Original paper
Radiation damage in zircons
Biagini, R.; Memmi, I.; Olmi, F.
Neues Jahrbuch für Mineralogie - Monatshefte Jg. 1997 Heft 6 (1997), p. 257 - 270
22 references
published: May 27, 1997
DOI: 10.1127/njmm/1997/1997/257
ArtNo. ESP156199706001, Price: 29.00 €
Abstract
Metamictization effects have been investigated in zircons having different uranium and thorium contents and different degrees of metamictization. U and Th contents range from 57 to 2890 ppm and from 27 to 420 ppm, respectively. Parallel to the U and Th increase, density decreases from 4.80 to 4.10 (g/cm³) and change in X-ray powder diffraction are noticed. Powder diffraction maxima decrease in intensity, shift to lower 2Θ values, broaden and become asymmetrical with the increment of diffuse-scattering component. Unit cell parameters systematically increase (a = 6.60-6.68 Å, c = 5.97-6.11 Å, V = 260-272 ų) The powder IR spectra show similar variations as X-ray diffraction patterns. There are only minor differences in the two sequences. On the other hand, powder X-ray diffraction patterns and IR spectra give different results during annealing: after heating at 950°C, X-ray diffraction patterns become sharp and well resolved and display a nearly complete structural recovery; IR spectra show that the recovery in the structure in the two metamict zircons is significant, but seems incomplete if compared with the more crystalline samples.
Keywords
Zircon • radiation damage • metamictization processes • high level waste storage