Diffusion Studies in Nonmetallic System. Part I.
Final rept. 1 May 70-30 Apr 74,
PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MATERIALS SCIENCE
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The rate of formation of NiAl2O4 by reaction between single crystals of NiO and Al2O3 is described. In NiO the behavior of the diffusion coefficient as a function of concentration supports the Lidiard theory of diffusion by impurity-vacancy pairs. The free energy of association for pairs was calculated. The interdiffusion coefficients in the spinel showed a constant small increase with the increase of the aluminum ions dissolved in the spinel. The mechanism of the interdiffusion in systems AO-B2O3 is discussed. The experimental data obtained on interdiffusion of B3 ions e.g. Cr3 and AL3 in an AO compound e.g. MgO and NiO implies that no association of defects occurs. This relationship was observed in systems Cr2O3-MgO and Cr2O3-NiO at temperatures higher than 1300C. From interdiffusion studies the activation energy of motion for B3 ions can be obtained.
- Solid State Physics