Abstract Lead (Pb) as a traditional shielding material is limited due to its toxicity and heaviness. Recently, nanomaterials in different forms have attracted considerable attention for radiation shielding applications, due to their prominent chemical and physical properties. This work aims to evaluate the effects of size and morphology on the X-ray shielding performance. Both micro- and nano-sized Bi2O3 films with different morphologies (e.g. particles, wires, flowers) were synthesized via a ball milling process and a hydrothermal treatment, respectively. X-ray transmission tests were conducted using a superficial X-ray unit at energies of 30, 50 and 80 kVp (effective energies converted as 14, 24 and 29 keV), which were then compared with mass attenuation coefficient of Bi2O3 obtained from XCOM database. The results showed that the nanoflower (388 ± 30 nm) Bi2O3 film gave the best X-ray shielding performance among all three energies (60.49 % improvement at 30 kVp, especially) compared to the bulk Bi2O3 film, indicating the synergy effects of both particle size and morphologies impact on low energies of X-ray attenuation. Moreover, the nanoparticle (830 ± 30 nm) Bi2O3 film enhanced the X-ray attenuation, up to 13.27 % at 30 kVp relative to microparticle (1.21 ± 0.14 μ m) films. However, the nanoflower (388 ± 30 nm) Bi2O3 film gave the best X-ray shielding performance (45.93 % and 47.49 % improvement at 30 kVp, respectively) compared to the microwire (1.30 ± 0.13 μ m) and nanoparticle (830 ± 30 nm) Bi2O3 film, due to its large surface-to-volume ratio, showing that morphological variations can significantly impact the X-ray transmission to enhance the radiation shielding performance compared to the particle size. Theoretical data from XCOM database compared with experimental measurements showed the limitation of simulation as it can only calculate the ideal condition of regular distributions in materials with standardized geometry. This work concluded that the synergy effect of the particle size and morphology should be considered when designing effective radioprotective garments.

中文翻译：

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用于 X 射线屏蔽的氧化铋薄膜：粒度和结构形态的影响

摘要 铅（Pb）作为一种传统的屏蔽材料，由于其毒性和重量而受到限制。最近，不同形式的纳米材料由于其突出的化学和物理特性而在辐射屏蔽应用中引起了相当大的关注。这项工作旨在评估尺寸和形态对 X 射线屏蔽性能的影响。分别通过球磨工艺和水热处理合成了具有不同形态（例如颗粒、线、花）的微米和纳米尺寸的 Bi2O3 薄膜。使用表面X射线单元在30、50和80 kVp（有效能量转换为14、24和29 keV）下进行X射线透射测试，然后与从XCOM数据库获得的Bi2O3的质量衰减系数进行比较. 结果表明，与块状 Bi2O3 薄膜相比，纳米花 (388±30 nm) Bi2O3 薄膜在所有三种能量中提供了最好的 X 射线屏蔽性能（尤其是在 30 kVp 下提高了 60.49%），表明这两种颗粒的协同效应尺寸和形态对 X 射线衰减的低能量有影响。此外，纳米颗粒 (830 ± 30 nm) Bi2O3 薄膜增强了 X 射线衰减，相对于微粒 (1.21 ± 0.14 μ m) 薄膜，在 30 kVp 时高达 13.27%。然而，与微丝（1.30 ± 0.13 μ m）和纳米颗粒（830 ± 30 nm) Bi2O3 薄膜，由于其较大的表面积与体积比，表明与颗粒尺寸相比，形态变化可以显着影响 X 射线透射，从而增强辐射屏蔽性能。来自 XCOM 数据库的理论数据与实验测量结果相比，显示了模拟的局限性，因为它只能计算具有标准化几何形状的材料中规则分布的理想条件。这项工作得出的结论是，在设计有效的辐射防护服时，应考虑颗粒大小和形态的协同效应。