发表机构
MARUM - Center for Marine Environmental Sciences, University of Bremen; Faculty of Geosciences, University of Bremen; ESRF, The European Synchrotron; MAPEX Center for Materials and Processes, University of Bremen（不来梅大学 MARUM 海洋环境科学中心; 不来梅大学地球科学学院; 欧洲同步辐射装置 ESRF; 不来梅大学 MAPEX 材料与工艺中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过单晶漫散射结合3D-ΔPDF、力场计算和蒙特卡洛模拟，揭示了天然透长石中K/Na短程有序驱动的关联骨架畸变，解释了蝴蝶结状漫散射的起源。
AI 中文摘要
天然透长石在环境条件下通常保留亚稳态化学无序，但由于仅依赖平均结构分析，与这种无序相关的局部结构相关性仍知之甚少。在此，我们研究了来自德国德拉亨费尔斯的一块天然透长石的单晶漫散射，并在来自德国拉赫湖和意大利维苏威的额外样品中观察到一致的结果。衍射数据揭示了显著的各向异性漫散射特征，包括倒空间中特征性的蝴蝶结状强度分布。为解析这些特征的起源，我们结合了三维差分对分布函数（3D-ΔPDF）分析、力场计算和蒙特卡洛模拟。3D-ΔPDF显示了与平均结构的关联偏差，并表明占据无序和位移无序之间存在强耦合。力场计算表明，铝硅酸盐骨架对局部碱金属占据有强烈响应，最大的结构变化沿a方向发生。在这些观察的指导下，我们构建了一个无序模型，其中K/Na占据短程有序与化学约束的Al/Si分布及局部骨架弛豫相结合。该模型再现了主要的实验漫散射特征，并表明蝴蝶结状漫散射源于主要由局部K/Na有序驱动的关联骨架畸变。
英文摘要
Natural sanidine commonly preserves metastable chemical disorder at ambient conditions, but the local structural correlations associated with this disorder remain poorly understood due to a reliance on average-structure analysis alone. Here, we investigate single-crystal diffuse scattering in a natural sanidine from Drachenfels, Germany, with consistent observations across additional samples from Laacher See, Germany, and Vesuvio, Italy. The diffraction data reveal pronounced anisotropic diffuse features, including characteristic bowtie-like intensity distributions in reciprocal space. To resolve the origin of these features, we combine three-dimensional difference pair distribution function (3D-$Δ$PDF) analysis with force-field calculations and Monte Carlo modelling. The 3D-$Δ$PDF shows correlated deviations from the average structure and indicates a strong coupling between occupational and displacive disorder. Force-field calculations demonstrate that the aluminosilicate framework responds strongly to the local alkali occupancy, with the largest structural variation occurring along the $a$ direction. Guided by these observations, we construct a disorder model in which K/Na occupational short-range order is combined with chemically constrained Al/Si distributions and local framework relaxations. The model reproduces the main experimental diffuse-scattering features and shows that the bowtie-like diffuse scattering arises from correlated framework distortions driven primarily by local K/Na order.
