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Update: I found out that the color does not come from Hf metal or lower Hf oxides or any other heavy metal. I made a series of glasses using the same compounds but with no addition of Hafnium. Changes in temperature and processing time resulted in different shading / color of the glass up to colorless species. Further investigation is needed 😎 ... See MoreSee Less
Please do elaborate 🔥💎👍
Hafnium doped borate glass.
Another 'what-the-hell..' glass!! 😲 Hafnium doped borate glass should be colorless. In this case the hafnium appears in the +4 state.
I tried to get a lower Hf oxidation state and was quite surprised that the colorless liquid glass turned almost black within a few seconds and after cooling I got these mind-blowing blood red beads.
My first thought was, that this is Hf3+ or even Hf2+ but the color change by cooling reminded me of the reaction with gold ruby and Tellurium ruby glass, i.e. Hafnium nano particles!? Is this another example?
But the most surprising was the deep red luminescence under 365nm UV. I didn't find any scientific articles or mentions about it.🧐🤓 ... See MoreSee Less
Obviously you had a reduction reaction there, either to nanoparticles of Hf or somehow an inferior oxidation state. What do you think had such a strong reducing power in your initial composition, what was your maximum temperature you went to?
Another "surprise" glass: Rhenium doped Barium phosphate glass. I expected a colorless or pale yellow glass which it was when still hot. On cooling the color changed to pale blue which cannot be the +7 state of Re as stated in the literature!? ... See MoreSee Less
Those are gorgeous! It depends if you use an oxidative or reducing mixture to produce the doped barium phosphate. Also it depends what Re compound you have used..... I am planning to try Re in 3, 5, 6 and 7 oxidation state in different starting mixtures soon.
NH4ReO4 will be reduced to Re nanoparticles immediately.
This effect only occurred at higher temperatures when phosphate glasses have reducing properties. I did not manage to get more than these two beads. Re is horrible as dopant, it also evaporates relatively fast.
I think that the oxidation state of the rhenium compound does not matter in this case. I used Re powder and NH4ReO4 with same result.
Chromium 3+ doped Large Phosphate glass beads.
High melting point Sodium Aluminum Zinc phosphate glass doped with 0.15 mol% Cr2O3. The glass is very durable and chemically resistant. ... See MoreSee Less
Zinc Aluminum Phosphate-Tellurite glass
A new glass containing 5mol% Tellurium Oxide which forms metallic nano clusters and causes this beautiful red-pink color. ... See MoreSee Less
TeO2 or TeO3 ?
A new batch of rare earth doped barium phosphate glass ingots. From above left to right: Pr3+, Dy3+, Ho3+,Er3+, Tb3+. The three ingots on the right are mirror polished on the back side. Diameter ~ 40mm, Height ~ 16mm ... See MoreSee Less
Chromium 6+ doped Sodium Lanthanum borate glass.
Hexavalent Chromium ions cause a yellowish green color. A high basicity of the glass matrix is needed to obtain Cr6+. In phosphate glasses the only stable ion is Cr3+
The doping concentration needs to be very low (~ 0.01 - 0.05mol%) ... See MoreSee Less
Selenium discharge tube & spectrum.
On the picture you see the strong discharge from pure selenium. The ampoule needs to be heated before to get enough selenium gas pressure. You can also see condensed red selenium on the inner surface of the tube The lower picture shows its emission spectrum. ... See MoreSee Less