next week, I will again synthesize YbF3 from Yb nitrate source and will also sinter that at 900C for 3 hours.
and can you please suggest me how to remove the YbOOH or YbOF peaks from coming in XRD when using Yb nitrate as a source material?
You should be aware that primary particle size might be 40 nm or less, after sintering you will have aggregates of them, which you will not be able to redisperse into primary particle size.
Thank you very much Titus Sobisch and Onyeka. I have tested at 900C for 3 hours. And powder color was also white and there was no peak of YbOOH or YbOF. All peaks were of YbF3 but particles were very large (more than 2 micrometers).
I think I should find some post sintering process to get the particle size below 100 nm.
Now question is what is potential application. E.g. if it is for catalyst you may first cover the surface of a supporting material with individual particles and then start sintering.
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