Yttrium oxide, also known as yttria, is Y2O3. It is an air-stable, white solid substance.
YN 135 (OTTO) Yttrium oxide nanopowder, APS 80-100 nm, 99.5%Cas no 1314-36-9 - used in oxidation resistance and ductility (in Fe-Cr alloys), conductivity (in Al-Zr alloys), conductivity and strength (in Cu alloys).