DOPANT DISTRIBUTIONS IN RARE-EARTH-DOPED ALUMINA

The distribution of yttrium and lanthanum dopants has been mapped in y ttrium- and lanthanum-doped polycrystalline aluminas using imaging sec ondary-ion mass spectrometry (imaging-SIMS), Both dopants segregate to grain boundaries and pore surfaces, On average, yttrium occupies 7.1% -9.0% of the available grain-boundary cation sites, whereas lanthanum occupies only 2.0%-5.2%, In 1000-ppm-yttrium-doped alumina, an abundan ce of yttrium aluminum garnet precipitates also is observed. Implicati ons of these observations to the creep behavior of alumina are discuss ed, The similarity in the segregation behavior of yttrium and lanthanu m highlights the potential of lanthanum-doped alumina for improved cre ep properties.