A series of experiments on monazites from Victoria, Australia, is presented to further understand their fission track etching properties. Using a 6 M HCl etchant at 90 °C, SEM images on crystal (100) pinacoid faces reveal well-etched rhombic spontaneous fission track openings. Average rhombic etch pit diameters Dpc and Dpb, parallel to the crystallographic c- and b-axes are 0.81 ± 0.20 µm and 0.73 ± 0.26 µm, respectively. An angular distribution experiment on (100) faces found that spontaneous fission tracks initially etch anisotropically, being preferentially revealed at an azimuth of 90° to the crystallographic c-axis up to ~60 min of etching. As etching continues, however, the distribution becomes progressively more uniform and is essentially isotropic by 90 min. Two experimental methods determined the rate at which the etchant penetrated along the lengths of implanted 252Cf fission tracks. This involved the application of a focused ion beam scanning electron microscope (FIB-SEM) to mill progressively into slightly etched monazite crystals followed by an etch-anneal-etch approach. Results indicate that at least the greater part of the etchable ranges of the latent fission tracks were penetrated by the 6 M HCl etchant within the first few minutes. Continued etching to 5 min indicates that track etching slows down toward the ends of the tracks, but the maximum ranges are estimated to be reached after 5–15 min, which represents the longest time the latent segments of the tracks are exposed to potential annealing at the etchant temperature. Taking into account that implanted 252Cf fission tracks in monazite anneal on average ~4% of their length at 90 °C after 1 h (Jones et al. 2019), suggests that a much shorter duration for exposure to this temperature causes less than ~1% of fission track length reduction during etching.

中文翻译：

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独居石裂变轨道的蚀刻：来自光学和聚焦离子束扫描电子显微镜的进一步证据

对来自澳大利亚维多利亚的独居石进行了一系列实验，以进一步了解它们的裂变轨迹蚀刻特性。在 90 °C 下使用 6 M HCl 蚀刻剂，晶体 (100) pinacoid 面上的 SEM 图像显示蚀刻良好的菱形自发裂变轨道开口。平行于晶体 c 轴和 b 轴的平均菱形蚀刻坑直径 Dpc 和 Dpb 分别为 0.81 ± 0.20 µm 和 0.73 ± 0.26 µm。在 (100) 面上进行的角分布实验发现，自发裂变轨迹最初以各向异性方式蚀刻，在与晶体 c 轴成 90° 的方位角处优先显示，直至蚀刻约 60 分钟。然而，随着蚀刻的继续，分布变得越来越均匀，并且在 90 分钟内基本上是各向同性的。两种实验方法确定了蚀刻剂沿注入的 252Cf 裂变轨道的长度渗透的速率。这涉及应用聚焦离子束扫描电子显微镜 (FIB-SEM) 逐步研磨成轻微蚀刻的独居石晶体，然后采用蚀刻-退火-蚀刻方法。结果表明，在最初的几分钟内，至少大部分潜在裂变轨道的可蚀刻范围被 6 M HCl 蚀刻剂穿透。继续蚀刻到 5 分钟表明轨道蚀刻向轨道末端减慢，但估计在 5-15 分钟后达到最大范围，这代表轨道的潜在段暴露于潜在退火的最长时间蚀刻剂温度。