X-ray diffraction study of NaF nano-crystals in photo-thermo-refractive glass
X-ray diffraction study of NaF nano-crystals in photo-thermo-refractive glass
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DOI：
10.1016/j.jnoncrysol.2014.09.019
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发表时间：
2014-12-01
影响因子：
3.5
通讯作者：
Glebov, Leonid B.
中科院分区：
文献类型：
--
作者：
Lumeau, Julien;Chamma, Karima;Glebov, Leonid B.
PTR玻璃是一种光敏硅酸盐玻璃，它在紫外线照射和热显影后产生折射率变化。光敏性的来源可以用NaF晶体在玻璃基体内的析出来解释。虽然在FIR玻璃中NaF的成核已经得到了深入的研究，但NaF晶体的生长机制却引起了有限的兴趣。为了研究NaF的生长，采用了多种技术：光谱学、干涉测量、DSC和XRD。通过衍射线的展宽，发现在紫外照射的FIR玻璃中，NaF晶体的尺寸不超过类似于20 nm。NaF晶体的生长受到玻璃基体内Na+F-的耗尽以及晶体周围玻璃粘度的增加的限制，后者作为进一步生长的动力学屏障。通过对NaF粉末的x射线衍射分析，可以计算出晶体的体积分数和平均尺寸。这些参数与瑞利散射模型相结合，可以预测任何波长和任何热处理的散射，证明了散射是由单晶决定的。(C) 2014 Elsevier B.V.版权所有
PTR glass is a photosensitive silicate glass which imparts refractive index change after UV-exposure and thermal development. The origin of photosensitivity is explained by the precipitation of NaF crystals inside the glass matrix. While nucleation of NaF in FIR glass has been thoroughly studied, the mechanisms of growth of NaF crystals have drawn a limited interest. To study the NaF growth, several techniques were combined: optical spectroscopy, interferometry, DSC and XRD. It was found that the size of NaF crystals in UV-exposed FIR glass, as determined by the broadening of the diffraction lines does not exceed similar to 20 nm. The NaF crystals' growth is limited by the exhaustion of Na+F- within the glass matrix as well as the increase of the viscosity of the glass surrounding the crystals that act as a kinetics barrier for further growth. X-ray diffraction analysis of NaF powder allowed calculating the crystals' volume fraction and their average size. A combination of these parameters with Rayleigh scattering model allowed the prediction of scattering at any wavelength and any thermal treatment, proving that scattering is determined by single crystals. (C) 2014 Elsevier B.V. All rights reserved.