Intergranular glassy films: An overview
Intergranular glassy films: An overview
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DOI：
10.1016/j.msea.2006.01.004
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发表时间：
2006-04
期刊：
影响因子：
6.4
通讯作者：
A. Subramaniam;C. Koch;R. M. Cannon;M. Rühle
中科院分区：
文献类型：
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作者：
A. Subramaniam;C. Koch;R. M. Cannon;M. Rühle
在某些陶瓷如Si 3 N4、SiC、SrTiO 3、Al 2 O3等中，晶界（GB）区可以具有约1-2nm厚的非晶膜。这些晶间玻璃膜（IGFs）的特点是由一个几乎恒定的厚度，这是基本上是独立的边界晶粒的取向，但取决于陶瓷的组成。IGF对结晶有抗性，并且被认为代表平衡构型。IGF的存在，沿着其结构，在决定陶瓷整体性能方面起着重要作用。在这些特性中，重要的是断裂、蠕变、氧化和电气行为，请记住基于系统的特性。根据体系的不同，可以采用液相烧结、固态活化烧结、晶体周围玻璃的结晶化等多种合成途径，导致了IGFs的形成。还合成了平衡厚度的表面非晶膜，其被认为是IGFs的表面类似物。显微镜技术的重要进展为IGFs的结构及其与晶体的界面提供了沿着宝贵的见解。这些技术包括：高分辨率显微镜、菲涅耳对比度成像、漫射暗场成像、衍射分析、电子全息术、高角度环形暗场成像、能量色散X射线分析和电子能量损失光谱学。现在逐渐认识到IGF内的组成和结构是分级的，即，它具有与边界晶体的扩散界面，并且IGF中的非晶材料不同于在该系统中形成的块状玻璃。由IGF上的结合晶体诱导的顺序被视为渐变的贡献因素。尽管取得的成就，很多开放的问题仍然存在关于IGFs的形成，其行为与温度，其依赖于晶体学的边界晶粒，等这一概述的目的是介绍IGFs的非专业观众，总结了该领域的重要进展，并概述了悬而未决的问题。
In certain ceramics like Si3N4, SiC, SrTiO3, Al2O3, etc., the grain boundary (GB) region can have an amorphous film of about 1–2nm thickness. These intergranular glassy films (IGFs) are characterized by a nearly constant thickness which is basically independent of the orientation of the bounding grains, but is dependent on the composition of the ceramic. The IGF is resistant to crystallization and is thought to represent an equilibrium configuration. The presence of the IGF, along with its structure, plays an important role in determining the properties of the ceramic as a whole. Important amongst these properties, keeping in mind the system based specificities, are fracture, creep, oxidation and electrical behaviour. Depending on the system, various synthetic routes like liquid phase sintering, solid-state activated sintering, crystallization of glass surrounding the crystal, etc., have led to the formation of IGFs. Equilibrium thickness amorphous films on surfaces have also been synthesized which are considered to be the surface analogue of IGFs. Important advances in the microscopy techniques have provided invaluable insights into the structure of IGFs, along with its interface with the bounding crystals. These techniques include: high-resolution microscopy, Fresnel contrast imaging, diffuse dark field imaging, diffraction analysis, electron holography, high-angle annular dark field imaging, energy-dispersive X-ray analysis and electron energy loss spectroscopy. It is now being progressively realized that the composition and structure within the IGF is graded, i.e., it has a diffuse interface with the bounding crystals and that the amorphous material in the IGF is different from the bulk glass forming in that system. The order induced by the bounding crystals on the IGF is seen as a contributing factor to the gradation. In spite of the achievements, a lot of open questions remain regarding the formation of IGFs, its behaviour with temperature, its dependence on crystallography of the bounding grains, etc. This overview aims at introducing IGFs to a non-specialist audience, summarizing the important advances in the field and outlining the outstanding issues.