Measurement of iron self-diffusion in hematite single crystals by sims and comparison of cation self-diffusion in corundum-structure oxides.

Abstract

Iron bulk self-diffusion coefficients were measured in Fe2O3 single crystals using an original methodology based on the utilization of 57Fe stable isotope as iron tracer, and depth profiling by secondary ion mass spectrometry (SIMS). The iron self-diffusion coefficients were measured along and perpendicular to c-axis direction, between 900 and 1100o C, in oxygen atmosphere. Along caxis they can be described by D//c (cm2/s)= 5.2x106 exp [-510 (kJ/mol)/RT], and are close to reliable data available in the literature, obtained by means of radioactive techniques. Perpendicular to c-axis, D⊥c (cm2/s)= 83 exp [-430 (kJ/mol)/RT], and the coefficients are smaller than coefficients along caxis. The results are compared with previously obtained results of cation bulk self-diffusion in Cr2O3 and in Al2O3 single crystals.