as another contribution to the #SciencePic series, I want to show you today a five years old picture - please excuse if the quality is not up-to-date.
At these days, during my Ph.D. research, I worked with intermetallic compounds which were mostly alkaline earth silicides and gallides. One option to synthesize these compounds is to melt them in a metal ampoule, e.g. made of niobium or tantalum. Probably, I will show you another option in another post.
This time, I used niobium ampoules and wanted to heat them at about 1000 °C. Because metals oxidize when they are in contact with air at higher temperatures, I protected the ampoules in a fused silica ampoule in vacuo. Maybe, the glass was a little bit too thin this time or the metal lay in a bad way and expanded too much upon heating. Anyways, as you can see on the right side, the silica ampoule broke.
I find it quite funny, that two of the metal ampoules oxidized and kept their shape without falling to pieces. So if you want a special shape of niobium oxide, maybe you can try to shape the metal first and then put in in the oven at higher temperature?
See you next time!