Extending the Range: Novel Rare-Earth Colorants

(08 April, 2005)

In the process of developing a glaze that precipitates crystals of calcium tungstate (CaWO4, Scheelite), I happened to dip the edge of a test tile into a solution of europium nitrate. Where the glaze and the dipped area overlapped, the glaze was brownish after I fired the tile.

Some time later, while I was refining the glaze, I decided to try Eu2O3 as a colorant, to see whether it would be of any interest. I started with 1%, and then added 6% of Er2O3 on top of that, to see what the combination would look like. The tiles were fired to cone 11 in mild reduction:


This seemed quite promising, but the glaze was thin and watery, rather than thick and cloudy, so I continued to revise it. The next firing was v0.4, this time to about cone 10.5, in moderate reduction; from left to right, plain, with 2.5% Eu2O3, and Eu plus 6% Er2O3:


It seemed like a good idea to try this with Mo in place of W, so I did, approximately an equimolar amount. Again, from the left: plain, 2.5% Eu, Eu + 6% Er:

As you can see, I used a soluble form of Mo (Ammonium Molybdate), because that’s what I had on hand. Not quite the expected result, but certainly interesting!

This work is supported by
The Joss Research Institute
19 Main St.
Laurel  MD  20707-4303   USA

Contact Information:

My email address is a@b.com, where a is jon and b=joss.

Phone: +1 240 604 4495.

Last modified: Sat Dec 23 21:31:21 EST 2006