Spontaneous and photo-induced crystallisation of photo-thermo-refractive glass
Spontaneous and photo-induced crystallisation of photo-thermo-refractive glass
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发表时间：
2007
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通讯作者：
J. Lumeau;A. Sinitskii;L. Glebova;L. Glebov
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作者：
J. Lumeau;A. Sinitskii;L. Glebova;L. Glebov
光热折射（PTR）玻璃是一种掺铈、银、氟和溴的钠锌铝硅酸盐玻璃，多年前由S。D. Stookey用于摄影，并在过去15年中被研究为全息图写入的可能候选人。PTR玻璃在紫外线暴露后表现出折射率变化，并且在Tg以上进一步热显影，这是由小于2wt%的氟化钠纳米晶体的结晶产生的。因此，这种玻璃和其产生的相位全息图是有吸引力的许多先进的应用，如光学过滤或光谱光束组合。在参考文献中给出了PTR玻璃中复杂的光热诱导结晶机制的描述。在紫外线曝光和未曝光区域精确控制PTR玻璃结晶需要深入了解其成核机制和动力学。本文采用非等温差示扫描量热法（DSC）和光学光谱相结合的方法研究了核化处理对PTR玻璃的影响。第一种方法是用来确定最佳的热处理，以增强光诱导成核和挫败（或至少减少）自发成核，即在未曝光的区域的样品结晶。第二种技术是用来试图获得更深入的了解PTR玻璃的成核机制。
Photo-thermo-refractive (PTR) glass is a sodium zinc aluminium silicate glass doped with cerium, silver, fluorine, and bromine, which was invented many years ago by S. D. Stookey for photography and has been studied as a possible candidate for hologram writing in the last 15 years. PTR glass exhibits refractive index changes after ultraviolet exposure and further thermal development above Tg resulting from the crystallisation of less than 2 wt% sodium fluoride nanocrystals. Therefore this glass and its resulting phase holograms are attractive for many advanced applications, such as optical filtering or spectral beam combining. A description of the complex photo-thermo-induced crystallisation mechanisms in PTR glass is given in reference. The precise control of PTR glass crystallisation in both ultraviolet exposed and unexposed areas require a deep knowledge of its nucleation mechanisms and kinetics. In this paper, we describe a study of the effect of nucleation treatment in PTR glasses by associating non-isothermal differential scanning calorimetry (DSC) and optical spectroscopy. The first method is used to determine the optimum thermal treatment to enhance photo-induced nucleation and frustrate (or at least decrease) spontaneous nucleation, i.e. crystallisation in unexposed regions of the specimen. The second technique is used in an attempt to gain a deeper insight into the nucleation mechanism in PTR glass.