Investigation of Mn2+ diffusion in lime (CaO) using electron magnetic resonance

The electron magnetic resonance (EMR) technique was used to investigate the diffusion of Mn2+ in lime (CaO). The EMR absorption intensity was measured for several annealing times and three different temperatures of isothermal annealing: 1273, 1323 and 1373 K. The activation energy for diffusion, calculated from the experimental data using a theoretical model based on the Fick equation, was found to be E A = 266 ± 27 kJ. Mol- 1, about 30% larger than the activation energy for diffusion of Mn2+ in magnesia (MgO), a compound with the same crystal structure. The difference is attributed to the fact that the Ca2+ has a larger ionic radius than Mg2+.