Effect of damage on the etching and X-ray diffraction properties of zircon

Abstract

Abstract The etching time of zircons with different amount of radiation damage is measured by using the etching technique developed by Gleadow et al . (1976) 1 but at an etching temperature of 220°C. Zircons of track density ranging from ∼ 4.5 x 10 5 tracks/cm 2 to ∼ 1 x 10 12 tracks/cm 2 is used in the study. It is found that as track density increases, shorter etching time is needed to reveal the tracks. For example, as the track density increases from ∼ 4.5 x 10 5 tracks/cm 2 to ∼ 2.6 x 10 8 tracks/cm 2 , the etching time, when the tracks are fully developed, decreases from ∼ 60 hours to only ∼ 18 hours. The change in X-ray diffraction angle (2θ) of (112) plane for zircon with different amount of radiation damage is also studied. A correlation is found between diffraction angle and fission track density. For zircon with natural track density of ≲ 3 x 10 6 tracks/cm 2 , there seems to be an inverse relation between track density and 2θ values suggesting that as the degree of radiation damage of the crystal increase, more atoms are forced inti interstitial positions. However beyond the track density of ∼ 3 x 10 6 tracks/cm 2 , the change in 2θ with increasing track density is not as rapid as before, approaching a saturation value of 35.62°.