• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Structures and optical properties of tellurite glasses and glass ceramics.
【24h】

Structures and optical properties of tellurite glasses and glass ceramics.

机译：碲酸盐玻璃和玻璃陶瓷的结构和光学性能。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The structures and optical properties of (K2O)15(Nb 2O5)15(TeO2)70 glass and glass ceramic have been studied in order to understand the second harmonic generation observed from the glass ceramic. We have used 93Nb NMR, Raman spectroscopy, differential scanning calorimetry, small angle x-ray scattering, transmission electron microscopy, and powder x-ray and neutron scattering. We find that there is a microstructure consistent with binodal phase separation leading to spherical inclusions ∼20 nm in size. Upon heat treatment, these domains become nanocrystals of K2Te 4O9. A theory of optical heterogeneity is used to describe the observed second harmonic generation which is ∼95 times more intense that quartz. The chi(2) value for this material is 3.0 x 10-9 esu.; A second project has used 125Te and 17O NMR to study alkali tellurite glasses in the system (M2O) x(TeO2)10-x, where M = Li, Na or K and x = 1, 2 or 3. The 125Te results show that complex models of network modification are needed to explain the resulting spectra that include a distribution of polyhedral tellurite units at all compositions. The 17O results show that there is a clear distinction between bridging and non-bridging oxygen sites in tellurite crystals and that sophisticated NMR experiments should be able to distinguish them in the glasses. Further, we have used Extended Huckel theory tight-binding calculations to predict the 17O NMR shifts of SiO2, GeO 2 and TeO2. We find that these calculations allow accurate predictions of the chemical shifts based solely on the trend in valence orbital size, and that expensive calculations of electron currents need not be used for this application.
机译：研究了（K2O）15（Nb 2O5）15（TeO2）70玻璃和玻璃陶瓷的结构和光学性质，以了解从玻璃陶瓷中观察到的二次谐波的产生。我们使用了93Nb NMR，拉曼光谱，差示扫描量热法，小角X射线散射，透射电子显微镜以及粉末X射线和中子散射。我们发现，存在一个与二面体相分离相一致的微观结构，从而导致了球形夹杂物的大小约为20 nm。热处理后，这些畴变为K2Te 4O9的纳米晶体。光学异质性理论用于描述观测到的二次谐波，其强度比石英高约95倍。该材料的chi（2）值为3.0 x 10-9 esu。第二个项目使用125Te和17O NMR研究系统（M2O）x（TeO2）10-x中的碱金属碲酸盐玻璃，其中M = Li，Na或K，x = 1，2或3。125Te结果表明：需要使用复杂的网络修改模型来解释所得的光谱，其中包括所有成分的多面体亚碲酸盐单元的分布。 17O结果表明，在亚碲酸盐晶体中的桥接和非桥接氧位之间有明显的区别，复杂的NMR实验应该能够在玻璃中区分它们。此外，我们已经使用扩展Huckel理论紧密结合计算来预测SiO2，GeO 2和TeO2的17O NMR位移。我们发现这些计算仅基于化合价轨道尺寸的趋势就可以准确预测化学位移，并且不需要为此应用使用昂贵的电子流计算。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号