Electron magnetic resonance investigation of gadolinium diffusion in zircon powders

The electron magnetic resonance (EMR) technique was used to investigate the diffusion of gadolinium in zircon (ZrSiO 4) powders. 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 =506±5 kJ mol −1. This value is close to the ones for the diffusion of Gd in UO 2 and CeO 2, but much larger than for the diffusion of gadolinium in a compound with the same crystal structure as zircon, YVO 4. This is attributed to a difference in the relative sizes of the ions involved in the diffusion process. ► EMR is an effective method to study solid state diffusion. ► Activation energy for diffusion of gadolinium in zirconium is 506±5 kJ mol −1. ► Different behavior of Gd 3+ in ZrSiO 4 and YVO 4 is attributed to the fact that Zr 4+ ions are smaller than Y 3+ ions.