Natural radiation-induced damage in quartz. I. Correlations between cathodoluminence colors and paramagnetic defects
Natural radiation-induced damage in quartz. I. Correlations between cathodoluminence colors and paramagnetic defects
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DOI：
10.2113/gscanmin.43.5.1565
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发表时间：
2005-10-01
影响因子：
0.9
通讯作者：
Sopuck, V
中科院分区：
文献类型：
--
作者：
Botis, S;Nokhrin, SM;Sopuck, V
萨斯喀彻温省阿萨巴斯卡盆地麦克阿瑟河铀矿床的石英颗粒具有三种不同类型的阴极发光（CL）特征：1)含铀和含钍矿物包裹体周围的晕状物，2)沿晶界和裂缝的斑状和3)连续边缘。这三种CL的宽度都在35 ~ 45 μ m之间，与α粒子的最大穿透深度一致，因此记录了α粒子引起的辐射损伤。相对于寄主颗粒，辐射损伤区在紫外（350 nm）和红光（620 ~ 650 nm）区域具有明显但较宽的CL波段。等时退火实验表明，紫外CL持续到500℃，但在600℃退火，而红色CL持续到至少800℃。电子顺磁共振（EPR）光谱，包括详细的饱和行为和热性能测量，发现六个顺磁缺陷：一个氧空位中心（E-1'），三个硅空位空穴中心[O-2(3-)/H+(I), O-2(3-)/H+(II)和O-2(3-)/M+]和两个O-2（-）过氧中心。光谱模拟证实了这些中心的存在。此外，经hf处理的样品的EPR谱显示，硅空孔中心和过氧中心集中在辐射损伤的边缘和断口。中心E-1′出现在整个石英晶粒中，并在500℃左右退火；因此，它不能对紫外线或红色CL负责。硅空孔中心全部在550 ~ 600℃之间退火，类似于紫外线CL的退火温度。过氧中心是唯一在600℃以上稳定的顺磁缺陷，对应于高温下辐射损伤区域的红色CL的保存。因此，硅空孔中心和过氧中心可能分别是石英中与辐射损伤的光晕、斑块和边缘相关的紫外和红色CL特征的原因。
Quartz grains from the McArthur River uranium deposit of the Athabasca Basin, Saskatchewan, are characterized by three distinct types of cathodoluminescence (CL): 1) halos surrounding U- and Th-bearing mineral inclusions, and 2) patches and 3) continuous rims along grain boundaries and fractures. These three types of CL have a constant width of similar to 35 to 45 mu m, consistent with the maximum depth of penetration of alpha particles, and therefore they record alpha-particle-induced radiation damage. Relative to the host grains, the radiation-damaged areas are characterized by pronounced but broad CL bands in the ultraviolet (similar to 350 nm) and red (similar to 620-650 nm) regions. Isochronal annealing experiments reveal that the ultraviolet CL persists to 500 degrees C but is annealed out at 600 degrees C, whereas the red CL persists to at least 800 degrees C. Electron paramagnetic resonance (EPR) spectroscopy, including detailed measurements on saturation behavior and thermal properties, revealed six paramagnetic defects: one oxygen vacancy center (E-1'), three silicon vacancy hole centers [O-2(3-)/H+(I), O-2(3-)/H+(II) and O-2(3-)/M+] and two O-2(-) peroxy centers. Spectral simulations confirm the presence of these centers. Moreover, EPR spectra of HF-treated samples show that the silicon vacancy-hole centers and the peroxy centers are concentrated in the radiation-damaged rims and fractures. Center E-1' appears to occur throughout the quartz grains and is annealed out at similar to 500 degrees C; it thus cannot be responsible for the ultraviolet or red CL. The silicon vacancy-hole centers are all annealed out between 550 degrees and 600C degrees, similar to the annealing temperature of the ultraviolet CL. The peroxy centers are the only paramagnetic defects stable above 600 degrees C, corresponding to the preservation of red CL in radiation-damaged areas at high temperatures. Therefore, the silicon vacancy-hole centers and the peroxy centers are probably responsible for the characteristic ultraviolet and red CL, respectively, associated with radiation-damaged halos, patches and rims in quartz.