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X-ray scattering study of water confined in bioactive glasses: experimental and simulated pair distribution function.
Acta Crystallographica Section A: Foundations and Advances ( IF 1.9 ) Pub Date : 2020-07-20 , DOI: 10.1107/s2053273320007834
Hassan Khoder 1 , Dominik Schaniel 1 , Sébastien Pillet 1 , El Eulmi Bendeif 1
Affiliation  

Temperature‐dependent total X‐ray scattering measurements for water confined in bioactive glass samples with 5.9 nm pore diameter have been performed. Based on these experimental data, simulations were carried out using the Empirical Potential Structure Refinement (EPSR) code, in order to study the structural organization of the confined water in detail. The results indicate a non‐homogeneous structure for water inside the pore, with three different structural organizations of water, depending on the distance from the pore surface: (i) a first layer (4 Å) of interfacial pore water that forms a strong chemical bond with the substrate, (ii) intermediate pore water forming a second layer (4–11 Å) on top of the interfacial pore water, (iii) bulk‐like pore water in the centre of the pores. Analysis of the simulated site–site partial pair distribution function shows that the water–silica (Ow–Si) pair correlations occur at ∼3.75 Å. The tetrahedral network of bulk water with oxygen–oxygen (Ow–Ow) hydrogen‐bonded pair correlations at ∼2.8, ∼4.1 and ∼4.5 Å is strongly distorted for the interfacial pore water while the second neighbour pair correlations are observed at ∼4.0 and ∼4.9 Å. For the interfacial pore water, an additional Ow–Ow pair correlation appears at ∼3.3 Å, which is likely caused by distortions due to the interactions of the water molecules with the silica at the pore surface.

中文翻译:

生物活性玻璃中水的X射线散射研究:实验和模拟对分布函数。

对受限于孔径为5.9 nm的生物活性玻璃样品中的水进行了随温度变化的总X射线散射测量。基于这些实验数据,使用经验势结构细化EPSR)进行了模拟)代码,以详细研究承压水的结构组织。结果表明,孔内水的结构不均匀,具有三种不同的水结构结构,具体取决于距孔表面的距离:(i)界面孔隙水的第一层(4Å),形成了强化学物质(ii)中间孔隙水在界面孔隙水的顶部形成第二层(4-11Å),(iii)孔隙中心的块状孔隙水。对模拟的站点-站点部分对分布函数的分析表明,水-二氧化硅(O w -Si)对的相关发生在〜3.75Å处。散装水与氧气-氧气的四面体网络(O w –O w)界面孔隙水在〜2.8,〜4.1和〜4.5Å处的氢键对相关性严重扭曲,而在〜4.0和4.9Å处观察到第二个相邻对相关性。对于界面孔隙水,在〜3.3Å处出现了一个额外的O w -O w对相关性,这很可能是由于水分子与孔隙表面二氧化硅的相互作用而引起的畸变引起的。
更新日期:2020-09-01
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