Electron spin resonance was used to investigate the diffusion of Cr3+ in powders. The electron spin resonance absorption intensity was measured for several annealing times and four different temperatures of isothermal annealing: 1223, 1273, 1323 and 1373K. The activation temperature for diffusion, calculated from the experimental data using a theoretical model based on the Fick equation, was found to be 212kJ/mol. This result was about 30% smaller than similar data obtained for single-crystal MgO using the radioactive-tracer sectioning technique. The difference was attributed to a higher concentration of defects in the powder relative to single crystals.

ESR Investigation of Cr3+ Diffusion in MgO Powders. R.S.de Biasi, M.L.N.Grillo: Solid State Communications, 2004, 132[2], 107-8