Synchrotron Pair Distribution Function analyses of Ye'elimite-based pastes

Raw data for: Synchrotron pair distribution function analyses of ye'elimite-based pastes

doi: https://doi.org/10.1680/jadcr.18.00097

The study of nanocrystalline phase atomic ordering is intrinsically complicated. The presence of additional crystalline phase(s) exacerbates this challenge. Here, we use the synchrotron pair distribution function (PDF) to characterize the local atomic order of the nanocrystalline phases in ye’elimite unaltered pastes. Here, a multi r-range analysis approach has been used, where the 30–50 Å r-range allows determining the crystalline phase contents and the 1.6-35 Å is used to characterize the atomic ordering in the nanocrystalline components. Quantitative phase contents have been also derived from these analyses. Specifically, we have prepared five stoichiometric ye’elimite pastes with variable anhydrite and water contents. For the pastes without anhydrite addition, ettringite was not present and two calcium aluminium monosulfate phases were required for good PDF fits. In addition to crystalline AFm (c »28.6 Å), a nanocrystalline AFm phase with a significantly smaller c-unit cell parameter value, c »26.8 Å, was required having about 60 Å of particle size. For a paste obtained with 31 wt% of anhydrite addition, the main crystalline phase was ettringite with the aluminium hydroxide having nano-gibbsite local structure with a quite small average particle size, »35 Å.

数据集原始数据：硫铝酸钙（ye'elimite）基浆体的同步辐射对分布函数（Pair Distribution Function, PDF）分析
doi: https://doi.org/10.1680/jadcr.18.00097

纳米晶相原子有序性的研究本质上极具复杂性，额外晶相的存在会进一步加剧这一研究难点。本研究采用同步辐射对分布函数（Pair Distribution Function, PDF），对未改性硫铝酸钙基浆体中的纳米晶相局部原子有序性进行表征。本次研究采用多r范围分析方法：其中30–50 Å的r范围用于确定晶相组成，而1.6–35 Å的r范围则用于表征纳米晶组分的原子有序性。通过上述分析还可得到定量的晶相含量结果。

具体而言，本研究制备了五组具有不同硬石膏与水掺量的化学计量比硫铝酸钙基浆体。对于未添加硬石膏的浆体体系，未检测到钙矾石（ettringite），且需采用两种单硫型铝酸钙相才能实现良好的PDF拟合效果。除晶胞参数c≈28.6 Å的晶态AFm相（Aluminum Ferrite Monosulfate, AFm）之外，还需引入一种晶胞参数显著更小的纳米晶AFm相，其晶胞参数c≈26.8 Å，平均粒径约为60 Å。对于掺加31 wt%硬石膏的浆体，其主要晶相为钙矾石（ettringite），同时体系中存在具有纳米三水铝石（gibbsite）局部结构的氢氧化铝相，该相平均粒径极小，约为35 Å。