Sciencemadness Discussion Board

The formation of the firely opal.

Admagistr - 13-11-2021 at 08:18

I found this advice to create a firely opal, in a physics forum. Does anyone have practical experience with this? I got tetraethylorthosilicate yesterday;-)
For the first solution Add 12-17 parts of tetraethyl orthosilicate (TEOS) to 100 parts of alcohol (ethanol) with stirring. For the second solution Add 30-50 parts of ammonium hydroxide to 250 parts of alcohol. Next: Add the TEOS/alcohol solution to the ammonia/alcohol solution slowly with stirring. Continue stirring for about an hour to allow the reaction to come to completion. Depending on the exact concentrations of reagents you will generate a milky suspension of 250-400 nanometer silica spheres. Pour the suspension into a tube and allow it to settle. A thin layer of opal color will form in a few days and within 2-3 weeks all the suspension will have settled out and formed a brightly diffracting layer of "opal" usually a few millimeters thick depending on how much solution and the size and shape of the container. You can continue to make new batches and add to the container to increase the thickness of the growing opal layer.

wg48temp9 - 13-11-2021 at 09:51

If you have not already seen it, check out The Thought Emporium youtube video on making opal

https://www.youtube.com/watch?v=d7MvGFX_VKo

Morgan - 4-6-2023 at 09:25

An interesting flashing effect using silica nano spheres is used by a clam.
The electric clam is at the 10:45 minute mark.
https://youtu.be/Qw68XQQu55s


https://youtu.be/GRzeNlqnRxU
More thoughts on the nano spheres reflection
https://youtu.be/OLyeqo1qRVg

Morgan - 6-6-2023 at 11:31

Quote: Originally posted by Morgan  
An interesting flashing effect using silica nano spheres is used by a clam.
The electric clam is at the 10:45 minute mark.
https://youtu.be/Qw68XQQu55s


https://youtu.be/GRzeNlqnRxU
More thoughts on the nano spheres reflection
https://youtu.be/OLyeqo1qRVg


A few tidbits perhaps of interest
How the Disco Clam Uses Light to Fight Super-Strong Predators | WIRED
https://youtu.be/3GLZAIaXudk