• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >Order and disorder in niobium tungsten oxides of the tetragonal tungsten bronze type
【24h】

Order and disorder in niobium tungsten oxides of the tetragonal tungsten bronze type

机译：四方钨青铜型铌钨氧化物的有序和无序

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

Two superstructures of the TTB type (tetragonal tungsten bronze) exist in the system Nb2O5/WO3 They are caused by an ordered arrangement of pentagonal tunnels filled with metal-oxygen strings. Besides the well known 4:9 phase (Nb8W9O47), which has a tripled b axis, evidence for a new orthorhombic structure, Nb6W8O39 (a = b = 27.3 Angstrom), has been found. The oxidation products of Nb7W10O47 and Nb4W13O47 frequently comprise less-ordered arrangements of filled tunnels, causing diffuse scattering. In Nb7W10O47.5 the electron diffraction patterns (along [011]) of many crystal fragments show circular diffuse scattering, which appears around the main reflections of the ?TB substructure with two distinct radii (r*). r* similar or equal to 0.33a* indicates the predominance of 4:9-type domains, whereas r* similar or equal to 0.41a* corresponds to Nb6W8O39. In Nb4W13O49 the diffuse scattering pattern is cross-shaped; this is due to the presence of long slabs of diamond-linked pentagonal columns. Structure models for these particular states of order have been derived from high-resolution transmission electron microscopy images. Some general principles for the formation of the different arrangements are deduced. Apparently, two distinct types of link between the filled pentagonal tunnels are important features which lead to the stability of these structures. [References: 26]
机译：Nb2O5 / WO3系统中存在两个TTB类型的上层建筑（四方钨青铜），这是由五边形隧道中有序排列的金属-氧气串构成的。除了众所周知的4：9相（Nb8W9O47）具有三倍的b轴外，还发现了新的正交结构Nb6W8O39（a = b = 27.3埃）的证据。 Nb7W10O47和Nb4W13O47的氧化产物通常包含填充隧道的无序排列，从而导致扩散散射。在Nb7W10O47.5中，许多晶体碎片的电子衍射图（沿[011]）显示出圆形的散射，出现在具有两个不同半径（r *）的TBTB亚结构的主反射周围。 r *相似或等于0.33a *表示4：9型域占优势，而r *相似或等于0.41a *对应于Nb6W8O39。在Nb4W13O49中，漫散射图案是十字形的。这是由于存在长的菱形连接的五边形柱板。这些特定的有序状态的结构模型已经从高分辨率透射电子显微镜图像中得出。推导了形成不同安排的一些一般原则。显然，填充的五边形隧道之间的两种不同类型的链接是重要特征，可导致这些结构的稳定性。 [参考：26]

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