How to prevent the aggregation of the cerium oxide nanoparticles? In the TEM analysis, i find the particles are aggregated together.
There are few ways:
1. Decrease the concentration;
2. Treat suspension with ultrasound (put the tube in a US-bath or use probe disperser (sonicator));
3. Use ultrasonic spraying technique for particle deposition.
Good luck!
Thanks for your suggestions Denis korneev.
But i tried dispersing CeO2 NPs in 0.2% NaHMP and put in sonicator bath for 4 cycles. even then my particles were not completely dispersed and with the few suspension i went for TEM analysis and it showed aggregates.
i would like to know what might be the good dispersion medium for CeO2 NPs.
Yes Kenneth M Towe. I tried in 0.2% Sodium hexametaphosphate, then sonicated and i synthesized them through hydroxide mediated precipitation.
If they're in dry form you'll never recover the original sizes. Always keep them wet. Have you considered that drying them in the TEM has caused the aggregation? You can measure your sizes with DLS in the wet state. Aggregates are not dispersible by sonication - agglomerates are. Here's a webinar. Take a look and the earlier referenced ones. You'll find CeO2 on slide 47 or so and TiO2 aggregates - slide 41 - (from 1941!) that I suspect are similar to your materials:
Nov 11th, 2008. Dispersion and nanotechnology
http://tinyurl.com/hpywsge
What's the specific surface area of the materials by BET? Take a look at:
Micron sized nano-materials Powder Technology 174(1):6-9 (May 2007)
DOI: 10.1016/j.powtec.2006.10.012
This also may be helpful:
November 3rd, 2015 Adhesion and cohesion
http://tinyurl.com/zwb2wlh
Thanks prof. Alan F Rawle.
I can give one more suggestion that
If you use any capping agent you can avoid agglomeration.
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