Measurement of iron self-diffusion in hematite single crystals by secondary ion-mass spectrometry (SIMS) and comparison with cation self-diffusion in corundum-structure oxides

• Published in: Philosophical magazine (Abingdon, England) England), 2005-11, Vol.85 (31), p.3643-3658
• Main Authors: Sabioni, A. C. S., Huntz, A. M., Daniel, A. M. J. M., Macedo, W. A. A.
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Material chemistry; Materials science; Physics
• ISSN: 1478-6435; 1478-6443; 1478-6433
• DOI: 10.1080/14786430500323795

Iron bulk self-diffusion coefficients were measured in Fe 2 O 3 single crystals using original methodology based on the utilization of 57 Fe 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 the c-axis, between 900 and 1100°C, in an oxygen atmosphere. Along the c-axis, the coefficients can be described by D ∥ c (cm 2 /s) = 5.2 × 10 6  exp[−510 (kJ/mol)/RT], and are close to reliable data, available in the literature, obtained by means of radioactive techniques. Perpendicular to the c-axis, D ⊥c (cm 2 /s) =  83 exp[−430 (kJ/mol)/RT], and the coefficients are smaller than coefficients along the c-axis. The data are compared with previously results of cation bulk self-diffusion in Cr 2 O 3 and Al 2 O 3 single crystals.