锗酸盐玻璃的稀土增强机理及其强场辅助纳米微晶化调控

Germanate glass has a very good prospect in the application field of infrared optical for its high transmittance in the 0.3-5.0um band. However, this engineering application is limited by the low mechanical strength of germanate glass. The results in our preliminary study shows that the bend strength of germanate glass strengthened significantly by doping of Y2O3. The present work researches this phenomenon theoretically. To obtain the strengthen mechanism of rare earth oxides on germanate glass, the local structure including the short-range and the medium-range structure of Y2O3 doped germanate glass will be investigated by means of NMR、EXAFS and XPS. In addition, the behavior and the mechanism of crystallization under the alternating strong field auxiliary heat treatment conditions will be researched according to the crystallization kinetics. The influences of the microstructure on the bending strength and the optical transmittance will be investigated in order to prepare the highly crystallized transparent germanate glass-ceramics with improved mechanical properties. The aim of the project is to solve the key technical problems in the preparation of the transparent strengthened glass-ceramics, which is to provide not only the key parameters for the development of new high-strength glass material in the composition design and the crystallization process, but also the technical reserves for the development of a new infrared optical window material.

锗酸盐玻璃由于在0.3-5.0um 波段具有高的光学透过率而在红外光学领域具有非常广阔的应用前景，然而低的机械强度是限制其工程化的瓶颈。本项目针对前期研究过程中发现的稀土氧化钇显著提高锗酸盐玻璃抗弯强度的现象进行基础理论研究，从玻璃的近程结构与中程结构入手、利用NMR、EXAFS、XPS等解析稀土掺杂锗酸盐玻璃的局域结构，探讨稀土离子显著增强锗酸盐玻璃的机理；并从析晶动力学角度出发，开展锗酸盐玻璃在交变强场辅助热处理条件下的受控晶化行为和析晶机理研究，探讨锗酸盐微晶玻璃显微结构对抗弯强度与光学透过率的影响，以期获得微晶尺寸为纳米级的高析晶度的透明高强度稀土掺杂锗酸盐微晶玻璃。本项目可解决高强度、高光学透过率锗酸盐微晶玻璃制备过程中的关键技术问题，不仅为开发新型高强度玻璃材料在组成设计和微晶化工艺研究上提供关键参数，也为发展新型红外光学窗口材料提供一定技术储备。

本课题以锗酸盐玻璃为研究对象，对锗酸盐玻璃的组成体系与配方调整做了大量研究，发现了稀土氧化钇显著增强锗酸盐玻璃抗弯强度的有趣现象，并对该现象的内在机理做了较深入的探讨，研究表明钇离子能够参与锗酸盐玻璃网络的形成，在锗酸盐玻璃结构中主要以[YO4]-基元形式存在；氧化钇加入至锗酸盐玻璃中后使得锗酸盐玻璃中非桥氧数量减少，从而提供给氢原子形成羟基的几率大大降低，降低了玻璃中羟基含量，而桥氧比例的增加则完善了玻璃的网络结构，提高了玻璃的性能；同时发现锗酸盐玻璃结构中铝离子的存在形式有四配位、五配位及六配位，氧化钇的加入有利于促进锗酸盐玻璃中铝离子由五配位及六配位向四配位转变，提高结构中[AlO4]的比例，使得锗酸盐玻璃的结构更加稳定。在锗酸盐微晶玻璃的制备方面，研究表明氧化钇能够提高锗酸盐玻璃的转变温度，降低其析晶开始温度与析晶峰值温度，促进锗酸盐微晶玻璃的析晶；析晶动力学表明，9.30 wt%的氧化钇能够使得锗酸盐玻璃的析晶活化能从305 KJ/mol降低至285 KJ/mol；课题着重探讨了交变场强辅助热处理条件下锗酸盐微晶玻璃的析晶行为和结构演变。采用交变电场辅助热处理工艺对锗酸盐玻璃进行微晶化处理，当施加电压为6000 V时，能够在一定程度上促进锗酸盐微晶玻璃中微晶体的长大，该工艺经进一步改进后有望在各体系微晶玻璃中推广使用，有望成为对微晶玻璃微观结构与宏观性能实现精确调控与剪裁的新方法。