Holmium (III) Oxide

[amphibole]

Holmium (III) Oxide exhibits some pretty dramatic color changes (see this attached photo), but I am uncertain about the mechanism that causes this change to occur. The literature on it is slim, and what exists on the subject is dense and jargon-y, as well as being behind a paywall that my school doesn't subscribe to. Can anyone here explain this phenomenon to me? 

 

Edited March 22, 2018 by amphibole

[StringJunky]

Here's a wiki explanation. Perhaps someone here can elaborate on it. I've bolded the part I think needs explaining:

Quote

Appearance
Holmium oxide has some fairly dramatic color changes depending on the lighting conditions. In daylight, it is a tannish yellow color. Under trichromatic light, it is a fiery orange red, almost indistinguishable from the way erbium oxide looks under this same lighting. This is related to the sharp emission bands of the phosphors.[2] Holmium oxide has a wide band gap of 5.3 eV[1] and thus should appear colorless. The yellow color originates from abundant lattice defects (such as oxygen vacancies) and is related to internal transitions at the Ho3+ ions.[2]   https://en.wikipedia.org/wiki/Holmium(III)_oxide

 

Edited March 22, 2018 by StringJunky

[amphibole]

Yeah, I went to the wiki page for it and that was the part I was confused about. I believe that a phosphor is a term used to describe any material that emits light without heat

[koti]

38 minutes ago, amphibole said:

Holmium (III) Oxide exhibits some pretty dramatic color changes (see this attached photo), but I am uncertain about the mechanism that causes this change to occur. The literature on it is slim, and what exists on the subject is dense and jargon-y, as well as being behind a paywall that my school doesn't subscribe to. Can anyone here explain this phenomenon to me? 

 

Holmium oxide color change depends on the type of light it is exposed to. In LED light it will appear yellowish, in fluorescent light it will appear more orange or pink. I don’t know the exact reason for it but it has to do with the light absorbtion properties and not with a chemical reaction over time. I’ve heard that other elements from the F block in the periodic table hold some interesting light absorbtion properties. 

Edited March 22, 2018 by koti

[amphibole]

1 minute ago, koti said:

Holmium oxide color change depends on the type of light it is exposed to. In LED light it will appear yellowish, in fluorescent light it will appear more orange or pink. I don’t know the exact reason for it but it has to do with the light absorbtion properties and not with a chemical reaction over time. I’ve heard that other elements from the F block in the periodic table hold some interesting light absorbtion properties. 

Yeah, I actually purchased some from a ceramics supplier, which prompted me to ask this question in the first place. It's beautiful to look at, but I sure wish I could figure out just what's going on!

[koti]

7 minutes ago, amphibole said:

Yeah, I actually purchased some from a ceramics supplier, which prompted me to ask this question in the first place. It's beautiful to look at, but I sure wish I could figure out just what's going on!

Google „f block elements color properties” it should get you on track.

I had a spectrophotometer guy selling some products at my work some years ago have a vial of Holmium oxide. Aparently it is used in spectrophotometers, it was beautiful to look at. Try different types of lighting on it.

Edited March 22, 2018 by koti