YTTRIUM DIFFUSION IN ALPHA-ALUMINA SINGLE-CRYSTAL

Yttrium bulk diffusion in single crystals of alpha-alumina is investig ated by the SIMS technique, in the temperature range 1150-1500 degrees C. The bulk diffusion coefficients obey the relation: D(Y) (1150-1500 degrees C) = 1.2 10(-10) exp (-295 (kJ mol(-1))/RT) (m(2) s(-1)). The se values are close to those of chromium diffusion in alumina, althoug h the size of Y3+ ion is significantly higher than that of Cr3+ ion. T he results are used to calculate the parameters of yttrium grain bound ary diffusion in alumina, from the penetration profiles obtained in a previous work in polycrystals by the radiotracer technique. (C) 1998 E lsevier Science Limited. All rights reserved.