ELECTRIC-FIELD-ENHANCED DIFFUSION OF DEUTERONS AND PROTONS IN ALPHA-AL2O3 CRYSTALS

Infrared-absorption measurements Were used to monitor diffusion of deu terons and protons in alpha-Al2O3 crystals. The threshold temperature for in-diffusion of deuterons was found to be similar to 1273 K and th e diffusion coefficient at 1323 K along the crystallographic axis was 8 x 10(-8) cm(2)/s. Below 1373 K the mechanism involves primarily repl acement of protons by deuterons. No OD- ions could be observed if no O H- ions were present in the virgin sample. The activation energy was s imilar to 5 eV. We demonstrate that the application of a moderate elec tric field has four effects. First, enhanced diffusion of deuterons ta kes place. Second, the threshold temperature lowers to 1200 K. Third, deuterons can be introduced without replacing protons; that is, OD- io ns can be formed in crystals with undetectable OH ions. Fourth, unlike purely thermal in-diffusion, the relative intensities of OD- (OH-) ba nds can be altered.