Recrystallization and structural recovery in α-decay damage in zircon samples have been studied using Raman spectroscopy. Fifteen zircon samples with different degrees of radiation damage have been thermally annealed between 600 K and 1800 K for up to 28 days and 8 hours. The experimental results from this study reveal that recrystallization in the damaged zircon samples is a multi-stage process that depends on the degree of initial damage of the samples. In partially damaged samples the lattice recovery of damaged crystalline ZrSiO 4 takes place at temperatures as low as about 700 K, as shown by a remarkable band-sharpening and a significant increase in the frequencies of ν 1 and ν 3 Si-O stretching vibrations together with the external band near 357 cm −1 with increasing temperature. A dramatic increase of Raman scattering intensity of ZrSiO 4 occurs in partially damaged samples near 1000 K due to a recrystallization process involving epitaxial growth. Heavily damaged samples tend to decompose into ZrO 2 and SiO 2 at high temperatures. Tetragonal ZrO 2 has been observed under annealing between 1125 K and about 1600 K in heavily damaged samples while monoclinic ZrO 2 appears above 1600 K. Weak signals from ZrSiO 4 were detected at 1125 K in highly metamict zircon although the main recrystallization appears to occur near 1500 K accompanied by a decrease of the volumes of ZrO 2 as well as SiO 2. This suggests that this recrystallization is associated with the reaction of ZrO 2 with SiO 2 to form ZrSiO 4. A possible intermediate phase has been observed, for the first time, by Raman spectroscopy in damaged zircons annealed at temperatures between 800 K and 1400 K. This phase is characterized by strong, broad Raman signals near 670, 798 and 1175 cm −1. Prolonged isothermal annealing at 1050 K results in a decrease of these characteristic bands and eventually the disappearance of this intermediate phase.

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