分类： 物理学 >> 交叉学科物理及相关领域的科学与技术 分类： 材料科学 >> 陶瓷学 提交时间： 2024-03-20
摘要： 高放废物固化体的长期辐照稳定性是评价其深地质处置安全性的关键指标之一。本文利用 500 keV He2+离子束辐照 2M、 3O 和 4M 型钙钛锆石陶瓷固化体， 研究高放核素长期α 衰变辐照对陶瓷结构的损伤行为。三种钙钛锆石样品通过传统高温固相法（1400 ℃， 48h两次烧结）合成。掠入射 X 射线衍射（GIXRD） 、 Raman 光谱和 XPS 研究结果发现在 α 粒子辐照下， zirconolite-2M 固化体在辐照非晶化的过程中经历了 zirconolite-2M 到 zirconolite-4M 到 pyrochlore 的结构演变； zirconolite-3O 在 5×1015 ions/cm2 剂量下部分晶体结构转变为钙钛矿，在 1×1016 ions/cm2 以上剂量快速转变为无序烧绿石； zirconolite-4M 样品在 1×1017 ions/cm2 剂量时依旧保留 zirconolite-4M 主相，次生无序烧绿石/缺陷萤石晶相。综上， 从维持晶体结构稳定性来看 zirconolite-2M 和 zirconolite-3O 的抗 α 粒子辐照能力相似，略弱于zirconolite-4M 固化体。
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： A theoretical framework in the spherical polar coordinate system is developed to systematically treat the correlation between intensity fluctuations (CIF) of electromagnetic light waves on scattering from a collection of particles of $\mathcal{L}$ types. Two $\mathcal{L}\times \mathcal{L}$ matrices called pair-potential matrix (PPM) and pair-structure matrix (PSM) are introduced to jointly formulate the normalized CIF of the scattered field for the first time. We build a closed-form relation that associates the normalized CIF with the PPM and the PSM as well as the spectral degree of polarization $\mathcal{P}$ of the incident field, showing that the normalized CIF is closely related to the trace of the product of the PSM and the transpose of the PPM, and its dependence on $\mathcal{P}$ is completely determined by the scattering polar angle and azimuth angle. For a special case where the spatial distributions of scattering potentials of particles of different types are similar and the same is true of their density distributions, the PPM and the PSM will reduce to two new matrices whose elements separately quantify the degree of angular correlation of the scattering potentials of particles and their density distributions, and the number of species of particles in this special case appears as a scaled factor to ensure the normalization of the CIF. The effects of the off-diagonal elements of the PPM and the PSM on the normalized CIF and its dependence on $\mathcal{P}$ are illustrated by two numerical examples.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： A new approach is developed within the first-order Born approximation to light scattering from a collection of particles with $\mathcal{L}$ types. Two $\mathcal{L}\times\mathcal{L}$ matrices called pair-potential matrix (PPM) and pair-structure matrix (PSM) are introduced to jointly formulate the coherence properties of the scattered field. We derive a closed-form relation that associates the cross-spectral density function of the scattered field with the PPM and the PSM, showing that the the cross-spectral density function equals the trace of the product of the PSM and the transpose of the PPM. Based on this, the spectral degree of coherence (SDOC) of the scattered field is further analysed. We show that for a special case where the spatial distributions of scattering potentials of different types of particles are similar and the same is true of their density distributions, the PPM and the PSM will reduce to two new matrices whose elements separately quantify degree of angular correlation of the scattering potentials of particles and their density distributions, and the number of species of particles in this special case as a scaled factor ensures the normalization of the SDOC. Two special hybrid particulate systems as examples are given to illustrate the importance of our new approach.
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