生物活性玻璃颗粒/生物液体界面短期物理化学反应的STEM中的X射线显微分析。O/Si原子比的测定
X-ray microanalysis in STEM of short-term physico-chemical reactions at bioactive glass particles / biological fluids interface. Determination of O/Si atomic ratios
摘要：
研究了生物活性玻璃颗粒与生物体液界面的短期物理化学反应，重点研究了O/Si原子比的测量。所研究的生物活性玻璃为SiO_2-Na_2 O-CaO-P_2O_5-K_2 O-Al_2 O_3-MgO系统。通过与EDXS和EELS相关的STEM在亚微米尺度下进行元素分析。我们先前开发了一种基于比率方法并考虑局部吸收校正的EDXS定量方法。通过这种方式，我们使用EELS数据通过迭代过程来确定局部质量厚度，这是EDXS光谱中校正吸收的重要参数。在模拟生物溶液中浸泡生物活性玻璃颗粒的不同延迟之后，结果显示在生物活性玻璃外围形成不同的表面层。在浸没一天之前，我们观察到在外围已经显示的（Si，O，Al）富集层的存在。在本文中，我们证明了一个薄的电子致密的（Si，O）层上形成的（Si，O，Al）层。在这个（Si，O）层，贫铝，我们指出的氧重量浓度的增加，这可以解释的Si（OH）4基团的存在下，允许（Ca，P）层的形成。铝在玻璃溶解度中起作用，并且可以抑制磷灰石成核。在（Ca，P）层形成开始后，电子致密（Si，O）层的尺寸减小并趋于消失。浸泡两天后，（Ca，P）层的厚度增加，并导致磷灰石沉淀
英文摘要：
Short-term physico-chemical reactions at the interface between bioactive glass particles and biological fluids are studied and we focus our attention on the measurements of O/Si atomic ratio. The studied bioactive glass is in the SiO2-Na2O-CaO-P2O5-K2O-Al2O3-MgO system. The elemental analysis is performed at the submicrometer scale by STEM associated with EDXS and EELS. We previously developed an EDXS quantification method based on the ratio method and taking into account local absorption corrections. In this way, we use EELS data to determine, by an iterative process, the local mass thickness which is an essential parameter to correct absorption in EDXS spectra. After different delays of immersion of bioactive glass particles in a simulated biological solution, results show the formation of different surface layers at the bioactive glass periphery. Before one day of immersion, we observe the presence of an already shown (Si,O,Al) rich layer at the periphery. In this paper, we demonstrate that a thin electron dense (Si,O) layer is formed on top of the (Si,O,Al) layer. In this (Si,O) layer, depleted in aluminium, we point out an increase of oxygen weight concentration which can be interpreted by the presence of Si(OH)4 groups, that permit the formation of a (Ca,P) layer. Aluminium plays a role in the glass solubility and may inhibit apatite nucleation. After the beginning of the (Ca,P) layer formation, the size of the electron dense (Si,O) layer decreases and tends to disappear. After two days of immersion, the (Ca,P) layer grows in thickness and leads to apatite precipitation
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